Pharmacokinetics>Bioavailability Comparison Practice Test

A pharmacokinetic crossover study compared two oral formulations of Drug M: an immediate-release (IR) tablet and an extended-release (ER) capsule. Using IV dosing as the reference (100%), the relative bioavailability (F) of the IR tablet was 50% when taken fasting and increased to 60% when taken with a high-fat meal. The ER capsule achieved 40% when taken fasting and 45% with a high-fat meal. The investigators noted that food modestly increased absorption for both, with a greater effect on the IR formulation, while the ER was designed to slow absorption without improving overall F.

A pharmacist counsels a patient on Drug N available as an oral tablet and a sublingual tablet. In a study, oral administration under fasting conditions resulted in bioavailability (F) of 35% due to significant first-pass metabolism. Co-administration of grapefruit juice (a gut CYP3A4/P-gp inhibitor) increased oral F to 55%. Proper sublingual administration (held under the tongue until fully dissolved) bypassed much of first-pass metabolism and achieved F of 65%. When the sublingual tablet was swallowed immediately, systemic exposure resembled oral swallowing with F of 35%.