GAMSAT Pharmacology Fundamentals 3

Question 1

A partial agonist differs from a full agonist primarily because it:

Accepted Answer

Produces a lower maximal effect even when all receptors are occupied

Answer

A partial agonist has intrinsic efficacy less than 1, so even at full receptor occupancy it cannot achieve the maximal response that a full agonist produces.

Question 2

Which route of administration completely bypasses first-pass metabolism?

Accepted Answer

Sublingual

Answer

Sublingual administration delivers drug directly into the systemic venous circulation via the oral mucosa, entirely avoiding portal circulation and hepatic first-pass metabolism.

Question 3

Drug A has a half-life of 8 hours. Approximately how long will it take to reach steady-state plasma concentration during regular dosing?

Accepted Answer

40 hours

Answer

Steady state is reached after approximately 4–5 half-lives; 5 × 8 h = 40 h is the standard approximation used clinically.

Question 4

Which of the following best describes the mechanism of non-competitive (irreversible) antagonism?

Accepted Answer

The antagonist covalently binds to the receptor, permanently reducing the number of functional receptors

Answer

Irreversible antagonists form covalent bonds with the receptor, permanently inactivating it so that even large concentrations of agonist cannot restore the maximal effect.

Question 5

Bioavailability is defined as the fraction of administered drug that:

Accepted Answer

Reaches systemic circulation in unchanged, active form

Answer

Bioavailability (F) represents the proportion of an administered dose that reaches systemic circulation intact and is available to exert pharmacological effects.

(GAMSAT) Graduate Medical School Admissions Test Practice Test

(GAMSAT) Graduate Medical School Admissions Test Practice Test

GAMSAT Pharmacology Fundamentals 3