Anti-Hypertensive Drugs

There is a wide range of medication that can reduce blood pressure to bring it within normal limits.

Some of the more commonly prescribed drugs used in hypertension include:

Diuretics or water pills - These are often the first agents used to control essential hypertension and examples include hydroclorathiazide, thiazide, indapamide and chlorathalidone. As their name suggests, these drugs act on the kidneys to increase the amount of water expelled from the body in the urine, which lowers the blood volume inside the body and therefore the blood pressure.

In addition, some diuretics also help to dilate or relax the walls of the arteries meaning blood can flow more easily through these vessels, which also reduces blood pressure.

Beta blockers
Examples of beta blockers include atenolol, metoprolol, nadolol, pindolol, carvedilol and labetelol. These agents block the beta receptors of the heart and lower the force the heart pumps with. Beta blockers also lower the heart rate.

Calcium channel blockers
These agents block the flow of calcium in the muscles of the blood vessels causing them to relax and dilate. This reduces the pressure against which the heart has to pump and, in turn, the blood pressure. Examples of these agents are amlodipine, nifedipine, nicardipine and verapamil.

Angiotensin converting enzyme (ACE) inhibitors
These drugs stop the action of angiotensin II, which normally narrows blood vessels. Blocking its action dilates blood vessels and reduces blood pressure. Some examples of these agents are enalapril, captopril and ramipril.

Angiotensin receptor blockers
These drugs act by preventing the action of angiotensin II on its receptor and therefore exert similar effects to as ACE inhibitors. Examples include drugs such as losartan, candesartan, and telmesartan.

Centrally acting sympatholytics
These are substances that act on the central nervous system to induce blood vessel dilation and, in turn, blood pressure. Drugs in this class include methyldopa and clonidine. Methyldopa is suitable for pregnant women with hypertension.

Alpha blockers
These act by blocking the alpha adrenergic receptors, which relaxes and dilates the blood vessels. This reduces the pressure against which the heart has to pump and therefore the blood pressure.

Vasodilators
Drugs of this class include hydralazine and minoxidil which relax the smooth muscle of the blood vessels causing the vessels to relax and dilate. Again, this reduces the pressure against which the heart has to pump and therefore the blood pressure.