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PHARMACOLOGY

Author: Alene Burke RN, MSN
16 Contact Hours

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DESCRIPTION:

Pharmacology is the study of medications and how they work on the body. A thorough and current knowledge of all medications that are given enables us to safely administer them as well as to effectively monitor and assess the patient and their responses to them. This course covers all the required content for a pharmacology disciplinary course in the state of Florida and other states.

This course covers numerous medication classifications, their actions, uses, precautions, contraindications, interactions, side effects, adverse drug reactions and implications. The content also includes the various routes and forms of medication, some route and form considerations, how to accurately compute dosages and solutions using dimensional analysis and ratio & proportion, some age specific considerations, such as caution with the elderly, which must be taken when medications are given, acceptable and nonacceptable pharmacological abbreviations and pharmacology resources.

OBJECTIVES:

1. Detail numerous medication classifications in terms of the actions, uses, precautions, contraindications, interactions, side effects, adverse drug reactions and implications for the medications within the classification.
2. Describe the various routes and forms of medication as well as some route and form considerations.
3. Accurately compute dosages and solutions using dimensional analysis and ratio & proportion.
4. Relate some age specific considerations, such as caution with the elderly, which must be taken when medications are given.
5. List various acceptable and nonacceptable pharmacological abbreviations.
6. Utilize pharmacology resources.

INTRODUCTION

Pharmacology is the study of medications and how they work on the body. A thorough and current knowledge of all medications that are given enables us to safely administer them as well as to effectively monitor and assess the patient and their responses to them.

ROUTES AND FORMS OF MEDICATION

Medications are manufactured in different forms and for a specific route of administration. Some medications come in more than one form and some can also be administered via more than one route, provided the correct form of that medication is used.

Complete medication orders specify the route of administration and some may also contain the form that the patient should get.

COMPLETE MEDICATION ORDERS

A doctor or another licensed independent practitioner, such as a nurse practitioner, must write a complete and legible order for a medication before it is administered.

Minimally, a complete medication order must contain the:

• date and the time of the order,
• name of the medication,
• dosage,
• route of administration,
• time or frequency of administration,
• physician or licensed independent practitioner's signature.

All incomplete and/or illegible orders must be questioned with the ordering person before they are administered. The person administering the medication is accountable and responsible for all of the medications that they give.

FORMS OF MEDICATION

Medications come in the following forms:

• tablets
• capsules (regular and sustained release)
• elixirs
• suppositories
• oral suspensions
• syrups
• tinctures
• ointments
• pastes
• creams
• drops (eye)
• IV suspensions and solutions
• metered dose inhalers

MEDICATION ADMINISTRATION ROUTES

The routes of administration include:

• oral
• buccal
• sublingual
• topical
• ophthalmic
• otic
• vaginal
• rectal
• nasal
• via a nasogastric or gastrostomy tube
• inhalation
• subcutaneous
• intramuscular
• intradermal
• transdermal
• intravenous
• intrathecal
• intracardial
• intra-articular

ROUTE AND FORM CONSIDERATIONS

The oral route of administration is the preferred route of administration for children. When a patient has a swallowing disorder, as is the case with many geriatric patients, the following things can be considered:

• crushing the medication tablet or opening the capsule and placing the medication in something like applesauce. Note, however, that time release capsules, enteric coated tablets, effervescent tablets, medications irritating to the stomach, foul tasting medications and sublingual medications should not be opened or crushed. Consult a pharmacist or a drug reference book to determine whether or not a particular medication can be crushed.
• substituting a liquid form of the medication with the doctor's order

AGE SPECIFIC ROUTE AND FORM CONSIDERATIONS

Infants

• Use a syringe, dropper or nipple for oral liquid medications.
• The vastus lateralis, rectus femoris and ventrogluteal sites are the preferred sites for intramuscular injections.
• Do NOT use the deltoid or the gluteus maximus muscles because these muscles have not yet developed in the infant.

Toddler

• Use a spoon or a cup for liquid oral medications.
• The vastus lateralis, rectus femoris and ventrogluteal sites can be used for intramuscular injections.
• The gluteus maximus muscle can be used only if the toddler has been walking for at least one year.

Preschool and School Age Children

• Most children in these age groups are able to take capsules and tablets.
• The gluteus maximus muscle and the deltoid muscle can be used for intramuscular injections.

Adolescents

• Adult dosages, routes and forms of medications are indicated and acceptable.

ADMINISTERING MEDICATIONS VIA VARIOUS ROUTES

Topical Administration

Do not use topical medications on skin that is not intact unless, of course, the medication is being used to treat broken skin,. The procedure for administering a topical medication is as follows:

1. Open the tube or container.
2. Place the top upside down to prevent contamination.
3. Don gloves.
4. Place the topical medication on a tongue depressor. Use a cotton tipped applicator or sterile gauze for facial areas.
5. Apply the medication in long strokes following the direction of hair growth.

Transdermal Administration

The procedure for administering a medication using the transdermal route is as follows:

1. Remove the old transdermal patch if there is one.
2. Wash the application site with soap and water. The site should be without hair and on the person's upper arm or chest.
3. Dry the site.
4. Don gloves.
5. Measure the ordered dose onto the patch or strip without allowing the ointment to touch your own skin.
6. With the medication against the skin gently move the strip over a 3 inch area to spread it out. Do NOT rub.
7. Secure the site with a plastic wrap or another semipermeable membrane and tape in place.
8. Note the date, time and your initials on the dressing.

Oral Dosage Administration

Oral medications are administered as below.

1. Give the patient the medication. Remain with the patient until the medication(s) are swallowed.

Buccal and Sublingual Administration

Buccal medications are placed between the teeth and the inner aspect of the cheek. Sublingual medications are administered under the back of the tongue. The procedure is as follows:

1. Don gloves.
2. Place the buccal medication in the buccal pouch and the sublingual medication under the tongue.
3. Tell the patient to leave the drug in its position so that it can be completely dissolved.

Ophthalmic Medication Administration

1. Don gloves.
2. Position the patient in a sitting position or in a supine position.
3. Have the patient tilt their head back and toward the eye getting the drops or ointment. This prevents the medication from entering the tear duct.
4. Have the patient look up and away. This helps to prevent touching the eye with the dropper tip or tube tip.
5. Rest your hand against the person's forehead to steady it.
6. To administer drops, pull down the lower lid and instill the ordered number of drops into the conjunctival space.
7. To administer an ointment, pull down the lower lid and squeeze the ointment into the conjuntival space from the inner to the outer canthus of the eye. Do not touch the eye with the tip of the tube.
8. Ask the person to now close their eyes. Blinking will spread the drops and rolling the closed eyes will spread the ointment over the eye.
9. Clean excess with a tissue.

Otic Administration

1. Warm the ear drops to body temperature.
2. Instruct the person to lie on their side so that the ear to receive the medication is up.
3. Straighten out the ear canal by pulling the auricle up and back. Straighten out the young child's (less than 3 years of age) ear canal by pulling the auricle down and back.
4. Instill the ordered drops against the side of the inner ear and hold the auricle in place until the medication is no longer visible. Release the auricle.
5. Have the person remain in the side lying position for at least 10 minutes.

Inhalation Administration
There are two different types of inhalers that administer medications via the inhalation route. These two types are:

• Metered-dose inhalers and
• Turbo inhalers.

The steps to using a metered dose inhaler are:

1. Shake the bottle and remove the cap
2. Ask the person to exhale.
3. Have the person then firmly place their lips around the mouthpiece.
4. Compress the bottle against the mouthpiece while the person is taking in a long, slow inhalation
5. Have the person hold their breath for a couple of seconds and then slowly exhale.
6. Have the patient rinse their mouth with water and then spit it out. This prevents an fungal infection of the mouth.

The steps to using a turbo inhaler are:

1. Slide the sleeve away from the mouthpiece.
2. Turn the mouthpiece counter-clockwise in order to unscrew it.
3. Place the colored part of the medication into the stem of the mouthpiece.
4. Rescrew the inhaler.
5. Slide the sleeve all the way down to puncture the capsule.
6. Tilt the head backwards and after a full exhalation, tell the patient to deeply inhale and hold their breath for several seconds.
7. Repeat inhalations until all of the medication has been used.
8. The patient can then gargle if they like.

Nasogastric Administration

1. Position the patient in a Fowler's position.
2. Gently instill about 10 ml of air into the tube while auscultating the abdomen about 3 inches below the sternum to confirm that the nasogastric tube is in the stomach and not in the lung. An air bubble is heard when the tube is in the stomach.
3. Gently pull back on the syringe to reconfirm that the tube is in the stomach. If gastric contents become visible in the tube, the nasogastric tube is in the stomach where it should be.
4. Prepare the medication(s) to be administered.
5. Insert the syringe without the piston into the end of the nasogastric tube.
6. Pour the medications into the syringe and allow them to flow with gravity.
7. Follow the administration with about 30 to 50 ml of water for an adult and 15 to 30 ml for children to clear the tube and to maintain its patency.
8. Leave the person in a Fowler's position for at least 30 minutes after instillation. If the person cannot remain in a Fowler's position, place the patient on the right side with the head elevated.

Vaginal Administration

The procedure for the administration of a vaginal suppository is as follows:

1. While the patient is in the recumbent position, assist the person into the lithotomy position.
2. Drape the patient exposing only the perineum.
3. Remove the suppository from the wrapper and lubricate it with a water soluble jelly.
4. Don gloves.
5. Spread the labia and insert the suppository about 3 to 4 inches into the vagina.
6. If an applicator was used, discard it if it is for single use or wash it with soap and water.

Rectal Administration

The procedure for the administration of a rectal suppository is as follows:

1. Position the patient on their left side in the Sim's position.
2. Drape the patient exposing only the buttocks.
3. Remove the suppository from the wrapper and lubricate it with a water soluble jelly.
4. Don gloves.
5. Lift the person's upper buttock with the nondominant hand and insert the suppository with the tapered end first about 3 inches into the rectum past the rectal sphincter while the patient is taking deep breaths to relax the sphincter and to decrease anxiety.
6. Instruct the person to lie still so the suppository can be retained. If the person has the urge to defecate, place a gauze pad over the rectum and press until the urge to defecate passes.

The procedure for the administration of a rectal ointment is as follows:

1. Drape the patient exposing only the buttocks.
2. Don gloves.
3. Place the ointment on a gauze pad and apply to the rectum.
4. If an applicator is used, follow steps 4 and 5 above.

Subcutaneous Injections

Subcutaneous injections can be given in the abdomen, upper arms and the front of the thighs. The procedure is as follows:

1. Select the site.
2. Don gloves and position the patient if necessary.
3. Clean the injection site with an alcohol swab in an outward circular pattern of about 2 inches.
4. Gently pinch the site so a 1 inch fat fold appears.
5. Position the needle with the bevel up and insert at a 45 degree angle unless you CANNOT pinch an inch or more. In this case, use a 90 degree angle. Heparin is always injected at a 90 degree angle.
6. Release the skin pinch.
7. Pull the plunger back to check for blood. If blood appears withdraw the needle and start again.
8. Slowly inject the medication.
9. Withdraw the needle and cover the site with an alcohol swab. 10.Gently massage the site, except if you are injecting heparin. Discard the needle and syringe in the proper container. Do NOT recap needles.

Intramuscular Administration

1. Select and identify the site (deltoid, ventrogluteal, etc.) using bony landmarks.
2. Don gloves and position the patient if necessary.
3. Clean the injection site with an alcohol swab.
4. Position the needle with the bevel up and insert at a 90 degree angle.
5. Pull the plunger back to check for blood. If blood appears withdraw the needle and start again.
6. Slowly inject the medication.
7. Withdraw the needle and cover the site with an alcohol swab.
8. Gently massage the site.
9. Discard the needle and syringe in the proper container. Do NOT recap needles.

If more than 5 mls are needed, split the dose and use two different sites for injection.

Intravenous Bolus Administration (IV Push)

The procedure for IV push without an existing IV line is as follows:

1. Select the largest vein suitable for the medication.
2. Don gloves.
3. Apply a tourniquet, locate the vein, prep the skin and insert the needle at a 30 degree angle with the bevel up.
4. Lower the angle when you are in the vein.
5. Check for blood backflow.
6. Remove the tourniquet and slowly inject the medication at the ordered or recommended rate.
7. Withdraw the needle, cover the site with a gauze pad and pressure for 3 minutes.
8. Place a bandage over the site.

The procedure for IV push with an existing IV line is as follows:

1. Make sure that the medication is compatible with the IV solution and any additives.
2. Don gloves.
3. Close the flow clamp on the IV tubing or pinch the tubing just above the injection port.
4. Prep the injection port with alcohol.
5. Inject the medication slowly over several minutes.
6. Open the flow clamp and readjust the flow rate to the ordered rate.

Intravenous Piggy Back or Secondary Line Administration

This procedure is as follows:

1. Make sure that the medication is compatible with the IV solution and any additives.
2. Hang the secondary IV set (piggy back).
3. Clean the injection port with alcohol.
4. Insert the secondary set needle or needless system into the injection port of the primary IV tubing.
5. Lower the primary IV using an extension hook to run only the piggy back medication. Keep the primary and the secondary containers at the same level to run both solutions simultaneously.
6. Remove the secondary set when the medication is completely administered.

Adding Medications to IV Solutions

To add medications to IV solutions:

1. wipe off the injection port with alcohol,
2. insert the needle into the injection port and
3. inject the ordered medication.

