Tablet coating agents
Tablet coating agents are used to coat a tablet to protect against decomposition by atmospheric oxygen or humidity, to provide a desired release pattern, to mask taste or odor, or for aesthetic purposes. Coating may be sugar, film, or thick covering around a tablet. Sugar-coated tablets generally start to break up in the stomach. Film forms a thin cover around a formed tablet or bead. Unless it is enteric, film dissolves in the stomach. Enteric coating passes through the stomach to break up in the intestines. Some water-insoluble coatings (e.g., ethylcellulose) are used to slow the release of drug in the gastrointestinal tract.
Sugar Coating
- Liquid glucose
- Sucrose
Film coating
- Hydroxyethyl cellulose
- Hydroxypropyl cellulose
- Hydroxypropyl methylcellulose
- Methylcellulose (e.g., Methocel)
- Ethylcellulose (e.g., Ethocel)
Enteric coating
- Cellulose acetate phthalate
- Shellac (35% in alcohol, pharmaceutical glaze)