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Yohimbine for erectile dysfunction

Clinical bottom line: Yohimbine is useful in treating erectile dysfunction. The benefit is likely to be of clinical relevance, but further work is required to establish this, and to establish how yohimbine compares with other intervention. More trials are required to establish whether cause of erectile dysfunction, age or severity of condition determine the degree of benefit achieved with yohimbine.


Erectile dysfunction (ED) is common, particularly among certain patient groups such as diabetics. Approximately half of men between 40 and 70 report some degree of erectile dysfunction, and approximately 4% to 9% in the general population. Yohimbine, an alkaloid derived from the bark of the African yohimbine tree, has alpha 2 -adrenoreceptor blocking activity and produces a rise in sympathetic drive by increasing noradrenaline release. Yohimbine also interacts with choline, dopamine and vaso-intestinal polypeptide receptors.

Systematic review

Ernst E, Pittler MH. Yohimbine for erectile dysfunction: a systematic review and meta-analysis of randomized clinical trials. Journal of Urology 1998; 159:433-6.

Date review completed: 1997

Number of trials included: 7

Number of patients: 419

Control group: placebo

Main outcomes: self-report of success (various methods)

Inclusion criteria were double-blind, randomised, placebo-controlled trials of yohimbine for erectile dysfunction; adequate statistical evaluation; score of at least 3 on the 5 point Jadad quality scale; any language; published and unpublished trials.

Reviewers provided descriptive summary of trials and calculated odds ratios with 95% confidence intervals using percentage response rates (random effects model). We have assumed significant benefit if confidence intervals did not cross one.

Findings

Trials were of moderate to high quality, and included crossover and parallel designs. Doses ranged from 15 mg to 44 mg/day over two to ten weeks. Outcome measures varied, and patients included had organic and non-organic erectile dysfunction. Trial size ranged from eleven to 100 patients.

Five of seven trials reported benefit of yohimbine compared with placebo

Highest quality trials

One trial of 61 men with chronic erectile impotence reported significant benefit with approximately 16 mg/day of yohimbine for eight weeks, based on patient report of quality and frequency of erection. Trialists reported no difference in response between men with organic and non-organic ED. Odds ratio just reached significance.

One trial of 82 men with mixed cause of ED received increasing doses of yohimbine over four weeks (approximately 22 mg rising to 44 mg). Yohimbine was significantly better than placebo by four weeks, with 34% of men with full or partial response compared with approximately 7% receiving placebo. Trialists noted that the effect took two to three weeks to establish, that success did not appear to be determined by ED cause, but that younger men may have a better response. Odds ratio was significant.

Moderate to low quality trials

For the remaining five trials, three reported significant benefit and had significant odds ratios, and two were not significant according to statistical analysis or odds ratios. One of these was very small (eleven men) and the second looked at low doses (18 mg/day) in men with organic ED.

Combined odds ratio was 3.85 (95% CI, 6.67 to 2.22), which reviewers describe as clinically relevant.

Adverse effects

Reviewers extracted information on type, severity and frequency of adverse effects where available. Most trials appeared to have measured adverse effects, all of which were minor and reversible. In total eight patients withdrew due to adverse effects, and, where calculated, overall incidence ranged from 10% to 30% in men receiving yohimbine and 5% to 16% with placebo.

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