Pharmacology MCQs- 260

Q- Which of the following groups of medications prolongs GABA activity in the brain?

A- Alcohols

B- Barbiturates

C- Benzodiazepines

D- Methamphetamines

B- Barbiturates- Barbiturates prolong the duration of chloride channel opening at the GABA-A receptor, thereby prolonging GABA activity. Benzodiazepines increase the frequency,

not the duration. Alcohol also enhances GABA, but it is not the best answer here, and methamphetamines have no GABA-enhancing effect.

Q- Which of the following medications inhibits folic acid synthesis through its effect on dihydropteroate synthetase enzyme?

A- Methotrexate

B- Pyrimethamine

C- Sulfonamides

D- Trimethoprim

C- Sulfonamides- Sulfonamides inhibit dihydropteroate synthetase, blocking folic acid synthesis in bacteria. Methotrexate and trimethoprim inhibit dihydrofolate reductase, and pyrimethamine also targets the reductase enzyme in parasites, not dihydropteroate synthetase.

Q- Which of the following is the mechanism of action of misoprostol for the treatment of peptic ulcer?

A- Direct inhibition of the proton pump

B- Formation of a protective coating of the ulcer beds

C- Increased mucus and bicarbonate secretion and decreased HCL secretion

D- Suppression of secretory responses to food stimulation

C- Increased mucus and bicarbonate secretion and decreased HCL secretion- Misoprostol is a prostaglandin E₁ analog that protects the gastric mucosa by increasing mucus and bicarbonate production while simultaneously reducing gastric acid secretion.