Saudi Prometric Pharmacist Pharmacology and Therapeutics 2 — Questions and Answers
Question 1: What is the mechanism of action of metformin in type 2 diabetes?
- Stimulates insulin secretion from beta cells
- Decreases hepatic glucose production, increases insulin sensitivity, and reduces intestinal glucose absorption (Correct answer)
- Blocks glucose absorption completely
- Increases glucagon production
Correct answer: Decreases hepatic glucose production, increases insulin sensitivity, and reduces intestinal glucose absorption
Metformin works through multiple mechanisms: primarily reducing hepatic gluconeogenesis, enhancing peripheral insulin sensitivity (especially in muscle), and modestly decreasing intestinal glucose absorption. It does NOT stimulate insulin secretion, so hypoglycemia risk is low as monotherapy.
Question 2: What is the loading dose of clopidogrel for acute coronary syndrome?
- 75 mg
- 150 mg
- 300-600 mg (Correct answer)
- 25 mg
Correct answer: 300-600 mg
Clopidogrel loading dose for ACS is 300-600 mg (600 mg for PCI), followed by 75 mg daily maintenance. The loading dose rapidly achieves therapeutic platelet inhibition. Higher loading doses (600 mg) achieve faster onset of antiplatelet effect.
Question 3: Which antibiotic class is associated with QT prolongation and should be used cautiously?
- Penicillins
- Fluoroquinolones (especially moxifloxacin) (Correct answer)
- Cephalosporins
- Nitrofurantoin
Correct answer: Fluoroquinolones (especially moxifloxacin)
Fluoroquinolones, particularly moxifloxacin, can prolong the QT interval and increase risk of torsades de pointes. They should be avoided in patients with known QT prolongation, concurrent QT-prolonging drugs, or uncorrected hypokalemia/hypomagnesemia.
Question 4: What is the antidote for benzodiazepine overdose?
- Naloxone
- Flumazenil (Correct answer)
- N-acetylcysteine
- Protamine sulfate
Correct answer: Flumazenil
Flumazenil is a competitive antagonist at the benzodiazepine binding site on the GABA-A receptor. It reverses sedation but must be used cautiously: can precipitate seizures in chronic benzodiazepine users and does not reverse respiratory depression from opioids.
Question 5: What drug interactions must be considered when dispensing warfarin?
- Warfarin has no significant interactions
- Numerous interactions including with antibiotics (increase INR), NSAIDs (bleeding risk), vitamin K-rich foods, and CYP enzyme inhibitors/inducers (Correct answer)
- Only interacts with aspirin
- Only food interactions matter
Correct answer: Numerous interactions including with antibiotics (increase INR), NSAIDs (bleeding risk), vitamin K-rich foods, and CYP enzyme inhibitors/inducers
Warfarin has extensive interactions: antibiotics (metronidazole, fluconazole increase INR), NSAIDs (increase bleeding), CYP2C9 inhibitors (increase warfarin levels), vitamin K-rich foods (decrease effect), and enzyme inducers (rifampicin decreases warfarin effect). Careful INR monitoring is essential.
Question 6: What is the role of pharmacokinetics in drug dosing for patients with renal impairment?
- No dose adjustment is ever needed
- Drugs eliminated renally require dose reduction or interval extension based on creatinine clearance/GFR to prevent accumulation and toxicity (Correct answer)
- Only IV drugs need adjustment
- Renal impairment only affects antibiotic dosing
Correct answer: Drugs eliminated renally require dose reduction or interval extension based on creatinine clearance/GFR to prevent accumulation and toxicity
Renally cleared drugs (aminoglycosides, vancomycin, metformin, lithium, digoxin) require dose adjustment in renal impairment. Adjustments are based on CrCl/eGFR: either reducing the dose or extending the interval. Failure to adjust causes drug accumulation and toxicity.
Saudi Prometric Pharmacist Pharmacology and Therapeutics 2
What is the mechanism of action of metformin in type 2 diabetes?