Oral Phentolamine is another alpha-blocker which, unlike doxazosin, is marketed specifically as a treatment for erectile dysfunction and is, like Viagra, taken on demand . The trade name is Vasoviril. It has not been granted a licence in Europe or North America, but is approved in Brazil and Mexico.
CAUTION: All the alpha blockers should only be used under a doctor’s supervision, because they 1) interact very negatively with certain medications, 2) can have very serious side effects and 3) can cause priapism, an erection that does not go away and can damage the penis permanently. See my link on Common Causes of Priapism for more information on the latter. If you ever have an erection that will no go away after an hour or two, go to the E.R. Your sex life is at stake.
Phentolamine is a non-selective alpha-adrenergic blocker and thus is in the same general class as the well-known herb herbal erectile dysfunction remedy yohimbine. The alpha-adrenergic receptors are used by noradrenaline and noradrenaline to put the brakes on erections.
NOTE: You can find out more information about another alpha blocker by going to my page on Doxazosin and Erectile Dysfunction.
My experience on the Peak Testosterone Forum is that alpha blockers are rarely used to treat erectile dysfunction. However, some of the study work indicates that they can be very effective in many men. For example, a German trial in 1998 reported that phentolamine helped 50% of men. And there are other reports it works synergistically with PDE5i.
A paper in 2001 from the Boston School of Medicine reviewed data on Vasomax (now Vasoviril) and stated that two large scale trials have found that Vasomax was associated with significant increases in the IIEF-EF scale. However these trials were conducted when Viagra was being developed and many men on the trials left to join the Viagra testing. And Viagra is generally regarded as more successful.
A 2002 Californian study reported that
An August 2002 report in the International Journal of Impotence Research stated that, averaging two American trials, the mean change scores in the EF domain from baseline to the end of treatment in the parallel-design study were -2.3, 5.7 and 6.7 for the placebo, 40 mg, and 80 mg groups, respectively. So a healthy increase of 8 or 9 over a placebo. (The two trials were 28 Goldstein I, Carson C, Rosen R, Islam A. Vasomax for the treatment of male erectile dysfunction ; and Goldstein I. Oral phentolamine: an Alpha-1, Alpha-2 adrenergic antagonist for the treatment of erectile dysfunction.)
Oral Phentolamine is faster acting and shorter lasting than Viagra, and should be taken on an empty stomach. Users suggest it takes effect in about half an hour and it lasts about two to four hours. They also suggest Phentolamine works very well in combination with PDE5i. The cost is about twice that of Viagra.