Z Track Injections

1. Pull the skin to the side.
2. Inject the medication.
3. Release the skin.
4. Do NOT massage the site.

Drawing Up Medication From a Vial

1. Wipe the vial with an alcohol swab.
2. Remove the cap from the needle.
3. Pull back on the plunger to draw amount of air into syringe equivalent to volume of medication to be aspirated from vial
4. Insert the tip of needle, with bevel pointing up, through center of rubber seal and inject the air into the vial.
5. Let the air pressure in the vial to fill the syringe to the desired dose.
6. Tap the syringe to rid it of an air bubbles.

THE ACTIONS OF MEDICATIONS

Those that administer and dispense medications must be thoroughly knowledgeable about how medications act on the body. This knowledge enables us to plan patient care and assessments based on the medication's therapeutic effect as well as what the possible side effects and signs of toxicity may be.

Information about the actions of all medications can be found in a drug reference book like the Physicians' Desk Reference (PDR).

INDICATIONS FOR USE

All medications have intended uses. Most of these intended uses are related to the action of the medication, however, some uses are related to a medication's side effects. For example, diphenhydramine, an antihistamine, is used both as an antihistamine and for sleep because one of its side effects is drowsiness.

Approved uses are documented in drug reference books. At times a medication is used for a purpose not specified and approved. This use is referred to as "off label use".

PRECAUTIONS AND CONTRAINDICATIONS

Some medications are contraindicated for certain patients. For example, a medication can be contraindicated, or prohibited, for patients that have severe renal or hepatic disease and those that are pregnant or lactating. Other medications may be permitted with caution under certain circumstances. For example, a medication may be used with caution among the elderly population. When a medication is being used with caution, it is particularly important to monitor and assess the patient's responses to the medication.

The most commonly occurring contraindication is an allergy or sensitivity to a medication. The patient's allergies must be known and researched prior to the administration of any medication.

INTERACTIONS

Medications can interact with:

• other medications
• certain foods
• some herbs
• lifestyle habits (alcohol, etc)

Information about possible drug-drug, drug-food, drug-herb, drug-lifestyle interactions can be found in a drug reference book like the Physicians' Desk Reference (PDR) for every medication.

SIDE EFFECTS AND ADVERSE REACTIONS

All medications have side effects. Nausea and vomiting are the most commonly encountered side effects. Some side effects are desirable. For example, the side effect of drowsiness associated with diphenhydramine is desirable when this medication is given for sleep. Most side effects, however, are undesirable. For example, the drowsiness associated with diphenhydramine may place the person at risk when they are driving a car.

Some side effects are troublesome; others can be life threatening. Adverse drug reactions are serious and often life threatening side effects. Some medications also have toxic effects. For example, tinnitus is a sign of toxicity associated with aspirin.

A thorough knowledge about side effects, adverse drug reactions and toxic effects is necessary so that the patient can be monitored for not only therapeutic effects but the side effects of medication.

ALLERGIES AND SENSITIVITY

Any allergies or sensitivity to medications must be assessed and documented. All known allergies must be reviewed prior to the administration of medications.

DOSAGES

All medications have approved and recommended dosages and/or dosage ranges for adults and pediatric patients. Some recommended adult dosages may be decreased somewhat among the elderly because the normal physiological changes of the aging process make this age group more susceptible to side effects, adverse drug reactions, toxicity and overdosages.

Pediatric dosages are most often determined as based on the weight of the patient in terms of kilograms. Generally speaking, adolescents can safely take recommended adult dosages.

PHARMACOLOGY ABBREVIATIONS

Abbreviations save time however they can also jeopardize life. The pharmacology abbreviations that we have been using for many, many years are now being highly scrutinized. Some have led to disastrous medication errors.

The Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) offers some guidance and some regulations regarding the use of abbreviations in healthcare organizations. Some of these guidelines and regulations specifically address pharmacology.
Hospitals, nursing homes, assisted living facilities, and all other healthcare settings must now standardize their acceptable abbreviations, acronyms and symbols. JCAHO does not mandate that every facility make a complete list of all the abbreviations, acronyms and symbols that they will accept and use, however, they do mandate that all healthcare facilities make a list of all those that they will NOT use. Additionally, this accreditation body specifies several high risk abbreviations that cannot be used under any circumstances. (Joint Commission on the Accreditation of Healthcare Organizations, 2005).

Commonly used and acceptable abbreviations along with their meaning is found below.

ABBREVIATION	MEANING
a.c.	Before meals
ad	Up to
ad lib	Freely
a.m.	Morning
amp.	Ampule
aq.	Water
ASA	Aspirin
b.i.d	Twice a day
BM	Bowel movement
BP	Blood pressure
BS	Blood sugar
C (with line over it)	With
cap	Capsule
cc	Cubic centimeter
comp.	Compound
dil	Dilute
disc or D.C.	Discontinue
disp.	Dispense
div.	Divide
DW	Distilled water
D5W	Dextrose 5% in water
D5LR	Dextrose 5% in lactated Ringers solution
elix.	Elixir
ext	Extract
fl or fld	Fluid
g. or Gm. or g	Gram
gr	Grain
gtt.	Drop
h. or hr.	Hour
ID	Intradermal
IM	Intramuscular
inj.	Injection
IV	Intravenous
IVP	Intravenous push
IVBP	Intravenous piggy back
kg	killogram
L	Liter
mEq	Milliequivalent
min	Minute
mg	Milligram
mL	Milliliter
NaCl	Sodium Chloride
NPO	Nothing by mouth
NS	Normal saline
1/2 NS	Half-strength normal saline
NTG	Nitroglycerin
p.c.	After meals
p.m.	Evening
p.o.	By mouth
PR	Rectally
prn	When needed
q	Every
qh	Every hour
qid	Four times a day
R	Rectal
R.L. or R/L	Ringer's Lactate
s (with a line over it)	Without
SL	Sublingual
SOB	Shortness of breath
sol	Solution
ss.	One half
stat	Immediately
Sub Q	Subcutaneous
sup.	Suppository
susp.	Suspension
Syr.	Syrup
tab.	Tablet
tbsp	Tablespoonful
tid	Three times a day
tinc	Tincture
top	Topically
tr.	Tincture
tsp.	Teaspoon
ung.	Ointment
w/	With
w/o	Without

Prohibited abbreviations, suggested alternatives and the rationale for the prohibition are shown below.

ABBREVIATION	Mistaken For:	Instead, write
U (unit)	zero	"unit"
IU (international unit)	zero or ten	"international unit"
Q.D. (every day)	Q.O.D	"daily"
Q.O.D.(every other day)	Q.D	"every other day"
No trailing zero (.Xmg)	a whole number	"0.Xmg)
MS, MSO4 and MgSO4	eachother	"morphine sulfate" or "magnesium sulfate"

Some not yet prohibited abbreviations that JCAHO encourages us discard are below.

ABBREVIATION	Mistaken For:	Instead, write
mg (microgram)	mg	"mcg"
H.S.(half strength & at bedtime)	Each other	"half strength" or "at bedtime"
T.I.W.(3 times a week)	2 times a week or 3 times a day	"3 times a week"
S.C. or S.Q.(subcutaneous)	SL (sublingual)	"Sub-Q", "subQ", or "subcutaneously"
D/C (discharge)	Discontinue meds	"discharge"
c.c. (cubic centimeter)	U (units)	"ml"
A.S, A.D., A.U.(left, right and both ears)	OS, OD, OU	"left ear, right ear, both ears"

(Joint Commission on the Accreditation of Healthcare Organizations, 2004)

INTRODUCTION

Medications can be classified according to their use or function, the system that they treat and their chemical makeup. For example, they can be classified according to system, as follows:

• respiratory medications
• cardiac medications
• nervous system medications, etc.

They can also be classified according to their function or use. For example, they can be classified as below:

• nonsteroidal anti-inflammatory medications
• narcotic analgesics
• antidepressants, etc.

Lastly they can be classified according to their chemical makeup. Examples include:

• aminoglycosides
• estrogens
• opioids, etc.

Most of the medications within a classification group, like alpha-adrenergic blockers, are quite similar although they are not identical. Classification systems enable us to readily identify the similarities and differences among a large number of medications within and outside of a particular classification. One of the best and most efficient ways to master pharmacology is to become familiar with the classifications of medications and then to focus on the similarities and differences of medications within the same classification.

MEDICATION CLASSIFICATIONS

ALPHA-ADRENERGIC BLOCKERS

Actions: They bind to α-adrenergic receptors thus leading to the dilation of peripheral blood vessels, lowering of peripheral resistance and the lowering of blood pressure.

Uses: Hypertension and prevention of necrosis secondary to extravasation.

Adverse Reactions and Side Effects: Hypotension, stuffed nasal passages, tachycardia, diarrhea, nausea, and vomiting.

Contraindications: Myocardial infarction (MI) and coronary artery disease, including angina.

Implications: Check K, Na, Cl, CO2, daily weights, I&O, BP standing and lying.

Examples of Medications in This Classification:

• dihydroergotamine mesylate
• phentolamine mesylate

Actions: They contain magnesium, aluminum, calcium and a combination of these compounds. They slow down the rate of gastric emptying and neutralize gastric acidity.

Uses: Gastritis, peptic ulcer, hiatal hernia and reflux esophagitis.

Adverse Reactions and Side Effects: Constipation, diarrhea, flatus, abdominal distention, alkaluria.

Contraindications: Allergy and sensitivity

Implications: Assess epigastric pain, GI symptoms and renal problems and electrolytes.

Examples of Medications in This Classification:

• aluminum carbonate
• calcium carbonate

This classification is further divided into:

• nitrates,
• calcium channel blockers, and
• b-adrenergic blockers.

Actions:

Nitrates - dilate coronary arteries, decrease preload and afterload.

Calcium channel blockers- also dilate coronary arteries, but they also decrease SA/AV node conduction

β -Adrenergic blockers- slow the heart rate, thus decreasing O2 use.

Uses: Angina. Calcium channel blockers and β-blockers can also be used for hypertension and dysrhythmias.

Adverse Reactions and Side Effects: Postural hypotension, fatigue, dysrhythmias, headache, edema, dizziness.

Contraindications: Increased intracranial pressure, cerebral hemorrhage and sensitivity.

Implications: Monitor for side effects and orthostatic B/P. Continue to assess angina pain.

Examples of Medications in This Classification:

• propranolol
• verapamil hydrochloride
• nitroglycerine

Actions: Inhibit acetylcholine (autonomic nervous system)

Uses: Many uses- some decrease GI, urinary and billiary motility; others decrease GI secretions, decrease involuntary movement, and relieve nausea, and vomiting.

Adverse Reactions and Side Effects: Dryness of the mouth, paralytic ileus, constipation, urinary problems (retention and hesitancy) dizziness and headache.

Contraindications: GI or urinary obstruction, narrow-angle glaucoma, and myasthenia gravis.

Implications: Monitor urinary and bowel function as well as vital signs. Keep the patient in bed for one hour after parenteral dose.

Examples of Medications in This Classification:

• atropine sulfate
• scopolamine

Actions: Prevent clot formation.

Uses: MI, pulmonary embolus, deep vein thrombosis, disseminated intravascular clotting syndrome (DIC), and atrial fibrillation. It is also used with dialysis.

Adverse Reactions and Side Effects: Hemorrhage, diarrhea, fever, rash and blood disorders (leukopenia, thrombocytopenia, etc.) depending on the specific drug.

Contraindications: Bleeding disorders, such as hemophilia and leukemia, ulcers, blood dyscrasias, nephritis, endocarditis and thrombocytopenia purpura.

Implications: Observe for bleeding (oral, black stools, stool occult blood, ecchymosis, etc.). Monitor blood and BP (hypertension may occur).

Examples of Medications in This Classification:

• warfarin sodium
• heparin

This classification is further divided into:

• barbiturates,
• hydantoins,
• succinimides,
• benzodiazepines and
• others.

Actions: Act to prevent seizures.

Uses: Depending on the specific drug, they prevent tonic-clonic seizures, psychomotor seizures, status epilepticus, petit mal seizures and cortical focal seizures.

Adverse Reactions and Side Effects: Bone marrow depression, which can be life-threatening, GI problems, CNS effects like confusion, ataxia and slurring of speech.

Contraindications: Sensitivity

Implications: Monitor hepatic and renal function, blood, mental status, blood dyscrasias, and toxicity (ataxia, bone marrow depression, nausea, vomiting, cardiovascular problems, Stevens-Johnson syndrome)

Examples of Medications in This Classification:

• phenytoin
• diazepam

Antidepressants are further divided into:

• MAOIs,
• tricyclics, and
• others.

Actions:

MAOIs- inhibit MAO and thus they increase epinephrine, norepinephrine, serotonin, and dopamine.

Tricyclics- block the reuptake of serotonin and norepinephrine in the nerve endings, thus increasing the actions of both in the nerve cells.

Uses: Depression. Nocturnal enuresis in children.

Adverse Reactions and Side Effects: Orthostatic hypotension, mouth dryness, dizziness, drowsiness, urinary retention, hypertension, renal failure and paralytic ileus.

Contraindications: Hypertrophy of the prostate, seizure disorders, renal, hepatic and cardiac disease.

Implications: Monitor standing and lying BP, blood, mental status, hepatic function. Observe for extrapyramidal symptoms and urinary retention. Withdrawal symptoms occur with abrupt cessation.

Examples of Medications in This Classification:

• sertraline
• amitriptylyline
• bupropion
• phenelzine

Antidiabetics are also subdivided into the following groups:

• insulins of varying kinds, and
• oral hypoglycemic agents.

Actions:

Insulin- lowers blood sugar, potassium and phosphate

Oral hypoglycemic agents- stimulate the β -cells of the pancreas to release insulin.

Uses: Diabetes and ketoacidosis

Adverse Reactions and Side Effects: Hypoglycemia, hepatotoxicity, allergic responses

Contraindications: Sensitivity. Oral agents are contraindicated for juvenile diabetes and ketoacidosis.

