How do the irbesartan and hydrochlorothiazide components of CoAprovel lower blood pressure?

In CoAprovel, irbesartan selectively blocks angiotensin-II AT₁ receptors, reducing aldosterone, while hydrochlorothiazide increases renal sodium and chloride excretion and reduces plasma volume, although its antihypertensive mechanism is not fully known; together they lower blood pressure more than either component alone.