Tadalafil improves erectile function regardless of dutasteride use
The phosphodiesterase type 5 inhibitor tadalafil significantly improved the erectile function of patients receiving the 5-alpha reductase inhibitor (5-α RI) dutasteride for the management of bladder outlet obstruction, according to a Turkish study.
Researchers prospectively evaluated 208 patients (mean age 61.2 years) who were receiving tadalafil 10 or 20 mg for erectile dysfunction (ED). Of these, 50 percent were given dutasteride while the other half comprised the age-matched control group who were not receiving any other medication for ED or lower urinary tract symptoms. [Turk J Urol 2018;44:294-297]
Compared with the pre-tadalafil phase, tadalafil treatment led to significant improvements in IIEF* scores in both the dutasteride (mean, 12.2 vs 21.5; p<0.001) and the control arms (mean, 11.9 vs 21.9; p<0.001).
Dutasteride blocks the enzyme responsible for the conversion of testosterone to dihydrotestosterone, and its effect on testosterone metabolism has drawn controversy regarding the effects of 5-α RIs on sexual function (ie, persistent ED, decreased libido, and ejaculatory dysfunction). [J Clin Endocrinol Metab 2004;89:2179-2184] Despite evidence showing a higher ED risk among 5-α RI-treated patients, other studies revealed no adverse associations between 5-α RI use and erectile function. [J Sex Med 2016;13:1297-1310; BMJ 2016;354:i4823]
“Although [these] studies show controversies about the effect of dutasteride on erectile function, the elderly population is the target for the prescription of both dutasteride and tadalafil,” the researchers pointed out. “[T]herefore, we believe that the evaluation of [tadalafil] response in dutasteride users is important.”
Tadalafil has been shown to be effective in ED treatment and has also been considered an alternative for the management of bladder outlet obstruction. [Turk J Urol 2015;41:88-92; Eur Urol 2015;67:1099-1109; Drugs 2003;63:2203-2214] Nonetheless, despite its proven clinical efficacy in ED, its efficacy still depends on other medical conditions. [Urology 2002;60:434-441] “[T]he favourable response to tadalafil … cannot be generalized and associated with [5-α RI]-related ED.”
While it was not established whether ED development was related to dutasteride use or not, patients still managed to respond well to tadalafil treatment, noted the researchers. “[Our findings suggest] that dutasteride treatment does not have a negative impact on response to tadalafil among ED patients. However, [as] the current study does not focus on a population of dutasteride-induced ED … a further prospective study on this issue would be helpful,” they said.