Implications: Monitor blood glucose, assess for hypoglycemia, rotate insulin injection sites, and use human insulin with pork or beef sensitivity.

Examples of Medications in This Classification:

• insulin
• glyburide

Actions: Varying. Come decrease water content of stool, some slow down GI peristalsis.

Uses: Diarrhea

Adverse Reactions and Side Effects: Constipation, paralytic ileus, abdominal pain.

Contraindications: Colitis

Implications: Used for short term therapy (48 hours or less). Monitor electrolytes and bowel response.

Examples of Medications in This Classification:

• bismuth subgallate
• kaolin and pectin mixtures

Antidysrhythmics are subdivided into five groups:

• Class I
• Class II
• Class III
• Class IV
• Others

Actions:

Class I- decreases any disparity in the refractory period, increases the duration of action potential and effective refractory period

Class II- slows down the rate of SA node discharge and conduction through the AV node. Increases recovery time and decreases the heart rate, thus lowering O2 consumption in the myocardium

Class III- increases effective refractory period as well as the duration of action potential

Class IV- decreases SA node discharge and slows the conduction velocity through the AV node. They also inhibit calcium movement across the cell.

Others- slows conduction through the AV node (adenosine) and increases the refractory period in the AV node and decreases conduction velocity (digoxin)

Uses: Atrial and ventricular arrhythmias (atrial fibrillation, PVCs, and tachycardia), hypertension, and angina

Adverse Reactions and Side Effects: Hypotension, bradycardia, other arrhythmias and various other wide ranging side effects.

Contraindications: Various. Check each medication.

Implications: Monitor rate and rhythm, blood pressure, potassium, dependent edema and I & O

Examples of Medications in This Classification:

• digoxin
• procainamide
• quinidine
• acebutolol
• bretylium
• verapamil

Actions: Decreases sodium, potassium and nutrients in the cell and increases cell permeability.

Uses: Fungal infections such as cryptococcosis, aspergillosis, histoplasmosis, blastomycosis, coccidiomycosis, , phycomycosis, and candidiasis

Adverse Reactions and Side Effects: Renal, liver damage and failure, gastroenteritis, hypokalemia, anorexia, nausea and vomiting.

Contraindications: Sensitivity and bone marrow depression.

Implications: For IV administration, use a filter, check for extravasation and protect from light (cover with foil). Monitor vital signs, I & O, blood, weight, renal and hepatic function, hypokalemia and ototoxicity.

Examples of Medications in This Classification:

• nystatin
• amphoteracin B

Actions: Antagonists of histamine.

Uses: Allergies, pruritus and rhinitis.

Adverse Reactions and Side Effects: Most cause drowsiness, headache, urinary retention, blood dyscrasias, thickened bronchial secretions and GI effects

Contraindications: Sensitivity, asthma, peptic ulcer, narrow angle glaucoma.

Implications: Monitor urinary, respiratory and cardiac status. Also monitor for blood dyscrasias.

Examples of Medications in This Classification:

• diphenhydramine hydrochloride
• chlorpheniramine maleate

This classification is further divided into:

• angiotensin-converting enzyme (ACE) inhibitors,
• b-adrenergic blockers,
• calcium channel blockers,
• centrally acting adrenergics,
• diuretics,
• peripherally acting antiadrenergics, and
• vasodilators.

Actions:

Angiotensin-converting enzyme inhibitors- dilatation of the arterial and venous systems occur through the suppression of renin-angiotensin I to angiotensin II conversion

Centrally acting adrenergics- inhibit impulses in the CNS and the sympathetic nervous system, decreases cardiac output, blood pressure and pulse rate

Peripherally acting antiadrenergics- inhibit the release of norepinephrine thus decreasing sympathetic vasoconstriction

Vasodilators- reduce blood pressure, cardiac rate and cardiac output because these medications relax and dilate the smooth muscle of the arteries

b-Blockers, calcium channel blockers, and diuretics are discussed in another section below.

Uses: Hypertension, heart failure, angina and some dysrhythmias

Adverse Reactions and Side Effects: Hypotension, tachycardia, bradycardia, nausea, vomiting and headache.

Contraindications: Heart block, hypersensitivity

Implications: Check for edema, monitor renal function, blood and for symptoms of congestive heart failure.

Examples of Medications in This Classification:

• captopril
• propranolol hydrochloride
• reserpine
• nitroprusside sodium

Antiinfectives are divided further into the following groups:

• penicillins,
• cephalosporins,
• aminoglycosides,
• sulfonamides,
• tetracyclines,
• monobactam,
• erythromycins, and
• quinolones.

Actions: Inhibit the growth and/or replication of susceptible bacteria

Uses: Infection

Adverse Reactions and Side Effects: Diarrhea, nausea, vomiting, bone marrow depression and anaphylaxis (life threatening)

Contraindications: Hypersensitivity. Most people allergic to penicillins are also allergic to the cephalosporins.

Implications: Observe bowel pattern and urinary output. Monitor renal function, blood and for signs of a superinfection and bleeding.

Examples of Medications in This Classification:

• penicillin
• tetracycline

This classification is further divided into:

• alkylating agents,
• antimetabolites,
• antibiotic agents,
• hormonal agents, and
• others

Actions: Alkylating agents- interfere with DNA

Antimetabolites - inhibit DNA synthesis

Antibiotic agents- inhibit RNA synthesis by delaying or inhibiting mitosis

Hormones- change the effects of androgens, estrogen, luteinizing hormone, and follicle-stimulating hormone

Uses: Tumors, lymphoma, leukemia and Hodgkin's disease

Adverse Reactions and Side Effects: Anemia, thrombocytopenia, leukopenia, nausea, vomiting, hair loss, hepatotoxicity, cardiotoxicity and hepatotoxicity

Contraindications: Sensitivity, liver and renal damage.

Implications: Monitor blood studies (CBC, platelet count and differential (the drug may have to be held), renal and liver function, I & O. Observe for bleeding, jaundice, dependent edema, breaks in the skin and mucosal inflammation. Check for irritation and phlebitis with IV administration.

Examples of Medications in This Classification:

• fluorouracil
• cisplatin

This classification is further divided into:

• cholinergics and
• dopamine antagonists.

Actions:

Cholinergics- block acetylcholine receptors

Dopamine antagonists- activate dopamine receptors

Uses: Parkinson's disease

Adverse Reactions and Side Effects: Involuntary movement, insomnia, nausea, vomiting, orthostatic hypotension, dry mouth, numbness and headache

Contraindications: Sensitivity and narrow angle glaucoma

Implications: Monitor respirations, blood pressure and changes in mental and behavioral status

Examples of Medications in This Classification:

• levodopa
• entacapone

Again, this classification is subdivided. The groups are:

• phenothiazines,
• thioxanthenes,
• butyrophenones,
• dibenzoxazepines,
• dibenzodiazepines,
• indolones and
• other heterocyclic compounds.

Actions: All of these pharmacological agents block the dopamine receptors in the brain, the area that involves psychotic behavior

Uses: Schizophrenia, mania, paranoia, and anxiety. They are also sometimes used for unrelieved hiccups, nausea, vomiting, and pediatric behavioral problems as well as pre-operative relaxation.

Adverse Reactions and Side Effects: Some symptoms (EPS, dystonia, akathisia and tardive dyskinesia) can be controlled with antiparkinsonian medications. Others side effects include dry mouth, photosensitivity, agranulocytosis, hypotension, and life threatening cardiac problems and laryngospasm.

Contraindications: Coronary disease, severe hypertension, severe depression, bone marrow depression, blood dyscrasias, parkinsonism, cerebral arteriosclerosis, narrow angle glaucoma and children less than 12 years of age. Cautiously used with the elderly.

Implications: Monitor CBC, liver function, I & O, blood pressure lying and standing (orthostatic hypotension), EPS (antiparkinsonian agents should be used for this). Observe for dizziness, palpations, tachycardia, changes in affect, level of consciousness, gait and sleep patterns.

Examples of Medications in This Classification:

• haloperidol
• chlorpromazine

Actions: Decreases the replication of the offending bacillus through the inhibition of RNA or DNA

Uses: Pulmonary tuberculosis

Adverse Reactions and Side Effects: Anorexia, nausea, vomiting, rash, renal, hepatic and ototoxic effects, which could be severe.

Contraindications: Sensitivity, renal disease. Caution with hepatic disease, pregnancy and lactation

Implications: Check renal and hepatic status and for signs of anemia.

Examples of Medications in This Classification:

• isoniazid
• rifabutin
• rifampin

Actions:

Antitussives- suppression of the cough reflex

Expectorants- decrease the viscosity of thick, tenacious secretions

Uses: The expectorants are used with a cough associated with bronchitis, TB, pneumonia, cystic fibrosis and COPD. Antitussives are used for nonproductive coughs.

Adverse Reactions and Side Effects: Dizziness, drowsiness and nausea

Contraindications: Iodine sensitivity, pregnancy, lactation and hypothyroidism. Caution with the elderly and those with asthma

Implications: Monitor the cough and the sputum. Increase fluid intake and humidification to thin secretions.

Examples of Medications in This Classification:

• guaifenesin
• codeine

Actions: Interferes with the DNA needed for viral replication

Uses: HIV infections, herpes (herpes simplex virus and herpes genitalis), encephalitis (herpes simplex) and varicella zoster encephomyelitis

Adverse Reactions and Side Effects: Nausea, vomiting, diarrhea, headache, anorexia, vaginitis, moniliasis, blood dyscrasias, renal failure and metabolic encephalopathy which could be fatal

Contraindications: Immunosuppressed patients with herpes zoster and hypersensitivity. Caution with pregnancy, lactation, renal and liver disease and dehydration

Implications: Assess for renal and liver problems. Observe for signs of infection and allergic reactions (itching, rash, urticaria). Monitor the blood for dyscrasias.

Examples of Medications in This Classification:

• acyclovir sodium
• cidofovir

Actions: Decreases impulse transmission to the cerebral cortex

Uses: Epilepsy, sedation, insomnia, anesthesia, cholestasis with some medications in this classification.

Adverse Reactions and Side Effects: Drowsiness, nausea, blood dyscrasias and Stevens-Johnson syndrome

Contraindications: Allergy, poor liver function, porphyria, pregnancy (category D). Caution with the elderly renal or hepatic disease (slowed metabolism)

Implications: Monitor seizure control, blood, hepatic and renal function. Observe for toxicity (insomnia, hallucinations, hypotension, pulmonary constriction; cold, clammy skin; cyanosis of lips, nausea, vomiting, delirium, weakness)

Examples of Medications in This Classification:

• phenobarbital
• secobarbital

Actions: Decreases anxiety by potentiating g-aminobutyric acid and other CNS inhibitory transmitters

Uses: Anxiety secondary to phobic disorders and other conditions, acute alcohol withdrawal and pre-operative relaxation.

Adverse Reactions and Side Effects: Physical dependence and abuse, dizziness, drowsiness, orthostatic hypotension, and blurred vision

Contraindications: Narrow angle glaucoma, infants less than 6 months old, hypersensitivity, lactation (diazepam) and liver disease (clonazepam). Caution with the elderly as well as those with renal and/or hepatic disease

Implications: Monitor lying and standing blood pressure (notify MD if B/P drops 20 mm Hg or more), pulse, hepatic and renal function and signs of dependency. Administer with milk or food to prevent GI symptoms.

Examples of Medications in This Classification:

• diazepam
• clonazepam

β-Blockers are divided into two categories:

• selective blockers and
• nonselective blockers.

Actions:

Selective blockers- block the stimulation of b1-receptors in the cardiac smooth muscle with chronotropic and inotropic effects.

Nonselective blockers- lowers blood pressure (plasma renins are reduced) without a reduction in heart rate or reflex tachycardia.

Uses: Hypertension, angina prophylaxis and ventricular dysrhythmias

Adverse Reactions and Side Effects: Orthostatic hypotension, diarrhea, nausea, vomiting, bradycardia, blood dyscrasias, CHF and bronchospasm

Contraindications: Heart block, cardiogenic shock and CHF. Cautious use with the elderly and those patients with COPD, coronary artery disease, asthma, renal disease, thyroid disease, pregnancy.

Implications: Monitor blood pressure, I&O, daily weights, pulse and renal function. Observe for edema and take the apical and radial pulse before administration in order to determine if significant changes have occurred.

Examples of Medications in This Classification:

• metroprolol
• propranolol

This classification is further subdivided into:

• anticholinergics,
• α/β -adrenergic agonists,
• β -adrenergic agonists, and
• phosphodiesterase inhibitors.

Actions:

Anticholinergics- inhibit the interaction of acetylcholine at receptor sites on bronchial smooth muscle

α/β -adrenergic agonists- increase the diameter of nasal passages and relax bronchial smooth muscle

β-adrenergic agonists- relax the smooth muscle of the bronchii

Phosphodiesterase inhibitors- increased smooth muscle relaxation in the respiratory system

Uses: Asthma, bronchospasm, COPD, emphysema, Cheyne-Stokes respirations

Adverse Reactions and Side Effects: Dyspnea, bronchospasm, anxiety, tremors, throat irritation, nausea and vomiting.

Contraindications: Narrow angle glaucoma, severe cardiac disease, tachydysrhythmias and sensitivity. Cautious use with hypertension, seizure disorders, pregnancy and lactation, hyperthyroidism and prostatic hypertrophy

Implications: Assess for a therapeutic response (absence of dyspnea and/or wheezing) and patient/family education about the use of the inhaler

Examples of Medications in This Classification:

• albuterol
• aminophylline

Actions: Inhibits the flow of calcium ions across the cell membrane of cardiac and vascular smooth muscle, thus relaxing the coronary vascular smooth muscle, dilating the coronary arteries, slowing SA/AV node conduction, and dilating peripheral arteries.

