Page 33 - Pharmaceutics III_ 02-06-01304_Fall 2025_ Pharm D_Electronic book

Equipment:
• Conventional coating pan (modified for spray).
• Perforated pan (Accela-Cota, Driacoater).
• Fluidized bed coater (for pellets).

Film coating parameters:
• Inlet air temperature 40–60°C.
• Atomizing air pressure 1.5–3 bar.
• Spray rate adjusted to avoid overwetting.

3. Compression coating (dry coating):
An outer layer of dry powder is compressed around a preformed core tablet using special
double compression machines.
Advantages:

• Avoids moisture and heat.
• Can be used for incompatible drugs (core vs coat).
• Allows modified release.
Disadvantages:
• Requires special equipment and die alignment.

4. Enteric coating:
Applied to delay release of the drug until it reaches the intestine (pH > 5.5).
Materials:

• Cellulose acetate phthalate (CAP)
• Hydroxypropyl methylcellulose phthalate (HPMCP)
• Polyvinyl acetate phthalate (PVAP)
• Methacrylic acid copolymers (Eudragit L & S)
Mechanism:
Resistant to gastric acid, soluble in intestinal fluid.

5. Sustained or controlled release coating:
Coating retards drug release over prolonged period.
Materials:

• Ethyl cellulose

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