Domain 1.3Foundational Knowledge and Medical Terminology
Basic Pharmacology
Last updated July 16, 2026
Overview
Welcome to your study guide for Basic Pharmacology! As a Medical Assistant, you are a vital link in the chain of patient safety, especially when it comes to medications. From preparing injections and calling in prescriptions to educating patients, your understanding of basic pharmacology is not just about passing an exam—it's about protecting your patients every single day.
This guide breaks down essential concepts, focusing on high-yield topics that frequently appear on the medical assistant exam. It covers drug classifications, safety protocols, calculations, and the fundamental principles of how medications work in the body.
1. The Foundations of Pharmacology
Before memorizing drug names, you must understand how drugs interact with the body.
A. Pharmacokinetics: What the Body Does to a Drug
Pharmacokinetics is the study of the journey a drug takes through the body. A simple mnemonic to remember the four phases is ADME:
- A - Absorption: How the drug gets into the bloodstream from the site of administration (e.g., stomach for an oral pill, muscle for an IM injection).
- D - Distribution: How the drug is transported by the bloodstream to its site of action.
- M - Metabolism (Biotransformation): The chemical breakdown of the drug, which primarily occurs in the liver. The liver acts as a processing plant, converting the drug into a form that can be easily removed.
- Exam High-Yield: In older adults, liver function often declines. This slows metabolism, causing the drug to build up in the body and increasing the risk of toxicity.
- E - Excretion: How the drug is eliminated from the body, primarily through the kidneys in urine.
Memory Tip:
- PharmacoKinetics = The drug's journey or 'Kourse' through the body (ADME).
- PharmacoDynamics = What the Drug Does to the body (its effects).
B. Key Terminology: Side Effects vs. Adverse Effects
| Term | Definition | Example |
|---|---|---|
| Indication | The specific medical condition for which a drug is approved and prescribed. | The indication for Metformin is Type 2 Diabetes. |
| Contraindication | A specific situation where a drug should not be used because it may be harmful. | Pregnancy is a contraindication for Category X drugs. |
| Side Effect | A predictable, often mild, and unavoidable secondary effect of a drug at a therapeutic dose. | Drowsiness from an antihistamine. |
| Adverse Effect | An unintended, undesirable, and often more severe reaction to a medication. It requires reporting. | Persistent tachycardia (fast heart rate) after a nebulizer treatment is an adverse effect that must be reported immediately. |
| Anaphylaxis | A severe, life-threatening, whole-body allergic reaction. Signs include hives, difficulty breathing, and a drop in blood pressure. | A patient developing wheezing and hives minutes after a penicillin injection. |
| Prophylactic | A medication or treatment used to prevent a disease or condition from occurring. | Vaccines are prophylactic against viruses. Antibiotics given before surgery to prevent infection. |
2. Drug Classifications and Common Medications
You must be able to identify common drug classes and know their primary use. Focus on the examples that appeared in the sample questions.
| Drug Class | Primary Use (Indication) | Common Examples | Key Takeaway / Mnemonic |
|---|---|---|---|
| Analgesics | Pain Relief | NSAIDs: Ibuprofen (OTC); Opioids: Oxycodone, Hydrocodone, Morphine (Controlled Substances) | Analgesic works Against pain. |
| Anticoagulants | Prevents Blood Clots | Warfarin (Coumadin), Enoxaparin (Lovenox) | Warfarin wages war on blood clots. Vitamin K is the antidote! |
| Antihypertensives | Lowers High Blood Pressure | ACE Inhibitors: Lisinopril; Diuretics: Furosemide (Lasix) | Lisinopril helps blood vessels 'chill'. |
| Diuretics | Reduces Fluid Retention (Promotes Urination) | Furosemide (Lasix) | Diuretics help you get rid of diluting excess fluid. Monitor potassium levels! |
| Antipyretics | Reduces Fever (Pyrexia) | Acetaminophen, Ibuprofen | A funeral pyre is hot; anti-pyretic fights the heat of a fever. |
| Antiemetics | Prevents Nausea & Vomiting | Ondansetron (Zofran) | Vomiting is called emesis. An anti-emetic works against it. |
