Abstract
α1-Adrenoceptors, in particular the α1A-subtype, show a pronounced expression and promote contraction of the bladder neck, urethra and prostate to enhance bladder outlet resistance, especially in elderly men with an enlarged prostate. On the other hand, the α1B-subtype is reported to help maintain vascular smooth muscle tone. Therefore, α1A-subtype-selective antagonist was suggested to be useful for the treatment of lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH).
Silodosin can selectively bind to α1A-subtype with sub-nanomolar affinity. Clinical studies have clearly indicated that silodosin achieves significant improvement in LUTS associated with BPH, as well as quality of life. The improvements were observed in both voiding and storage symptoms. This higher selectivity for the α1A-subtype contributing to inhibition of sympathetic nerve stimulation resulted in significant relaxation of the muscle tone of lower urinary tract tissues. In addition, the clinical effects were observed in the earlier treatment phase, and not only in the mild cases, but also in severe symptoms.
This article reviews the therapeutic usefulness of silodosin for LUTS associated with BPH from the preclinical and clinical points of view, which are supported by its higher affinity and selectivity for the α1A-subtype.
