SPEX SPEX Pharmacology 5

Question 1

A patient receiving aminoglycoside therapy develops nephrotoxicity. Which aminoglycoside dosing strategy best minimizes this risk while maintaining efficacy?

Accepted Answer

Once-daily extended-interval dosing

Answer

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.

Question 2

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

Accepted Answer

Methadone

Answer

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

Question 3

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

Accepted Answer

Anticholinergics

Answer

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

Question 4

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

Accepted Answer

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

Answer

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.

Question 5

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

Accepted Answer

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

Answer

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.

SPEX Exam Practice Test

SPEX Exam Practice Test

SPEX SPEX Pharmacology 5