Degradation of drug

1. Physical Degradation :
• Definition :
• It is the degradation which results into the change of physical
nature of drug. The formulation is totally changed by way of
appearance, organoleptic properties, hardness, brittleness,
particle size.
• Physical degradation includes:
• Loss of volatile components
• Loss of water
• Absorption of water

2. • Crystal growth
• Polymorphic changes
• Colour changes
• 1. LOSS OF VOLATILE COMPONENTS:
• Volatile components such as alcohol, ether, camphor, iodine, volatile
oil etc. escape from the formulation e.g. Nitroglycerine from drugs
evaporates.

3. Measures to Prevent Loss of Volatile
Components:
• Such products should be placed in well closed container.
• To decrease temperature as increase in temperature will increase
volatility, product should be placed in a cool place.
• 2. LOSS OF WATER:
• Loss of water from o/w emulsions thus the stability changes.
• Water evaporates from efflorescent salts such as Borax and sodium
bisulphate etc.
• Water evaporates causing crystal growth.

4. Measures to Prevent Loss of Water:
• Water loss may be prevented by storing the product in well closed
container.
• 3. CRYSTAL GROWTH:
• In solutions after super saturation of solvent crystal growth occurs
e.g. injection of calcium gluconate
• In suspension crystals settle down and caking occurs and suspension
becomes unstable e.g. ophthalmic preparations.

5. Prevention of Crystal Growth:
• In case of solutions stabilizers are employed.
• In case of suspension minimum temperature flocculation should be
managed.
• Incorporation of surface active agents.
• By increasing viscosity of suspending medium.
• 4. ABSORPTION OF WATER:
• Hygroscopic drugs such as glycerin suppositories absorb
• Water from atmosphere causing physical degradation.

6. Preventive measure for absorption of water:
• Product should be placed in well closed container.
• 5. POLYMORPHIC CHANGES:
• In polymorphic changes crystals form change. A stable crystal form is
lost.
• Measures to prevent polymorphic changes:
• Formulated product should contain a stable crystalline form of the
drug.

7. 6. COLOUR CHANGES:
• Colour changes are of two types:
• Loss of color
• Development of color
• Loss of color is due to pH changes.
• Development of color is due to reducing agents, water and U.V rays.
• Prevention of Colour Changes:
• PH should not be changed.
• Exposure to light should be avoided.