Uses: Angina, hypertension, and dysrhythmias.

Adverse Reactions and Side Effects: Dysrhythmias, edema, fatigue, headache, and drowsiness.

Contraindications: Systolic blood pressure of less than 90 mm HG, Wolff-Parkinson-White syndrome, 2nd or 3rd degree heart block, sick sinus syndrome, and cardiogenic shock. CHF may get worse in the presence of edema. Cautious use with hepatic and renal disease.

Implications: Monitor blood pressure, pulse and respirations. Administer at bedtime and before meals.

Examples of Medications in This Classification:

• verapamil
• felodipine

Actions: Cardiac output and cardiac contractility are enhanced by making more calcium available.

Uses: CHF and tachycardia

Adverse Reactions and Side Effects: Cardiac changes, hypotension, GI symptoms, blurred vision, yellowish-green halos and headache.

Contraindications: Hypersensitivity, ventricular fibrillation, ventricular tachycardia and carotid sinus syndrome. Caution among patients with imbalances of potassium, magnesium and/or calcium, acute MI, severe respiratory disease, AV block, renal or liver disease, hypothyroid and the elderly.

Implications: Assess vital signs, check apical rate for one full minute prior to administration (if less than 60, hold the dose and notify the MD), electrolytes (sodium, potassium, chloride and magnesium), renal and hepatic function. Monitor I & O. If K level is less than 3mg/dl, potassium supplements may be ordered.

Examples of Medications in This Classification:

• digitoxin
• digoxin

Actions: These medications prevent the destruction of acetylcholine, thus increasing its concentration, which enhances the transmission of impulses.

Uses: Myasthenia gravis, bladder distention, urinary distention, and postoperative paralytic ileus

Adverse Reactions and Side Effects: Bronchospasm, laryngospasm, respiratory depression, convulsion, paralysis, respiratory arrest, nausea, vomiting and diarrhea

Contraindications: Renal or intestinal obstruction. Cautious use with children, lactation, bradycardia, hypotension, seizure disorders, bronchial asthma, coronary occlusion, and hyperthyroidism

Implications: Monitor vital signs, I & O. Assess for urinary retention, bradycardia, bronchospasm, hypotension, respiratory depression.

Examples of Medications in This Classification:

• neostigmine
• bethanechol

Actions: Blocks the autonomic nervous system's acetylcholine

Uses: Prevention of surgical secretions, to decrease the motility of the urinary, biliary and GI tracts, reverses neuromuscular blockade. Some are used for parkinsonian symptoms secondary to the use of neuroleptic medications

Adverse Reactions and Side Effects: Constipation and dryness of the mouth.

Contraindications: GU or GI obstruction, angle closure glaucoma, myasthenia gravis, and hypersensitivity. Cautious use among the elderly and with patients who have prostatic hypertrophy or tachycardia

Implications: Monitor urinary status and I & O with particular attention to any dysuria, frequency or retention. The medication may be discontinued with these signs. Observe mental status and for constipation. Administer oral doses with milk or food and administer parenteral doses slowly with the person in a recumbent position to prevent postural hypotension

Examples of Medications in This Classification:

• atropine
• scopolamine

This classification is also subdivided. These groups are:

• glucocorticoids and
• mineralcorticoids.

Actions:

Glucocorticoids- increase capillary permeability and suppress the movement of fibroblasts and leukocytes, thereby decreasing inflammation.

Mineralcorticoids- increase potassium and hydrogen excretion in the distal tubule by increasing the resorption of sodium

Uses:

Glucocorticoids- decrease inflammation. Some are used for adrenal insufficiency, allergies and cerebral edema.

Mineralcorticoids- adrenal insufficiency

Adverse Reactions and Side Effects: Insomnia, euphoria, behavioral changes, peptic ulcer (GI irritation), sodium and fluid retention, hypokalemia, hyperglycemia, and carbohydrate intolerance (metabolic reactions)

Contraindications: Fungal infections, amebiasis, hypersensitivity, and lactation. Caution with the elderly, children and pregnant women, diabetes, seizures, peptic ulcers, glaucoma, CHF, hypertension, impaired renal function, myasthenia gravis and ulcerative colitis

Implications: GI symptoms can be prevented when the dose is given with food or milk. Monitor blood sugar, potassium, weight, I & O, plasma cortisol levels, adrenal insufficiency and for any signs of infection. Observe for mood changes, particularly depression

Examples of Medications in This Classification:

• cortisone
• dexamethasone
• hydrocortisone

This classification of medications is subdivided into:

• thiazides and thiazide-like diuretics,
• loop diuretics,
• carbonic anhydrase inhibitors,
• osmotic diuretics, and
• potassium-sparing diuretics.

Actions:

Thiazides and thiazide-like diuretics- slow resorption in the distal tubule, thus increasing the excretion of sodium and water

Loop diuretics- inhibit the resorption of sodium and chloride in the loop of Henle.

Carbonic anhydrase inhibitors- decrease the sodium-hydrogen ion exchange in the tubule, thus increasing sodium excretion

Osmotic diuretics- decrease the absorption of sodium by increasing the osmotic pressure of glomerular filtrate

Potassium-sparing diuretics- decrease potassium excretion by interfering with sodium resorption at the distal tubule

Uses: Hypertension and edema with CHF

Adverse Reactions and Side Effects: Hypokalemia, hyperglycemia and hyperuricemia (mostly with thiazides), blood dyscrasias, aplastic anemia, volume depletion, and dehydration (thiazides, loop diuretics, and carbonic anhydrase inhibitors)

Contraindications: Electrolyte imbalances (K, Cl, Na), anuria, dehydration. Caution among the elderly as well as in the presence of renal or hepatic disease

Implications: A potassium supplement may be needed. Monitor electrolytes, blood sugar, and lying and standing blood pressures. Observe for signs of hypokalemia and metabolic alkalosis. The medication should be given in the morning to prevent the need for frequent nocturnal voiding.

Examples of Medications in This Classification:

• furosemide
• hydrochlorothiazide

Actions: Inhibits histamine in the parietal cells, thereby inhibiting the secretion of gastric acid secretion

Uses: Gastric and duodenal ulcers, gastroesophageal reflux disease

Adverse Reactions and Side Effects: Thrombocytopenia, neutropenia agranulocytosis, aplastic anemia, confusion (not ranitidine), diarrhea and headache.

Contraindications: Hypersensitivity. Cautious use with children less than 16 years of age, hepatic or renal disease, organic brain syndrome, lactation and pregnancy

Implications: Monitor I & O, creatinine, BUN and gastric pH. The pH should be maintained above 5. Give slowly IV over 30 minutes to avoid bradycardia and administer oral doses with meals to prolong the effect of the medication

Examples of Medications in This Classification:

• cimetidine
• ranitidine

Action: Inhibits lymphocytes

Uses: Prevention of organ transplant rejection

Adverse Reactions and Side Effects: Proteinuria, renal failure, albuminuria, hematuria, hepatotoxicity, oral Candida, gum hyperplasia, headache and tremors

Contraindications: Hypersensitivity. Caution with severe hepatic or renal disease and pregnancy

Implications: Monitor liver and kidney function, and drug blood levels. Observe for signs of hepatotoxicity, which can include itching, light colored stools, jaundice and dark urine. Administer with meals to avoid GI symptoms

Examples of Medications in This Classification:

• cyclosporine
• azathioprine

This group is also subdivided as below:

• bulk products,
• lubricants,
• osmotics,
• saline laxative stimulants, and
• stool softeners

Actions:

Bulk laxatives - absorb water thus adding bulk to the stool

Lubricants- increase water retention in the stool

Stimulants- speed up peristalsis

Saline laxatives- pull water into the intestines

Osmotics- enhance peristalsis and increase distention

Stool softeners- reduce the surface tension of liquids within the bowel.

Uses: Constipation, as a bowel prep and a stool softener

Adverse Reactions and Side Effects: Cramping, diarrhea, and nausea

Contraindications: Megacolon, abdominal pain, nausea, vomiting, impaction, GI obstruction or perforation, gastric retention and colitis. Caution with large hemorrhoids and rectal bleeding

Implications: Monitor blood, I & O, and urine electrolytes. Administer only with water to enhance absorption. Do not administer within one hour of taking an antacid, cimetidine or drinking milk.

Examples of Medications in This Classification:

• psyllium
• docusate sodium
• magnesium hydroxide
• mineral oil
• bisacodyl

This classification is divided into:

• depolarizing blockers and
• nondepolarizing blockers.

Actions: Inhibition of nerve impulse transmission

Uses: The facilitation of endotracheal intubation and skeletal muscle relaxation (surgery, general anesthesia and mechanical ventilation)

Adverse Reactions and Side Effects: Apnea, respiratory depression, bronchospasm, and bradycardia

Contraindications: Hypersensitivity. Cautious use with collagen, thyroid and cardiac disease, lactation, pregnancy, children less than two years of age, dehydration, electrolyte imbalances, and myasthenia gravis

Implications: Monitor potassium and magnesium (imbalances may increase the action of this medication), vital signs every 15 minutes until recovery, and I & O. IV doses must be given over 1 to 2 minutes by a person qualified and competent to do so (usually an anesthesiologist)

Examples of Medications in This Classification:

• gallamine
• pancuronium

Actions: Decreases prostaglandin synthesis

Uses: Mild to moderate pain, arthritis and dysmenorrhea

Adverse Reactions and Side Effects: Blood dyscrasias, nephrotoxicity (oliguria, azotemia, hematuria and dysuria), abdominal pain, cholestatic hepatitis, anorexia, dizziness and drowsiness.

Contraindications: Asthma, severe liver and/or renal disease, hypersensitivity. Cautious use with the elderly, children, lactation, pregnancy and for patients with GI, cardiac and/or bleeding disorders.

Implications: Monitor blood, renal and hepatic function. Baseline hearing and eye exams are recommended so that changes can be identified. Toxicity may be signaled with tinnitus and/or blurred vision.

Examples of Medications in This Classification:

• ibuprofen
• naproxen

This classification includes:

• opiates and
• nonopiates.

Actions: Depression of the pain impulse transmission at the level of the spinal cord

Uses: Moderate to severe pain

Adverse Reactions and Side Effects: GI (constipation, nausea, vomiting, anorexia, cramps), sedation, respiratory depression, circulatory depression and increased intracranial pressure

Contraindications: Upper airway obstruction, bronchial asthma, hypersensitivity, addiction. Cautious use with renal, hepatic, respiratory and heart disease.

Implications: Monitor respiratory, urinary and mental status, level of consciousness. An antiemetic can be used for nausea and vomiting. Continue to assess level of pain

Examples of Medications in This Classification:

• codeine
• fentanyl

Actions: Antipyretic (inhibits the heat regulation center in the hypothalamus), anti-inflammatory (inhibits prostaglandin), analgesic (inhibits prostaglandin)

Uses: Mild to moderate pain, inflammation (arthritis), fever, and thromboembolitic disorders

Adverse Reactions and Side Effects: Rash, GI symptoms, hepatotoxicity, blood dyscrasias, hearing problems and tinnitus (a sign of possible toxicity)

Contraindications: Frequently occurring hypersensitivity. Contraindicated with a vitamin K deficiency, GI bleeding, a bleeding disorder, children with Reye's syndrome. Caution with Hodgkin's disease, hepatic and renal failure, anemia

Implications: Monitor renal and hepatic function, blood. Observe for signs of hepatotoxicity (clay colored stool, dark urine, diarrhea, yellow sclera and skin, itching, fever, abdominal pain) and ototoxicity (ringing or roaring in the ears, tinnitus)

Examples of Medications in This Classification:

• aspirin
• salsalate

Actions: These medications convert plasminogen into plasmin which is able to break down the fibrin of clots

Uses: Pulmonary emboli, deep vein and arterial thrombosis, with or after MI, arteriovenous cannula occlusion

Adverse Reactions and Side Effects: Anaphylaxis, GI, GU, intracranial retroperitoneal bleeding, and anaphylaxis. The most common side effects are decreased Hct, urticaria, headache, and nausea.

Contraindications: Hypersensitivity, people with CNS neoplasms, bleeding, renal or hepatic disease, hypertension, COPD, subacute bacterial endocarditis, rheumatic valvular disease, cerebral embolism or thrombosis or hemorrhage, and recent surgery

Implications: Monitor vital signs and neuro signs q 4 hours, be alert for internal bleeding (temperature of more than 104 degrees), arrhythmias, retroperineal bleeding (leg weakness, back pain, and poor pulses), allergic responses (rash, fever, itching, chill), ecchymosis, hematuria, hematemesis, epistaxis. Monitor blood before and during therapy. Thrombolytics are not effective if the thrombi is more than one week old. Use 0.8 mm filter with IV administration

Examples of Medications in This Classification:

• streptokinase
• urokinase

Actions: Increase metabolism cardiac output, blood volume, oxygen consumption, and respiratory rate

Uses: Thyroid replacement

Adverse Reactions and Side Effects: Palpitations, tachycardia, insomnia, tremors, angina, weight loss, dysrhythmias, thyroid storm.

