Irbesartan Hydrochlorothiazide Tablets is an angiotensin II receptor antagonist, irbesartan and thiazide diuretic hydrochlorothiazide composed of a combination of drugs. It is capable of lowering blood pressure and has a synergistic effect, making it more clinically effective than one product alone in lowering blood pressure. Irbesartan is a potent and orally effective selective angiotensin II receptor antagonist, which has a selective antagonistic effect on angiotensin II receptors, leading to an increase in plasma renin and angiotensin II levels and a decrease in plasma aldosterone levels. Hydrochlorothiazide is a thiazide diuretic that affects electrolyte reabsorption by the renal tubules, directly increases sodium and chloride excretion, reduces blood volume, increases plasma renin activity, increases aldosterone secretion, and thus increases urinary excretion of potassium and carbonate. The combination of irbesartan, which is able to reverse the loss of potassium associated with diuretics by blocking the renin-angiotensin-aldosterone system, is clinically indicated mainly in the treatment of hypertension.