TA: I'm impressed! You included me in your Vivus Update. Your most balanced and informative update...ok, I'm biased.
Here's some additional information concerning the Vasomax study referred to by Edderd in this month's Journal of Urology. In this study, sponsored by Zonagen, efficacy was less than 40%.
Listed below is an editor's comments on the study.
Good investing!
BigKNY3
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The Journal of Urology Vol. 159, April 1998, pg. 1216
ORAL PHENTOLAMINE AS TREATMENT FOR ERECTILE DYSFUNCTION
EDITORIAL COMMENT
Despite excellent results and minimal side effects, vasoactive intracavernosal pharmacotherapy of erectile dysfunction has poor patient acceptance and high discontinuation rates. Given the magnitude of the clinical problem, less invasive therapeutic approaches, in particular oral medication, demand attention, even if initial results may appear discouraging.
Patients for this prospective, double-blind, placebo controlled trial or oral phentolamine were carefully selected by an elaborate evaluation, which also included an interview by a psychiatrist, to avoid "obvious" psychogenic impotence. In addition, potential candidates were subjected to a placebo run-in period which resulted in exclusion of 10% of patients because of a positive response to placebo. Nevertheless, 20% of the patients in the placebo arm of the final study reported a successful response. In comparison 40% patients on active drug arms were considered to be responders, which is lower than reported previously in placebo controlled trials by Gwinup (reference explanation could be differences in drug preparation and/or dosage, although a clear dose/response relation was not unequivocally shown (success rates per total number of attempts at intercourse may bias the results by giving good individual responders more weight). More likely, patients with psychogenic disorders were excluded more vigorously.
Responders were younger and apparently had normal cavernous tissue and an intact autonomous supply. Is this treatment of psychogenic impotence or of early organogenic impotence, or a disguised placebo effect? As stated by the authors, the small number of patients does not permit a valid statistical analysis. Given the multiple variables that seem to influence outcome, even the statement that "oral phentolamine may be of benefit" must be viewed with caution. Only a similar study with patient populations large enough to permit valid statistical analysis will provide the answer. The authors' pleas for less stringent end points in defining success appears logical from a clinical standpoint. For determining the true benefit of a novel therapeutic approach the use of more subjective end points, such as satisfying intercourse, dilutes the protocol and hence automatically requires even larger patient numbers for meaningful results.
Michael Marberger
Urologische Klinik
Der Universitat Wien
Vienna, Austria |
