n article in the June issue about ViagraTM (Viagra: Is the Stampede Misdirected?) misstated the drug's effect on reducing non-organic impotence. Viagra also reduces organic erectile dysfunction. Of eight double-blind placebo studies referred to in the Viagra package insert, only some cases of impotence could be described as non-organic (ie, psychogenic or mixed etiologies). In the largest study, quoting the insert, "erectile dysfunction was attributed to organic (58%; generally not characterized, but including diabetes and excluding spinal cord injury), psychogenic (17%), or mixed (24%) etiologies. Sixty-three percent, 74%, and 82% of the patients on 25 mg, 50 mg and 100 mg of Viagra, respectively, reported an improvement in their erections, compared to 24% on placebo." Some researchers believe that nitric oxide, produced entirely in the body from the amino acid, arginine, can help correct up to 90% of all penile dysfunction.
In the same article the mechanism of yohimbe is described as acting to increase noradrenaline activity. Actually, yohimbine, the active ingredient of yohimbe, is an alpha adrenergic blocker. This means that it inhibits certain aspects of noradrenergic activity. A supplement containing yohimbe is reported to help increase energy, particularly physical energy, and improve libido (men and women) and erections in men. Sometimes it causes erections even in the absence of any sexual stimulation.