Pharmacology Pharmacodynamics and Mechanism of Action Questions and Answers

Question 1

A non-competitive antagonist is added to a preparation containing an agonist. How will this affect the agonist's dose-response curve?

Accepted Answer

The maximal effect (Emax) will be reduced, and the EC50 will remain unchanged.

Answer

The curve will shift to the right, increasing the EC50, with no change in Emax.

Answer

The maximal effect (Emax) will increase, and the EC50 will decrease.

Answer

The curve will shift to the left, decreasing the EC50, with no change in Emax.

Question 2

A patient addicted to a full opioid agonist is started on buprenorphine for medication-assisted treatment. Buprenorphine effectively reduces cravings and withdrawal symptoms but has a lower risk of respiratory depression at higher doses compared to the full agonist. This is because buprenorphine acts as a:

Accepted Answer

Partial agonist

Answer

Competitive antagonist

Answer

Inverse agonist

Answer

Non-competitive antagonist

Question 3

Which of the following statements best describes the clinical significance of a drug's therapeutic index (TI)?

Accepted Answer

It provides a measure of the drug's margin of safety.

Answer

It is the primary indicator of a drug's potency.

Answer

It determines the drug's mechanism of action.

Answer

It reflects the drug's peak plasma concentration after a single dose.

Question 4

Which of the following receptor types has an intrinsic enzymatic domain that is activated upon ligand binding, leading to intracellular signaling cascades through phosphorylation?

Accepted Answer

Enzyme-linked receptors

Answer

G-protein coupled receptors (GPCRs)

Answer

Ligand-gated ion channels

Answer

Intracellular steroid receptors

Question 5

Drug A produces a maximal analgesic effect at a dose of 10 mg. Drug B produces the same maximal analgesic effect at a dose of 50 mg. Drug C, even at its highest tolerated dose of 200 mg, only produces 60% of the maximal analgesic effect of Drugs A and B. Which statement is correct?

Accepted Answer

Drug A is more potent than Drug B, and both are more efficacious than Drug C.

Answer

Drug B is more potent than Drug A.

Answer

Drug C has greater efficacy than Drug A.

Answer

Drug C is the most potent of the three drugs.

Question 6

A patient using a topical decongestant spray containing an alpha-adrenergic agonist for several consecutive days finds that it is no longer effective for relieving nasal congestion, even with more frequent use. This rapid loss of drug effect is best described as:

Accepted Answer

Tachyphylaxis

Answer

Pharmacokinetic tolerance

Answer

An idiosyncratic reaction

Answer

A Type B adverse drug reaction