Efficacy and Safety of Oral Combination of Yohimbine and L-Arginine (SX) for the Treatment of Erectile Dysfunction: A Multicenter, Randomized, Double Blind, Placebo-Controlled Clinical Trial

Article excerpt

Objective: The objective of this study was to assess the efficacy and safety of SX (combination of yohimbine and L-arginine) in the treatment of erectile dysfunction (ED).

Methods: This trial was a 4-week, double blind study of parallel groups of patients with mild to moderate ED. Forty married male patients with ED of mild-to-moderate severity were screened for the study entry ;among them, those aged 25-50 who reported a minimum of a- 3-month history of ED were eligible to enroll in this study. The severity of ED was based on EF domain scores on the international index of erectile function (IIEF). The scores of 15- 25 was considered as mild to moderate ED. Patients were randomized to receive one capsule of SX or placebo on demand in a 1:1 ratio using a computer-generated code.

Results: The difference between the two groups was significant at week 4 (endpoint) (P=0.03). Four adverse events were observed over the study. The difference between the SX and placebo was not significant in the frequency of adverse events.

Conclusion: This study indicates that SX is safe and effective for the treatment of mild to moderate ED at least in the short-term.

Keywords: Erectile Dysfunction; L-Arginine; Yohimbine

Iran J Psychiatry 2010;5:1-3

Approximately 30 million American men are afflicted with Erectile Dysfunction (ED). Because of increasing life expectancies, the prevalence of ED is expected to increase by more than 30% over the next 25 years (1). The prevalence and severity of ED have been shown to increase with age. The causes of ED are divided into 3 broad categories: psychogenic, organic, and mixed. Psychogenic factors are involved alone or in combination with organic causes in a substantial number of ED cases (1-3).

Orally administered phosphodiesterase 5 (PDE5) inhibitors have become the first-line treatment option for ED. PDE5 inhibitors have been shown to enhance erectile response in patients with ED by mediating the relaxation of the vascular smooth muscle of the penis. Nevertheless, the available approved medications for ED are often unsatisfactory, and there may be a place for alternative medicines (2, 3).

Yohimbine (Yocon, Yohimex) is derived from an herbal remedy. It appears to boost erectile function by improving blood flow (4, 5). Studies have been inconclusive about its benefits, but a recent analysis of seven trials reported that between 34% and 75% of men achieved favorable results when taking 5 mg to 10 mg (4, 5). L-arginine, while not an herb, is a naturally occurring amino acid present in foods. Studies on Larginine have shown mixed results (2, 3)

The objective of this study was to assess the efficacy and safety of SX (combination of yohimbine and Larginine) in the treatment of ED.

Materials and Methods

This trial was a 4-week, double blind study of parallel groups of patients with mild to moderate ED and was undertaken in two centers from September 2009 to December 2009.

Participants

Forty married male patients with ED of mild-tomoderate severity were screened for the study entry. Those men aged 25-50 who reported a minimum of a - 3-month history of ED were eligible to enroll in this study. The severity of ED was based on EF domain scores on the international index of erectile function (IIEF) (6). The scores of 15-25 were considered as mild to moderate ED (6). Patients were excluded from the study if they met any of the exclusion criteria specified in the protocol. These criteria included clinically significant penile deformities or penile implants; a recent history of stroke or spinal cord trauma; unstable cardiovascular status (eg, unstable angina, myocardial infarction, or myocardial revascularization within the prior 90 days); cancer chemotherapy, or antiandrogens; or failure to achieve any erection following radical prostatectomy or pelvic surgery. No other approved or experimental medications or treatments or devices to treat ED were allowed during the study. …