| Hypoglycemics | Lowers Blood Sugar | Oral: Metformin (first-line for Type 2); Injectable: Insulin (Type 1) | The biggest risk for insulin is HYPOglycemia (think 'hypo' means 'low'). |
| Bronchodilators | Opens Airways (for Asthma/COPD) | Albuterol | Bronchodilators can make the heart race. Monitor for tachycardia. |
| Antineoplastics | Stops or Slows Cancer Growth | Chemotherapy drugs | A neoplasm is a 'new growth' (tumor). Anti-neoplastics fight it. |
| Vasodilators | Widens Blood Vessels (for Angina) | Nitroglycerin | For Nitro-Speed relief from angina, nitroglycerin dilates vessels. |
Topical Agents and Local Anesthetics
| Agent | Purpose | Key Feature |
|---|---|---|
| Silver Nitrate | Cauterization | Used to chemically burn/seal bleeding capillaries or small sores (like mouth ulcers). Looks like a matchstick. |
| Lidocaine | Local Anesthetic | Numbs the skin or tissue before a procedure (suturing, biopsy). |
| Lidocaine w/ Epinephrine | Anesthetic + Vasoconstrictor | Epinephrine constricts blood vessels. When added to Lidocaine, it reduces bleeding at the site and keeps the anesthetic local longer. |
Over-the-Counter (OTC) vs. Prescription Medications
- OTC: Can be bought "on the counter" without a prescription (e.g., lower-dose Ibuprofen, Acetaminophen).
- Prescription (Rx): Requires an order from a licensed provider due to higher risk, dosage, or potential for abuse (e.g., Amoxicillin, Lisinopril, Alprazolam).
3. Controlled Substances
The Drug Enforcement Administration (DEA) classifies drugs with potential for abuse into five "schedules." Proper storage is non-negotiable: controlled substances must be stored separately from other medications in a double-locked location.
Abuse vs. Dependence
- Abuse: The misuse or excessive use of a substance (using it in a way not prescribed).
- Dependence: A physiological state where the body adapts to the drug. Key differentiator: If the drug is stopped, the patient experiences withdrawal symptoms.
| Schedule | Potential for Abuse | Medical Use | Examples |
|---|---|---|---|
| Schedule I | Highest | No accepted medical use | Heroin, LSD |
| Schedule II | High | Yes, but with severe restrictions | Oxycodone, Hydrocodone, Morphine, Adderall |
| Schedule III | Moderate to Low | Yes | Tylenol with codeine, testosterone |
| Schedule IV | Low | Yes | Alprazolam (Xanax), Zolpidem (Ambien) (for insomnia/sleeplessness) |
| Schedule V | Lowest | Yes | Cough syrups with small amounts of codeine |
Exam Tip: Schedule I drugs have NO medical use. Potent opioids used for pain (like Oxycodone) fall into the next highest-risk category: Schedule II.
4. The Rights of Medication Administration
To get medication administration right, you must check the Rights. This is your final, non-negotiable safety checklist to prevent errors.
- Right Patient: Use at least two identifiers (e.g., name and DOB).
- Right Medication: Check the label three times. Watch for look-alike/sound-alike drugs (Prozac vs. Prilosec).
- Right Dose: Double-check your calculations.
- Right Route: The prescribed path (oral, IM, etc.). Administer using the correct physical technique.
- Right Time: Administer on schedule to maintain therapeutic blood levels.
- Right Documentation: Document after administration, never before.
- Right to Refuse: A competent patient has the right to refuse medication.
- Right to Not Be Expired: Checking the expiration date ensures the drug's potency and safety. An EXpired drug has lost its EXpected effectiveness.
5. Routes of Administration
The route determines the speed of onset. The faster a drug reaches the bloodstream, the quicker its effect.
| Route | Description | Speed of Onset | Clinical Example |
|---|---|---|---|
| Intravenous (IV) | Directly into a vein | Fastest (Immediate) | Emergency medications in a hospital setting. |
| Sublingual (SL) | Under the tongue | Very Fast | Nitroglycerin for acute angina. |
| Intramuscular (IM) | Into a muscle | Fast | Most vaccines, some antibiotics. |
| Subcutaneous (Sub-Q) | Into the fatty tissue | Slower | Insulin, Enoxaparin (Lovenox). |
| Oral (PO) | Swallowed | Slow | Pills, capsules, liquids. Must be absorbed by GI tract. |
| Transdermal | Patch on the skin | Very Slow (for continuous release) | Nicotine patches, Fentanyl patches. |
| Vaginal | Inserted into the vagina | Varies (local effect) | Creams and suppositories for yeast infections. |
Memory Tip: IV is the medication 'Insta-Vein' express lane—the quickest route of all.