Contraindications: MI, adrenal insufficiency and thyrotoxicosis. Cautious use with the elderly, pregnant and lactating women, and for patients with diabetes, hypertension, angina, and cardiac disease

Implications: Administer at the same time of day. Check the blood pressure before each dose. Monitor I & O, weight, cardiac status and for irritability, excitability and nervousness

Examples of Medications in This Classification:

• thyroid
• levothyroxin

Actions: Various modes for each. Check a drug reference book for specifics

Uses: Hypertension, angina, intermittent claudication, vasospasm, arteriosclerosis

Adverse Reactions and Side Effects: Both hypotension and hypertension, changes in EKG, nausea, headache

Contraindications: Tachycardia, acute MI and thyrotoxicosis. Cautious use with peptic ulcer and uncompensated heart disease

Implications: Administer with meals to reduce any GI symptoms. Check bleeding times and cardiac status

Examples of Medications in This Classification:

• amyl nitrate
• hydralazine

ASEPSIS AND INFECTION CONTROL

Standard precautions in healthcare have greatly reduced the risk of occupational exposures to HIV and other blood borne pathogens. Other infection control measures that decrease the risk of spreading infection in our healthcare facilities include:

• frequent handwashing;
• engineering controls, such as "needleless" systems to replace needles;
• work practice controls;
• the use of personal protective equipment, such as gowns, goggles, gloves and masks; and
• the proper handling of sharps and regulated, biohazardous waste.

The greatest occupational risks appear to remain in areas where invasive procedures are done. Sharps, including needles, appear to be the culprits in these high-risk areas.

The following routine infection control measures must be taken when administering medications and providing care, if indicated:

• ALWAYS wash your hands before and after each patient contact.
• Wear gloves whenever you may have contact with blood and other bodily fluids as well as when touching skin that is not intact. Wash your hands before donning gloves and wash your hands after removing the gloves. Gloves are not a substitute for handwashing.
• Wear a waterproof gown, goggles and a surgical mask if you may come in contact with bodily fluids, splashes and spills.
• Handle needles and other sharps with extreme caution.
• NEVER recap a needle.
• Dispose of sharps in the proper container.

Medical and Surgical Asepsis
The following medication routes are considered clean and, therefore, medical asepsis practices must be adhered to.

• oral,
• buccal,
• sublingual,
• topical,
• vaginal,
• rectal,
• nasal,
• inhalation
• NG and G tube, and
• transdermal

The following medication routes are considered sterile and, therefore, surgical asepsis practices must be adhered to.

• subcutaneous
• intramuscular
• intradermal
• intravenous
• intrathecal
• intracardial
• intra-articular

HOW THE AGING PROCESS AFFECTS MEDICATIONS

The following characteristics of the normal aging process affect medications and how they act in the body of a geriatric patient.

Renal Function

• Decrease in the clearance and elimination of medications from the body
• Renal blood flow is diminished
• Creatinine clearance can be reduced
• Tubular and glomerular function is decreased
• Renal mass is decreased
• Dehydration, if present, will further diminish renal clearance

Hepatic Function

• Hepatic mass is decreased
• Hepatic blood flow is decreased. This can impair hepatic elimination and, therefore, increase concentrations and bioavailability of medications

Absorption

• Decreased surface area of the small intestine
• Increased gastric acid pH

Distribution

• Decrease in serum albumin, which can increase serum concentrations of the unbound portion of the medication
• Increase in the percentage of body fat as compared to total body weight. This can increase the half-life of lipophilic drugs
• Decrease in total body water by as much as 15%, therefore, the concentrations of water soluble medications can increase

Other Age Related Characteristic of the Elderly That Affect Medications' Actions

• Greater risk of adverse drug reactions
• Increased sensitivity to medications
• Increased risk of toxicity, especially with nonsteriodal anti-inflammatory medications (NSAIDS), heparin, long acting benzodiazepines, aminoglycosides, thiazides, warfarin, isoniazid and many antiarrhythmics
• Some medications, such as benzodiazepines, produce significantly higher central nervous system depression and sedation than is produced in younger people
• Increasing frequency of drug-drug, drug-food, drug-lifestyle and drug-herb interactions
• Increased possibility of adverse reactions and idiosyncratic reactions as a result of the presence of multiple chronic disease processes

The Implications of Aging on Medication Administration

• Start with the lowest possible dose and increase the dosage slowly over time until the therapeutic effect is achieved
• The initial dosage may be only 50% of the recommended adult dosage
• Compliance with the medication regimen may be increased with a simple, rather than complex, medication schedule
• Cost is something that must be considered since most elders live on a limited and/or fixed income
• Closely assess and reassess the elderly person in terms of side effects, adverse drug reactions, toxicity and therapeutic effect

Medications That Pose the Greatest Risk to the Elderly

• diuretics
• antihypertensive medications
• anticoagulants
• antiarrhythmic medications
• anti-Parkinsonian medications
• psychotropics
• analgesics
• hypoglycemic agents

CALCULATION OF DOSAGES AND SOLUTIONS

Systems of Measurement Used in Pharmacology

Many dosage calculations require knowledge of mathematical conversion equivalents to move from one measurement system to another. We use metric, apothecary, and household measurement systems in pharmacology.

The Metric System of Measurement

Length
The standard unit of length in the metric system is the meter. Other units of length and their equivalents in meters are as follows:
1 millimeter (mm) = 0.001 meter (m)
1 centimeter (cm) = 0.01 meter (m)
1 decimeter (dm) = 0.1 meter (m)
1 kilometer (km) = 1000 meters (m)

Volume
The standard unit of volume in the metric system is the liter. One liter is equal to 1000 cubic centimeters in volume. Other units of volume and their equivalents in liters are as follows:
1 milliliter (mL) = 0.001 liter (l)
1 centiliter (cl) = 0.01 liter (l)
1 deciliter (dl) = 0.1 liter (l)
1 kiloliter (kl) = 1000 liters (l)
1000 mL = 1 liter (l)
1 mL = 1 cubic centimeter (cc) in volume

Weight
The standard unit of mass in the metric system is the gram. Other units of weight or mass and their equivalents in grams are as follows:
1 milligram (mg) = 0.001 gram (g)
1 centigram (cg) = 0.01 gram (g)
1 decigram (dg) = 0.1 gram (g)
1 kilogram (kg) = 1000 grams (g)
1 kilogram (kg) = 2.2 pounds (lbs)

The Apothecary System of Measurement

The grain is the basic unit of measurement in the apothecary system of measurement for weight. The ounce, dram and the minim are the basic units of measurement in the apothecary system of measurement for volume.

The Household System of Measurement

The basic units of measurement in the household system of measurement are drop, teaspoon, and tablespoon.

ABBREVIATIONS FOUND IN OUR SYSTEMS OF MEASUREMENT

gr g, gm or G kg l mL cc dr gtt lb m mg mcg tsp oz tbs U

grain gram kilogram liter milliliter cubic centimeter dram drop pound minum milligram microgram teaspoon ounce tablespoon unit

COMMONLY USED EQUIVALENTS

It is suggested that you refer to a table of equivalents for the less frequently used mathematical conversion equivalents and memorize the ones that you use most often. Some of the commonly used conversion equivalents are as follows:

1 gr = 60 mg
1 g = 15 gr
1G = 1000 mg
1 mL = 15 m
1 kg = 2.2 lb
1 tsp = 5 mL
1 tbsp = 15 mL
1 oz = 30 mL
1 kg = 2.2 lbs

DIMENSIONAL ANALYSIS

Most schools of nursing and pharmacy teach ratio and proportion and the "desired over have" method of calculation to students. Although these methods give us accurate answers, these methods are difficult to use and remember. They tend to be a source of great confusion and consternation. When two or more conversions are needed in order to perform the calculation these methods pose very real challenges. Additionally, different methods have to be memorized in order to solve each of many types of problems.

Dimensional analysis, on the other hand, uses only one method to calculate all kinds of problems. All problems are set up and solved in the same manner. This consistency not only decreases confusion and the need to memorize many approaches, it will increase your accuracy and confidence.

This course will teach you one simple and consistent method of calculating all dosages using dimensional. There is no longer a need to memorize cumbersome and easy-to-forget rules. Dimensional analysis easily and systematically solves a wide variety of oral, intramuscular, subcutaneous, and intravenous calculations.

Throughout the course you will get practice problems so you can master this simple calculation method. It will also teach you a one- step, no-rules method that rapidly and accurately calculates the number of drops per minute at which an ordered intravenous solution must to be run.

An Introduction to Dimensional Analysis Calculations

In order to calculate dosages using dimensional analysis, you set up an equation that consists of:

• a starting factor,
• one or more conversion factors, and
• the answer unit.

Once this equation is written, the final step is to cancel out numbers using simple math and then multiply the remaining numbers.

For example, if you want to know how many dimes there are in $3.00, you have to consider:

• the starting factor- the known factor of $3.00
• the conversion factor- the number of dimes in each dollar, that is, 10 dimes in each dollar
• the answer unit- which is dimes

What you want to calculate is the number of dimes in $3.00 if there are 10 dimes in each dollar.

The starting factor always appears first in the equation and The answer unit is the last part of the equation and it is followed by = sign. For example:

Starting Factor X Conversion Factor = Answer Unit

You would set up the dimensional analysis equation in the below manner using the number of dimes in $3.00 example.

Starting factor	x	Conversion factor	=	Answer unit
3 dollars	x	10 dimes	=	____ dimes
		1 dollar

If you want to find out how many inches there are in 12 feet, you have to consider the starting factor of 12 feet, the number of inches in 1 foot (the conversion factor) and what you are trying to find out, that is, the number of inches (answer unit) in 9 feet.

Below is an example of how to set up a dimensional analysis equation using this starting factor, the conversion factor, and the answer unit. .

Starting factor	x	Conversion factor	=	Answer unit
12 ft	x	12 inches	=	____ inches
		1 ft

The numerator is the number on top of a fraction and the denominator is the number on the bottom of a fraction. When you set up the equation, each numerator label should cancel out a denominator label so that the answer in the conversion factor. Now, only "inches" in the answer unit remains.

As shown below, the unit of feet in the starting factor cancels out the feet unit in the conversion factor. The final answer is then computed by simply multiplying 12 by 12.

12 ft	x	12 inches	=	144 inches
		1 ft

In more complex calculations, once all the units of measurement that can be canceled have been struck out, the remaining numerators are multiplied and this product, or answer, is then divided by the product of all the remaining denominators.

If the numerators and denominators can be divided by a common number, or reduced, the multiplication of the numerators and denominators as well as the final division will be somewhat simpler and less mathematically challenging. You will be taught how to reduce in this course.

The conversion factors that are used to calculate dosages and IV flow rates can consist of either established mathematical conversion equivalents or a manufacturer's equivalents.

Some examples of mathematical conversion equivalents are:

• 12 inches = 1 foot
• 2.2 lbs = 1 kg
• 15 gr = 1 g

Manufacturers produce medications of different dosages and IV tubings that deliver different amounts of fluids in each drop. Doctors will also order medications as based on body weight. Manufacturers' and ordered equivalents can include some like these:

• 1 tablet = 250 mg
• 5 gr per kg of body weight
• IV tubing that delivers 20 gtt = 1 mL

Oral Dosages Using Dimensional Analysis

The following sample calculations show you how to compute oral dosage calculations using dimensional analysis.

Sample Calculation 1
Doctor's order: tetracycline syrup 250 mg po
Medication label: tetracycline syrup 50 mg/mL
How many mL should you administer?

In this example, The starting factor is the dosage in the doctor's order, that is, 250 mg. The conversion factor is 50 mg/1 mL, the number of mg that are contained in each mL of the syrup. The answer unit is the number of mL that you would administer to the patient.

Starting factor	x	Conversion factor	=	Answer unit
250 mg	x	1 mL	=	____ mL
		50 mg

All dimensional analysis problems are set up as an equation in the same way and the calculations are performed in the same manner.

1. Cancel out and reduce the numerators and denominators,
2. multiply all the remaining numerators and denominators, and
3. then divide to get the final answer.

Cancel out and reduce these numerators and denominators by dividing each by 50:

5
250 mg	x	1 mL	=	____ mL
		50 mg
		1

Multiply the numerators (5 x 1) and the denominators (1), and finally divide the product of the numerators by the denominator to get the final answer:

5	x	1	=	5 mL	=	5 mL
		1		1

Sample Calculation 2
Doctor's order: Lanoxin 0.250 mg po
Medication label: Lanoxin 0.125 mg per tablet
How many tablets should you give?

The starting factor is 0.5 mg, The conversion factor is 0.25 mg/1 tablet, and The answer unit is the number of tablets you would give.

Starting factor	x	Conversion factor	=	Answer unit
0.250 mg	x	1 tablet	=	____ tablets
		0.125 mg

Cancel out and reduce the numerators and denominators:

0.250 mg	x	1 tablet	=	____ tablets
		0.125 mg

2
0.250	x	1 tablet	=	____ tablets
		0.125
				1

Multiply the numerators and the denominators and divide their products to get the final answer:

2	x	1	=	2	=	2 tablets
		1		1

Sample Calculation 3
Doctor's order: flucytosine 50 mg/kg/day in four divided doses. The patient weighs 40 kg.
Medication label: flucytosine 250 mg/cap
How many capsules should you give for each of the four doses?

The starting factor is 40 kg. In this example, there are two conversion factors. One of the conversion factors is the number of mg ordered for each kg, or 50 mg/kg, and the other conversion factor is the manufacturer's equivalent, or 250 mg/cap. The answer unit is the number of caps.

Starting factor	x	Conversion factors			=	Answer unit
40 kg	x	50 mg	x	1 cap	=	______ caps
		1 kg		250 mg

Cancel out and reduce the numerators and denominators:

		1
40 kg	x	50 mg	x	1 cap	=	______ caps
		1 kg		250 mg
				5

Multiply the numerators and the denominators and then divide their products:

40	x	1	x	1 cap	=	40	=	8 caps/day
		1		5		5

Because the doctor's order read "flucytosine 50 mg/kg/day in four divided doses," it is necessary to divide the total of 8 caps by 4 to determine the number of capsules that would be given for each of the doses:

8	= 2 caps for each dose
4

Now, let's take a few minutes to practice some calculations.

