Pharmacology for the Soldier Medic
Given a patient/casualty with known symptoms.
As a soldier medic, you will be dealing with a number of drugs to treat various conditions. In order to provide the patient with useful information and to protect the patient, you must understand how drugs affect the body.
Terms and Definitions
a. Drug - agents used in the treatment, prevention or diagnosis of a disease, or in the promotion or prevention of pregnancy
b. Pharmacology - study of the effects of drugs on living systems, and their therapeutic uses
c. Bio-availability - amount of drug that is available to the target tissue after the drug has been administered. The amount of drug available to produce the desired effect
d. Toxicology - the science of poisons
e. Usual dose - the amount of a drug that will ordinarily produce the effect for which the drug is intended
f. Minimum dose - the smallest dose of a drug that produces the therapeutic effect
g. Maximum dose - the largest dose of a drug that can be safely administered
h. Single dose - the amount of drug to be administered at one time
i. Daily dose - the amount of drug to be taken in a 24-hour period. The daily dose of a drug is usually divided into several single doses
j. Maintenance dose - the amount of that substance taken to maintain a desired therapeutic effect. Some drugs must be taken on a daily basis in order to maintain the desired therapeutic effect. For example, drugs used to treat high blood pressure often must be taken daily to maintain a lowered blood pressure
a. Plants
(1) Belladonna
(2) Opium
b. Animals
(1) Heparin
(2) Insulin
c. Minerals
(1) Iodine
(2) Iron
d. Microorganisms
(1) Antibiotics - penicillin, tetracycline
(2) Vaccines
e. Synthetics
(1) Aspirin
(2) Acetaminophen
Use of Drugs
a. To maintain health
(1) Treatment of disease - antibiotics and chemotherapeutic (anticancer) agents are commonly used in medicine today
(2) To relieve symptoms - drugs which act to relieve symptoms but do not cure the patient. Instead, they help to make the patient more comfortable in order for the patient to work or function.
b. To prevent disease
(1) Immunization - vaccines and toxoids are used to prevent disease
(2) Nutrition - vitamins and minerals
c. To diagnose disease - radiopharmaceuticals are used to diagnose many diseases
d. To prevent pregnancy
Factors that Affect the Desired Effect of a Drug
a. Age - as a general rule, the very young and the very old require smaller doses than the average adult
b. Size
(1) Weight - obese or larger patients may require a higher dose of medication to achieve the same effect than a thin or smaller patient
(2) Surface area - this takes into account both the patients height and weight for the determining of the proper dose of medication. This method is more accurate than using just the patient's weight and is routinely used for antineoplastic (cancer) medications
c. Sex - females have more adipose (fat) cells than males, in proportion to their body weight. As a result, females may need higher doses of fat-soluble drugs to achieve the same effects. The utilization and metabolism of various hormones is also effected by gender.
d. Time of administration - the time of day a medication is administered may alter the amount of drug that is absorbed. For example, many antibiotics are having a higher degree of bio-availability if taken before meals (on an empty stomach), while some actually work better if taken after a meal
e. Drug interactions - the interaction between two or more drugs may affect the overall effectiveness of each drug
(1) Synergistic - the joint action of drugs. The combined effect is greater then the sum of the individual effects. (1 + 1 = 3)
(2) Additive - the combined effect is equal to the sum of the effects of the individual agents. (1 + 1 = 2) (i.e., 1 Aspirin and 1 Acetaminophen given together for fever.)
