Impotence Drugs Duke It Out

Nov. 17, 2003 -- Start your engines: Of the medications for erectile dysfunction, more guys say Levitra gives them better performance.

This result -- from what the researcher calls the first head-to-head study of the three drugs -- is being presented at the 6th Congress of the European Society for Sexual Medicine in Istanbul, Turkey this week.

Viagra and Levitra are FDA-approved to treat erectile dysfunction. Cialis is currently under review by the FDA to treat erectile dysfunction and a final word is expected later this year. Levitra is co-developed by Bayer Pharmaceuticals and GlaxoSmithKline, a WebMD sponsor. Cialis is manufactured by Eli Lilly and Company, a WebMD sponsor. Viagra's manufacturer is Pfizer.

Even though Cialis' effects may last longer, nearly 50% of all patients preferred Levitra at the recommended starting dose at 10 mg, researcher Frank Sommer, MD, PhD, a urology specialist at the University Medical Centre in Cologne, Germany, tells WebMD.

"What they really liked was the quick onset of action, it was very reliable, and it produced satisfactory hardness of the erection," Sommer explains.

In Sommer's study, 47 men received each of the drugs for six weeks with a one-week drug-free period in between. Sommer also tested different dosages of the medications. Each drug was taken prior to sexual activity.

All three of the drugs were effective in men with erectile dysfunction. Compared to the placebo all of these drugs produced a significant improvement in erections for vaginal penetration and completion of intercourse.

At the maximum dose -- 20 mg of Cialis, 20 mg of Levitra, 100 mg of Viagra -- 43% preferred Levitra, 40% liked Cialis best, and 17% preferred Viagra.

In the half-maximum dose group, 47% preferred Levitra, 34% preferred Viagra, and 19% rated Cialis best.

Men who preferred Cialis did so because they felt their erections lasted longer. And the men who preferred Levitra and Viagra listed their main reasons as ease of getting erections and hardness of erections.

Two men taking Cialis had such severe back pain that they went to the hospital emergency room, reports Sommer. Since no spinal problems were evident, the pain was linked with Cialis.

Other studies have shown that between 4% to 6% of all men taking Cialis complain about back pain, and for some people it's very severe back pain, says Sommer.

Another Viewpoint

The study "shows the potency of Levitra," says Myron Murdock, MD, who sits on the national medical advisory boards for Cialis and Levitra.

But there's one problem that could skew results: "These patients knew which drug they were taking, and that makes a very big difference," he tells WebMD.

Also, all three drugs work through the same mechanism -- and over time, the effect becomes cumulative, he says. "The longer you take any of these drugs, the more effective the drug becomes." Therefore, whatever drug a guy was taking at the study's end may show the best results.