Peptides have a number of attractive properties that make them an interesting modality for drug development, including their ability to bind challenging targets, their high target specificity, and their non-toxic metabolic products. However, a major limitation of peptides as drugs is
their typically poor oral availability, hindering their convenient and flexible application as pills. Of the more than 60 approved peptide drugs, the large majority is not orally applicable. The oral delivery of peptides is hampered by their metabolic instability and/or limited intestinal
uptake. In this article, we review the barriers peptides need to overcome after their oral administration to reach disease targets, we highlight two recent successes of pharma companies in developing orally applicable peptide drugs, and we discuss efforts of our laboratory towards the generation
of bioavailable cyclic peptides.
Oral delivery of protein and peptide drugs: from non-specific formulation approaches to intestinal cell targeting strategies
