Purpose: The goal of this double-blind, placebo-controlled, three-way crossover, randomized clinical trial was to compare the efficacy and safety of the combination of 6g of L-arginine glutamate and 6 mg of yohimbine hydrochloride (AY) with that of 6 mg of yohimbine hydrochloride (YP) alone and that of placebo (PP) alone, for the treatment of erectile dysfunction (ED).
Materials and methods: Forty-five patients were included in this study. During each of the 2-week, crossover periods, drug was administered orally, one to two hours before intended sexual intercourse. The primary endpoint was change in the Erectile Function Domain score of the International Index of Erectile Function (IIEF). The secondary endpoints were patient and investigator assessments of treatment success.
Results: At the end of each treatment period, the Erectile Function Domain scores for AY, YP and PP were 17.2+/-7.17, 15.4+/-6.49 and 14.1+/-6.56, respectively. The difference between AY and PP was statistically significant (p=0.006). When stratified according to baseline scores over 14, those patients with mild to moderate MED had a better Erectile Function Domain response to treatment (AY=22.2+/-4.99, YP=18.2+/-5.59, PP=16.9+/-6.91, respectively) than those with scores 14 and below (AY=12.4+/-5.48, YP=12.7+/-6.25, PP=11.4+/-5.02, respectively). Investigators' and patients' assessment of efficacy was significantly improved by YP over PP.
Conclusions: This pilot study shows that the on-demand oral administration of the L-arginine glutamate 6g and 6 mg yohimbine combination is effective in improving erectile function in patients with mild to moderate ED. It appears to be a promising addition to first-line therapy for ED.