Bioavailability Enhancement: Drug Stability Enhancement and GI Retention

A drug’s stability in the GI tract can be improved through various methods.

Polymer coating prevents drug release in the stomach, improving drug absorption in the gastric milieu.

The stability can also be enhanced by using complexing agents like β-cyclodextrins.

Some approaches, like bioadhesive delivery systems and controlled-release microencapsulated systems, co-administer the drug with metabolism inhibitors to enhance bioavailability.

For example, the co-administration of erythromycin can significantly enhance the bioavailability of cyclosporin.

Gastro-retentive drug delivery systems localize the delivery device in the stomach, improving GI tract retention.

Bioadhesive or swelling excipients like cellulose ethers or natural gums increase contact with epithelial surfaces, prolonging stomach residence time and delaying intestinal transit.