(3) Antagonistic - the combined effect is actually less then the action of either agent (1+1=0)
f. Tolerance - after taking a medication for some time, a patient may require a larger dose to obtain the desired effect (opiates, cocaine, amphetamines, and barbiturates). This is especially true for narcotic analgesics. Cross-tolerance - the use of one drug can cause tolerance to another - addicts can develop tolerance to sedatives and anesthetics
g. Genetic factors - different ethnic groups may metabolize certain drugs at different rates
h. Physical condition of patient - weak, ill, or debilitated patients may require less medication. Patients in severe pain may require a higher dose of analgesics to relieve the pain
i. Routes of administration - the route of administration may determine the rate of absorption, or the amount of drug that is metabolized
j. Psychological condition of the patient - in some cases, if a patient believes that the medication will work, the patient may obtain a positive clinical response. This is termed the placebo effect
a. Oral
(1) Tablet; capsule; liquid
(2) Usually taken for systemic effect
(3) Must pass through stomach and be absorbed
(4) Delayed onset of action
b. Sublingual
(1) Dissolved under tongue
(2) Taken for systemic effect
(3) Rapid onset of action
(4) Avoids gut
c. Buccal
(1) Dissolved in pouch of cheek
(2) Taken for systemic effect
(3) More rapid onset of action than oral route, but less than sublingual route
(4) Avoids gut
d. Rectal
(1) Cream, suppository, or liquid
(2) Used for local and systemic effect
(3) Useful in unconscious or pediatric patients
e. Vaginal/urethral
(1) Cream or suppository
(2) Used for local effect
(3) Should not irritate tissue
(4) May be absorbed
f. Inhalation
(1) Sprays, gases, powders
(2) Used for local or systemic effect
(3) May be administered nasally or orally
g. Topical
(1) Sprays, creams, powders, gels, ointments, patches
(2) Used for local or systemic effect
h. Parenteral
(1) Advantages
(a) By-pass the G.I. tract
(b) Rapid onset of action
(c) Prolonged action, depending on vehicle
(d) Used for local or systemic effects
(2) Disadvantages
(a) Painful to the patient
(b) Inconvenient
(c) Once medication is administered, you can't recover the drug
(d) May expose nursing staff to blood or body fluids
(3) Types of parenteral routes
(a) Intravenous (I.V.)
1) Most rapid onset
2) Drug injected directly into vein
(b) Intramuscular (I.M.)
1) Drug injected deep into muscle
2) If aqueous base, absorption is rapid, but slower than the intravenous route
3) If oil base, absorption is slow
(c) Intradermal (I.D.)
1) Drug injected into dermal layer of the skin
2) Used for diagnostic tests
(d) Subcutaneous (SQ/SC)
1) Drug injected into the fatty layer below skin, but not into the muscle
2) Route is slower than the IM route, because the subcutaneous tissue is less vascular than the muscular tissue
3) Must be nonirritating or it may cause tissue necrosis
(e) Spinal (Intrathecal, Epidural, & Caudal) - Drug injected into or near the spinal cord
a. Direct toxicity
(1) Blood dyscrasias - damaging to the components of the blood (RBCs, WBCs, platelets etc.)
(2) Hepatotoxicity - damaging to the liver (liver is organ which detoxifies drugs)
(3) Nephrotoxicity - damaging to the kidney (kidney eliminates water soluble toxic agents)
(4) Teratogenicity - causes birth defects (drugs can cross the placental barrier). The fetus is most susceptible in the first trimester of the female pregnancy. Referred to as teratogenic.
b. Allergic reactions - hypersensitivity
(1) Caused by prior exposure to agent or similar drug-sensitization
(2) Reaction varies from rash to anaphylaxis
c. Side effects
(1) Most drugs affect more than one system
(2) Some side effects are minor, others are so distressing as to cause the patient to stop taking the drug (i.e. vomiting, diarrhea)
d. Drug dependence
(1) Psychological - patient convinced that he/she has a need for the drug. The mind tells the patient that they must have the drug to function normally
(2) Physiological - body develops a need for the drug, if drug is taken away, patient goes through withdrawal, tremors, nausea, vomiting, and convulsions. The body exhibits physical signs of the need for the drug. The classic example is a narcotic addict
a. Oral medications
(1) For fever and pain
(a) Acetaminophen - non-narcotic analgesic and antipyretic
1) Indications
a) Mild pain
b) Fever
2) Contraindications - patients with hypersensitivity to the drug
3) Side effects - rare
a) May cause liver damage in high doses or unsupervised long-term use
