Conclusions and future prospects
Proteins and peptides display an increasingly important role as therapeutic agents for the treatment of various diseases (Zhou, 1994). Thus, improved non-parenteral delivery technologies are essential in ensuring optimal patient compliance and acceptance. The three major challenges with the delivery of proteins and peptides through non-parenteral routes (particularly the oral route) as assimilated in this review are their low bioavailability, susceptibility to enzymatic degradation and low membrane permeability (Maher and Brayden, 2012). Several oral delivery strategies have been proposed to enhance the permeation of protein and peptide molecules through the GIT. The aim of these strategies is to improve the oral bioavailability either by protecting the molecules from enzymatic degradation within the GIT or by improving their transport across intestinal cell barriers. Several technologies have been proposed which specifically target these barriers to successfully deliver oral proteins and peptides. Results from clinical trials conducted on the various technologies show positive results for its formulation into effective oral protein and peptide delivery systems. However, challenges still exist with each of the technologies proposed and these need to be addressed to enable optimal oral delivery. In general, the research and development of protein and peptide-based therapeutics are a dynamic field of research, with increasing numbers of candidates entering clinical studies in a wide variety of therapeutic categories. There is no doubt that pharmaceutical and biotechnology industries will continue to focus on these versatile molecules in association with the development of new oral formulations and delivery technologies.