The Daily Therapy With L-Arginine 2,500 mg and Tadalafil 5 mg in Combination and in Monotherapy for the Treatment of Erectile Dysfunction: A Prospective, Randomized Multicentre Study

Introduction: A synergistic effect of the combination therapy tadalafil plus L-Arginine is conceivable in patients affected by erectile dysfunction (ED). Aim: To evaluate the effectiveness and tolerability of tadalafil 5 mg and L-Arginine 2.5 grams in monotherapy and combination therapy. Methods: Recruited patients completed the International Index of Erectile Function - Erectile Function domain (IIEF-EF) and Sexual Encounter Profile diaries completed at baseline and after treatment. The survey was randomized into 3 groups with an equal allocation ratio. Group A received daily L-Arginine 2,500 mg, group B received daily tadalafil 5 mg, and group C received both daily L-Arginine 2,500 mg plus daily tadalafil 5 mg. The duration of therapy in all 3 groups was 12 weeks. Safety was assessed by evaluating all reported treatment-emergent adverse events. Main outcome measure: The main outcome measure was the change in IIEF-EF score and in per-patient percentage of "yes" responses to Sexual Encounter Profile Question 3 from baseline to after treatment. Results: 300 eligible patients were enrolled, and 100 subjects for each group were allocated. Based on the IIEF-EF score, the participants were divided into 3 categories: severe, moderate, and mild ED. IIEF-EF score increased in group A from 15 ± 7 to 18.1 ± 9.2, in group B from 14.8 ± 6.9 to 20.8 ± 7.3, and in group C from 14.9 ± 7.1 to 22 ± 7.5. In mild ED group, the mean IIEF-EF score increased from 22.1 ± 2.2 to 27.5 ± 2.3 in group A; from 22.1 ± 2.2 to 27.8 ± 2 in group B, and from 22.2 ± 2.2 to 29.3 ± 0.9 in group C. We report a total of 11, 53, and 67 cases of adverse events in group A, B, and C respectively. Conclusions: Combination therapy was superior to monotherapies. Gallo L, Pecoraro S, Sarnacchiaro P, et al. The Daily Therapy With L-Arginine 2,500 mg and Tadalafil 5 mg in Combination and in Monotherapy for the Treatment of Erectile Dysfunction: A Prospective, Randomized Multicentre Study. Sex Med 2020;8:178-185.