Excipients Used in Site-Specific-Release Formulations

EXCIPIENTS USED IN SITE-SPECIFIC-RELEASE FORMULATIONS 

Enteric coatings are a commonly used class of excipients for delaying the release of drug from dosage forms until the dosage forms reach the small intestine. Enteric coatings are useful for protection of drugs that are labile to acidic environment in 

Shellac (purified lac) dissolves at pH greater than 7 and can be used alone or in combination with other materials. It is soluble in ethanol, propylene glycol, and alkaline solutions. 

Cellulose acetate phthalate (CAP) dissolves at pH higher than 6 and is soluble in ketones, ethers, esters, and alcohols. Permeation of water vapor and gastric fluids is a concern but can be overcome by adding other materials such as shellac. Plasticizers that are used with CAP include diethyl phthalate, triacetin, tributyl citrate, and acetylated monoglyceride. 

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