Formulations of Microspheres and Nanoparticles for Peptide Delivery
Delivery of peptide drugs using microspheres has been used in a number of commercial drug formulations and this area continues to grow to overcome potential challenges with the intrinsic properties of peptides and proteins. The use of microparticles as an alternative delivery system for peptide and protein drugs has attracted substantial interest in recent years. Encapsulation of peptides or proteins in such carrier systems during formulation could potentially benefit the drug profile. Several examples of peptide and protein delivery using microsphere formulations are included. Different types of microspheres, their preparation, characterization, factors affecting drug delivery and mechanism of drug delivery are discussed. Peptide drugs on the market such as leuprolide, triptorelin, octreotide, lanreotide, human growth hormone, buserelin, abarelix and exenatide use microsphere-based formulations. Drug nanoparticle formulations have been demonstrated to show increased solubility and thus enhanced bioavailability, with additional ability to cross the blood–brain barrier, enter the pulmonary system and be absorbed through the tight junctions of endothelial cells of the skin, primarily owing to their small size and large surface area. Nanoparticle formulations based on liposomes, polymeric micelles, polymeric nanoparticles, nanoemulsions, nanogels, dendrimers, fullerenes, carbon nanotubes, magnetic nanoparticles, metal nanoparticles and quantum dots have been extensively discussed in the literature. Selected examples of peptide/protein nanoparticle formulations are discussed with special emphasis on various delivery routes and delivery mechanisms.