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Abstract: Sulfonylureas promote insulin secretion and potently lower blood glucose levels, however, they induce hypoglycemia and undergo a reduction in efficacy when administered long-term (secondary failure). The dipeptidyl peptidase (DPP)-IV inhibitor ASP8497, (2S,4S)-4-fluoro-1-({[4-methyl-1-(methylsulfonyl)piperidin-4-yl]amino}acetyl)pyrrolidine-2-carbonitrile monofumarate, inhibits the degradation of glucagon-like peptide-1 (GLP-1), an incretin hormone, and promotes insulin secretion in a glucose-dependent manner. ASP8497 is therefore less likely to induce hypoglycemia and less likely to show reduced efficacy even after repeated administration. Here, to determine whether or not ASP8497 improves glucose tolerance in Zucker fatty rats, we examined the effects of ASP8497 and gliclazide, a sulfonylurea, on glucose tolerance after repeated administration. We also developed an animal model of secondary failure using streptozotocin–nicotinamide-induced diabetic mice. Results: ASP8497 (3mg/kg) improved glucose intolerance in Zucker fatty rat without any attenuation (blood glucose AUC: P =0.034 vs. vehicle) while gliclazide (10mg/kg) did not (P =0.916 vs. vehicle). Furthermore, ASP8497 (3, 10mg/kg) was found to effect glucose tolerance dose-dependently (3mg/kg: P =0.230, 10mg/kg: P =0.003 vs. glibenclamide (10mg/kg)) by enhancing insulin secretion in mice inadequately controlled with glibenclamide. Our results suggest that ASP8497 may be effective even in patients with secondary failure who are unable to maintain satisfactory glycemic control using sulfonylureas. [Copyright &y& Elsevier]

Gastrointestinal hormone glucagon-like peptide-1 (GLP-1) has a potent glucose-dependent insulinotropic effect and is rapidly degraded by dipeptidyl peptidase (DPP)-IV. Therefore, the use of DPP-IV inhibitors is being actively explored as a novel approach to the treatment of type 2 diabetes. The present study investigated the antidiabetic effects of the DPP-IV inhibitor ASP8497 in streptozotocin-nicotinamide-induced mildly diabetic mice which possess aggravation of glucose tolerance due to loss of early-phase insulin secretion. ASP8497 exhibited good oral bioavailability with potent inhibition of plasma DPP-IV activity. This inhibitory activity lasted up to 24 h when administered at 5 mg/kg twice a day or 10 mg/kg once a day. A single oral administration of ASP8497 (0.3–3 mg/kg) significantly improved glucose tolerance by increasing plasma insulin and GLP-1 levels during the oral glucose or liquid meal tolerance tests. These effects were seen not only immediately, but also 8 h after administration. In contrast, ASP8497 (0.3–10 mg/kg) had no significant effect on blood glucose and plasma insulin levels under fasting conditions. Furthermore, repeated administration of ASP8497 (5 mg/kg twice a day or 10 mg/kg once a day) for 25 days significantly decreased nonfasting blood glucose and HbA1c levels. These results suggest that ASP8497 is a potent and long-acting DPP-IV inhibitor that improves glucose tolerance through glucose-dependent insulinotropic action via the elevation of the GLP-1 level in streptozotocin-nicotinamide-induced mildly diabetic mice. It is expected to be useful as a therapeutic agent for impaired glucose tolerance and type 2 diabetes. Copyright © 2009 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Dipeptidyl peptidase-IV (DPP-IV) is the primary inactivator of glucoregulatory incretin hormones, and DPP-IV inhibitors are expected to become a useful new class of anti-diabetic agent. The aim of the present study is to characterize the chronic in vivo profile of the DPP-IV inhibitor ASP8497. In streptozotocin-nicotinamide-induced diabetic mice, ASP8497 was administered orally for 3 weeks at 1, 3, or 10 mg/kg once daily, which improved the hemoglobin A1c, non-fasting plasma insulin, fasting blood glucose levels, glucose intolerance, and lipid profiles (plasma triglyceride, non-esterified fatty acid and total cholesterol) with neutral effect on body weight. The pancreatic insulin content and hepatic phosphoenolpyruvate carboxykinase (PEPCK) activity recovered dose-dependently in ASP8497-treated groups. These results revealed that ASP8497 was successful in improving glycemic control and metabolic parameters in streptozotocin-nicotinamide-induced diabetic mice. It is therefore suggested that ASP8497 may be a potential agent for the treatment of type 2 diabetes. [ABSTRACT FROM AUTHOR]

Abstract: Several combination therapies have been investigated in an effort to achieve and maintain glycemic control in patients with type 2 diabetes. In this study, we combined the novel dipeptidyl peptidase (DPP)-IV inhibitor ASP8497 with the antidiabetic drugs metformin, glibenclamide, voglibose, rosiglitazone, and insulin to examine the effects of each combination on glucose tolerance in streptozotocin-nicotinamide-induced mildly diabetic mice. Single treatments with ASP8497 (1 mg/kg), metformin (300 mg/kg), glibenclamide (3 mg/kg), voglibose (0.3 mg/kg), rosiglitazone (10 mg/kg), or insulin (0.2 IU/kg) significantly improved glucose tolerance during the liquid meal tolerance test. In addition, combination treatment with ASP8497 and each antidiabetic drug additively improved glucose tolerance. Among these, the combination of ASP8497 and glibenclamide or insulin additively ameliorated glucose tolerance with an additive increase in the plasma insulin level; however, it did not affect the fasting blood glucose lowering effects of glibenclamide or insulin. These profiles indicate that the combination of ASP8497 with existing antidiabetic drugs could be useful for correcting the postprandial hyperglycemia seen with type 2 diabetes. [Copyright &y& Elsevier]

Abstract: Dipeptidyl peptidase (DPP)-IV inhibitors are expected to become a useful new class of antidiabetic agent. The aim of the present study is to characterize the in vitro and in vivo profile of ASP8497, (2S,4S)-4-fluoro-1-({[4-methyl-1-(methylsulfonyl)piperidin-4-yl]amino}acetyl)pyrrolidine-2-carbonitrile monofumarate, which is a novel DPP-IV inhibitor. ASP8497 inhibited DPP-IV in plasma from mice, rats, dogs and humans with IC50 values of 3.86, 2.36, 5.53 and 5.30nM, respectively. In contrast, ASP8497 did not potently inhibit DPP8 or DPP9 activity (IC50 >200nM). Kinetic analysis indicated that ASP8497 inhibits DPP-IV activity in a competitive manner. In streptozotocin–nicotinamide-induced diabetic mice, ASP8497 (3mg/kg) significantly reduced glucose excursion during the oral glucose tolerance test conducted 0.5 and 8.5h after administration, with increases in plasma insulin and active glucagon-like peptide-1 (GLP-1) levels. In contrast, ASP8497 (3 and 30mg/kg) did not cause hypoglycemia in fasted normal mice. Furthermore, administration of exogenous GLP-1 induced significant inhibition of gastric emptying and small intestinal transit rates, but ASP8497 (30mg/kg) had no significant effects in normal mice. These present preclinical studies indicate that ASP8497 is a novel selective DPP-IV inhibitor with long-acting antidiabetic effect that might be a potential agent for type 2 diabetes. [Copyright &y& Elsevier]