4. Purpose of CoatingPurpose of Coating::
1. Protection against light, air and moisture.
2. Protecting API against digestive fluids.
3. Ensure Controlled Release
4. Avoiding Side effects, masking taste.
5. Ensure eligible appearance.
6. Increase drug safety by better identification.
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14. Polymer.
Function: film former.
A.Immediate Release coating polymers:
Readily soluble in aqueous media.
a. Cellulose Derivatives: HPMC, HPC,MC.
(Have good mechanical properties).
b. Vinyl Derivatives: PVP, PVA.
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15. B. Modified Release Coating Polymers
a. Extended Release Coating polymers:
- They are dissolved in organic solvent or dispersed
in aqueous medium, such as (EC).
b. Enteric Coating polymers
- Methacrylic acid and polyacrylate derivatives such
as Eudragit.
- Phthalate esters like cellulose acetate phthalate
(CAP).
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16. Plasticizers
- Increasing elasticity of the coat.
- They have low molecular weight.
- Alter the physical properties of the
polymer.
- Examples:
PEG, Phthalate esters, Castor oil,
monoglycerides and coconut oil. 16