Which equation is used to predict the stability of a drug product at room temperature from experiments at accelerated temperature?

Correct Answer: C

Rationale: The Arrhenius equation (C), k = Ae^(-Ea/RT), predicts drug stability at room temperature by relating reaction rate (k) to temperature (T), using activation energy (Ea) from accelerated studies (e.g., 40°C). Stokes (A) addresses viscosity, Yong (B) is undefined here, Michaelis-Menten (D) is enzyme kinetics, and Hixson-Crowell (original E) models dissolution. This exponential relationship extrapolates shelf life (e.g., 25°C) from higher-temperature degradation rates, critical in pharmaceutical development for ensuring potency and safety over time.

Correct Answer: C

Rationale: A ceramic mortar is preferable when comminution is desired in addition to mixing (C), its rough surface grinding particles effectively (e.g., reducing tablet fragments), unlike smooth glass. Volatile oils (A) risk loss regardless of mortar. Dyes (B) stain ceramics, favoring glass. No option D or original E exists. Ceramic's abrasive texture enhances particle size reduction, critical in extemporaneous compounding for uniform powders, improving dissolution and bioavailability in solid dosage forms.

Correct Answer: A

Rationale: Acidic drugs mainly bind to albumin (A), the most abundant plasma protein, with sites for weak acids (e.g., warfarin, ibuprofen), affecting free drug levels. α₁-acid glycoprotein (B) binds basic drugs (e.g., lidocaine). Option C is incorrect as acidic drugs favor albumin. Option D is false. This binding, reversible and saturable, reduces free drug for distribution, prolonging action but risking displacement interactions (e.g., with aspirin), a key pharmacokinetic factor in dosing and toxicity.

Correct Answer: B

Rationale: A large apparent volume of distribution (V_D) (B) is the earliest evidence of tissue storage, indicating drug distribution beyond plasma into tissues (e.g., digoxin, V_D > 500 L), calculated as dose/plasma concentration. Increased plasma binding (A) reduces V_D. Decreased metabolism (C) affects clearance, not distribution. Side effects (D) or reduced free drug (original E) are downstream. High V_D reflects lipophilicity or tissue affinity, guiding dosing (e.g., loading doses), critical in pharmacokinetics for drugs with extensive tissue uptake.

Correct Answer: A

Rationale: The rate of blood flow to tissue (A) chiefly determines initial drug distribution, as perfusion delivers drug to organs (e.g., brain > fat), seen in anesthetics' rapid onset. GFR (B) affects excretion, not distribution. Stomach emptying (C) influences absorption. Tissue affinity (D) and plasma binding (original E) shape later distribution. Perfusion-limited kinetics prioritize highly vascular tissues, critical for acute therapies, with redistribution (e.g., thiopental) altering duration, a fundamental pharmacokinetic principle.