[PSCI-05] Physical Pharmaceutics: Rheology, Micromeritics, Interfacial Phenomena & Chemical Kinetics

PSCI-05 • 4. Pharmaceutics

Learning Objectives

Differentiate Newtonian and Non-Newtonian flow (Plastic/Bingham, Pseudoplastic, Dilatant, Thixotropy) with viscometer selection.; Calculate angle of repose (θ), Carr's Compressibility Index, and Hausner's Ratio to evaluate powder flowability.; Calculate zero-order, first-order, and second-order degradation rate constants, shelf-life (t90), and Arrhenius accelerated stability predictions.

Chapter Overview & Core Explanation

Physical pharmaceutics applies physics and physical chemistry to drug materials—measuring how powders flow into tablet dies, how creams and gels deform when squeezed from a tube, and how fast drug molecules degrade over shelf storage.

Key Exam & Clinical Takeaways

• Liquid suspensions of hydrolysable drugs (like [3.39] Aspirin or reconstituted [8.1] Amoxicillin) follow Apparent Zero-Order degradation kinetics because dissolved drug is continuously replenished from the solid reservoir at saturation solubility (C_s).
• India is classified in ICH Climatic Zone IVb (30°C ± 2°C / 75% RH ± 5% RH for long-term stability studies).

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