The following statements concerning aspirin are true, EXCEPT:

Correct Answer: C

Rationale: Rationale: C: Aspirin inhibits phospholipase A2. This statement is FALSE. Aspirin does not directly inhibit phospholipase A2. The correct answer is C. Summary: A: TRUE - Aspirin irreversibly inhibits COX. B: TRUE - Aspirin interferes with the chemical mediators of the kallikrein system. D: TRUE - Aspirin inhibits thromboxane A2 formation.

Correct Answer: B

Rationale: Step 1: Identify the statement - "Vitamin K enhances the anticoagulant property of coumarins." Step 2: Recall that Vitamin K is actually involved in blood clotting, counteracting anticoagulants. Step 3: Understand that coumarins are anticoagulants that work by inhibiting Vitamin K. Step 4: Therefore, the statement is FALSE as Vitamin K doesn't enhance but counteracts coumarins. Summary: Choice A is incorrect because the statement is false, Choice C and D are incorrect as they do not apply to the given scenario.

Correct Answer: A

Rationale: The correct answer is A because nicotinic acid (niacin) increases the rate of catabolism of VLDL by inhibiting lipolysis in adipose tissue, leading to decreased free fatty acids available for VLDL synthesis. This results in decreased VLDL production and increased clearance, thus lowering plasma VLDL levels. Option B is incorrect because nicotinic acid does not decrease VLDL catabolism. Option C is incorrect as not all choices are correct. Option D is incorrect as there is a correct answer.

Correct Answer: A

Rationale: Rationale: A: Correct. Calcitriol regulates calcium and phosphate levels, leading to potential ectopic calcification. Monitoring is crucial. B: Incorrect. Calcitriol does undergo enterohepatic circulation. C: Incorrect. Calcitriol is not toxic to osteoclasts; it has a role in bone health. D: Incorrect. Calcitriol has a complex relationship with bioavailability, affected by several factors.

Correct Answer: C

Rationale: Rationale: Hydrochlorothiazide blocks NaCl cotransporters in the distal tubule, reducing sodium reabsorption and increasing diuresis. Acetazolamide inhibits carbonic anhydrase in the proximal tubule. Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb. Spironolactone is a mineralocorticoid receptor antagonist acting on the principal cells of the collecting duct. Therefore, the correct answer is C, as it directly targets the distal tubule's mechanism of sodium reabsorption.