Medical Knowledge Pharmacology 3 — Questions and Answers
Question 1: What is the therapeutic index of a drug?
- Ratio of toxic dose to effective dose (Correct answer)
- Maximum safe single dose
- Minimum effective dose
- Rate of drug clearance
Correct answer: Ratio of toxic dose to effective dose
The therapeutic index is the ratio of the toxic dose (TD50) to the effective dose (ED50), measuring a drug's safety margin.
Question 2: Which oral anticoagulant requires regular INR monitoring?
- Aspirin
- Heparin
- Warfarin (Correct answer)
- Clopidogrel
Correct answer: Warfarin
Warfarin inhibits vitamin K-dependent clotting factors and has a narrow therapeutic range requiring frequent INR monitoring.
Question 3: What is the mechanism of action of ACE inhibitors?
- Block calcium channels
- Inhibit angiotensin-converting enzyme (Correct answer)
- Block beta-adrenergic receptors
- Increase potassium excretion
Correct answer: Inhibit angiotensin-converting enzyme
ACE inhibitors prevent conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone-driven fluid retention.
Question 4: Which type of drug reaction involves immune system activation and is not dose-dependent?
- Toxic reaction
- Idiosyncratic reaction
- Allergic reaction (Correct answer)
- Side effect
Correct answer: Allergic reaction
Allergic drug reactions involve immunological mechanisms such as IgE-mediated hypersensitivity and can occur with even tiny amounts of the drug.
Question 5: What does 'QD' mean in prescription writing?
- Every 6 hours
- Twice daily
- Every other day
- Once daily (Correct answer)
Correct answer: Once daily
QD (quaque die) is a Latin abbreviation meaning once daily, used in medication orders.
Question 6: Which medication class reduces gastric acid secretion by blocking the proton pump?
- H2 blockers
- Antacids
- Proton pump inhibitors (Correct answer)
- Anticholinergics
Correct answer: Proton pump inhibitors
Proton pump inhibitors (PPIs) irreversibly inhibit the H+/K+-ATPase enzyme in gastric parietal cells, reducing acid secretion.
Medical Knowledge Pharmacology 3
What is the therapeutic index of a drug?