Telmisartan + Hydrochlorothiazide Used For Hypertension

How it works

Telmisartan : Telmisartan is an orally effective and specific angiotensin II receptor subtype 1 (AT1) antagonist. Angiotensin II is formed from angiotensin I in a reaction catalyzed by angiotensinconverting enzyme (ACE, kininase II). Angiotensin II is the principal pressor agent of the renin-angiotensin system, with effects that include vasoconstriction, stimulation of synthesis and release of aldosterone, cardiac stimulation, and renal reabsorption of sodium. Telmisartan blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II by selectively blocking the binding of angiotensin II to the AT1 receptor in many tissues, such as vascular smooth muscle and the adrenal gland. Its action is therefore independent of the pathways for angiotensin II synthesis. In patients with hypertension telmisartan reduces both systolic and diastolic blood pressure without affecting pulse rate. Telmisartan has much greater affinity (>3,000 fold) for the AT1 receptor than for the AT2 receptor. Hydrochlorothiazide : Hydrochlorothiazide is a thiazide diuretic. Thiazides affect the renal tubular mechanisms of electrolyte reabsorption, directly increasing excretion of sodium and chloride in approximately equivalent amounts. The diuretic action of hydrochlorothiazide reduces plasma volume, increases plasma renin activity, increases aldosterone secretion, with consequent increases in urinary potassium and bicarbonate loss, and decreases in serum potassium. Presumably through blockade o f the renin-angiotensin-aldosterone system, co-administration of telmisartan tends to reverse the potassium loss associated with thiazide diuretics.