Efficacy of Tadalafilin the Treatment of Methadone Induced Sexual Dysfunction in Males with Opioid use Disorder under Methadone Maintenance therapy (MMT): Adouble-Blind, Randomized, Placebo-Controlled Clinical Trial

Abstract

Methadone-induced sexual dysfunction (MISD) is one of the most common adverse effects of long-term use of this medication, which may affect the life quality of patients under Methadone maintenance therapy (MMT) and can decrease medication compliance and increase the risk of relapse to drug use. While there is no standard treatment for MISD, we aimed to investigate the efficacy of tadalafil, a well-known medication for the treatment of men's sexual dysfunction, in the treatment of this disorder in male opioid users under MMT. In a double-blind, randomized, and placebo-controlled clinical study, a total of 132 male married patients aged 20-60 years under MMT suffering from MISD were randomly assigned either to the intervention ( taking 10 to 20mg tadalafil every 72h) or to the control (placebo) group. International Index of Erectile Function-5 (IIEF-5) and Brief Function Sexual Index (BFSI) was administered to evaluate the sexual dysfunction symptoms at the baseline, 2 weeks, and 4-weeks after the intervention. The study was registered by the Iranian registry for clinical trials (IRCT NO 20150822023705N10).  The mean scores of sexual desire, erection, ejaculation, level of overall satisfaction, and the overall score of sexual function were significantly increased in the medication group compared to the control group. The interaction between time and group was significant which showed the influence of time over the treatment outcomes (λ = 0.871, P = 0.008, F = 3.077, τ^2 = 0.129).  Our findings suggest that tadalafil could improve symptoms of sexual dysfunction among patients with MISD.