Cardiovascular effects of alpha-blockers used for the treatment of symptomatic BPH: impact on safety and well-being.

Abstract

Alpha-adrenoceptor antagonists (alpha-blockers) are efficacious in treating lower urinary tract symptoms (LUTS) suggestive of benign prostatic obstruction (BPO), also termed symptomatic benign prostatic hyperplasia (BPH), causing bladder outlet obstruction (BOO). There is little difference among the various alpha-blockers in terms of efficacy in treating LUTS. However, conventional quinazoline derivatives such as terazosin, doxazosin and alfuzosin, originally developed for hypertension, have inherent cardiovascular extension effects, which influence the well being and safety of patients with LUTS by impairing physiological blood pressure (BP) control, even when their effect on unchallenged BP may be quite low. Preclinically, tamsulosin, a sulphonamide-substituted phenethylamine, has a relative selectivity for the alpha 1-adrenoceptors of the lower urinary tract. Clinically, this is associated with fewer cardiovascular extension effects with tamsulosin (modified release capsule) 0.4 mg once daily. This allows the use of convenient regimens of 0.4 mg tamsulosin administered once daily after breakfast from initiation of treatment without the need for 'step-up' increases of dose to avoid 'first-dose' hypotension. Extensive investigation, including multiple orthostatic stress testing (which otherwise is unusual in the characterization of alpha-blockers because of their inherent safety), confirms that tamsulosin 0.4 mg definitely carries a lower risk of impaired BP control.