Phosphodiesterase type 5 inhibitors for lower urinary tract symptoms associated with benign prostatic hyperplasia

Erectile dysfunction (ED) and lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) are two common diseases among men aged over 50. Population or community-based epidemiologic studies have shown higher prevalence of male ED among men with LUTS associated with BPH. The exact mechanisms are unclear, but nitric oxide/cyclic guanosine monophosphate signal may be involved in the common pathway in the pathogenesis via smooth muscle relaxation control. Phosphodiesterase type 5 (PDE5) inhibitors have become the mainstay treatment of choice for male ED since the launch of sildenafil citrate in 1998. However, more evidence has shown that men receiving PDE5 inhibitors for their ED treatment have also benefited from improvement on their LUTS. Early randomized clinical studies has shown that daily dosing with PDE5 inhibitors (sildenafil, tadalafil and vardenafil) could improve the irritative or obstructive symptoms based on reduction in the International Prostate Symptom Score but had little effect on uroflow rate or post-voiding residuals. The combined use of PDE5 inhibitors and α-blockers has revealed more promising results on LUTS alleviation, but the safety profiles of this kind of combined use should be further evaluated and confirmed by greater-scale, randomized and comparative clinical studies.