Isoniazid is a primary antitubercular agent that:

Correct Answer: A

Rationale: Step-by-step rationale for choice A being correct: 1. Isoniazid can lead to pyridoxine deficiency. 2. Pyridoxine supplementation helps prevent neurotoxicity. 3. Thus, isoniazid therapy requires pyridoxine supplementation. Summary of why other choices are incorrect: B: Isoniazid does not effectively penetrate the BBB. C: Ocular complications of isoniazid are generally irreversible. D: Ototoxicity and nephrotoxicity are not common side effects of isoniazid.

Correct Answer: B

Rationale: The correct answer is B: Primaquine. Primaquine is a radical curative drug for Plasmodium vivax malaria, targeting the liver stage of the parasite to prevent relapse. It is also used as prophylaxis in Chloroquine sensitive regions due to its effectiveness against both the liver and blood stages of the parasite. Quinine (A) is mainly used for treating severe malaria. Mefloquine (C) is used for prophylaxis but not as a radical curative for Plasmodium vivax. Chloroquine (D) is effective against Plasmodium vivax but not as a radical curative.

Correct Answer: A

Rationale: The correct answer is A: Tetracycline. Tetracycline should be avoided in patients with liver disease due to its potential hepatotoxicity. Tetracycline is primarily metabolized in the liver and can exacerbate liver damage in patients with pre-existing liver conditions. Cotrimoxazole, Cephalexin, and Ethambutol are generally considered safe for use in patients with liver disease as they are not known to cause significant liver toxicity.

Correct Answer: D

Rationale: The correct answer is D: Acetazolamide. Acetazolamide is a carbonic anhydrase inhibitor that helps in the treatment of edema and metabolic alkalosis by promoting diuresis and increasing renal excretion of bicarbonate. It is effective in treating conditions associated with fluid retention and alkalosis. A: Digoxin is a cardiac glycoside used to treat heart conditions like heart failure and atrial fibrillation, not edema or metabolic alkalosis. B: Spironolactone is a potassium-sparing diuretic commonly used for conditions like hypertension and heart failure, but not specifically for metabolic alkalosis. C: Dobutamine is a beta-adrenergic agonist used in acute heart failure or shock situations, not for edema or alkalosis. In summary, Acetazolamide is the correct choice as it directly targets edema and metabolic alkalosis by affecting renal excretion of bicarbonate. Other options are

Correct Answer: B

Rationale: The correct answer is B: Lithium. Lithium is known to cause nephrogenic diabetes insipidus, leading to inappropriate secretion of ADH. This results in excessive thirst and copious urination. Diazepam (A) does not affect ADH secretion. Haloperidol (C) and Phenytoin (D) are not associated with ADH dysregulation.