alpha-Blocker Therapy: Current Update

Abstract

alpha-Blockade is the predominant form of medical therapy for the treatment of symptomatic bladder outlet obstruction due to benign prostatic hyperplasia (BPH). Recent research has shown that there is a series of alpha(1) receptor subtypes present in humans and that the alpha(1A) subtype appears to play a primary role in mediating prostatic smooth muscle contraction. Recent interest has therefore focussed on the development of agents specific to this alpha(1A) receptor subtype. The approval by the Food and Drug Administration of tamsulosin, an alpha(1A)-specific antagonist, offers physicians in the United States the opportunity to prescribe a selective alpha(1)-blocker for the treatment of BPH. Tamsulosin offers a pharmacologic means to better target alpha-blockade specifically to the prostatic smooth muscle and spare the vascular smooth muscle. Use of this agent has resulted in a lower incidence of clinically relevant effects on blood pressure or heart rate and minimal cardiovascular adverse effects.

Figure 1

Distribution of α-adrenoreceptors in the lower urinary tract: α₁ receptors predominate in the prostate capsule and are responsible for mediating smooth muscle tone.

Figure 2

The role of α₁-adrenoreceptors in lower urinary tract symptoms (LUTS). Adapted from Schwinn DA. BJU Int. 2000;86(suppl 2):11–22.