FPGEE Pharmacology 5 — Questions and Answers
Question 1: Which drug is used to reverse the effects of benzodiazepine overdose?
- Flumazenil (Correct answer)
- Naloxone
- Physostigmine
- N-acetylcysteine
Correct answer: Flumazenil
Flumazenil is a competitive benzodiazepine receptor antagonist that rapidly reverses sedation, but has a short half-life and may precipitate seizures in dependent patients.
Question 2: Which antifungal mechanism involves disruption of ergosterol synthesis by inhibiting lanosterol 14-alpha-demethylase?
- Azole antifungals (e.g., fluconazole) (Correct answer)
- Polyene antifungals (e.g., amphotericin B)
- Echinocandins (e.g., caspofungin)
- Allylamines (e.g., terbinafine)
Correct answer: Azole antifungals (e.g., fluconazole)
Azoles inhibit CYP51 (lanosterol 14-alpha-demethylase), blocking ergosterol biosynthesis and disrupting fungal cell membrane integrity.
Question 3: In a patient with renal failure, which pharmacokinetic parameter is most directly affected for renally-cleared drugs?
- Clearance decreases, leading to prolonged half-life (Correct answer)
- Volume of distribution increases significantly
- Bioavailability decreases due to poor absorption
- Protein binding increases due to uremia
Correct answer: Clearance decreases, leading to prolonged half-life
Reduced GFR directly decreases renal clearance of drugs, prolonging their half-life and increasing the risk of accumulation and toxicity.
Question 4: Which mechanism explains why aspirin irreversibly inhibits platelet aggregation?
- Irreversible acetylation of cyclooxygenase (COX-1) preventing thromboxane A2 synthesis (Correct answer)
- Reversible inhibition of ADP-mediated platelet activation
- Permanent blockade of GPIIb/IIIa fibrinogen receptors
- Covalent inhibition of phosphodiesterase increasing cAMP
Correct answer: Irreversible acetylation of cyclooxygenase (COX-1) preventing thromboxane A2 synthesis
Aspirin covalently acetylates a serine residue in COX-1, permanently blocking TXA2 production; since platelets lack nuclei, they cannot synthesize new COX.
Question 5: A patient with gout is prescribed allopurinol. What is the mechanism of this drug?
- Inhibits xanthine oxidase, reducing uric acid production (Correct answer)
- Increases renal uric acid excretion by blocking URAT1
- Promotes uricase-mediated conversion of uric acid to allantoin
- Inhibits purine synthesis de novo via PRPP amidotransferase
Correct answer: Inhibits xanthine oxidase, reducing uric acid production
Allopurinol and its active metabolite oxypurinol inhibit xanthine oxidase, the enzyme that converts hypoxanthine and xanthine to uric acid.
Question 6: Which receptor mechanism best explains the action of beta-blockers in reducing heart rate?
- Block beta-1 adrenergic receptors in the SA node, reducing cAMP and slowing spontaneous depolarization (Correct answer)
- Block muscarinic receptors to decrease parasympathetic tone
- Activate alpha-2 receptors to inhibit sympathetic outflow
- Block calcium channels in nodal tissue
Correct answer: Block beta-1 adrenergic receptors in the SA node, reducing cAMP and slowing spontaneous depolarization
Beta-1 blockade at the sinoatrial node reduces adenylyl cyclase activity and cAMP, slowing the rate of phase 4 spontaneous depolarization.
Question 7: Which drug used for type 2 diabetes carries the highest risk of lactic acidosis in patients with renal impairment?
- Metformin (Correct answer)
- Glipizide
- Sitagliptin
- Pioglitazone
Correct answer: Metformin
Metformin accumulates in renal failure, inhibiting mitochondrial complex I and increasing lactate production, leading to potentially fatal lactic acidosis.
FPGEE Pharmacology 5
Which drug is used to reverse the effects of benzodiazepine overdose?