HEALTH: VIAGRA VS. ITS COMPETITORS - WHICH IS BETTER?MANILA,December 1, 2004 (STAR) AN APPLE A DAY By Tyrone M. Reyes, M.D. - Believe it or not, it has been almost six years since Viagra (sildenafil) introduced erectile dysfunction into our everyday lexicon. The little blue pill, which allows many otherwise impotent men to achieve an erection, was approved by the US Food and Drug Administration (FDA) in 1998.
Talk about a makeover: Viagra not only brought impotence out of the closet, but also changed its name (from impotence to erectile dysfunction) and its image (from shameful to clinical). Over six years, Viagraís status as a cultural phenomenon has grown: The pill has an entry in the Shorter Oxford English Dictionary, and itís the subject of countless sex jokes.
The pre-Viagra remedies werenít terribly appealing. The FDA approved yohimbine as an impotence pill before Viagra. But men had to take it three weeks before seeing any effect. Even then, 60 percent didnít experience a benefit. Other treatments included medications inserted up or injected into the penis (apparently not as painful as it might seem, but never likely to be popular), and vacuum devices designed to increase penile blood flow.
Viagra works in just one hour (perhaps faster on an empty stomach), so itís not surprising that it has been a blockbuster. When a new treatment is discovered, the condition it fixes is almost always diagnosed more often, but this increase has been even greater than usual with Viagra. The number of men diagnosed with erectile dysfunction in the United States has increased by 250 percent since Viagra was introduced in 1998.
However, such a boon had to come with strings attached. Soon, studies were showing that Viagra users might be at risk of nerve damage to the eye or cardiac death. Early studies funded by Pfizer, Viagraís manufacturer, determined that the erectile dysfunction drug posed no risk to men with stable hearts. Independent research using stationary bicycles to simulate the exertion of sex later reached the same conclusion. More recent studies, however, concluded that Viagra isnít for everyone: It probably is not safe if youíve had a recent heart attack, suffer from severe heart disease, or are on a medication containing nitrates.
Now, there are two new-drugs that work in much the same way. The FDA-approved vardenafil (Levitra) in August 2003. Taladafil (Cialis), which was already on the market in Europe, was approved by the FDA in November 2003. Both are now available in the Philippines. Like Viagra, these new pills facilitate an erection by routing more blood to the penis and trapping it there.
The chief selling point of Levitra seems to be the dose. Itís just 10 milligrams (mg) compared with the usual starting dose of 50 mg for Viagra. But studies have shown that Viagra is often effective at 25 mg, so the difference might not be so large. Levitra may also work faster than Viagra (25-30 minutes vs. an hour), although the FDA says that, like Viagra, it should be taken an hour before sexual activity.
Finally, some studies have shown that Levitra will help men who donít respond to Viagra, which may be about half of those who try it. (In clinical trials, only 20-30 percent were Viagra nonresponders, but those trials are often designed to produce the most favorable results.) Dr. Michael OíLeary, an erectile dysfunction expert at Brigham and Womenís Hospital in Boston, says that heíll have to see more data before heís convinced that Levitra is the answer when Viagra isnít. Yet he also tells his patients that thereís nothing wrong with giving Levitra a try if Viagra hasnít worked.
Cialis stays active in the body much longer than the two other drugs. Viagra and Levitra last about 4-5 hours. With Cialis, the window of opportunity ranges from 24 to 36 hours, depending on which study you believe. No, this doesnít mean a two-day erection! Like Viagra and Levitra, Cialis does not automatically produce an erection, but makes an erection possible with sexual arousal.
So far, the risks and side effects of these three drugs seem to be roughly the same. They all work by relaxing smooth muscle cells, thereby widening blood vessels Ė primarily in the penis, but also in other parts of the body. The resulting side effects may include headaches and flushing. Some men get heartburn because these drugs relax the sphincter muscle that normally keeps stomach juices from backing up into the esophagus. Nasal congestion is another possible side effect. Mainly at a high, 100-mg dose, Viagra affects color vision in some men (about 3 percent), giving things a bluish tinge. Thatís because the drug interferes with an enzyme in the rod and cone cells of the retina. The FDA has also received reports of eye pain and bloodshot eyes from Viagra.
The major worry with Viagra has been heart and blood pressure problems. Within one to two hours of taking the drug, blood pressure tends to drop slightly: Systolic (the top number) by 8-10 mm Hg and diastolic (the bottom number) by 5-6 mm Hg. Usually, it bounces back after four hours, when the drug is no longer active in the body. And studies have shown that the increased cardiovascular risks from Viagra alone are very slight, if they exist at all. Still, men are told not to take Viagra if theyíve recently had a serious cardiovascular problem.
The main danger is mixing Viagra with medications containing nitrates Ė nitroglycerine for angina is one of the most common Ė because they compound each otherís blood pressure-lowering effects. The nitrates, nitrites, and L-arginine in food arenít a problem, however.
Like Viagra, Levitra should not be mixed with nitrate medications. The FDA also advises against taking it with alpha-blockers, a class of medications used to treat benign prostatic hyperplasia (BPH) and high blood pressure. Cialis should not be used with nitrates or with alpha-blockers other than Harnal (Tamsulosin), according to the FDA.
Meanwhile, the uses for Viagra seem to be growing. A study published in the Journal of the American Medical Association in January 2003 showed that Viagra successfully counteracts some of the sexual side effects experienced by men who take Prozac (Fluoxetine) or similar antidepressants. Researchers at Pfizer are also intrigued by reports that because it dilates blood vessels, Viagra may help reduce pulmonary hypertension, an often deadly, difficult-to-treat form of high blood pressure that affects the lungs.
If these findings hold with further research, more men might start taking Viagra. Already, users are getting younger. Six years ago, the typical patient was a married man in his 60s. Today, heís still married but more likely in his 50s.
A Boon To Many Men
Despite the potential for abuse and the usual risks associated with any physical activity like sex, Viagra has been a boon to many men. "It still is the most patient-friendly method of treating erectile dysfunction," says Dr. Ira Sharlip, assistant clinical professor of urology at the University of California at San Francisco.
Although Viagra doesnít work for everyone, itís what most patients want to try first, before turning to such alternatives as injections, vacuum pumps and surgical implants. As for the competitors, the bottom line is this: The two new drugs for erectile dysfunction work like Viagra and carry similar risks and benefits. Their subtle differences, however, may make a difference for some men.
Reported by: Sol Jose Vanzi
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