A good example of chemical antagonism

Correct Answer: A

Rationale: Heparin and protamine (A) is a good example of chemical antagonism, where protamine, a positively charged protein, binds and neutralizes negatively charged heparin, reversing its anticoagulant effect without receptor interaction. Protamine and zinc (B) form insulin complexes, not antagonism. Heparin and prothrombin (C) interact indirectly via clotting factors, not chemical binding. Option D is incorrect. This direct physicochemical interaction, distinct from receptor-based antagonism, is clinically vital in heparin overdose, rapidly restoring coagulation, showcasing a unique pharmacokinetic intervention.

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: Waxed paper (A) best protects hygroscopic powders (e.g., sodium chloride), its water-resistant coating preventing moisture absorption. Glassine (B) is grease-resistant, less moisture-proof. White bond (C) and blue bond (D) are absorbent, unsuitable. Vegetable parchment (original E) offers some resistance but less than wax. This barrier property maintains powder stability, critical in dispensing hygroscopic drugs, preventing clumping or degradation, ensuring accurate dosing and shelf life in humid conditions.

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.