Pharmacology Antimicrobial and Chemotherapeutic Agents 4

Question 1

A patient with HIV is started on antiretroviral therapy. Which drug class inhibits HIV integrase, preventing viral DNA from inserting into the host genome?

Accepted Answer

Integrase strand transfer inhibitors (INSTIs)

Answer

Integrase strand transfer inhibitors (e.g., raltegravir, dolutegravir) block the HIV integrase enzyme, preventing integration of viral cDNA into the host cell nucleus.

Question 2

Which antibiotic is bacteriostatic and works by binding the 30S ribosomal subunit to inhibit aminoacyl-tRNA binding?

Accepted Answer

Tetracycline

Answer

Tetracyclines reversibly bind the 30S ribosomal subunit at the A site, blocking aminoacyl-tRNA attachment and thereby halting protein elongation in a bacteriostatic manner.

Question 3

Caspofungin belongs to which antifungal class, and what is its mechanism of action?

Accepted Answer

Echinocandin; inhibits beta-(1,3)-D-glucan synthase

Answer

Caspofungin is an echinocandin that inhibits beta-(1,3)-D-glucan synthase, disrupting cell wall synthesis — a mechanism with no human cell wall equivalent, resulting in selective toxicity.

Question 4

A patient taking rifampin for tuberculosis reports that their oral contraceptives have become less effective. The most likely explanation is:

Accepted Answer

Rifampin induces CYP450 enzymes, accelerating contraceptive metabolism

Answer

Rifampin is a potent CYP450 inducer that increases hepatic metabolism of estrogens and progestins, significantly reducing plasma levels of oral contraceptives.

Question 5

Which antibiotic is the treatment of choice for Lyme disease caused by Borrelia burgdorferi in adults?

Accepted Answer

Doxycycline

Answer

Doxycycline is first-line treatment for early Lyme disease in adults and is also effective against early disseminated Lyme disease without neurologic involvement.

Pharmacology Practice Test

Pharmacology Practice Test

Pharmacology Antimicrobial and Chemotherapeutic Agents 4