Diazoxide-d is intended for use as an internal standard for the quantification of diazoxide by GC- or LC-MS. Diazoxide is an activator of sulfonylurea receptor 1 (SUR1) linked to ATP-sensitive potassium channel K6.2 (EC = 14.1 µM in a FLIPR assay using HEK293 cells). It also activates SUR2A/K6.2 and SUR2B/K6.2 channels in HEK293T cells in a patch-clamp assay when used at concentrations of 30 and 300 µM. Diazoxide inhibits glucose-induced insulin release from isolated rat pancreatic β cells and induces relaxation of isolated rat aortic rings precontracted with potassium chloride (ICs = 22.6 and 22.4 µM, respectively). It reduces mean arterial pressure and cerebral blood flow in spontaneously hypertensive rats when administered intravenously as a 5 mg/kg bolus dose. Diazoxide (50 mg/kg, i.p.) increases blood glucose levels in mice. Formulations containing diazoxide have been used in the treatment of hypoglycemia.