Olmesartan medoxomil-d6 is intended for use as an internal standard for the quantification of olmesartan medoxomil by GC- or LC-MS. Olmesartan medoxomil is an orally bioavailable prodrug form of olmesartan , a nonpeptide angiotensin II antagonist that is selective for the angiotensin 1 (AT1) receptor over the AT2 receptor. Olmesartan medoxomil (0.1 mg/kg) inhibits the angiotensin II pressor response in normotensive rats. It reduces both systolic and diastolic blood pressure in fructose-fed rats, a model of insulin resistance, when administered at a dose of 10 mg/kg per day, as well as in chow-fed control animals when administered at a dose of 11.4 mg/kg per day. Olmesartan medoxomil also inhibits increases in plasma levels of triglycerides and non-esterified fatty acids in fructose-fed rats. Formulations containing olmesartan medoxomil have been used in the treatment of hypertension.