In the extemporaneous preparation of a suspension, levigation is used to

Correct Answer: C

Rationale: Levigation reduces particle size (C) in suspension preparation, mixing a solid with a levigating agent (e.g., glycerin) to form a smooth paste, improving uniformity and dispersion (e.g., zinc oxide suspensions). Reducing zeta potential (A) stabilizes colloids, not levigation's goal. Avoiding bacterial growth (B) requires preservatives, not levigation. Enhancing viscosity (D) or reducing it (original E) isn't the aim; particle size is. This wet-grinding technique ensures palatability and consistent dosing in extemporaneous compounding, critical for patient acceptance and efficacy.

Correct Answer: A

Rationale: Excessive moisture (A) is the most likely reason for picking (1) in tablet granulation, where wet granules stick to punches, causing defects. Entrapment of air (B) causes capping (3), splitting tablets. Tablet friability (C) reflects poor binding, not moisture. Degraded drug (D) affects potency, not physical defects like mottling (2) or sticking (4). Option E (original) about hardness is unrelated. Moisture control during granulation ensures tablet integrity, a key manufacturing challenge impacting quality and patient safety.

Correct Answer: D

Rationale: The Noyes-Whitney equation (D), dC/dt = kA(Cs - C), describes the rate of drug dissolution from a tablet, factoring surface area (A), solubility (Cs), and concentration (C), key in bioavailability (e.g., aspirin tablets). Fick's law (A) governs diffusion across membranes. Henderson-Hasselbalch (B) calculates pH-ionization. Law of mass action (C) is chemical equilibrium. Michaelis-Menten (original E) is enzyme kinetics. This equation guides formulation (e.g., particle size reduction), ensuring rapid dissolution for absorption, critical in solid dosage design.

Correct Answer: D

Rationale: The loading dose (D_L) is based on the apparent volume of distribution (V_D) and desired plasma concentration (D), calculated as D_L = V_D × C_p, ensuring rapid therapeutic levels (e.g., digoxin). Clearance (A) affects maintenance, not loading. Protein binding (B) and urinary excretion (C) influence free drug but aren't primary. AUC (original E) is outcome-based. V_D reflects tissue distribution, critical for initial dosing in drugs with large V_D, balancing speed and safety.

Correct Answer: A

Rationale: For a zero-order reaction, dA/dt = -k (A) is true, indicating a constant rate of drug elimination (e.g., ethanol above Km), independent of concentration. Option B (t₁₂=0.693/k) is first-order. Option C (A=A₀e⁻ᵏ) is first-order decay. No options D or original E exist, but C is incorrect here. Zero-order kinetics, rare in drugs, means half-life increases with dose, complicating dosing (e.g., phenytoin overdose), contrasting with first-order's constant half-life, key in pharmacokinetics.