Page 66 - Pharmaceutics III_ 02-06-01304_Fall 2025_ Pharm D_Electronic book
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o Measured using micrometer.
o ±5 % variation acceptable.
2. Porosity:
o Determined using mercury porosimetry.
3. Tensile strength:
o Force per unit area; important for coating adhesion.
4. Friability under stress:
o Simulates handling conditions.
Moisture Determination:
Loss on drying (LOD) measured using infrared balance at 105 °C until constant weight.
Importance:
• Prevent microbial growth.
• Maintain stability.
• Avoid sticking during compression.
Tablet Storage Stability Issues:
1. Hydrolysis:
o Common for esters, amides.
o Example: aspirin → salicylic acid.
o Preventive: use desiccant, low moisture excipients.
2. Oxidation:
o For drugs containing phenol, aldehyde, or unsaturated groups.
o Example: ascorbic acid, adrenaline.
o Preventive: antioxidants (BHT, sodium metabisulfite).
3. Photolysis:
o Example: riboflavin, nifedipine.
o Preventive: amber containers, opaque coating.
4. Polymorphic transformation:
o Change in crystal form → altered dissolution.
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