Pharmacology Flashcards
6 cards from real USMLE practice questions. Tap to flip, then mark Knew It or Still Learning โ missed cards come back until you master them.
Read the first 6 Pharmacology flashcards as text
A patient on methotrexate develops mucositis and bone marrow suppression. Which agent is given to rescue normal cells?
Answer: Leucovorin (folinic acid)
Leucovorin (folinic acid) bypasses DHFR inhibition by methotrexate, rescuing normal rapidly dividing cells from folate depletion.
Which antifungal drug inhibits 14-alpha demethylase (CYP51) to block ergosterol synthesis?
Answer: Fluconazole
Fluconazole and other azole antifungals inhibit 14-alpha demethylase (CYP51), blocking the conversion of lanosterol to ergosterol in the fungal cell membrane.
A patient develops torsades de pointes after starting a new antiarrhythmic. Which drug is most likely responsible?
Answer: Sotalol
Sotalol (Class III) prolongs the QT interval by blocking K+ channels, predisposing to torsades de pointes, especially in patients with bradycardia or hypokalemia.
Which receptor does naloxone primarily antagonize to reverse opioid overdose?
Answer: Mu (ฮผ) opioid receptor
Naloxone is a competitive antagonist primarily at mu-opioid receptors, rapidly reversing opioid-induced respiratory depression, sedation, and analgesia.
A patient with myasthenia gravis is treated with pyridostigmine. What is its mechanism of action?
Answer: Reversible inhibition of acetylcholinesterase
Pyridostigmine reversibly inhibits acetylcholinesterase, increasing acetylcholine availability at the neuromuscular junction to compensate for autoimmune receptor loss.
Which drug is a selective serotonin reuptake inhibitor (SSRI) with the longest half-life and is used to minimize withdrawal syndrome?
Answer: Fluoxetine
Fluoxetine has the longest half-life (~1-4 days) among SSRIs due to its active metabolite norfluoxetine, making discontinuation syndrome rare.