Diuretics

Thiazides and related drugs are the most widely used drugs for uncomplicated hypertension. Chlorothiazide, hydrochlorothiazide and chlorthalidone are the commonly used thiazides.

Mechanism of action

Thiazide diuretics are used in uncomplicated mild to moderate hypertension and have a long duration of action. They should be administered in a low dose i.e., 12.5 mg of hydrochlorothiazide or chlorthalidone. If the antihypertensive response is not adequate, the dose can be increased upto 25 mg per day. Beyond this dose thiazides are not safe. Potassium sparing diuretics are usually given with thiazides to counteract the K⁺ loss.

Adverse effects:

Hypokalemia, hyperglycemia, hyperuricemia, hyperlipidemia, hypercalcemia, impotence and decreased libido.

Advantages with thiazide diuretics-

i) Have long duration of action,

ii) Cheaper,

iii) Well tolerated even in elderly patients.

Loop diuretics have shorter duration of action therefore, they are not used in hypertension except in the presence of renal or cardiac failure.

Category: Pharmacology Notes