TARGETING OF PEPTIDE AND PROTEIN DRUGS TO SPECIFIC SITES IN THE ORAL ROUTE

Although the distal small intestine has less lumenal and apical proteo lytic activities, it has high activities of some apical peptidases. Co lonic proteolytic activities are substantial, but their nature is less understood. The small intestine has di- and tripeptide transporter, f acilitating absorption, and P-glycoprotein, an efflux pump suggested t o limit absorption of small peptides. Several peptide and nonpeptide d rugs have higher absorption in the ileum; however, enhancement on thei r absorption by enhancers varies from site to site. Specific delivery systems can target drugs to the distal intestine utilizing distinct re gional pHs and specific microbial enzymes, but the key is how to achie ve a reliable release.