Alpha Blockers are drugs that treat a variety of conditions, such as high blood pressure, benign prostatic hyperplasia (enlarged prostate) and Raynaud’s disease. They work by blocking the stress hormone norepinephrine (noradrenaline). Norepinephrine normally acts in the body to stimulate the muscles in the walls of smaller arteries and veins causing them to contract. Alpha blockers prevent norepinephrine from binding with the muscle cells. This relaxes vessel walls (reducing blood pressure) and increases blood flow to the heart.

Alpha blockers are also called alpha-adrenergic antagionists. Some alpha blockers that are available are: Doxazosin, Prazosin, and Terazosin (these are not brand names).

Figure 1: Alpha blockers
Figure 2: Norepinephrine (Noradrenaline) is produce by the body.
Figure 3: Norepinephrine (Noradrenaline) binds to the surface of smooth muscle cells causing them to contract.
Figure 4: Alpha blockers block the receptor allowing the artery to dilate.