Overcoming the Challenges of Taking Peptide Drugs by Mouth Instead of Injection

This is a comprehensive narrative review of the recent literature on oral delivery strategies for protein and peptide therapeutics. The authors surveyed and critically evaluated published research on chemical modifications, permeation enhancers, encapsulation techniques, and novel delivery systems, providing comparative analysis of each approach's advantages and limitations.

The ability to take peptide drugs orally instead of by injection would dramatically improve patient compliance and quality of life for millions of people managing conditions like diabetes, obesity, and osteoporosis. Oral delivery could also reduce healthcare costs and expand access to peptide therapies in settings where injection-based treatment is impractical.

As peptide therapeutics become one of the fastest-growing drug classes — with GLP-1 drugs, insulin, and others reaching massive patient populations — the push for oral formulations has become a major industry priority. Oral semaglutide (Rybelsus) proved the concept is achievable, and this review maps the broader technological landscape that could extend oral delivery to many more peptide drugs.

As a review, this paper synthesizes existing research rather than generating new data. Many of the strategies discussed remain in preclinical stages, and the gap between laboratory success and commercial oral peptide products remains large. The review acknowledges that translating multi-barrier strategies into practical, scalable formulations is a major unresolved challenge.