Actions of mifepristone (RU-486) include:

Correct Answer: D

Rationale: The correct answer is D because mifepristone (RU-486) acts in multiple ways to terminate pregnancy. It inhibits ovulation by blocking progesterone receptors, suppresses midcycle gonadotropin release, inhibits progesterone action on the uterus during the luteal phase, induces prostaglandin release from the endometrium, facilitates luteolysis, induces menstruation, increases uterine motility, softens the cervix, and causes detachment of the embryo. Therefore, all the actions described in options A, B, and C are correct, making option D the correct choice. Options A, B, and C are incorrect because they each only describe a single aspect of mifepristone's mechanism of action, whereas option D encompasses all the actions of mifepristone.

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.

Correct Answer: B

Rationale: The correct answer is B because pamidronate has a skeletal half-life of about 10 years, not 24 hours. A: Pamidronate is not available orally due to poor bioavailability and potential esophageal irritation. C: Fever and lymphocytopenia are reversible side effects of pamidronate. D: Pamidronate can irritate the esophagus if not washed down promptly to the stomach, leading to esophageal ulceration.