Doxazosin mesylate, a quinazoline compound sold by Pfizer under the brand names Cardura and Carduran, is an alpha blocker used to treat high blood pressure and urinary retention associated with benign prostatic hyperplasia (BPH). On February 22, 2005, the US FDA approved a sustained release form of doxazosin, to be marketed as Cardura XL. It is an alpha-1 adrenergic receptor blocker that inhibits the binding of norepinephrine (released from sympathetic nerve terminals) to the alpha-1 receptors on the membrane of vascular smooth muscle cells. The primary effect of this inhibition is relaxed vascular smooth muscle tone, which decreases peripheral vascular resistance, leading to decreased blood pressure...