Glentel Tabs 40 H 30’S contains Telmisartan and hydrochlorothiazide. Both of these substances help to control high blood pressure. This drug belongs to a group of medicines called angiotensin II receptor antagonists. Angiotensin-II causes your blood vessels to narrow thus increasing your blood pressure. Glentel blocks the effect of angiotensin II so that the blood vessels relax and lower your blood pressure. On the other hand hydrochlorothiazide causes your urine output to increase hence lowering your blood pressure.