b) Patients should be warned that excessive ingestion of alcohol while using acetaminophen could result in severe liver damage
4) Dosage
a) Adults - 325-650 mg P.O. (by mouth) every 4-6 hours or 1 Gram every 6-8 hours as needed for fever or mild pain
b) May also be given as a rectal suppository - 650 mg every 4-6 hours as needed for mild pain or fever
c) Maximum daily dose (24 hours) should not exceed 4 grams
5) Considerations
a) Use cautiously in patients with history of chronic alcohol use-liver damage has occurred with therapeutic doses
b) Many over the counter products contain acetaminophen. Be aware of this when calculating total daily dose
6) Common brand name - Tylenol
(b) Ibuprofen - non-steroidal anti-inflammatory drug (NSAID)
1) Indications
a ) Mild to moderate pain relief to include headaches (analgesia)
b) Fever reduction (antipyretic)
2) Contraindications
a) Patients with hypersensitivity to the drug
b) Patients with known ulcer disease
3) Side effects – Increases bleeding time for 8 hours
a) Gastrointestinal (GI) pain
b) Nausea
c) Occult gastrointestinal bleeding
4) Dosage
a) For mild to moderate pain 400-800 mg P.O. every 6-8 hours
b) For fever, 200-800 mg P.O. every 6-8 hours
c) Maximum daily dose (24 hours) 3200 mg
5) Considerations
a) Take with meals or milk to reduce GI side effects
b) Do not use with aspirin or alcohol, which may increase risk of GI reactions
c) Serious GI bleeding can occur in patients taking NSAIDs despite absence of symptoms
d) Patients should be taught the signs and symptoms of GI bleeding (dark, tarry, stools; coffee ground or bloody emesis) and instructed to notify the MD/PA immediately if they occur
6) Common brand names
a) Motrin
b) Advil
c) Nuprin
(2) For cough, colds, and sinus allergies
(a) Actifed -Combination of two drugs-psuedoephedrine HCL (decongestant) 60 mg and Tripolidine HCL (antihistamine) 2.5 mg
1) Indications
a) Colds
b) Nasal congestion
c) Seasonal allergy symptoms
2) Contraindications
a) Patients with hypersensitivity to psuedoephedrine or tripolidine
b) Should not be given to patients with hypertension, acute asthma, peptic ulcer disease, severe coronary artery disease, arrhythmias, glaucoma, angina pectoris, severe cardiovascular disease or patients taking MAO (monoamine oxidase) inhibitors
3) Side effects
a) Can cause drowsiness, dizziness, dry nose, mouth and throat
b) May cause restlessness, anxiety, nervousness or insomnia in some patients
c) Some patients may experience photosensitivity skin reactions during prolonged sun exposure
4) Dosage - one tablet p.o. (by mouth) every 8 hours
5) Considerations
a) Should be taken with food or milk to reduce gastrointestinal distress
b) Patient should avoid alcohol, driving and other activities that require alertness until the CNS effects are known by the patient
c) Dry mouth can be relieved with gum, hard candy or ice chips
d) Advise patients to use sun block for possible photosensitivity
6) Common brand name - Actifed
(b) Pseudoephedrine HCL (decongestant)
1) Indications - Symptomatic relief of nasal congestion associated with rhinitis and sinusitis and for eustachian tube congestion
2) Contraindications
a) Hypersensitivity to Sudafed
b) Severe hypertension
c) Coronary artery disease
d) Glaucoma
e) Hyperthyroidism or for patients taking MAO inhibitors
3) Side effects
a) Transient restlessness
b) Stimulation
c) Tachycardia
d) Nervousness
e) Dizziness
f) Dry mouth
4) Dosage
a) 30 - 60 mg P.O. every 4-6 hours for adults
b) Maximum daily dose (24 hours) is 240 mg
5) Considerations
a) Drug may act as a stimulant
b) Avoid taking within 2 hours of bedtime
c) Advise patient to stop taking medication if extreme restlessness occurs and consult MD/PA
d) Advise patients that many over the counter (OTC) drugs may contain ephedrine or other sympathomimetic amines and might intensify the action of psuedoephedrine if taken together
6) Common brand name - Sudafed
(c) Chlorpheniramine - antihistamine
1) Indications - Symptomatic relief of rhinitis and seasonal allergy symptoms
2) Contraindications
a) Hypersensitivity to antihistamines
b) Lower respiratory tract symptoms
c) Narrow-angle glaucoma
d) Severe hypertension
e) Severe cardiovascular disease
f) Bronchial asthma
g) Patients taking MAO inhibitors
3) Side effects - Low incidence of side effects
a) Drowsiness
b) Dizziness
c) Dryness of mouth and nose
4) Dosage
a) 8 mg P.O. every 8 hours (t.i.d.)
b) Maximum daily (24 hours) dose is 24 mg
5) Considerations
a) Drug may cause drowsiness
b) Driving and other potentially hazardous activities should be avoided until the response to the drug is known
c) Avoid alcohol use when taking this drug. Antihistamines have additive effects with alcohol.
