Linagliptin is a competitive and reversible dipeptidyl peptidase (DPP)-4 enzyme inhibitor that slows the breakdown of insulinotropic hormone glucagon-like peptide (GLP)-1 for better glycemic control in diabetes patients. GLP and glucose-dependent insulinotropic polypeptide (GIP) are incretin hormones that increase the production and release of insulin from pancreatic beta cells and decrease the release of glucagon from pancreatic alpha cells. This results in a overall decrease in glucose production in the liver and increase an of insulin in a glucose-dependent manner.
Linagliptin is a more potent inhibitor of DPP-4 than other drugs that belong to the same class with an IC50 of 1 nM. In comparison, sitagliptin, saxagliptin, and vildagliptin have an IC50 of 19, 50, and 62 nM respectively. A dose of 2.5 and 5 mg reduces the activity of DPP-4 by 72.7% and 86.1% from baseline respectively in healthy male subjects. In diabetes patients, a dose of 5 and 10 mg inhibits >90% of DPP-4. Linagliptin is also selectively inhibits DPP-4 as indicated by the lack of DPP-8 or DPP-9 inhibition at therapeutic exposures in vitro.
Linagliptin is not extensively metabolized, 90% of dose is excreted unchanged. The small portion of drug that is metabolized, the main metabolite is CD 1790 and is pharmacologically inactive. Glucuronidation forms some of its other minor metabolites.