Tablet coating is performed for various reasons: masking taste or odor, improving appearance, protecting the drug from the environment, or modifying drug release.
Sugar Coating
Traditional method involving multiple layers of sugar-based solution.
Advantages: Appealing appearance, good taste masking.
Disadvantages: Time-consuming, significant increase in tablet size and weight, skilled labor required.
Film Coating
Application of a thin polymeric film onto the tablet surface.
Advantages: Faster, minimal weight increase, durable, can be functional (enteric or sustained release).
Disadvantages: Possible organic solvent use (unless using aqueous-based coatings) and need for specialized equipment.
Enteric Coating
Special type of film coating that resists gastric pH but dissolves in the intestinal pH.
Purpose: Protect acid-labile drugs or protect the stomach from irritant drugs.
Press Coating (Compression Coating)
Dry coating method where a core tablet is compressed into a coating layer.
Advantages: No liquid involved, suitable for moisture-sensitive drugs, possible for controlled release.
Functional Coatings
Sustained/controlled release coatings.
Targeted release coatings (e.g., colonic release).