Which of histamine H1 antagonists is noted for the serotonin-blocking effect?

Correct Answer: B

Rationale: Step-by-step rationale for choice B (Cyproheptadine) as the correct answer: 1. Cyproheptadine is a potent H1 receptor antagonist. 2. It is also known for its significant serotonin-blocking effect. 3. This dual mechanism of action makes it effective for treating conditions involving both histamine and serotonin imbalances. 4. Brompheniramine (A), Suprastine (C), and Dimedrol (D) do not exhibit significant serotonin-blocking effects, making them incorrect choices.

Correct Answer: A

Rationale: Hypercholesterolemia is indeed an abnormally high concentration of cholesterol in the blood, making choice A true. Choice B is incorrect as hypercholesterolemia is a recognized medical condition. Choice C, stating "All," is incorrect as it is too vague and does not provide a clear answer. Choice D, stating "None," is also incorrect because hypercholesterolemia is a valid medical term and condition.

Correct Answer: D

Rationale: The correct answer is D because the metabolic products of probenecid are not uricosuric. Probenecid itself is uricosuric, meaning it promotes the excretion of uric acid from the body by inhibiting its reabsorption in the kidney tubules. Choice A is correct as probenecid does indeed promote the renal tubular secretion of penicillin. Choice B is correct as probenecid is used in the treatment of gout by lowering uric acid levels in the blood. Choice C is correct as probenecid, at appropriate doses, promotes the excretion of uric acid, thereby helping to manage conditions like gout.

Correct Answer: C

Rationale: The correct answer is C, Calcium chloride (0.68-1.36 meq calcium/mL), as it has the highest concentration of calcium per mL among the options. This makes it the most preferable for IV injection, providing a more efficient delivery of calcium to the body. Choice A, Calcium gluceptate, has a lower calcium concentration compared to Calcium chloride, making it less preferable for IV injection. Choice B, Calcium gluconate, also has a lower calcium concentration compared to Calcium chloride, making it less optimal for IV administration. Therefore, Calcium chloride is the best choice for IV injection due to its higher calcium concentration, ensuring effective calcium supplementation.

Correct Answer: C

Rationale: Metolazone acts at the distal convoluted tubule. It inhibits sodium and chloride reabsorption, leading to increased diuresis. The distal convoluted tubule is where sodium and chloride reabsorption are regulated by aldosterone. Metolazone's mechanism of action aligns with this site, making choice C the correct answer. Choices A, B, and D are incorrect because Metoljson's action is not targeted at the proximal convoluted tubule, ascending thick limb of the loop of Henle, or the collecting duct.