Peptide delivery via the pulmonary route: A valid approach for local and systemic delivery

Protein and peptide delivery via non-injectable routes is currently receiving enormous attention due to the increasing number of 'biotechnology' molecules which are being developed. Attempts to design systems for oral peptide, protein and gene delivery have met with limited success providing the impetus for exploring alternative routes of delivery. In the literature, there are reports on more than 40 peptides, proteins and genes which have been administered via the lung in animals to explore the potential for local or systemic delivery. In these studies, molecules ranging in size from a few hundred to greater than 100 000 Da have been demonstrated to be appropriate candidates for aerosol delivery in animals. In addition, several of these molecules including insulin, leuroplide, the cystic fibrosis transmembrane regulator (CFTR) gene and recombinant human DNase (rhDNase) have also been administered to man. In the case of rhDNase, the FDA have recently approved its use for cystic fibrosis. Based on the encouraging results obtained to date and the rapid advances being made in aerosol device and formulation approaches for these molecules, it can be anticipated that additional biotherapeutics will be developed for aerosol delivery in the near future.