Practice Oral Dosages

Grab your pencil and paper and do these problems.

Practice Problem 1
Doctor's order: KCl 20 meq po
Medication label: KCl 15 meq/11.25 mL
How many mL would you administer?

Practice Problem 2
Doctor's order: Gantrisin 250 mg po
Medication label: Gantrisin 0.5 g/tab
How many tabs would you administer?

Practice Problem 3
Doctor's order: trimethoprim 5 mg/kg po. The patient weighs 80 kg.
Medication label: trimethoprim 160 mg/tab. The tabs are scored in half.
How many tabs would you administer?

Practice Problem 4
Doctor's order: nystatin 3 mg/kg po. The patient weighs 115 lb.
Medication label: nystatin 100 mg/tab
How many tabs would you administer?

Answers

1. 15 mL
2. ½ tab
3. 2½ tabs
4. 1½ tabs

Here is how each of the problems was set up and solved:

Practice Problem 1
The starting factor is 20 meq
The conversion factor is 15 meq/11.25 mL
The answer unit is ____ mL

4
20 meq	x	11.25 mL	x	45	=	15 mL
		15 meq		3
		3

Practice Problem 2
The starting factor is 250 mg
The conversion factors are:

• 1,000 mg = 1 g
• 0.5 g/tab

The answer unit is ____ tabs

1
250 mg	x	1 g	x	1 tab	=	1	=	½ tab
		1,000 mg		0.5 g		2
		4

Practice Problem 3
The starting factor is 80 kg
The conversion factors are:

• 5 mg/kg
• 160 mg/tab

The answer unit is ____ tabs

		1
80 kg	x	5 mg	x	1 tab	=	80	=	2 ½ tabs
		1 kg		160 mg		32
				32

Practice Problem 4
The starting factor is 115 lb
The conversion factors are:

• 1 kg = 2.2 lbs
• 3 mg/kg
• 100 mg/tab

The answer unit is ____ tabs.

23
115 lb	x	1 kg	x	3 mg	x	1 tab	=	69	=	1.56 tabs (1 ½ tabs)
		2.2 lb		1 kg		100 mg		44
						20

Intramuscular and Subcutaneous Dosages Using Dimensional Analysis

Intramuscular and subcutaneous dosages are calculated in the same manner as oral dosages when you are using dimensional analysis, however, there are some addition things that you must remember. These special considerations include:

1. It is often necessary to round off when calculating intramuscular and subcutaneous dosages. The dosage is rounded off to the nearest hundredth (0.01) of a mL or cc when you are using a regular syringe or a tuberculin syringe. Your arithmetic must be carried out to the thousandths place (the third decimal place) in order to round off to the hundredths place. If the number in the third decimal place, or thousandths place, is 5 or higher, you round up one number in the hundredths place to determine the dosage. For example, if you are calculating a dosage for a tuberculin syringe and your mathematical calculation gives you 0.187 mL, you would round it off to 0.19 mL because the 7 in thousandths place is greater than or more than 5.
2. Heparin is given in a tuberculin syringe using the subcutaneous route of administration.
3. Insulin is also administered via the subcutaneous route of administration. Most often the insulin is Units 100 insulin and the syringe that is used is also a Units 100 syringe. A 1cc Units 100 syringe can hold up to 100 Units of insulin; a ½cc Units 100 syringe can hold only half of that amount, that is, it can hold up to 50 Units of insulin. At times you may encounter Units 80, Units 60, etc. insulin. There are 80 Units of Units 80 insulin per cc and 60 Units of Units 60 insulin in one cc. A matching syringe (Units 80 and Units 60 syringe) can be used to administer these kinds of insulin, however, calculation using dimensional analysis can also be done.
4. An additional consideration for intramuscular injections is that many calculations, particularly those necessary to determine an antibiotic dosage, require a conversion factor that reflects the amount of the drug per mL after a powder is reconstituted with sterile water or normal saline solution for injection.

Below are some sample problems involving intramuscular and subcutaneous dosages. These calculations are set up and performed using dimensional analysis procedures in the same manner as that used above for the oral dosage calculations.

Sample Calculation 1
Doctor's order: meperidine 30 mg IM q4h prn for pain
Medication label: 50 mg/mL
How many mL or cc would you give?

The starting factor is 30 mg
The conversion factoris 50 mg/1 mL
The answer unit is ____ mL or cc

Starting factor	x	Conversion factor	=	Answer unit
30 mg	x	1 mL	=	_____ mL
		50 mg
30 mg	x	1 mL	=	3	=	0.6 mL
		50 mg		5

Sample Calculation 2
Doctor's order: amikacin 5 mg/kg IM tid. The patient weighs 130 lb.
Medication label: amikacin 500 mg/2 mL
How many mL would you administer?

The starting factor is 130 lb
The conversion factors are:

• 1 kg/2.2 lb
• 5 mg/kg
• 500 mg/2 mL

The answer unit is ____ mL

Starting factor	x	Conversion factors					=	Answer unit
130 lb	x	1 kg	x	5 mg	x	2 mL	=	_____ mL
		2.2 lb		1 kg		500 mg
				1		1
130 lb	x	1 kg	x	5 mg	x	2 mL	=	130 mL	=	1.18 mL
		2.2 lb		1 kg		500 mg		110
		1.1				100

Rounded Off to: 1.2 mL

Sample Calculation 3
Doctor's order: heparin 3,000 Units subcutaneously
Medication label: 5,000 Units/mL
How many mL would you administer?

The starting factor is 3000 Units
The conversion factor is 5,000 Units/mL
The answer unit is ____ mL

Starting factor	x	Conversion factor	=	Answer unit
3,000 Units	x	1 mL	=	_____ mL
		5,000 Units
3
3,000 Units	x	1 mL	=	3	=	0.6 mL
		5,000 Units		5
		5

Sample Calculation 4
Doctor's order: ticarcillin 600 mg IM
Medication label: ticarcillin reconstituted with 2 mL of sterile water to yield 1 g of ticarcillin in 2.6 mL of solution.
How many mL would you administer?

The starting factor is 600 mg

The conversion factors are:

• 1 g/2.6 mL
• 1g/1,000 mg

The answer unit is ____ mL

Starting factor	x	Conversion factors			=	Answer unit
600 mg	x	1 g	x	2.6 mL	=	_____ mL
		1,000 mg		1 g
6
600 mg	x	1 g	x	2.6 mL	=	15.6	=	1.56 mL
		1,000 mg		1 g		10
		10

Rounded Off to: 1.6 mL

Sample Calculation 5
Doctor's order: neomycin 30 mg/kg/day IM in three divided doses. The patient weighs 140 lb.
Medication label: neomycin 250 mg/mL
How many mL would you administer for each of the three doses?

The starting factor is 140 lb

The conversion factors are:

• 30 mg/1 kg
• 1 kg/lb
• 250 mg/1 mL

The answer unit is ____ mL The starting factor is 120 lb. The conversion factors are, , and. The answer unit is the number of mL.

Starting factor	x	Conversion factors					=	Answer unit
140 lb	x	1 kg	x	30 mg	x	1 mL	=	_____ mL
		2.2 lb		1 kg		250 mg
70				6
140 lb	x	1 kg	x	30 mg	x	1 mL	=	____ mL
		2.2 lb		1 kg		250 mg
		1.1				50

70	x	1	x	6	x	1	=	42	=	7. 63 mL
		2.2 lb		1 kg		250 mg
1.1	1	50	5.5

Because the doctor ordered 30 mg/kg over one day in three divided doses, it is necessary to divide the 7.63 mL for the day by 3 to determine how many mL would be given in each of the doses:

7.63	=	2.54, or 2.5 mL per dose
		3

Practice Intramuscular and Subcutaneous Dosages

Now try these intramuscular and subcutaneous dosage calculations:

Practice Problem 1

Doctor's order: heparin 3,000 Units subcutaneously
Medication label: 4,500 Units/ mL
How many mL would you administer?

Practice Problem 2 Doctor's order: cefuroxime 500 mg IM
Medication label: The addition of 3.2 mL of sterile water yields a suspension of 750 mg in 4.2 mL
How many mL would you administer?

Practice Problem 3

Doctor's order: cephalothin 400 mg IM
Medication label: The addition of 4 mL of sterile water yields 0.5 g in 2.2 mL of suspension.
How many mL would you administer?

Practice Problem 4

Doctor's order: neomycin 20 mg/kg/day IM in three divided doses. The patient weighs 120 lb.
Medication label: neomycin 250 mg/mL
How many mL would you administer for each of the three doses?

Practice Problem 5

Doctor's order: 450,000 Units of ampicillin
Medication label: 250,000 Units/mL
How many mL would you administer?

Now, check your answers. The answers are:

Answers

1. 0.7 mL
2. 2.8 mL
3. 1.8 mL
4. 1.4 mL
5. 1.8 mL

Here is how each of the problems is set up and solved:

Practice Problem 1

The starting factor is 3,000 Units
The conversion factor is 1mL/4,500 Units
The answer unit is ____ mL

6
3,000 Units	x	1 mL	=	6	=	0.66 mL
		4,500 Units		9
		9

Rounded Off to: 0.7 mL

Practice Problem 2

The starting factor is 500 mg

The conversion factor is 750 mg/4.2 mL

The answer unit is ____ mL

2
500 mg	x	4.2 mL	=	8.4	=	2.8 mL or with more cancellations:
		750 mg		3
		3

2		1.4
500 mg	x	4.2 mL	=	2.8	=	2.8 mL
		750 mg		1
		3
		1

Practice Problem 3

The starting factor is 400 mg

The conversion factors are:

• 1g/1,000 mg
• 0.5g/2.2 mL

The answer unit is ____ mL

2
400mg	x	1 g	x	2.2 mL	=	4.4 mL	=	1.76 mL
		1,000 mg		0.5 g		2.5
		5

Rounded Off to: 1.8 mL

Practice Problem 4

The starting factor is 120 lb
The conversion factors are:

• 1 kg/2.2 lbs
• 20 mg/1 kg
• 250 mg/1 mL

The answer unit is ____

60				4
120 lb	x	1 kg	x	20 mg	x	1 mL	=	24 mL	=	4.36 mL
		2.2 lb		1 kg		250 mg		5.5
		1.1				50

Because the doctor ordered 20 mg/kg over one day in three divided doses, it is necessary to divide the 4.36 mL for the day by 3 to determine how many mL would be given in each of the doses:

4.36	mL = 1.45 mL rounded off to: 1.4 mL
3

Practice Problem 5

The starting factor is 450,000 Units
The conversion factor is 250,000 Units/1 mL
The answer unit is ____ mL

9
450,000 U	x	1 mL	=	9	=	1.8 mL
		250,000 Units		5
		5

Calculating IV Flow Rates Using Dimensional Analysis and the One-Step, No-Rules Method

This final portion of this course will teach you:

• how to calculate, or compute, IV flow rates and other IV dosage calculations using dimensional analysis and also
• a one-step, no-rules IV flow rate method to determine the number of drops per minute when you know the ordered number of cc per hour.

IV Flow Rates Using Dimensional Analysis

As you probably know, IV tubing is manufactured by a number of different companies. Each tubing set has a drop factor that indicates whether it delivers 10, 15, 20, or 60 drops (gtt) per mL of solution. The 60 gtt per mL tubing, which is often referred to as microdrop tubing or pediatric tubing, delivers the smallest drops of all the sets. The 10 gtt/mL tubing delivers the largest drops of solution.

When calculating the number of drops per minutes, the number of drops is rounded off to the nearest whole drop.

The IV flow rate calculations immediately below are set up and performed using dimensional analysis.

Sample Calculation 1

Doctor's order: 0.9% NaCl solution at 100 mL per hour
How many gtt per minute would you give if the tubing delivered 20 gtt/mL?

The starting factor is 1 minute
The conversion factors are:

• 1 h/ 60 min
• 100 mL/ h
• 20 gtt/ 1 mL

The answer unit is ____ gtts/min

Starting factor	x	Conversion factors					=	Answer unit
1 min	x	1 h	x	100 mL	x	20 gtt	=	____ gtt
		60 min		1 h		1 mL

				5
				10
1 min	x	1 h	x	100 mL	x	20 gtt	=	100	=	33.3 gtt
		60 min		1 h		1 mL		3
		6
		3

Rounded Off to: 33 gtt/min

Sample Calculation 2

Doctor's order: 1,000 mL of 5% D 0.45 normal saline solution to infuse over 4 hours
How many gtt per minute would you give if the tubing delivers 10 gtt/mL?

The starting factor is 1 minute

The conversion factors are:

• 1 h/ 60 min
• 1000 mL/ 4 h
• 10 gtt/ 1 mL

The answer unit is ____ gtts/min

Starting factor	x	Conversion factors					=	Answer unit
1 min	x	1 h	x	1,000 mL	x	10 gtt	=	____ gtt
		60 min		4 h		1 mL

				250		1
1 min	x	1 h	x	1000 mL	x	10 gtt	=	250	=	41.6 or 42 gtt
		60 min		4 h		1 mL		6
		6		1

Sample Calculation 3

Doctor's order: 30 mL/h of 5% D 0.45 normal saline solution

How many gtt per minute would you give if the tubing delivered 60 gtt/mL?

The starting factor is 1 minute
The conversion factors are:

• 1 h/ 60 min
• 30 mL/h
• 60 gtt/ 1 mL

The answer unit is ____ gtts/min

Starting factor	x	Conversion factors					=	Answer unit
1 min	x	1 h	x	30 mL	x	60 gtt	=	____ gtt
		60 min		1 h		1 mL

						1
1 min	x	1 h	x	30 mL	x	60 gtt	=	30 gtt
		60 min		1 h		1 mL
		1

Sample Calculation 4

Doctor's order: 25 mL/h of 5% D 0.45 normal saline solution
How many gtt per minute would you give if the tubing delivered 60 gtt/mL?

