Which of the following drugs may inhibit the hepatic microsomal P450 responsible for warfarin metabolism

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: 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.

Correct Answer: A

Rationale: Capsule size 5 (A) has the smallest capacity (~0.13 mL), per standard pharmaceutical sizing, where higher numbers indicate smaller volumes, used for low-dose drugs (e.g., thyroid). Size 4 (B, ~0.2 mL), 1 (C, ~0.5 mL), and 0 (D, ~0.68 mL) are larger; 000 (original E, ~1.37 mL) is largest. This sizing aids precise dosing, minimizing excipient use, critical in oral solid formulations for patient compliance and manufacturing efficiency.

Correct Answer: A

Rationale: Trituration (A) best describes rubbing or grinding a substance in a mortar with a rough inner surface (1), reducing particle size (e.g., sulfur). Spatulation (B) mixes without grinding. Levigation (C) uses a liquid for a paste (3). Pulverization by intervention (D) adds a solvent (2). Tumbling (original E) is industrial mixing. Trituration's mechanical action ensures fine powders, enhancing dissolution in extemporaneous preparations, a fundamental pharmacy skill.