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Pharmacology Flashcards

7 cards from real NBME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. A patient receives succinylcholine for rapid sequence intubation. Which condition represents an absolute contraindication to its use?

    Answer: Crush injury 5 days ago

    Denervation injuries or crush injuries cause upregulation of extrajunctional acetylcholine receptors; succinylcholine causes massive K+ efflux leading to fatal hyperkalemia.

  2. Which opioid analgesic is most appropriate for a patient with severe renal impairment requiring chronic pain management?

    Answer: Fentanyl

    Fentanyl is the preferred opioid in renal failure because it has no active metabolites that accumulate; morphine-6-glucuronide accumulates and causes toxicity in renal impairment.

  3. Methotrexate kills cancer cells primarily by inhibiting which enzyme?

    Answer: Dihydrofolate reductase

    Methotrexate competitively inhibits dihydrofolate reductase (DHFR), depleting tetrahydrofolate and blocking purine and thymidylate synthesis.

  4. A patient receiving cyclophosphamide for lymphoma develops painless hematuria. Which complication is occurring?

    Answer: Hemorrhagic cystitis from acrolein metabolite

    Cyclophosphamide is metabolized to acrolein, which accumulates in urine and causes direct urothelial damage resulting in hemorrhagic cystitis.

  5. Atropine is administered to reverse the effects of organophosphate poisoning. Which toxic effect of organophosphates does atropine NOT reverse?

    Answer: Skeletal muscle paralysis

    Atropine blocks muscarinic receptors but has no effect on nicotinic receptors at the neuromuscular junction; pralidoxime (2-PAM) must be used to reverse skeletal muscle effects.

  6. A surgeon needs to provide postoperative analgesia while minimizing opioid use. Which mechanism do NSAIDs use to reduce pain and inflammation?

    Answer: Inhibit cyclooxygenase, reducing prostaglandin synthesis

    NSAIDs inhibit COX-1 and COX-2 enzymes, preventing arachidonic acid conversion to prostaglandins that sensitize pain receptors and mediate inflammation.

  7. Neostigmine is used to reverse neuromuscular blockade after surgery. Which agent must always be co-administered with neostigmine to prevent bradycardia?

    Answer: Atropine

    Neostigmine inhibits acetylcholinesterase, increasing ACh at all cholinergic synapses; atropine is co-administered to block the unwanted muscarinic (bradycardic) effects.