An Outlook on Oral Peptide Delivery
Oral delivery of therapeutic peptides has been a constant source of frustration for delivery and formulation scientists over the last 50 years. Peptides are poorly absorbed via the oral route due to digestion and poor movement across the gut wall. For a long time the problem was limited to insulin and the non-peptide heparin, but today there are 60+ peptide drugs marketed worldwide, the majority of which are delivered using needles. Effort to enable more convenient oral delivery is associated with a minefield of proof-of-concept delivery systems, which to date have failed to translate into successful oral formulations. The extensive literature on oral peptide delivery has helped to shape specialities such as biopharmaceutics, although the volume of delivery systems that fail to deliver on their promise—especially those that have progressed to clinical testing—has raised concerns about whether peptides can be delivered via the oral route.