Pharmaceutics and Pharmaceutical Technology
What the exam tests
Pharmaceutics and Pharmaceutical Technology covers dosage-form design, manufacturing unit operations, stability, and quality-by-design. Expect calculations on dissolution similarity, degradation kinetics, and sterilization, plus reasoning about why a formulation fails.
Core rules
- Noyes–Whitney: dissolution rate is proportional to surface area × (Cs − C)/h. Micronization raises surface area, but too fine a powder may be poorly wettable and agglomerate.
- BCS: Class I high solubility/high permeability; Class II low solubility/high permeability (formulation-limited); Class III high solubility/low permeability (permeability-limited); Class IV low/low.
- Stability: first-order degradation gives t90 = 0.105/k; zero-order gives t90 = 0.1C0/k0. Arrhenius extrapolation is valid only when the mechanism is unchanged.
- Sterilization: moist heat at 121 °C, 15 min, 15 psi is defined by F0; dry heat needs higher temperature and longer time; filtration suits heat-labile solutions, not suspensions.
Worked example
Two dissolution profiles are compared at four time points; mean differences (reference − test) are 5, 8, 3, and 6%. Sum of squares = 25 + 64 + 9 + 36 = 134; divided by n = 33.5; f2 = 50 log10[100/√(1 + 33.5)] = 50 log10(17.03) = 61.5. Since f2 is at least 50, the profiles are similar. The f2 calculation is invalid if either product has a mean release above 85% at 15 min or if fewer than three points are used.
Traps
Do not report t90 as t1/2 (0.693/k); do not apply Arrhenius across a phase change; do not call a Class II drug permeability-limited; and remember that f2 compares mean profiles, not individual tablets.