Page 68 - Pharmaceutics III_ 02-06-01304_Fall 2025_ Pharm D_Electronic book
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Zero-order kinetics:
Rate = k₀; concentration decreases linearly with time.
First-order kinetics:
Rate = k₁C; log concentration vs time gives straight line.
t₉₀ (shelf life) = 0.105/k (for first-order).
Accelerated stability:
• Arrhenius equation: k = Ae^(-Ea/RT).
• Testing at 40°C and 75 % RH for 6 months approximates 2 years at 25°C.
Regulatory Guidelines:
ICH Q1A(R2): Stability Testing of New Drug Substances and Products.
ICH Q8: Pharmaceutical Development.
ICH Q10: Quality System.
Tablet and Capsule Appearance Standards:
• Uniform color, free from cracks, pinholes, spots.
• Coated tablets: smooth, even gloss.
• Capsules: no dents, no leakage, intact lock.
Examples of Typical Tablet and Capsule Defects:
Dosage Form Defect Observation Possible Cause
Tablet Mottling Color unevenness Dye migration
Tablet Lamination Split layers Overcompression
Tablet Capping Top detached Air entrapment
Tablet Picking Surface removed Moisture
Capsule Softening Sticky shell High humidity
Capsule Brittleness Cracking Low humidity
Evaluation of Flow Properties:
1. Angle of repose: tanθ = h/r.
o Excellent: <25°, Good: 25–30°, Passable: 30–40°.
2. Bulk density (ρb): W/V₀.
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