What equation describes the rate of drug dissolution from a tablet?

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: 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.

Correct Answer: A

Rationale: Hydrolases (A) uncouple peptide linkages, cleaving bonds with water (e.g., pepsin in digestion), breaking proteins into amino acids. Ligases (B) form bonds. Oxidoreductases (C) handle redox. Transferases (D) move groups. Isomerases (original E) rearrange. Hydrolases' role in proteolysis impacts drug metabolism (e.g., prodrugs like enalapril) and digestion, central to biochemistry and pharmacology, affecting bioavailability and clearance.

Correct Answer: A

Rationale: IgG (A) has the longest serum half-life (~21 days) and opsonizes antigens via Fc receptors and complement activation, enhancing phagocytosis (e.g., bacterial clearance). IgM (B) is short-lived, pentameric. IgA (C) protects mucosae. IgE (D) drives allergies. No original E. IgG's persistence and dual opsonization (FcγR and C3b) make it key in immunity and monoclonal antibody drugs (e.g., rituximab), impacting pharmacokinetics and therapeutic longevity.

Correct Answer: B

Rationale: Diazepam (B) does not undergo hydrolysis; it's metabolized by CYP450 oxidation and glucuronidation (e.g., to nordazepam). Procaine (A), aspirin (C), and lidocaine (D) hydrolyze via esterases (e.g., procaine to PABA), cleaving ester bonds. No original E. Hydrolysis, a phase I reaction, increases polarity for excretion, but diazepam's oxidative path prolongs its action, impacting its use as a long-acting anxiolytic, distinct in metabolism profiles.