Emerging delivery platforms for mucosal administration of biopharmaceuticals: a critical update on nasal, pulmonary and oral routes.

INTRODUCTION: Protein and peptide-based drugs are preferred therapeutics due to their specificity but are mainly administered by injection. Alternative routes for peptide delivery are preferred because of their ease of administration and increased patient compliance. Areas covered: This review provides a critical overview of current strategies for non-invasive mucosal delivery routes of therapeutic proteins and peptides, with emphasis on their advantages and limitations. Selected new trends and interesting novel formulations in advanced preclinical and clinical development stages for the pulmonary, nasal and the oral route are discussed for the most relevant peptide and protein drugs in terms of their specific requirements and intended therapeutic applications. Expert opinion: Despite the low frequency of clinical breakthroughs with non-invasive routes, these remain an active research area not only due to their improved therapeutic potential, but also due to the attractive commercial outcomes they offer. Currently, a number of technologies are adopted, including combinations of penetration enhancers with protease inhibitors and/or nanotechnology-based products and a few candidates are anticipated to be approved in the near future.