Alpha blocker

Alpha blockers, also known as α-blockers or α-adrenoreceptor antagonists, are a class of pharmacological agents that act as antagonists on α-adrenergic receptors (α-adrenoceptors).

Historically, alpha-blockers were used as a tool for pharmacologic research to develop a greater understanding of the autonomic nervous system. Using alpha blockers, scientists began characterizing arterial blood pressure and central vasomotor control in the autonomic nervous system. Today, they can be used as clinical treatments for a limited number of diseases.

Alpha blockers can treat a small range of diseases such as hypertension, Raynaud's disease, benign prostatic hyperplasia (BPH) and erectile dysfunction. Generally speaking, these treatments function by binding an α-blocker to α receptors in the arteries and smooth muscle. Ultimately, depending on the type of alpha receptor, this relaxes the smooth muscle or blood vessels, which increases fluid flow in these entities.

When the term "alpha blocker" is used without further qualification, it can refer to an α₁ blocker, an α₂ blocker, a nonselective blocker (both α₁ and α₂ activity), or an α blocker with some β activity. However, the most common type of alpha blocker is α₁.

Non-selective α-adrenergic receptor antagonists include:

Selective α₁-adrenergic receptor antagonists include:

Selective α₂-adrenergic receptor antagonists include:

Finally, the agents carvedilol and labetalol are both α and β-blockers.