Vildagliptin

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) are incretin hormones that regulate blood glucose levels and maintain glucose homeostasis. It is estimated that the activity of GLP-1 and GIP contribute more than 70% to the insulin response to an oral glucose challenge. They stimulate insulin secretion in a glucose-dependent manner via G-protein-coupled GIP and GLP-1 receptor signalling. In addition to their effects on insulin secretion, GLP-1 is also involved in promoting islet neogenesis and differentiation, as well as attenuating pancreatic beta-cell apoptosis. Incretin hormones also exert extra-pancreatic effects, such as lipogenesis and myocardial function. In type II diabetes mellitus, GLP-1 secretion is impaired, and the insulinotropic effect of GIP is significantly diminished.

Vildagliptin exerts its blood glucose-lowering effects by selectively inhibiting dipeptidyl peptidase-4 (DPP-4), an enzyme that rapidly truncates and inactivates GLP-1 and GIP upon their release from the intestinal cells. DPP-4 cleaves oligopeptides after the second amino acid from the N-terminal end. Inhibition of DPP-4 substantially prolongs the half-life of GLP-1 and GIP, increasing the levels of active circulating incretin hormones. The duration of DPP-4 inhibition by vildagliptin is dose-dependent. Vildagliptin reduces fasting and prandial glucose and HbA1c. It enhances the glucose sensitivity of alpha- and beta-cells and augments glucose-dependent insulin secretion. Fasting and postprandial glucose levels are decreased, and postprandial lipid and lipoprotein metabolism are also improved.