6. Dosage Calculations and Conversions
Mastering dosage calculation is essential for patient safety.
The Universal Formula
(Dose you WANT / Dose you HAVE) x Vehicle (e.g., mL or tablet) = Amount to Administer
Example 1: Order: 75 mg. On Hand: 50 mg/mL solution.
- (75 mg / 50 mg) x 1 mL = 1.5 mL
Example 2: Order: 1 gram. On Hand: 250 mg capsules.
- Step 1: Convert! 1 g = 1000 mg.
- Step 2: Calculate. (1000 mg / 250 mg) x 1 capsule = 4 capsules
Example 3: Order: 0.5 mg, three times a day (tid) for 3 days. On Hand: 1 mg scored tablets.
- Step 1: Dose per day. 0.5 mg/dose x 3 doses/day = 1.5 mg/day.
- Step 2: Total for the course. 1.5 mg/day x 3 days = 4.5 mg total.
- Step 3: Tablets needed. 4.5 mg needed / 1 mg/tablet = 4.5 tablets
Weight-Based Dosage Calculation
Sometimes a provider orders a dose based on the patient's weight (e.g., "0.02 mL per pound").
Formula: Weight x Rate = Total Dose
- Example: Order: 0.02 mL/lb. Patient Weight: 190 lbs.
- Calculation: 190 lbs x 0.02 mL/lb = 3.8 mL
Must-Know Conversions
| Unit Conversion | Mnemonic |
|---|---|
| 1 gram (g) = 1,000 milligrams (mg) | Think of 1 dollar being 1000 pennies (mg). |
| 1 tablespoon (tbsp) = 15 milliliters (mL) | A Table is bigger than a Teacup. |
| 1 teaspoon (tsp) = 5 milliliters (mL) |
7. Special Topics in Pharmacology
A. Medication Safety and Resources
- Allergies: Always ask about allergies before administering any medication. This is the most critical safety check.
- Look-Alike/Sound-Alike Drugs: Be vigilant for drugs with similar names, such as Prilosec (for acid reflux) and Prozac (an antidepressant).
- Physician's Desk Reference (PDR): This is your go-to resource for comprehensive drug information, including dosages, contraindications, and adverse effects.
B. FDA Pregnancy Risk Categories
This system classifies the risk of a drug to a fetus.
- Category A: Safest. No demonstrated risk in human studies. (A = A+)
- Category B: No evidence of risk in humans.
- Category C: Risk cannot be ruled out.
- Category D: Positive evidence of risk.
- Category X: Contraindicated. Fetal risk clearly outweighs any benefit. (X = Forbidden)
8. Final Key Takeaways
- ADME: Remember the four phases of Pharmacokinetics are Absorption, Distribution, Metabolism (in the liver), and Excretion.
- Drug Classes: Know the indication for common classes like Analgesics, Anticoagulants, Antihypertensives, Diuretics, and Hypoglycemics.
- Controlled Substances: Schedule II drugs (Oxycodone, Hydrocodone) have a high potential for abuse. They must be stored in a separate, double-locked location.
- The Rights: The "Rights of Medication Administration" are your fundamental safety checklist. Know what each right protects (e.g., Right Time maintains therapeutic levels).
- Fastest Routes: IV is the fastest route, followed by Sublingual (used for Nitroglycerin in acute angina).
- Dosage Math: Always convert to the same unit first (e.g., grams to milligrams). Master the WANT / HAVE x Vehicle formula.
- Critical Conversions: 1 g = 1000 mg and 1 tbsp = 15 mL.
- Patient Safety First: Always verify allergies. Monitor for adverse reactions (like tachycardia with albuterol or hypoglycemia with insulin) and report them immediately.
- Pregnancy Categories: Category A is the safest; Category X is absolutely forbidden.