The common side effect of thyroid hormones is following:

Correct Answer: B

Rationale: The correct answer is B: Angina pectoris. Thyroid hormones can increase cardiac output and oxygen demand, potentially leading to angina. A: Increases in basal metabolic rate is a common therapeutic effect of thyroid hormones. C: Tremors may occur as a sign of hyperthyroidism but not a direct side effect of thyroid hormone therapy. D: Exopthalmos is a clinical sign of Graves' disease, not a direct side effect of thyroid hormone therapy.

Correct Answer: A

Rationale: The correct answer is A because an immediate allergy reaction, also known as a type I allergic reaction, typically occurs within minutes to about an hour after exposure to an antigen. This rapid onset is characteristic of type I hypersensitivity reactions mediated by IgE antibodies. It involves the release of histamine and other inflammatory mediators from mast cells and basophils, leading to symptoms such as hives, itching, swelling, and in severe cases, anaphylaxis. Choice B is incorrect because it describes a delayed allergic reaction, which usually takes hours to days to develop. Choice C is incorrect as it describes type II hypersensitivity reactions involving IgM or IgG antibodies, not type I reactions. Choice D is incorrect as it describes type III hypersensitivity reactions involving antigen-antibody complexes, not type I reactions.

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.