VASODILATOR ANTIHYPERTENSIVE DRUGS

Vasodilator has a potent hypotensive effect, especially when used in combination with a beta-blocker and a thiazide. Thiazide is moderately potent diuretics. They inhibit sodium reabsorption at the beginning of the distal convulated tubule. They act within 1 to 2 hours of oral administration and most have a duration of action of 12 to 24 hours.

In the management of hypertension, a low dose of a thiazide produce a maximal or near-maximal blood pressure lowering effect with very little biochemical disturbance. Higher doses causes more marked changes in plasma potassium, sodium, uric acid, glucose and lipids with little advantage in blood pressure control.

The example of antihypertensive drugs for vasodilator effect is Minoxidil. It act to lowering high blood pressure in patients who do not respond to other therapy. It is a vasodilator that relaxes (widens) blood vessels and improves blood flow. It is usually given together with two other medications including a diuretic (water pill) and a bêta-blocker. Usually, the dose for this drug is 5mg per day in one or two divided dose.

Minoxidil tablets contain Minoxidil, an antihypertensive peripheral vasodilator. Minoxidil occurs as a white to off-white, odorless, crystalline solid that is soluble in water to the extent of approximately 2 mg/mL, is readily soluble in propylene glycol or ethanol, and is almost insoluble in acetone, chloroform or ethyl acetate. The chemical name for Minoxidil is 2,4-pyrimidinediamine, 6-(1-piperidinyl)-, 3-oxide.

There are several side-effect when using this drug including :
1) gastro-intestinal disturbances
2) pericardial effusion
3) tamponade
4) angina pectoris
5) rashes.

The contra-indication for this drug is in pheochromocytoma, because it may stimulate secretion of catecholamines from the tumor through its antihypertensive action. Minoxidil is contraindicated in those patients with a history of hypersensitivity to any of the components of the preparation.



there are others several drugs that can be used as vasodilator hypertensive drugs such as Diazoxide, Hydralazine, Ambrisentan and others.