Currently used antithyroid drugs include the following EXCEPT:

Correct Answer: B

Rationale: Step-by-step rationale: 1. Diatrizoate sodium is a contrast agent, not an antithyroid drug. 2. Propylthiouracil, Methimazole, and Potassium perchlorate are antithyroid drugs. 3. Propylthiouracil and Methimazole inhibit thyroid hormone synthesis. 4. Potassium perchlorate blocks iodine uptake by the thyroid gland, reducing hormone production. 5. Thus, Diatrizoate sodium is the correct answer as it is not an antithyroid drug.

Correct Answer: B

Rationale: Delayed allergy reaction (type IV allergic reaction) is characterized by a delayed onset, typically appearing hours after exposure. This differs from immediate allergic reactions (type I) that occur within minutes. Choice A refers to an immediate allergic response. Choice C describes type III allergic reactions involving antigen-antibody complexes, not type IV. Choice D is related to tissue damage caused by elevated antigen-antibody complexes, which is not specific to delayed allergy reactions. Thus, choice B is correct as it aligns with the delayed nature of type IV allergic reactions.

Correct Answer: D

Rationale: The correct answer is D because coenzymes are nonprotein organic substances that combine with specific apoenzymes to form active enzyme systems. This is essential for catalyzing biochemical reactions. Choice A describes vitamins, not coenzymes. Choice B describes anti-nutrients, not coenzymes. Choice C describes enzymes, not coenzymes. Thus, the correct answer is D.

Correct Answer: B

Rationale: The correct answer is B, Allopurinol. Allopurinol is a xanthine oxidase inhibitor, which helps reduce uric acid levels in conditions like gout. Xanthine oxidase is an enzyme involved in the production of uric acid. Physostigmine (A) is a cholinesterase inhibitor used in conditions like myasthenia gravis. Aminocaproic acid (C) is an antifibrinolytic agent. Acetazolamide (D) is a carbonic anhydrase inhibitor used in conditions like glaucoma and altitude sickness. Therefore, Allopurinol is the correct choice as a xanthine oxidase inhibitor.

Correct Answer: A

Rationale: Rationale: Cholestyramine binds bile acids in the GI tract, preventing their reabsorption and promoting excretion. This helps lower cholesterol levels. Nicotinic acid, gemfibrozil, and probucol work through different mechanisms and are not bile acid binders. Nicotinic acid lowers LDL and triglycerides, gemfibrozil decreases triglycerides, and probucol increases HDL. Therefore, the correct answer is A.