Background　“Anagliptin is a novel dipeptidyl peptidase-4（DPP-4）inhibitor, and the pharmacokinetic and pharmacodynamic properties of anagliptin have been investigated in healthy volunteers and type 2 diabetes patients. In this study, we investigated the drug interaction between anagliptin and metformin in type 2 diabetes patients.
Methods　Total 18 subjects were enrolled and treated with 100 mg of anagliptin twice a day and/or with 500 mg of metformin twice a day for 3 days in an open-label 3-period crossover design. The pharmacokinetic and pharmacodynamic parameters were analyzed in each period.
Results　The pharmacokinetic profiles of anagliptin and metformin were not affected significantly by their concomitant administration. Furthermore, the inhibition rate of DPP-4 activity by anagliptin did not change markedly after concomitant administration with metformin. The postprandial plasma glucose levels were significantly lower in subjects treated with concomitant use of two drugs than in those treated with anagliptin or metformin alone. In addition, the postprandial levels of active glucagon-like peptide-1（GLP-1）were more significantly increased by concomitant administration than by each of these drugs alone. We did not observe any significant adverse events.
Conclusions　Concomitant use of anagliptin and metformin improved blood glucose control and increased the postprandial level of plasma active GLP-1 more effectively than anagliptin or metformin alone. These results suggest that combination therapy with anagliptin and metformin would be effective in patients with type 2 diabetes.