FPGEE Pharmacokinetics 5

Question 1

A patient on warfarin (narrow therapeutic index, highly albumin-bound) is started on a second drug that also binds albumin avidly. What is the initial expected pharmacokinetic consequence?

Accepted Answer

Transiently increased free warfarin concentration

Answer

Displacement from albumin transiently increases free warfarin fraction, raising pharmacological effect until clearance of the newly freed drug re-establishes equilibrium.

Question 2

Which of the following best describes the concept of 'flip-flop' kinetics after extravascular drug administration?

Accepted Answer

Absorption is slower than elimination, so absorption rate limits the terminal slope

Answer

Flip-flop kinetics occurs when absorption rate constant (ka) < elimination rate constant (ke), making the absorption process the rate-limiting step controlling the terminal plasma decline.

Question 3

Creatinine clearance is used clinically to estimate which parameter for drug dosing in renal impairment?

Accepted Answer

Glomerular filtration rate (GFR)

Answer

Creatinine clearance is a surrogate marker for GFR and is used to estimate renal drug elimination capacity for dose adjustments.

Question 4

After repeated dosing at steady state, peak and trough concentrations fluctuate around the average Css. What determines the magnitude of fluctuation?

Accepted Answer

The ratio of dosing interval to drug half-life

Answer

Greater fluctuation occurs when the dosing interval is long relative to half-life; shorter intervals relative to half-life produce less peak-to-trough variation.

Question 5

A drug is administered as a prodrug that requires hepatic conversion to its active metabolite. In severe hepatic disease, the expected effect is:

Accepted Answer

Reduced therapeutic effect due to impaired prodrug activation

Answer

Hepatic disease impairs conversion of prodrug to active metabolite, reducing therapeutic efficacy; the prodrug itself has little or no pharmacological activity.

FPGEE Exam Practice Test

FPGEE Exam Practice Test

FPGEE Pharmacokinetics 5