Investigation of ejaculatory disorder by silodosin in the treatment of prostatic hyperplasia

The subjects of this study were 91 patients who had been clinically diagnosed to have LUTS/BPH at this hospital, who were administered silodosin at 4 mg twice a day, and who gave response to a questionnaire survey related to ejaculatory disorder. Sexual intercourse and masturbation were regarded as sexual actions in this study.Ejaculatory disorder occurred in 38 (42%) of the 91 silodosin administration cases. Forty (44%) of the 91 patients answered that they carried out sexual actions after oral intake of silodosin. When the investigation was conducted only in those who exercised sexual actions, ejaculatory disorder was observed in 38 (95%) of these 40 patients, indicating a high incidence. When asked if disturbed by the ejaculatory disorder, 29 (76%) of the 38 patients who had ejaculatory disorder answered yes. Oral silodosin was discontinued due to the ejaculatory disorder in 2 (5%) of these patients. On the whole, the discontinuation rate of oral silodosin was 2% (2/91 patients).It was demonstrated that the administration of silodosin induced ejaculatory disorder at a high incidence. Since it is possible that the high frequency of ejaculatory disorder by silodosin may reduce QOL, it is considered necessary to provide sufficient information related to ejaculatory disorder at the time of treatment with silodosin.Sympathetic nerve α1 receptor has receptor subtypes α1A, α1B and α1D. Recently, the research on α1A receptor subtype has made much progress so that various drugs to treat LUTS by BPH have been commercialized [1,2]. The affinity of tamuslosin hydrochloride to α1A receptor is comparatively high while naftopidil is characterized to have comparatively high affinity to α1D receptor subtype [3,4]. On the other hand, silodosin acts on α1A receptor in a very specific manner [5]. The practical clinical application of silodosin started in Japan in 2006. However, this drug frequently causes ejaculatory disorder as an adverse reaction. The incidence of ejaculatory diso