Mifepristone (RU-486) is used as a contraceptive and abortifacient. This consideration is:

Correct Answer: A

Rationale: The correct answer is A: TRUE. Mifepristone is a progesterone receptor antagonist that can be used for both contraception and abortion. As a contraceptive, it prevents implantation by altering the endometrium. As an abortifacient, it induces uterine contractions and softens the cervix, leading to expulsion of the embryo. Incorrect choices: B: FALSE - Mifepristone is indeed used for contraception and abortion, so this statement is inaccurate. C: None - This choice does not provide any information or contribute to the discussion, making it irrelevant. D: All of the above - This is incorrect as not all choices are true. Mifepristone being used for contraception and abortion does not mean that all choices are correct.

Correct Answer: B

Rationale: The correct answer is B because antivitamins are substances that interfere with the absorption, metabolism, or utilization of vitamins, preventing them from exerting their typical metabolic effects. This definition directly aligns with the concept of antivitamins. Option A is incorrect because it describes vitamins themselves, not antivitamins. Option C describes enzymes, not antivitamins. Option D refers to coenzymes, which are necessary for enzyme function, but it does not accurately define antivitamins. Thus, B is the correct choice.

Correct Answer: D

Rationale: Acetazolamide is a carbonic anhydrase inhibitor. It works by blocking carbonic anhydrase enzyme, reducing the production of bicarbonate ions and consequently decreasing fluid production in the eye, reducing intraocular pressure. Physostigmine is an acetylcholinesterase inhibitor used in glaucoma. Selegiline is a monoamine oxidase inhibitor used in Parkinson's disease. Aminocaproic acid is an antifibrinolytic used to treat excessive bleeding. Therefore, the correct answer is D as it directly inhibits the carbonic anhydrase enzyme.

Correct Answer: B

Rationale: Step 1: Lovastatin inhibits HMG-CoA reductase, an enzyme involved in cholesterol synthesis. Step 2: Inhibiting HMG-CoA reductase leads to upregulation of LDL receptors, enhancing LDL clearance. Step 3: Therefore, Lovastatin both inhibits an enzyme and indirectly enhances LDL clearance. Summary: A: Cholestyramine binds bile acids, not related to LDL clearance. C: Nicotinic acid primarily affects HDL levels, not directly related to LDL clearance. D: Probucol mainly acts by increasing HDL levels, not directly related to LDL clearance.

Correct Answer: D

Rationale: The correct answer is D: Intravenous. Pamidronate is a bisphosphonate used to treat bone diseases like osteoporosis. Intravenous route ensures rapid and complete absorption, leading to optimal therapeutic effects. Oral administration (A) would result in poor bioavailability. Subcutaneous (B) and intranasal (C) routes are not commonly used for pamidronate due to inconsistent absorption and inadequate therapeutic levels. Therefore, intravenous administration is the preferred route for pamidronate to achieve the desired clinical outcomes.