Page 29 - Pharmaceutics III_ 02-06-01304_Fall 2025_ Pharm D_Electronic book
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o Elastic deformation: Particles regain shape after stress removal → poor
cohesion.
o Plastic deformation: Particles stay deformed → strong cohesion retained.
Most powders show both; whichever predominates determines the process:
• Plastic deformation → Direct compression.
• Elastic deformation → Granulation (plastic binders or diluents such as Avicel are
used).
Methods of Tablet Preparation
I. Granulation
• a) Wet granulation
• b) Dry granulation (less common)
II. Direct compression
I-a- Wet granulation:
It's the most common & most widely used method.
Advantages:
1. Improves the flow & compressibility of the drug.
2. Minimizes segregation of powder blend.
Disadvantages:
1. Costly & time consuming.
2. May not be suitable for moisture or heat sensitive drugs.
Steps of wet granulation:
1. Weighing and mixing:
The drug, diluent, disintegrant (intra-granular portion) and other excipients are weighed
accurately and blended to achieve uniformity.
2. Preparation of the binder solution:
Binder is dissolved in water or hydroalcoholic mixture depending on binder type and
drug sensitivity.
3. Wet massing:
The binder solution is added gradually to the powder mixture while stirring to form a
uniform damp mass of desired consistency.
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