This drug is converted to an active metabolite after absorption:

Correct Answer: C

Rationale: Rationale for the correct answer (C - Enalapril): 1. Enalapril is a prodrug that requires conversion to its active form, enalaprilat, in the liver. 2. Enalaprilat has potent ACE inhibitory effects, making it the active metabolite responsible for the drug's therapeutic action. 3. The conversion process enhances the drug's bioavailability and ensures a consistent pharmacological response. Summary of why other choices are incorrect: A: Labetalol is not converted to an active metabolite after absorption; it exerts its effects directly. B: Clonidine acts directly on alpha-2 adrenergic receptors without requiring conversion to an active form. D: Nifedipine is a calcium channel blocker that does not need metabolic activation for its pharmacological effects.

Correct Answer: D

Rationale: Step-by-step rationale for why choice D is correct: 1. Biguanides like metformin are not used in hyperglycemic shock due to their slower onset of action. 2. In hyperglycemic shock, rapid-acting medications like insulin are needed for immediate correction. 3. Choices A, B, and C are incorrect because biguanides are commonly used as an initial treatment for type 2 diabetes to improve insulin sensitivity and reduce glucose production in the liver.

Correct Answer: C

Rationale: The correct answer is C: Metamizole (Analgin). Metamizole is a pyrazolone derivative due to its chemical structure containing a pyrazolone ring. Ibuprofen (A) is a propionic acid derivative, Indomethacin (B) is an indole derivative, and Diclofenac (D) is a phenylacetic acid derivative. Pyrazolone derivatives like Metamizole are known for their analgesic, antipyretic, and anti-inflammatory properties.

Correct Answer: D

Rationale: The correct answer is D because I.V. IgG preparations compete for Fc receptors with autoantibodies. This blocks the binding of autoantibodies to their target antigens, thereby preventing autoimmune reactions. Choice A is incorrect as I.V. IgG does not inhibit CD3 receptors. Choice B is incorrect as it does not inhibit calcineurin. Choice C is incorrect as I.V. IgG does not induce complement-mediated cytolysis of T lymphocytes.

Correct Answer: A

Rationale: The correct answer is A: Scurvy is a disease caused by a deficiency of vitamin C. This deficiency leads to symptoms such as spongy bleeding gums, bleeding under the skin, and weakness. - Choice B is incorrect because extreme dryness of the conjunctiva is not a symptom of scurvy, and it is more related to a deficiency of vitamin A. - Choice C is incorrect because it describes symptoms of pellagra, a disease caused by a deficiency of niacin, not scurvy. - Choice D is incorrect because it includes all the incorrect options, making it incorrect as well. In summary, the correct choice (A) accurately describes the cause and symptoms of scurvy, while the other choices describe different diseases with unrelated symptoms.