Silodosin for the Treatment of Benign Prostatic Hyperplasia: Pharmacology and Cardiovascular Tolerability

Abstract

Relief of benign prostatic hyperplasia (BPH)-related lower urinary tract symptoms by α-blockers (α₁-adrenoceptor antagonists) is mediated primarily through the blockade of α(1A)-receptors, leading to relaxation of smooth muscle in the prostate and bladder neck. Early α-blockers that were nonselective for adrenoceptor subtypes have been associated with blood pressure-related adverse effects, such as orthostatic hypotension, that may be attributed at least in part to the blockade of α(1B)-adrenoceptors in arterial vessels. Silodosin, a novel α-blocker with exceptionally high selectivity for α(1A-) versus α(1B)-adrenoceptors, was recently approved in the United States for the treatment of urinary symptoms related to BPH. The unique receptor selectivity profile likely accounts for some of the desirable clinical features of the drug. Silodosin possesses an excellent cardiac- and blood pressure-related safety profile, and data have demonstrated that it does not promote QT-interval prolongation. Therapeutic doses of silodosin are safe for men with mild-to-moderate liver dysfunction; dosage adjustment is recommended in those with moderate renal impairment. The drug should not be taken with potent cytochrome P450 3A4 inhibitors. Silodosin may be especially beneficial in patients who need to maximize cardiovascular tolerability.