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Amlodipine Besilate BP and Olmesartan Medoxomil BP
This product is a combination of two antihypertensive drugs: a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker), amlodipine besilate, and an angiotensin II receptor blocker, olmesartan medoxomil. The amlodipine component inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle, and the olmesartan medoxomil component blocks the vasoconstrictor effects of angiotensin II.
Absorption: After oral administration of therapeutic doses of amlodipine, absorption produces peak plasma concentrations between 6 and 12 hours. Absolute bioavailability is estimated as between 64% and 90%. The absolute bioavailability of olmesartan medoxomil is approximately 26%. After oral administration, the peak plasma concentration (Cmax) of olmesartan is reached after 1 to 2 hours. Distribution: Approximately 93% of the circulating amlodipine is bound to plasma proteins in hypertensive patients. Steady-state plasma levels of amlodipine are reached after 7 to 8 days of consecutive daily dosing. The volume of distribution of olmesartan is approximately 17 L. Olmesartan is highly bound to plasma proteins (99%).
Metabolism & Excretion: Amlodipine is extensively (about 90%) converted to inactive metabolites via hepatic metabolism. Its terminal elimination half-life is about 30 to 50 hours. 10% of the parent compound and 60% of the metabolites are excreted in the urine. Following the rapid and complete conversion of olmesartan medoxomil to olmesartan during absorption, there is virtually no further metabolism of olmesartan. Total plasma clearance of olmesartan is 1.3 L/h; with a renal clearance of 0.6 L/h. Approximately 35% to 50% of the absorbed dose is recovered in urine while the remainder is eliminated in feces via the bile. Its terminal elimination half-life is approximately 13 hours.