Which of the following NSAIDs is a nonselective COX inhibitor

Correct Answer: A

Rationale: The correct answer is A: Piroxicam. Piroxicam is a nonselective COX inhibitor because it inhibits both COX-1 and COX-2 enzymes. This makes it effective for reducing inflammation by blocking prostaglandin synthesis. Rofecoxib (B) is a selective COX-2 inhibitor, while Celecoxib (C) is also a selective COX-2 inhibitor. Therefore, choices B and C are incorrect. Choice D is incorrect as well because not all listed NSAIDs are nonselective COX inhibitors.

Correct Answer: B

Rationale: The correct answer is B: Vitamin BC, also known as folic acid. Folic acid improves megaloblastic anemia by aiding in DNA synthesis. It does not protect against neurological manifestations of pernicious anemia because those are primarily caused by Vitamin B12 deficiency. Vitamin B12 is needed for nerve function and myelin synthesis. Vitamin PP refers to niacin, which is not directly related to these types of anemia. Vitamin D is important for bone health but is not directly involved in the treatment of megaloblastic anemia or pernicious anemia.

Correct Answer: B

Rationale: The correct answer is B: FALSE. Bile acid-binding resins work by binding bile acids in the intestine, not cholesterol directly. This binding leads to increased excretion of bile acids in feces and stimulates the liver to use more cholesterol to produce new bile acids, thus lowering blood cholesterol levels. Choice A is incorrect because bile acid-binding resins do not directly bind cholesterol. Choices C and D are incorrect as they do not accurately reflect the mechanism of action of bile acid-binding resins.

Correct Answer: D

Rationale: The correct answer is D. A: 1,25-dihydroxyvitamin D3 (calcitriol) is the active form of vitamin D and is the metabolite of choice for rapid action in raising serum calcium levels. B: Calcitriol does raise serum phosphate levels, but this effect may not be immediately observed. C: Calcitriol undergoes enterohepatic circulation, which means it is reabsorbed in the intestines and recycled through the liver. Therefore, all statements A, B, and C are true about 1,25-dihydroxyvitamin D3 (calcitriol), making option D the correct choice.

Correct Answer: A

Rationale: The correct answer is A: Acetazolamide (Diamox). Acetazolamide is a carbonic anhydrase inhibitor, primarily used to treat glaucoma and altitude sickness. Carbonic anhydrase is an enzyme that catalyzes the reversible hydration of carbon dioxide to bicarbonate and protons. By inhibiting this enzyme, acetazolamide reduces the production of aqueous humor in the eye and increases urinary bicarbonate excretion. Furosemide (B), Hydrochlorothiazide (C), and Spironolactone (D) are not carbonic anhydrase inhibitors and work through different mechanisms to treat conditions like hypertension and edema.