6) Common brand name - Chlor-Trimeton, CTM
(d) Robitussin (guiafenesin)
1) Indications
a) Used to liquefy thick tenacious sputum
b) Expectorant
2) Contraindications - Contraindicated in patients with known hypersensitivity to the drug
3) Side effects - rare
a) GI upset
b) Nausea
c) Drowsiness
4) Dosage
a) 200-400 mg P.O. every 4 hours
b) Maximum daily (24 hours) dose is 2,400 mg
5) Considerations
a) Take medication with plenty of fluids to help liquefy secretions
b) Persistent cough may indicate a more serious problem. Notify MD/PA if cough lasts longer than one week.
6) Common brand name - Hytuss, Robitussin, Humabid
(e) Robitussin DM (Guaifenesin with Dextromethorphan) Antitussive/Expectorant
1) Indications -Temporary relief of cough spasms in nonproductive coughs due to colds and flu
2) Contraindications
a) Hypersensitivity to the drug
b) Patients taking MAO inhibiters
c) Persistent or chronic coughs
3) Side effects - Rare
a) Dizziness
b) Drowsiness
c) Excitability, especially in children
d) GI upset
e) Constipation and abdominal discomfort
4) Dosage
a) 10-20 mg P.O. every 4 hours or 30 mg P.O. every 6-8 hours
b) Maximum daily (24 hours) dose is 120 mg
5) Considerations
a) Drug produces no analgesia or addiction and little or no CNS depression
b) Dextromethorphan 15-30 mg is equivalent to 8-15 mg codeine as an antitussive
c) Patient should understand that a persistent cough might indicate a more serious problem
d) Coughs lasting for longer than a week should be evaluated by a MD/PA
6) Common brand names - Robitussin DM
(f) Diphenhydramine (antihistamine)
1) Indications
a) Temporary symptomatic relief of various allergic conditions and to treat or prevent motion sickness and vertigo
b) Used in anaphylaxis as an adjunct to epinephrine
c) Used as a sedative
2) Contraindications
a) Contraindicated in patients who have a known hypersensitivity to the drug
b) Do not give if patient has an enlarged prostrate gland
3) Side effects
a) Drowsiness
b) Dry mouth
c) Palpitations
d) Some patients may experience nervousness, restlessness and insomnia
4) Dosage
a) 25 to 50 mg P.O. three times a day (t.i.d.) or four times a day (q.i.d.)
b) Maximum daily dose (24 hours) is 300 mg
5) Considerations
a) May cause GI upset
b) Administer with food or milk
c) Warn patients about possible additive CNS depressant effects with concurrent use of alcohol
d) Patient should not engage in activities that require alertness and coordination until response to the drug is known
e) Drowsiness is most prominent during the first few days of therapy and often disappears with continued therapy
f) The drug has an atropine-like drying effect, which makes it a popular drug for use with the common cold
g) Antihistamines have no therapeutic effects on the common cold and may make expectoration more difficult because it thickens bronchial secretions
h) Increase fluid intake while taking this drug
6) Common brand name - Benadryl
(3) Emetics - Syrup of Ipecac
(a) Indications - To induce vomiting in poisoning or overdose by ingestion in a conscious patient
(b) Contraindications
1) Stupor or coma
2) Absent gag reflex
3) Seizures
4) Pregnancy
5) Children under 6, or if the following is ingested: corrosives, hydrocarbons, strychnine or iodides
(c) Side effects
1) The risk of aspiration from vomiting is present
2) If the drug is not vomited, it may cause GI upset, diarrhea or slight CNS depression
3) May cause persistent vomiting. Syrup of ipecac can be cardiotoxic if not vomited.
(c) Dosage - only given under orders of MD/PA
1) Children 3-5 teaspoons, Adults 1-2 tablespoons P.O.
