Tolbutamide-d9 is intended for use as an internal standard for the quantification of tolbutamide by GC- or LC-MS. Tolbutamide is an inhibitor of sulfonylurea receptor 1 (SUR1) linked to ATP-sensitive potassium channel Kir6.2 (IC50 = 4.9 μM). It is selective for SUR1/Kir6.2 over SUR2A/Kir6.2 and SUR2B/Kir6.2 channels (IC50s = 85 and 88 μM, respectively). Tolbutamide increases glucose-induced insulin secretion and calcium influx in isolated mouse pancreatic islets. In vivo, tolbutamide (80 mg/kg) reduces blood glucose levels in a mouse model of diabetes induced by streptozotocin (STZ; ). Formulations containing tolbutamide have been used in the treatment of type 2 diabetes.
