Mirabegron for Treatment of Erectile Dysfunction in Patients With LUTS Secondry to BPH: A Randomized Study

Erectile dysfunction (ED) is a major world-wide problem. In United Stated of America, ED affects 26/1000 man yearly (Gonzalgo et al., 2003). The prevalence of ED increases with age from 2-9% in men between 40-49 year, to 20-40% between 60-69 and between 50-100% over 70 years (Gur et al., 2006; Hojanned et al., 2000; Gades et al., 2009; Braun et al., 2000). Many factors may contribute in the occurrence of ED including neuronal, vascular, myogenic and psychological causes (Gur et al., 2016; Johannes et al., 2000, Lewis et al., 2000; Wu et al., 2010; Mallis et al., 2005).

Researchs during the past decade have firmly established that ED and ejaculatory dysfunction (EJD) are highly prevalent in aging men, particularly those with LUTS of BPH. Furthermore, it has been demonstrated that LUTS of BPH is an independent risk factor for male sexual dysfunction (Hansen BL. et al., 2004).

Although the underlying mechanisms responsible for the relationship between LUTS and male sexual dysfunction are not fully elucidated, possible common links are present including activation of a-adrenergic receptors, endothelial dysfunction, and alterations in sex hormone concentrations and receptor subtypes. Thus, it is now recommended that men presenting with LUTS should be evaluated for sexual dysfunction and those presenting with sexual dysfunction should be evaluated for LUTS (Price DT., et al., 1993).

Also , it is now recognized that certain oral therapies for LUTS/BPH can adversely affect sexual function in patients who are already at increased risk for sexual dysfunction. Moreover, the correction of LUTS was associated with improvement of ED. (De Rose AF., et al., 2002) Healthcare providers should discuss sexual function with BPH patients both before and during treatment. (Raymond C. Rosen et al., 2005) So, use of ED-treating drugs (phosphodiestrase -5 inhibitors) is now a guideline recommendation in the lines of treatment of BPH/LUTS alone or in combination with α blockers. (EUA guidelines, 2015, Gratzke C et., al., 2015).

Phosphodiesterase 5 inhibitors (PDE5i) are effective in treatment of ED. They treat ED through enhancement of the effect of nitric oxide (NO) by inhibition of cyclic guanosin monophosphate (cGMP) breakdown, therefore, increase blood flow through penile arteries. PDE5i are the first-line treatment of ED. Nevertheless, many patients may discontinue the treatment because of side effects, poor response or cost.