The drug is sometimes part of fixed-dose combinations used to treat essential hypertension:

Correct Answer: C

Rationale: Step-by-step rationale for why choice C is correct: 1. Hydrochlorothiazide is a diuretic commonly used to treat hypertension. 2. Amiloride is a potassium-sparing diuretic often used in combination with hydrochlorothiazide. 3. Fixed-dose combinations of both drugs are effective in managing essential hypertension. 4. Therefore, choice C, "Both of the above," is correct as it includes both hydrochlorothiazide and amiloride. Summary: - Choice A is incorrect because hydrochlorothiazide alone is not always part of fixed-dose combinations for essential hypertension. - Choice B is incorrect because amiloride alone is not commonly used to treat essential hypertension. - Choice D is incorrect because both hydrochlorothiazide and amiloride can be part of fixed-dose combinations for essential hypertension.

Correct Answer: D

Rationale: The correct answer is D because Streptomycin is known to cause ototoxicity and nephrotoxicity. Ototoxicity refers to the damage it can cause to the inner ear, leading to hearing loss and balance issues. Nephrotoxicity refers to its potential to harm the kidneys. The other choices are incorrect because cardiotoxicity (A) and hepatotoxicity (B) are not typically associated with Streptomycin use. Retrobulbar neuritis with red-green color blindness (C) is a side effect of Ethambutol, not Streptomycin.

Correct Answer: B

Rationale: The correct answer is B: Mebendazole or Albendazole. These drugs are commonly used for the treatment of echinococcosis due to their efficacy against tapeworm infections. Mebendazole and Albendazole work by inhibiting the parasite's ability to absorb glucose, leading to its death. Suramin (choice A) is used for African sleeping sickness, not echinococcosis. Piperazine (choice C) is used for roundworm infections, not echinococcosis. Iodoquinol (choice D) is used for amoebic infections, not echinococcosis.

Correct Answer: B

Rationale: The correct answer is B: Blockade of Na+ channels in the collecting duct. Triamterene is a potassium-sparing diuretic that works by inhibiting the epithelial sodium channels (ENaC) in the collecting duct of the nephron. By blocking these channels, triamterene reduces sodium reabsorption, leading to decreased potassium excretion. This mechanism helps maintain potassium levels in the body, making it an effective treatment for conditions like systolic cardiac failure where potassium loss is a concern. Summary: A: Enhancement of K+ reabsorption in the proximal tubule - This is incorrect as triamterene does not act on the proximal tubule for potassium-sparing effects. C: Enhancement of K+ reabsorption in the loop of Henle - This is incorrect as triamterene does not primarily affect potassium reabsorption in the loop of Henle. D: Blockade of aldosterone receptors in the collecting duct - This is

Correct Answer: C

Rationale: The correct answer is C: Demeclocycline. It is the most appropriate choice for the patient's condition due to its ability to treat syndrome of inappropriate antidiuretic hormone secretion (SIADH), characterized by excessive release of antidiuretic hormone causing water retention. Demeclocycline acts as a competitive antagonist of ADH, helping to correct the water imbalance. Desmopressin (A) is a synthetic form of ADH and would exacerbate the condition. Hydrochlorothiazide (B) and Amiloride (D) are diuretics that would further worsen the water imbalance in SIADH by increasing urine output.