CAPOZIDE (captopril and hydrochlorothiazide tablets, USP) for oral administration combines two antihypertensive agents: captopril and hydrochlorothiazide. The mechanism of action of captopril has not yet been fully elucidated. Captopril prevents the conversion of angiotensin I to angiotensin II by inhibition of ACE, a peptidyldipeptide carboxy hydrolase. Hydrochlorothiazide belongs to thiazide class of diuretics. It reduces blood volume by acting on the kidneys to reduce sodium (Na+) reabsorption in the distal convoluted tubule. CAPOZIDE (captopril and hydrochlorothiazide tablets, USP) is indicated for the treatment of hypertension. The blood pressure lowering effects of captopril and thiazides are approximately additive. Major side effects are: Black, tarry stools; chest pain; chills; cough; fever; painful or difficult urination; shortness of breath; sore throat; sores, ulcers, or white spots on lips or in mouth; swollen glands; unusual bleeding or bruising; unusual tiredness or weakness. It has been reported that indomethacin may reduce the antihypertensive effect of captopril, especially in cases of low renin hypertension. Captopril’s effect will be augmented by antihypertensive agents that cause renin release. For example, diuretics (e.g., thiazides) may activate the renin-angiotensin-aldosterone system.