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Published online: 10 January 2015
© Springer International Publishing Switzerland 2015
Abstract Silodosin is a highly selective α^sub 1A^-adrenoceptor antagonist indicated for the treatment of the signs and symptoms of benign prostatic hyperplasia (BPH). Oral silodosin had a rapid onset of effect in men with lower urinary tract symptoms (LUTS) associated with BPH, with improvements seen in voiding and storage symptoms, maximum urinary flow rate and health-related quality of life in well-designed, 12-week trials. Silodosin was noninferior to tamsulosin in terms of improving LUTS associated with BPH. The efficacy of silodosin was maintained in 9-month extension studies and was also seen in a phase IV study conducted in a real-world setting. Silodosin was generally well tolerated and was associated with a low risk of orthostatic hypotension. Abnormal ejaculation was the most commonly reported adverse event, although few patients discontinued treatment with silodosin because of this adverse event. In conclusion, silodosin is a useful option for the treatment of LUTS associated with BPH.
1 Introduction
The pathophysiology of lower urinary tract symptoms (LUTS) is multifactorial, with benign prostatic hyperplasia (BPH) an important contributing factor [1, 2]. LUTS associated with BPH can have a significant impact on health-related quality of life (HR-QOL) [3]. LUTS are classified as voiding (obstructive) symptoms (e.g. straining, weak stream, hesitancy) [usually attributed to bladder outlet obstruction], storage (irritative) symptoms (e.g. frequency, nocturia, urgency) [usually attributed to increased smooth muscle tone and resistance within the enlarged prostate gland] and postmicturition symptoms (e.g. sensation of incomplete emptying) [1, 4].
a1A-Adrenoceptors are located in the human prostate, bladder base, bladder neck, prostatic capsule and prostatic urethra and mediate smooth muscle contraction in these tissues [5]. Thus, blocking a1A-adrenoceptors is a rational approach to the treatment of LUTS associated with BPH.
The a1A-adrenoceptor antagonist silodosin (Rapaflo^, Urorec^, Silodyx^, Urief^, Silosin^, Thrupas^) is available in numerous countries for the treatment of the signs and symptoms of BPH. This article reviews the clinical efficacy and tolerability of silodosin in the treatment of LUTS associated with BPH, as well as summarizing its pharmacological properties.
2 Pharmacodynamic Properties
The pharmacodynamic properties of silodosin have been reviewed previously [6]; this section provides a brief overview.
Silodosin is a highly selective a1A-adrenoceptor antagonist [7-9]. Antagonism of a1A-adrenoceptors results in smooth muscle...