The starting factor is 1 minute

The conversion factors are:

• 1 h/ 60 min
• 25 mL/h
• 60 gtt/ 1 mL

The answer unit is ____ gtts/min

Starting factor	x	Conversion factors					=	Answer unit
1 min	x	1 h	x	25 mL	x	60 gtt	=	____ gtt
		60 min		1 h		1 mL
						1
1 min	x	1 h	x	25 mL	x	60 gtt	=	25 gtt
		60 min		1 h		1 mL
		1

Did you notice that the last two calculations, which use the microdrop or 60 gtt/mL IV tubing, yielded the same number of gtt per minute as the number of mL per hour that was ordered? Good observation!

Specifically, the first doctor's order was for 30 mL per hour. You would have to run the IV solution at 30 gtt per minute to deliver 30 mL per hour. The second doctor's order called for 25 mL per hour. You would have to run the IV solution at 25 gtt per minute in order to deliver 25 mL an hour.

If you look closely at these two calculations, you will see that the conversion factor of 60 min = 1 h cancels out the conversion factor of 60 gtt per mL. We will now move one step further with this observation.

IV Flow Rates Using the One-Step, No-Rules Method

In order to calculate using the one-step, no-rules method, you need to know the number of mL per hour ordered. Occasionally, the doctor's order clearly states the number of mL per hour, which is the easiest scenario. If the doctor's order specifies the number of mL per 8 hours, 12 hours, or any other number of hours rather than the number of mL for each hour, it is necessary to first determine the number of mL to be administered per hour.

For example, if the doctor orders 1,000 mL in 8 hours, you must divide 1,000 mL by 8 to determine the number of mL per hour. The answer is 125 mL/h.

Likewise, if the doctor orders 2 liters of IV fluid over 12 hours, the calculation to determine the number of mL per hour is as follows: 2,000 mL/12 = 166.6 mL, which rounds off to 167 mL/h.

Once you have observed that the number of mL/h is identical to the number of gtt/min, something that never changes when you are using a 60 gtt/mL tubing, it soon becomes apparent that for tubing with other drop factors (10 gtt/mL, 15 gtt/mL, and 20 gtt/mL), you must simply look at the relationship of the drop factor to the ever-present 60, the never-changing number of minutes in an hour.

For example, if you are using IV tubing with a 20 gtt/mL drop factor, you have to look at the relationship between the 20 in the tubing drop factor and the ever-present 60, the number of minutes in an hour. The relationship between 60 and 20 is 3; in other words, 60/20 = 3.

Similarly, if you are using IV tubing with a 10 gtt/mL drop factor, you have to look at the relationship between the 10 in the tubing drop factor and the number 60. The relationship between 60 and 10 is 6: 60/10 = 6. Finally, if you are using IV tubing that delivers 15 gtt/min, the relationship of 60 to 15, or 4, requires you to divide the number of mL an hour by 4.

Now that you know all the possible relationships, it is only necessary to divide the number of mL an hour:

• By 3 for a 20 gtt/mL drop factor tubing
• By 6 for a 10 gtt/mL drop factor tubing, and
• By 4 for a 15 gtt/mL drop factor tubing.

All you have to do is one step. There are no rules to forget, no complicated formulas, and no unnecessary steps!

Here are some examples:

If you are using a 10 gtt/mL set, the number of drops per minute will always be the number of mL an hour divided by 6.

100 mL/h: 100/6 = 16.6 = 17 gtt/min rounded off

125 mL/h: 125/6 = 20.8 = 21 gtt/min rounded off

150 mL/h: 150/6 = 25 gtt/min

If you are using 20 gtt/mL IV tubing, the number of drops per minute will always be the number of mL an hour divided by 3.

100 mL/h: 100/3 = 33.3 = 33 gtt/min rounded off

125 mL/h: 125/3 = 41.6 = 42 gtt/min rounded off

150 mL/h: 150/3 = 50 gtt/min

And, finally, if you are using 15 gtt/mL tubing, the number of drops per minute will be the number of mL an hour divided by 4.

100 mL/h: 100/4 = 25 gtt/min

125 mL/h: 125/4 = 31.2 = 31 gtt/min rounded off

150 mL/h: 150/4 = 37.5 = 38 gtt/min

This one-step, no-rules method of calculating the number of IV drops per minute works all the time because there are always 60 minutes in an hour. The one step involved in calculating the number of drops per minute consists of dividing the relationship number for the specific IV tubing set into the number of mL per hour ordered by the doctor. Pediatric (60 gtt/mL) tubing has an identity relationship; therefore, the number of drops per minute will always exactly match the number of mL per hour.

This one-step method is particularly useful because nurses caring for patients with IV infusions should count and verify the number of drops per minute at the bedside with each patient contact. Volumetric controllers and pumps are not always accurate and do not always function properly.

Other IV Calculations Using Dimensional Analysis

Calculating the number of drops per minute, or the flow rate, is probably the most frequently used IV calculation in nursing, however, there are other IV computations that you will also have to know. These include calculating the following:

• total infusion time;
• the concentration of a medication in an IV solution that should be given; and
• IV flow rates based on body weight.

Calculating Total Infusion Time

When you have adjusted an IV solution to run at a certain number of drops per minute, you will always want to know when the solution is should finish infusing so that you can anticipate the need to hang another bag of solution, if so ordered. Additionally, even when you are using a controller the accuracy of the flow rate is not always fail proof. Machines fail. You must, therefore, be able to calculate the total infusion time for the presently infusing bag.

Following is an example of how this type of calculation is accomplished using dimensional analysis.

Total volume of IV fluid: 800 mL

Infusion rate: 23 gtt/min

Drop factor: 10 gtt/mL

When will the liter of fluid run out?

The starting factor is 800 mL
The conversion factors are:

• 10 gtt/ 1 mL
• 23 gtt/ 1 min
• The answer unit is ____ a unit of time (min and/or hr and/or hr and min.

Starting factor	x	Conversion factors					=	Answer unit
800 mL	x	10 gtt	x	1 min	x	1 h	=	_____ h
		1 mL		23 gtt		60 min

				1
800 mL	x	10 gtt	x	1 min	x	1 h	=	800	=	5.79 h (5 h 47 min)
		1 mL		23 gtt		60 min		138
						6

Calculating the Concentration of a Medication in an IV Solution

On some occasions, a physician may order an hourly dosage of a medication that has been diluted in an IV fluid.

For example, the doctor may order an hourly dosage of 1,400 units of heparin that has 20,000 units of heparin diluted in 1,000 mL of normal saline solution. The nurse must then be able to calculate the flow rate of the fluid based not on the volume of the fluid ordered, but instead, on the dosage of the medication.

The starting factor is 1 h

The conversion factors are:

• 1,400 Units/1 h
• 20,000 Units/1,000 mL

The answer unit is ____ mL

The starting factor is 1 h; The conversion factors are 1,200 Units/1 h and; and The answer unit is the number of mL.

Starting factor	x	Conversion factors			=	Answer unit
1 h	x	1,400 Units	x	1,000 mL	=	_____ mL
		1 h		20,000 Units
		70		1
1 h	x	1,400 Units	x	1,000 mL	=	70 mL
		1 h		20,000 Units
				20
				1

Calculating IV Flow Rates Based on Body Weight

When a doctor's order specifies a volume of fluid or a dosage of a diluted medication over a period of time based on body weight, the calculation is similar to those described above with the addition of a conversion factor that allows for body weight.

For example, if you are caring for a patient that weighs 250 lb and the doctor orders 5 mcg/kg/min of a medication intravenously infused via 500 mL of an IV fluid that contains 250 mg of the medication, you would perform the following computation to determine the number of mL per minute or hour that the patient will receive.

The starting factor is 250 lb

The conversion factors are:

• 1 kg/2.2 lb
• 5 mcg/1 kg
• 1 mg = 1,000 mcg
• 250 mg/500 mL

The answer unit is ____ mL

Starting factor	x	Conversion factors							=	Answer unit
250 lb	x	1 kg	x	5 mcg	x	1 mg	x	500 mL	=	_____ mL
		2.2 lb		1 kg		1,000 mcg		250 mg

1

1

250 lb

x

1 kg

x

5 mcg

x

1 mg

x

500 mL

=

5

=

1.136 mL

2.2 lb

1 kg

1,000 mcg

250 mg

4.4

2

1

The number of mL to be administered per hour = 1.136 . 60 = 68.16 mL

Rounded Off to: 68.2 mL

Practice Problem 1

Total volume of IV fluid at the beginning of your shift: 350 mL

Infusion rate: 21 gtt/min

Drop factor: 15 gtt/mL

When will this fluid run out?

Practice Problem 2
How many mL/h would you administer if the doctor orders 30 Units/h of a medication that has been diluted in a solution with a total of 250 Units in 1,000 mL?

Practice Problem 3

If your patient weighs 100 lb and the doctor orders 5 mcg/kg/min of a medication intravenously infused via 500 mL of an IV fluid that contains 250 mg of the medication, how many mL/min and mL/h would you administer?

Here are the Answers 1. 4 h 10 min 2. 120 mL/h 3. 0.45 mL/h and 27 mL/h Practice Problem 1

The starting factor is 350 mL

The conversion factors are:

• 15 gtts/1 mL
• 21 gtts/ 1 min
• 1 h/ 60 min

The answer unit is ____ h or min

350 mL	x	15 gtt	x	1 min	x	1 h	=	_____ h
		1 mL		21 gtt		60 min

		1
350 mL	x	15 gtt	x	1 min	x	1 h	=	350	=	4.16 h (4 h 10 min)
		1 mL		21 gtt		60 min		84
						4

Practice Problem 2

The starting factor is 30 Units

The conversion factor is 250 Units/1,000 mL

The answer unit is ____ mL/h

30 Units	x	1,000 mL	=	_____ mL
		250 U

3
30 Units	x	1,000 mL	=	3,000	=	120 mL/h
		250 Units		25
		25

Practice Problem 3 The starting factor is 100 lb

The conversion factors are:

• 1 kg/ 2.2 lb
• 5mcg/1kg
• 1 mg/1,000 mcg
• 500 mL/ 50 mg

The answer unit is ____ mL/min and mL/h

100 lb	x	1 kg	x	5 mcg	x	1 mg	x	500 mL	=	_____ mL
		2.2 lb		1 kg		1,000 mcg		250 mg

1

1

1

10

100 lb

x

1 kg

x

5 mcg

x

1 mg

x

500 mL

=

1

=

0.45 mL

2.2 lb

1 kg

1,000 mcg

50 mg

2.2

10

50

1

1

Per hour:
0.45 . 60 = 27 mL/h

Summary

Dimensional analysis is a highly useful way to calculate dosage and solution problems of all types. It is an orderly and systematic mathematical process that results in consistent accuracy, provided the equation is set up correctly and careless mathematical errors are avoided.

RATIO AND PROPORTION

This portion of this course teaches the ratio and proportion method of calculating dosages. It provides the learner with an opportunity to use ratio and proportion calculations for a wide variety of oral, intramuscular, subcutaneous, and intravenous calculations as well as many practice calculations.

WHAT IS RATIO?

Ratio

Ratio is a relationship in terms of size, amount, or quantity of two or more things. They are pairs of numbers that are used to make comparisons between the numbers.

For example, the ratio of men compared to women included in a pharmacological research study may be 3 to 1. There are 3 times as many men in the study as there are women.

Ratios can be written in 3 different ways, as below:

• 1 to 4
• 1:4
• 1/4

Comparing Ratios

Write the ratios as fractions when you want to compare them. All ratios must be equal or they are not a ratio.

For example, the ratios 1/4 and 2/8 are equal. When you set up these ratios and criss cross multiple the numerators and denominators you end up with the same number, that is 8. These ratios are equal.

1	=	2
4		8

1 x 8 = 8 and
2 x 4 = 8

WHAT IS PROPORTION ?

Proportion

Proportion is the relationship of one part to another or to the whole in respect to size, size, amount or quantity. A proportion is an equation with a ratio on each side of the equal sign. Solving proportions involves criss cross multiplying and then finding out what the missing number is using division.

For example:

2	=	?
8		24

2 x 24	=	48	=	6
8		8

OR

1
2 x 24	=	24	=	6
8		4
4

Calculating Oral Dosages Using Ratio and Proportion

The doctor orders: 250 mg of a medication
The label on the medication states: 1 tablet = 125 mg
How many tablets will you administer?

250 mg: x tabs :: 125 mg: 1 tab
OR
250 mg: x tabs = 125 mg: 1 tab
OR

250 mg	=	125 mg
x tabs		1 tab

The immediately above setup allows us to more simply reduce numerators and denominators by dividing each by the same number and to more easily avoid errors as we criss cross multiply.

250 mg	=	125 mg	=	125 x	=	250	=
x tabs		1 tab
				x	=	250	=	2 tablets
						125

Doctor's order: tetracycline syrup 250 mg po
Medication label: tetracycline syrup 50 mg/mL
How many mL should you administer?

250 mg	=	50 mg	=	50 x	=	250
x mL		1 mL
				x	=	250	=	5 mL
						50

Grab your pencil and paper and do these problems.

Practice Problem 1
Doctor's order: KCl 20 meq po
Medication label: KCl 15 meq/11.25 mL
How many mL would you administer?

Practice Problem 2
Doctor's order: Gantrisin 250 mg po
Medication label: Gantrisin 0.5 g/tab
How many tabs would you administer?

