A PROMISING ORAL TREATMENT FOR ERECTILE DYSFUNCTION
Title: A PROMISING ORAL TREATMENT FOR ERECTILE DYSFUNCTION , Modern Medicine, 00268070, Aug97, Vol. 65, Issue 8
Section: clinical NEWS
An investigational oral drug, Sildenafil (Viagra), may bring some hope to men suffering from erectile dysfunction who are reluctant to undergo prosthetic-implant surgery or administer penile injections or suppositories. This is according to two studieson Sildenafil that were presented during the American Urological Association’s annual meeting in New Orleans.
Researchers say that the drug is effective and well tolerated, and it appears to benefit men with either organic or psychogenic impotence.
Sildenafil produces its pro-erectile effect by inhibiting type-5 phosphodiesterase, an isozyme that inactivates cyclic guanosine monophosphate (cGMP). cGMP, which is produced in response to sexual arousal, promotes smooth muscle relaxation in the corpus cavernosum. This is the action that is responsible for the vascular changes that produce an erectile response.
A look at the two studies:
EUROPEAN STUDY. Jacques Buvat, MD, conducted a multicenter, open-label trial of 311 men (mean age: 53) whose dysfunction was non-organic in nature.
For 1 year, the men took Sildenafil 1 hour before each anticipated intercourse. The starting dose was 25 mg; the men had the option of reducing the dose to 10 mg or increasing it incrementally to 50 mg and then to 100 mg, depending on tolerance and efficacy. The men were instructed to take the drug no more than once a day.
Forty men dropped out for various reasons, which left 271 (87%) who completed the trial. Of the 40 who did not finish, 13 stopped because of a lack of efficacy and 12 because of an adverse effect (only 3 of which were ascribed to Sildenafil ). Six men were lost to follow-up, 5 withdrew for unknown reasons, and 4 claimed that they were cured.
The remaining men reported that the quality of their erections was significantly better (more rigid, longer duration) than it was prior to treatment. More than 85% of the men said they were satisfied with the results.
The drug’s side effects, which were mild, consisted mainly of headache (11%) and facial flushing (4%).
Buvat points out that unlike the vasodilator drugs that are used to treat erectile dysfunction, Sildenafil requires that the patient have some degree of sexual desire in order for it to be effective.
U.S. STUDY. Tom F. Lue, MD, and colleagues conducted a double-blind, placebo-controlled, multicenter study of 416 men who had erectile dysfunction. Their impotence was the result of either an organic (73%) or a psychogenic (9%) cause, or a combination of the two (18%).
The men were randomized to take either placebo or Sildenafil at 5, 25, 50, or 100 mg about 1 hour prior to each anticipated sexual encounter. The trial lasted 8 weeks, and the drug’s efficacy was assessed with follow-up questionnaires.
The men who took Sildenafil rated the quality of their erections and sexual satisfaction much higher than those who took placebo (see chart, page 25).
Most of the side effects that were reported by the Sildenafil patients were mild. They included headache, vasodilation, dyspepsia, and diarrhea.
Lue told MODERN MEDICINE that he expects Sildenafil to be approved for use in the U.S. by the end of next year.
Dr. Buvat is an internist in Lille, France. He is the secretary-general of the International Society for Impotence Research.
Dr. Lue is a professor of urology at the University of California, San Francisco.
Efficacy of Sildenafil for the treatment of erectile dysfunction
Legend for chart:
A - Placebo
B - 5 mg
C - 25 mg
D - 50 mg
E - 100 mg
A B C D E
Improved
erection[*] 27.7 47.7 60.9 72.9 77.8
Ability to achieve
an erection
satisfactory for
intercourse[a] 2.00 2.69 2.93 3.28 3.69
Ability to maintain
an erection
satisfactory for
intercourse[a] 2.05 2.40 2.95 3.32 3.60
All dosages of Sildenafil were more effective than placebo, although the higher the dosage, the better the results,
* Percentages of men who had improved erections,
[a] Mean response score on a scale of 1 to 5, with 1 indicating “never” or “almost never” and 5 meaning “always” or “almost always.”
Source: Tom F. Lue, MD.
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Source: Modern Medicine, Aug97, Vol. 65 Issue 8, p25, 2p
