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SPEX Pharmacology Flashcards

7 cards from real SPEX 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 receiving aminoglycoside therapy develops nephrotoxicity. Which aminoglycoside dosing strategy best minimizes this risk while maintaining efficacy?

    Answer: Once-daily extended-interval dosing

    Once-daily extended-interval dosing exploits the aminoglycoside's concentration-dependent killing and post-antibiotic effect while allowing renal tubular cells to recover, reducing nephrotoxicity.

  2. Which opioid analgesic has the highest oral bioavailability and is least affected by first-pass metabolism?

    Answer: Methadone

    Methadone has high and variable oral bioavailability (~80%) partly because it undergoes less first-pass hepatic extraction compared to most other opioids.

  3. A patient with acute angle-closure glaucoma should NOT receive which drug class due to risk of worsening the condition?

    Answer: Anticholinergics

    Anticholinergics cause pupillary dilation (mydriasis), which can mechanically block aqueous humor outflow at the iridocorneal angle, acutely raising intraocular pressure.

  4. Selective COX-2 inhibitors (e.g., celecoxib) carry an increased cardiovascular risk primarily because they:

    Answer: Inhibit prostacyclin (PGI2) while sparing thromboxane A2 (TXA2)

    COX-2 is expressed in vascular endothelium and produces protective PGI2; its inhibition shifts the balance toward pro-thrombotic TXA2 activity from platelets, increasing MI and stroke risk.

  5. Which statement correctly describes the Vmax in Michaelis-Menten enzyme kinetics as applied to drug metabolism?

    Answer: It is the maximum rate of metabolism achieved when all enzyme active sites are saturated

    Vmax is the theoretical maximum metabolic rate reached when all available enzyme molecules are fully occupied with substrate, making it independent of further drug concentration increases.

  6. A patient taking phenytoin for epilepsy is started on isoniazid (INH) for tuberculosis. What is the expected pharmacokinetic outcome?

    Answer: Phenytoin levels increase due to CYP2C9 inhibition by INH

    Isoniazid inhibits CYP2C9 and CYP2C19, which are responsible for phenytoin hydroxylation, causing phenytoin accumulation and potential toxicity (nystagmus, ataxia).

  7. Which drug used in the treatment of Parkinson's disease works by inhibiting catechol-O-methyltransferase (COMT)?

    Answer: Entacapone

    Entacapone and tolcapone inhibit COMT, the enzyme that degrades levodopa and dopamine peripherally, thereby prolonging levodopa's effect and reducing 'off' periods.