Lopinavir, an HIV-protease inhibitor, is associated with the following:

Correct Answer: A

Rationale: Lopinavir is associated with lipodystrophy syndrome (A), a metabolic complication of protease inhibitors, causing fat redistribution (truncal gain, peripheral loss), linked to mitochondrial toxicity and insulin resistance, often boosted by ritonavir. Hyperglycemia (B) occurs, reflecting metabolic dysregulation. Peripheral neuropathy (C) is more tied to NRTIs like stavudine. Lactic acidosis (D) is rare with PIs, more common with NRTIs. It inhibits rifabutin metabolism (original E). Lopinavir's viral maturation block is potent in HIV, but its side effects, including diarrhea and lipid abnormalities, require dietary and pharmacologic management.

Correct Answer: A

Rationale: Cimetidine (A) inhibits hepatic microsomal P450 enzymes (e.g., CYP2C9), slowing warfarin metabolism, increasing its anticoagulant effect and bleeding risk. Ethanol (B) induces P450 (CYP2E1) chronically, not inhibiting warfarin's CYP2C9. Phenobarbital (C) induces P450 (e.g., CYP3A4), accelerating metabolism, reducing warfarin's effect. Procainamide (D) affects cardiac ion channels, not P450. Rifampin (original E) is a potent inducer, not inhibitor. Cimetidine's inhibition, via competitive binding to P450, exemplifies drug interactions altering pharmacokinetics, necessitating INR monitoring with warfarin to prevent toxicity, a classic clinical pharmacology example.

Correct Answer: C

Rationale: Physostigmine (C) is a prodrug less toxic in mammals than insects, as mammals metabolize it into less active forms, while insects lack this capacity, amplifying its cholinesterase inhibition (e.g., in insecticides). Acetylcholine (A) and bethanechol (B) are active cholinergic agonists, not prodrugs. Pilocarpine (D) is active directly, not a prodrug. Neostigmine (original E) enhances ACh, not a prodrug in this context. Physostigmine's selective toxicity exploits metabolic differences, making it safer in humans (e.g., glaucoma treatment) while lethal to pests, a key principle in pesticide design.

Correct Answer: C

Rationale: Colligative properties are related to the total number of solute particles in the solution (C), including ions and molecules (e.g., glucose or Na⁺/Cl⁻), determining osmotic pressure or freezing point depression. pH (A) reflects H⁺, not all particles. Number of ions (B) is incomplete, excluding non-ionic solutes. Unionized molecules (D) ignores ionized species. pKa (original E) is irrelevant. This particle dependence, governed by Raoult's law, underpins pharmaceutical solutions' design (e.g., isotonic saline), ensuring physiological compatibility and stability.

Correct Answer: A

Rationale: Carrier involvement (A) is common to both active and facilitated transport, using specific proteins (e.g., glucose transporters). Active transport (e.g., Na⁺/K⁺ pump) moves against the gradient (B) and requires energy (C, ATP), unlike facilitated transport (e.g., GLUT1), which is passive, down the gradient. Option D is incorrect as A is the exception. This carrier-mediated similarity distinguishes both from simple diffusion, but active transport's energy use enables uphill movement, critical for homeostasis and drug uptake (e.g., levodopa), impacting pharmacokinetics.