Sitagliptin phosphate (MK-0431 phosphate) is a dipeptidyl peptidase-4 (DPP4) inhibitor.

In vitro: Sitagliptin was a potent inhibitor for DPP-4 with an IC50 of 18 nM. Sitagliptin inhibited DPP-8 (IC50: 48 μM). Sitagliptin showed no effect on several related peptidases, including DPP-9, DPP-II, and aminopeptidase P [1].

In free-fed Han-Wistar rats, the ED50 values ??for the inhibition of plasma DPP-4 activity by sitagliptin phosphate were calculated as 7 hours post-dose at 2.3 mg/kg and 24 hours post-dose at 30 mg/kg [1]. A mouse model of streptozotocin-induced type 1 diabetes showed elevated plasma DPP-4 levels, which was significantly suppressed in mice on a sitagliptin phosphate diet. This is achieved through a positive effect on hyperglycemia regulation, possibly by prolonging islet graft survival. The plasma clearance and volume of distribution of sitagliptin phosphate in rats (40-48 mL/min/kg, 7-9 L/kg) were higher than those in dogs (9 mL/min/kg, 3 L/kg); its The half-life is shorter in rats, 2 hours in dogs and 4 hours in dogs[2].