Both Appear Effective, but Men With Heart Disease Should Use Caution
Two new erectile dysfunction drugs, Cialis and Levitra, are racing to the finish line for approval from the FDA, according to presentations at the annual meeting of the American Urological Association.
Although more than half of all men over the age of 40 suffer from some degree of erectile dysfunction -- the consistent inability to sustain an erection sufficient for sexual intercourse -- experts estimate that less than one fifth of men with ED are currently being treated. Ultimately, doctors will have to decide how the new erectile dysfunction drugs compare with Viagra despite initial concerns about safety in men at risk of heart attack or stroke.
Both Cialis and Levitra appear to be safe and effective, say some researchers, improving men's satisfaction with the quality of their erections, their ability to penetrate the vagina, and the successful completion of attempted intercourse. But not all researchers agree on the safety of Cialis.
Neither should be used by men taking nitroglycerin or related drugs, nor by men who should not engage in sexual activity because of disabling heart disease.
The effects of Cialis last for up to 36 hours after taking a single pill. Although the effects of Levitra only lasts five or six hours, it improves erections very rapidly -- within 16 minutes. Like Viagra, they require sexual stimulation for an effective erection to occur.
"[Cialis] worked very, very well. It was both very safe and effective in a diverse group including Hispanics and African-Americans," Allen D. Seftel, MD, associate professor of urology at Case Western Reserve University in Cleveland and lead researcher of one of the Cialis studies, tells WebMD.
In a study of 207 men with mild-to-severe erectile dysfunction in the U.S. and Puerto Rico, most participants had improved erections after taking Cialis, compared with a few of those who took a placebo pill. In men taking Cialis, more than three quarters of attempts at vaginal penetration were successful, compared with less than half of attempts in men taking placebo. Sexual intercourse was successfully completed in about two-thirds of attempts in men taking Cialis, and in about a quarter of attempts in men taking placebo.
"Only 5% on [Cialis] dropped out of the study, compared with 2% on placebo," Seftel says. "Headache was the number one treatment-related adverse event."
A second study presented at the meeting evaluated the long-term safety of Cialis in nearly 1,200 men with erectile dysfunction who had already been taking the drug for one year. Some of these men also had heart disease and diabetes, which are responsible for about 80% of cases of erectile dysfunction because of their effect on blood vessels. As in earlier studies of Cialis, the most common side effects were headache and upset stomach.
Although three men died during the study, the researchers did not think that any of the deaths were related to Cialis treatment.
A third study presented at the meeting suggested that Cialis did not affect sperm production. However, urologist Myron Murdock, MD, tells WebMD that some experts are still concerned that long-term use of Cialis could impair sperm function.
Cialis, developed by Lilly ICOS, is available by prescription in Europe, Australia, New Zealand, and Singapore. The FDA may reach a decision about approval by the second half of 2003. Bayer AG and GlaxoSmithKline are also far along in their efforts to have Levitra approved for erectile dysfunction by the FDA, as it was on March 6 by the European Commission. Lilly and GlaxoSmithKline are both WebMD sponsors.
Several studies of Levitra were also presented at the meeting. In a controlled study, 805 men with erectile dysfunction were randomly assigned to treatment with Levitra at various doses or to placebo. Neither the men nor the researchers knew which medications the men were taking.
After 26 weeks, satisfaction rate for erection firmness was on average three times greater in men taking 20 mg of Levitra than in those taking placebo (58% vs. 18%). Compared with men taking placebo, those taking 10 mg or 20 mg of Levitra had significant improvements in intercourse satisfaction, orgasmic function, and overall sexual experience. Side effects were generally not severe and included headache, facial flushing, and nasal congestion.
In a separate study, men with mild to severe erectile dysfunction received a four-week supply of Levitra or placebo and were asked to start sexual activity immediately after taking the medication. As early as 16 minutes after taking the pill, 34% of men taking Levitra had an erection allowing them to complete intercourse successfully, as did 24% of men taking placebo.
"Viagra is the most rapid onset (14 minutes) followed by [Levitra] (16 minutes) followed by [Cialis]," Haim Padma-Nathan, MD, lead researcher of the study and medical director of the Male Clinic in Beverly Hills, Calif., tells WebMD.
But Viagra is less potent than Levitra, according to Murdock, national medical director of hisandherhealth.com and of the Impotence Institute of America. Most men don't experience any effects from Viagra until 30 minutes or longer after they take it, and it has to be taken on an empty stomach.
"If a man goes out for a steak and a glass of wine with his partner and plans to have sex soon thereafter, he doesn't have to worry about fasting for two or three hours with Levitra as he would with Viagra," Murdock tells WebMD. "Levitra is more patient-friendly, and it's better for the sexual pattern of most men."
After taking Levitra, many men get a lasting erection within 15 minutes, and most do within 30 minutes. The effect of Levitra may last up to nearly five hours. "In the amount of time most men spend on foreplay, they'll be fully responsive," says Murdock, "Men taking Levitra don't have to wait for timing issues."
How does Cialis compare with Levitra? "There has been no head-to-head study, but overall, these drugs are both safe and effective," Seftel says. "[Cialis] ... may allow a man to engage in sex for a longer time period. Because it may be effective for up to 24 to 36 hours, that allows a man more freedom to decide when he will be sexually active during that time frame."
"Neither Cialis nor Levitra is as effective as Viagra; and Cialis may be unsafe -- it is probably cardiotoxic and will soon be shown to cause heart attacks and sudden death," Padma-Nathan says.
None of these drugs should be taken by men who use nitroglycerin or related drugs, or by men with disabling heart disease. All three "are good drugs," which have been tested in patients with heart disease, including those taking medications for high blood pressure, Murdock says.
"Any man with a cardiac history should check with his doctor before taking any of these drugs." Seftel says.
Source: WebMD Medical News
Friday, May 02, 2003