2) Follow administration of the drug with 1-2 glasses of tepid water. Do not give milk products.
3) May repeat the dose in 20 minutes if no results
(d) Considerations
1) Drug should be recovered by gastric lavage and activated charcoal if vomiting does not occur following the second dose
2) Notify MD/PA immediately if vomiting does not occur. If poisoning has occurred, call a poison control center or emergency room or contact an MD/PA before using ipecac syrup.
3) Do not exceed the recommended dosage
(e) Common brand name - Syrup of Ipecac
(4) Antidiarrheal
(a) Kaopectate Tabs
1) Indications - Acute nonspecific diarrhea
2) Contraindications - Patients with known hypersensitivity to the drug and in patients with dysentery or suspected bowel obstruction
3) Side effects - constipation
4) Dosage
a) 1.2 to 1.5 grams P.O. after each loose bowel movement
b) Not to exceed 9 grams in 24 hours
5) Considerations
a) Use cautiously in patients with dehydration
b) Encourage adequate fluid intake to compensate for fluid loss from diarrhea
c) Do not use if diarrhea is accompanied by fever or blood or mucous in the stool
6) Common brand names - Kaopectate, Donnagel
(b) Immodium
1) Indications - Acute nonspecific diarrhea
2) Side effects - constipation
3) Dosage
a) 2 - 2mg tabs, followed by 1 tab after each loose stool
b) Not to exceed 8 tablets a day
c) Do NOT give for bloody diarrhea
(5) Antacids - Calcium carbonate tabs
(a) Indications
1) Used for relief of transient symptoms of hyperacidity as in acid indigestion and heartburn
2) Also used as a calcium supplement
(b) Contraindications
1) Patients with hypercalcemia and hypercalciuria
2) Should also not be used in patients with calcium loss due to immobilization, severe renal disease, renal calculi, and GI hemorrhage or obstruction or cardiac disease
(c) Side effects
1) Constipation or laxative effect
2) Acid rebound
3) Nausea
4) Flatulence
(d) Dosage
1) 0.5-2 grams P.O. 4-6 times/day when used as an antacid
2) For use as calcium supplement 1-2 grams P.O. every 8 or every 12 hours
(e) Considerations
1) When used as an antacid, take one hour after meals and at bedtime
2) Acid rebound, which generally occurs after repeated use of antacids for one or two weeks, can lead to chronic use
3) Caution patient not to use antacids for more than two weeks without medical supervision
(f) Common brand names - Tums, Caltrate, Os-Cal
b. Injectable medications
(1) For pain
(a) Morphine (analgesic, narcotic (opiate) agonist) - Indications
1) Symptomatic relief of severe acute pain after non-narcotic analgesics has failed
2) Also used to relieve pulmonary edema and the pain of myocardial infarction
(b) Contraindications
1) Patients with known hypersensitivity to the drug or to opiates
2) Patients with increased intracranial pressure (head injuries), severe respiratory depression, acute bronchial asthma, convulsive disorders, chronic pulmonary diseases and undiagnosed acute abdominal conditions
(c) Side effects
1) Drowsiness
2) Pruritus (itching)
3) Respiratory depression
4) Euphoria
5) Disorientation
6) Nausea
7) Vomiting
8) Constipation
9) Occasionally patients will experience nervousness, restlessness, or insomnia
10) Urinary retention may occur
(d) Dosage
1) 2.5-15 mg intravenous (IV) every 4 hours
2) 1–2 mg IV doses titrated to pain relief
3) May also be given intramuscularly (IM) or P.O. (by mouth). IM dosage is 5-20 mg IM every 4 hours
4) Oral dosage is 10-30 mg every 4 hours
(e) Considerations
1) Monitor for respiratory depression
2) Evaluate patient frequently for pain relief
3) Patients who are ambulatory may experience nausea and orthostatic hypotension when moving from a supine to an upright position
NOTE: Morphine sulfate is a Schedule II Controlled Substance.
(f) Common brand name - Duramorph, MS Contin (oral)
(2) For chemical agent poisoning
(a) Atropine INJ 0.7 ml
1) Indications - Used to treat a chemical agent poisoning
2) Contrain