Sustained release and pharmacologic effects of human glucagon-like peptide-1 and liraglutide from polymeric microparticles

The GLP-1 class of peptide agonists has been shown to exert regulatory key roles in both diabetes, obesity and related complications. Given the short half-life of GLP-1 its use has been historically discouraged. We developed polymeric microparticles loaded with either human GLP-1 (7-37) or liraglutide peptides by double emulsion and solvent evaporation approach. The size distribution of all formulations was of about 30-50 μm. The in vitro kinetic release assays showed a sustained release of the peptides extending up to 30 to 40 days with varying profiles. Morphologic analysis demonstrated a more regular particle surface for those comprising polymers PLA, PLA-PEG and PLGA. In vivo evaluation in Swiss male mice demonstrated a similar extension of effect of decreasing in body weight gain for up to 25 days after a single subcutaneous administration of either hGLP-1 or liraglutide peptide-loaded microparticles (200 μg peptide / kg body weight) compared to controls. These demonstrate the effectiveness of hGLP-1 as a therapeutic agent in long-term, continuous release from peptide-load microparticles, and thus its plausibility as an unmodified therapeutic agent.