DHA Pharmacist Pharmacokinetics and Pharmacodynamics 3

Question 1

On a dose-response curve, potency refers to:

Accepted Answer

The dose required to produce 50% of the maximum effect (ED50)

Answer

Potency is indicated by the ED50 — a more potent drug requires a lower dose to produce 50% of maximal effect; it does not describe the magnitude of effect.

Question 2

A full agonist differs from a partial agonist in that a full agonist:

Accepted Answer

Produces maximal receptor activation (efficacy = 1)

Answer

A full agonist has intrinsic efficacy of 1, producing the maximum possible response; a partial agonist has intrinsic efficacy between 0 and 1, producing submaximal response even at full receptor occupancy.

Question 3

The therapeutic index (TI) of a drug is calculated as:

Accepted Answer

LD50 / ED50

Answer

TI = LD50 / ED50; a higher TI indicates a wider margin between effective and lethal doses, meaning a safer drug.

Question 4

A competitive antagonist differs from a non-competitive antagonist because a competitive antagonist:

Accepted Answer

Can be displaced by increasing agonist concentration, shifting the curve right

Answer

Competitive antagonists reversibly bind at the same site as the agonist; adding more agonist can displace them, restoring maximal effect but requiring higher doses.

Question 5

Drug tolerance is best described as:

Accepted Answer

A decreased response to a drug after repeated administration requiring higher doses for the same effect

Answer

Tolerance is a pharmacological adaptation where repeated drug exposure causes diminished response, necessitating dose escalation to achieve the original effect.

DHA Pharmacist Practice Test

DHA Pharmacist Practice Test

DHA Pharmacist Pharmacokinetics and Pharmacodynamics 3