Using microemulsion formulations for oral drug delivery of therapeutic peptides

Peptide drugs are increasingly becoming a very important class of therapeutic agents with the rapid advances in the field of biotechnology engineering. However, these drugs are generally not suitable for oral administration. In this review, the main physico-chemical and biopharmaceutical characteristics of peptides are summarized. The obstacles to peptide drug absorption and the different possibilities for solving these difficulties are listed. Results using this formulation approach for oral drug delivery of peptides are apparently promising with some specific peptides such as cyclosporin. Various mechanisms are only beginning to be understood and further investigations need to be performed in this area to explain the results obtained with some peptides.