Optimizing gastrointestinal delivery of drugs

There is currently a great deal of effort being aimed at achieving effective delivery of novel therapeutic drugs, such as peptides, by the oral route. Opportunities have been identified which could lead to more convenient delivery systems for this class of drug. It is likely that a polypeptide given unprotected into the gastrointestinal environment will be degraded significantly. However, it is well known that small quantities of dietary proteins can be absorbed, even though these may have little or no physiological effect. It is felt that the colon may provide an advantageous absorption site for peptides. As a consequence there has been considerable interest, not only in the development of colonic delivery systems, but also in the establishment of strategies designed to maximize peptide absorption from the colon. Traditionally, vaccine research has been concerned with producing systemic immunity by parenteral immunization. However, the gradual acceptance of the importance of IgA in protecting mucosal surfaces against infection from numerous pathogenic organisms has led to an increased interest in oral immunization. Because of the existence of the CMIS, oral immunization induces secretory immunity in both the genital and respiratory tracts. Therefore, oral immunization offers the possibility for development of easily administered vaccines that will be effective in prevention against important respiratory and genital tract infections. The recent advances in recombinant DNA technology and the development of antigen delivery systems have given rise to optimism that several new and improved oral vaccines may be available by the next millennium.