Practice Problem 3
Doctor's order: trimethoprim 5 mg/kg po. The patient weighs 80 kg.
Medication label: trimethoprim 160 mg/tab. The tabs are scored in half.
How many tabs would you administer?

Practice Problem 4
Doctor's order: nystatin 3 mg/kg po. The patient weighs 115 lb.
Medication label: nystatin 100 mg/tab
How many tabs would you administer?

Answers

1. 15 mL
2. ¼ tab
3. 2 ½ tabs
4. 1 ½ tabs

Practice Problem 1

20 meq	=	15 meq	=	15 x	=	20	X	11.25
x mL		11.25 mL
				15 x = 225
						45
				x	=	225	=	15 mL
						15
						3

Practice Problem 2

250 mg	=	1000 mg	=	1000 x	=	250
x g		1g
						1
				x	=	250	=	0.25 g
						1000
						4

This problem is a two step problem. Above we calculated the number of g for the 250 mg dose because the drug label is in g and not mg. Next we will calculate the dose to be administered in terms of g.

0.25 g	=	0.5 g	=	0.5	x	=	0.25
x tabs		1 tab
					x	=	0.25	=	0.5 or ½ tab
							0.5

Practice Problem 3

80 kg	=	1 kg	=	x	=	80 X 5	=	400 mg
x mg		5 mg

This problem is also a two step problem. Above we calculated the number of mg to be administered as per the patient's body weight. Next we will calculate the dose to be administered in terms of tablets as based on the patient's weight and the fact that the doctor has ordered 5 mg for each kg of body weight.

400 mg	=	160 mg	=	160	x	=	400
x tabs		1 tab
					x	=	400	=	2 ½ tablets
							160

Practice Problem 4

115 lb	=	2.2 lb	=	2.2	x	=	115
x kg		1 kg
					x	=	115	=	52.27 kg
							2.2

This problem is a three step problem. Above we calculated the number of kg a patient weighs as based on the patient's body weight in pounds. The patient weighs 115 pounds or 52.27 kg. This can be rounded off to 52 kg.

Next we will calculate the dose to be administered in terms of mg as based on the patient's weight in kg.

52 kg	=	1 kg	=	x	=	156 mg
x mg		3 mg

Finally, we will calculate how many tablets will be administered in terms of body weight when each tablet has 100 mg.

x tabs	=	1 tab	=	100	x	=	156
156 mg		100 mg
					x	=	156	=	1.56 tabs rounded off to 1 ½ tabs
							100

Calculating Intramuscular and Subcutaneous Dosages Using Ratio and Proportion

Sample Calculation 1
Doctor's order: meperidine 30 mg IM q4h prn for pain
Medication label: 50 mg/mL
How many mL or cc would you give?

30 mg	=	50 mg	=	50	x	=	30 mL
					x	=	30	=	0.6 mL
							50

Sample Calculation 2
Doctor's order: amikacin 5 mg/kg IM tid. The patient weighs 130 lb.
Medication label: amikacin 500 mg/2 mL
How many mL would you administer?
Again, there are multiple steps in this problem. First, we will calculate how many kg the patient weighs. Next, we will determine how many mg the patient will get in each tid dose. Lastly, we will calculate how may mL we will have to administer for the ordered number of mg.

130 lb	=	2.2 lb	=	2.2	x	=	130
x kg		1kg
					x	=	130	=	65 kg
							2.2

5 mg	=	x mg	=	1	x	=	65	X	5	=	325 mg
1 kg		65 kg

500 mg	=	325 mg	=	500	x	=	325	X	2
2 mL		x mL
					x	=	650	=	1.3 mL
							500

Sample Calculation 3
Doctor's order: heparin 3,000 Units subcutaneously
Medication label: 5,000 Units/mL
How many mL would you administer?

x mL	=	1 mL	=	5,000	x	=	3,000
3,000 Units		5,000 Units
					x	=	3,000	=	0.6 mL
							5,000

Sample Calculation 4
Doctor's order: ticarcillin 600 mg IM
Medication label: ticarcillin reconstituted with 2 mL of sterile water to yield 1 g of ticarcillin in 2.6 mL of solution.
How many mL would you administer?

600 mg	=	1,000 mg	=	1,000	x	=	600
x g		1 g
					x	=	600	=	0.6 g
							1000
0.6 g	=	1 g	=	x		=	0.6 X 2.6	=	1.56 m:
x mL		2.6 mL

Rounded Off to: 1.6 mL

Sample Calculation 5
Doctor's order: neomycin 30 mg/kg/day IM in three divided doses. The patient weighs 140 lb.
Medication label: neomycin 250 mg/mL
How many mL would you administer for each of the three doses?

140 lb	=	2.2 lb	=	2.2	x	=	140
x kg		1 kg
					x	=	140	=	63.63 or 64 kg
							2.2

30 mg	=	x mg	=	x	=	64	x 30	=	1902 mg
1 kg		64 kg
		1902 mg	=	250 mg	=	250	x	=	1902
		x mL		1 mL
					x	=	1902	=	7.6 mL
							250

Because the doctor ordered 30 mg/kg over one day in three divided doses, it is necessary to divide the 7.6 mL for the day by 3 to determine how many mL would be given in each of the doses:

7.6 divided by 3 is 2.5 mL per dose

Now try these intramuscular and subcutaneous dosage calculations:

Practice Problem 1
Doctor's order: heparin 3,000 Units subcutaneously
Medication label: 4,500 Units/ mL
How many mL would you administer?

Practice Problem 2
Doctor's order: cefuroxime 500 mg IM
Medication label: The addition of 3.2 mL of sterile water yields a suspension of 750 mg in 4.2 mL
How many mL would you administer?

Practice Problem 3
Doctor's order: cephalothin 400 mg IM
Medication label: The addition of 4 mL of sterile water yields 0.5 g in 2.2 mL of suspension.
How many mL would you administer?

Practice Problem 4
Doctor's order: neomycin 20 mg/kg/day IM in three divided doses. The patient weighs 120 lb.
Medication label: neomycin 250 mg/mL
How many mL would you administer for each of the three doses?

Practice Problem 5
Doctor's order: 450,000 Units of ampicillin
Medication label: 250,000 Units/mL
How many mL would you administer?

Now, check your answers. The answers are:

Answers

1. 0.7 mL
2. 2.8 mL
3. 1.8 mL
4. 1.4 mL
5. 1.8 mL

Here is how each of the problems is set up and solved:

Practice Problem 1

3,000 Units	=	4,500 Units	=	4,500	x	=	3,000
x mL		1 mL
					x	=	3,000	=	0.66 mL
							4,500

Rounded Off to: 0.7 mL

Practice Problem 2

500 mg	=	750 mg	=	750	x	=	500 X 4.2
x mL		4.2 mL
					x	=	2100	=	2.8 mL
							750

Practice Problem 3

400 mg	=	1,000 mg	=	1000	x	=	400
x g		1 g
					x	=	400	=	0.4 g
							1000

0.4 g	=	0.5 g	=	0.5	x	=	0.4 X 2.2
x mL		2.2 mL
					x	=	.88	=	1.76 mL
							0.5

Rounded Off to: 1.8 mL

Practice Problem 4

120 lb	=	2.2 lb	=	2.2	x	=	120
x kg		1 kg
					x	=	120	=	54.5 kg
							2.2

54.5	=	1 kg	=	x	=	54.5 X 20	=	1090 mg
x mg		20 mg				1
1090 mg	=	250 mg	=	250	x	=	1090
x mL		1 mL
					x	=	1090	=	4.36 mL
							250

Because the doctor ordered 20 mg/kg over one day in three divided doses, it is necessary to divide the 4.36 mL for the day by 3 to determine how many mL would be given in each of the doses:

4.36 divided by 3 is 1.45 mL This is rounded off to 1.4 mL

Practice Problem 5

450,000 Units	=	250,000 Units	=	250,000	x	=	450,000
x mL		5 mL
					x	=	450,000	=	1.8 mL
							250,000

Calculating Intravenous Flow Rates

The rule for calculating intravenous flow rates is as below.

gtts/min	=	Total number of mL	x	Drip or drop factor
		Total number of minutes

Sample Calculation 1

Doctor's order: 0.9% NaCl solution at 100 mL per hour

How many gtt per minute would you give if the tubing delivered 20 gtt/mL?

x gtts per minute	=	100	x	20	=	2000	=	33.3 gtt
		60				60

Rounded Off to: 33 gtt/min

Sample Calculation 2

Doctor's order: 1,000 mL of 5% D 0.45 normal saline solution to infuse over 4 hours

How many gtt per minute would you give if the tubing delivers 10 gtt/mL?

x gtts per minute	=	1000	x	10	=	10,000	=	41.6 gtt
		240				240

Rounded off to 42 gtt per minute

Sample Calculation 3

Doctor's order: 30 mL/h of 5% D 0.45 normal saline solution

How many gtt per minute would you give if the tubing delivered 60 gtt/mL?

x gtts per minute	=	30	x	60	=	1800	=	30 gtt
		60				60

Sample Calculation 4

Doctor's order: 25 mL/h of 5% D 0.45 normal saline solution

How many gtt per minute would you give if the tubing delivered 60 gtt/mL?

x gtts per minute	=	25	x	60	=	1,500	=	25gtt
		60				60

Now, do these practice problems.

Practice Problem 1

Doctor's order: 75 mL/h

How many gtt per minute would you give if the tubing delivered 60 gtt/mL?

Practice Problem 2

Doctor's order: 125 mL/h

How many gtt per minute would you give if the tubing delivered 15 gtt/mL?

Practice Problem 3

Doctor's order: 150 mL/h

How many gtt per minute would you give if the tubing delivered 20 gtt/mL?

Practice Problem 4

Doctor's order: 80 mL/h

How many gtt per minute would you give if the tubing delivered 10 gtt/mL?

Practice Problem 5 Doctor's order: 150 mL/h

How many gtt per minute would you give if the tubing delivered 15 gtt/mL?

Now, check your answers. The answers are:

Answers

1. 75 gtt
2. 31 gtt
3. 50 gtt
4. 13 gtt
5. 37 gtt

Here is how each of the problems is set up and solved:

Practice Problem 1

x gtts per minute	=	75	x	60	=	75 gtt
		60

Practice Problem 2

				1
x gtts per minute	=	125	x	15	=	31.2 or 31 gtt
		60
		4

Practice Problem 3

				1
x gtts per minute	=	150	x	20	=	50 gtt
		60
		3

Practice Problem 4

x gtts per minute	=	80	x	10	=	13.3 or 13 gtt
		60
		6

Practice Problem 5

				1
x gtts per minute	=	150	x	15	=	37.5 or 37 gtt
		60
		4

Ratio and proportion is useful way to calculate dosage and solution problems of all types. It is an orderly and systematic mathematical process that results in consistent accuracy, provided the equation is set up correctly and careless mathematical errors are avoided.

PHARMACOLOGY RESOURCES

Because of the complexities of pharmacology, the vast and ever increasing number of available medications on the market, and the fact that several medications are pulled from the market ever year, it is imperative that you are able to use current and reliable pharmacological resources, such as a formulary, the PDR or another drug reference book.

Referring to any reliable pharmacology resource book, answer the following questions.

1. What is the trade name of busulfan?
2. What is the generic name for Neoral?
3. What other medications have the same generic name as Neoral?
4. What classifications of medication does propantheline bromide belong to?
5. What is ifosfamide used for?
6. What is the recommended adult initial oral dosage of phenytoin for grand mal seizures?
7. What is the recommended adult loading IV dosage of phenytoin for status epilepticus?
8. What is hyaluronidase indicated for?
9. What are the contraindications for cyclobenzaprine hydrochloride?
10. What are some of the side effects and adverse drug reactions associated with menotropins?
11. What medications interact with pemoline?
12. What foods interact with ramipril?
13. What lifestyle components interact with chlorpheniramine maleate?
14. What forms and routes is metronidazole supplied in?
15. Which bodily systems and functions must be assessed prior to and during Parlodel therapy?

Answers

1. Myleran
2. cyclosporine or cyclosporin
3. Sandimmune and Sandimmun
4. anticholinergic and GI antispasmodic and antimuscarinic
5. testicular cancer
6. 100 mg tid
7. 10 to 15 mg/kg
8. It is used as an adjunct to increase the absorption and dispersion of other injected medications; hypodermoclysis and urography when a contrast medium is given subcutaneously
9. Hypersensitivity; post acute MI; heart block; patients who have taken MAO inhibitors within 14 days; conduction disturbances; arrhythmias and heart failure.
10. Nausea, vomiting, multiple births, ovarian enlargement, CVA, tachycardia, atelectasis, acute respiratory distress, pulmonary emboli, arterial occlusion, hypersensitivity, and anaphylaxis.
11. Insulin and oral hypoglycemic medications
12. Salt substitutes with potassium
13. Alcohol use
14. The forms are capsules, tablets, oral suspension, liquid for injection and powder to injection. The routes are oral and intravenous.
15. Hepatic, renal and cardiac systems; hematopoietic function

Care has been taken to confirm the accuracy of the information presented in this course and to describe generally accepted practices and drug information. However, the author and publisher are not responsible for errors or omissions or for any consequences from application of the information and make no warranty, express or implied, with respect to the contents of the publication.

REFERENCES

Joint Commission on Accreditation of Healthcare Organizations (2004)." 2004 National Patient Safety Goals - FAQs"
http://www.jcaho.org/accredited+organizations/patient+safety/04+npsg/04_faqs.htm

Skidmore-Roth, Linda (2004). Mosby's Rapid Reference Library. CD-ROM

Contact Hour: 16
Price: $79.95
Course Title: PHARMACOLOGY
Course Number: 20-67011

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