Consumer Reports on Viagra
consumerreports.org
Viagra: How safe is the new 'sex pill'?
The media have played up Pfizer's little blue pill as a miracle remedy for impotence ever since the Food and Drug Administration approved it in March. Does it work? You bet--which is why doctors have been writing 300,000 prescriptions a week, at about $10 per pill.
But the media have mostly played down or ignored Viagra's potential health hazards and side effects, despite a two-part study of 861 patients sponsored by Pfizer and published in the May 14 issue of The New England Journal of Medicine. The study indicates that side effects may occur more often than stated in the patient insert packed with the drug.
Coital coronaries?
Also known as sildenafil, Viagra was developed originally as a heart drug for angina patients. Its effectiveness as a treatment for impotence came as a complete surprise. The drug enhances the effects of nitric oxide, a chemical normally released by the body in response to sexual stimulation. Nitric oxide relaxes the smooth muscles and widens the blood vessels in the penis, increasing blood flow and enabling an erection to occur.
Viagra also widens other blood vessels in the body, temporarily reducing blood pressure slightly, so some doctors have been wary of prescribing Viagra for cardiac patients. However, common blood-pressure medications like ACE inhibitors, beta blockers, calcium channel blockers, and diuretics should be OK. So far, the only cardiac drugs identified as a hazard are nitrates, like nitroglycerin (Nitrostat, Nitro-Bid) and isosorbide (Imdur, Isordil), used to relieve chest pains. Taken with Viagra, nitrates could lower blood pressure to life-threatening levels. (About 5 percent of impotent men take nitrates.)
"Suppose a patient takes Viagra, has intercourse, and then has chest pains," says Dr. William Steers, chairman of the department of urology at the University of Virginia and one of the authors of the report in The New England Journal of Medicine. "If he then takes nitroglycerin, it could be the last time he'll have sex."
For patients who aren't on nitrates and whose cardiac condition is stable, there's no reason at present to withhold Viagra, according to Dr. Elizabeth Ross, a Washington, D.C., cardiologist and a spokeswoman for the American Heart Association. "If there are problems, we'll see them very quickly because of the large number of people taking Viagra." (At press time, the FDA was investigating the deaths of six Viagra users to see whether interaction with nitrates was involved.)
Ross adds, "All heart patients need to be cautioned about vigorous activity, and sex can be a vigorous activity."
Seeing blue
And then there's the tendency of Viagra to produce blue-tinged, blurred vision and light-sensitivity in some patients. In May, the American Academy of Ophthalmology issued this warning: "On the surface, seeing the world with a bluish tinge may just be annoying. It is not known, however, whether or not the drug causes any permanent changes in vision." The problem may occur soon after the drug is taken and persist for several hours.
Viagra "cross-reacts with a chemical in the visual cells in the retina," says the academy's spokesman, Dr. Michael Marmor, a professor of ophthalmology at the Stanford University School of Medicine. "It's always having a physical effect on the retina, and I'm not sure we have enough long-term data to know that damage isn't being caused--especially since many men taking this drug have underlying retinal problems." He also thinks the temporary light-sensitivity might pose a problem for some drivers, particularly at night, with headlight glare.
Unpleasant side effects
Pfizer's patient insert packed with each bottle of Viagra indicates that side effects are relatively rare. A Pfizer spokesman says the information in the insert is based mostly on a compilation of as many as 10 safety and efficacy trials in which 734 patients were on various dosages of Viagra and 725 on a placebo. But the two-part study published in The New England Journal of Medicine shows a much higher incidence of side effects predominantly among patients taking higher dosages.
The insert says, for example, that Viagra may cause headaches in about 16 percent of users, but the Journal study recorded headaches in up to 30 percent of users. The insert also indicates facial flushing in 10 percent of users (vs. 27 percent in the Journal study). A prominent table in the insert lists a 7 percent rate of acid stomach and a 3 percent rate of abnormal vision, including the blue tinge, light-sensitivity, and blurred eyesight discussed earlier. But reading further discloses that, at a 100-milligram dosage, the rates actually ranged to 17 and 11 percent, respectively--similar to the results reported in the Journal study.
As with any new drug, it will take "thousands, tens of thousands, millions of patients," says Steers, "before you find the unusual side effects."
Does it work for everyone?
The instant popularity of Viagra isn't hard to fathom. Taking a pill about an hour before having sex is clearly more appealing than any alternative medical treatments for impotence--penile injections, urethral suppositories, vacuum pumps, and implants.
"You can take the pill and do nothing, and you'll never know you took anything," says a 61-year old Viagra user who'd been impotent since prostate surgery in 1991. "But with stimulation, I stay erect until orgasm."
However, not all 30 million U.S. men who are impotent can expect such happy results. In part one of the two-part study in the Journal, 532 patients took a 25-, 50-, or 100-milligram dose of Viagra or a placebo. After 24 weeks, 72 percent of the men on the lowest dose and 85 percent on the highest dose achieved an erection sufficient for sexual intercourse at least about half the time. (Surprisingly, so did 50 percent of men taking the placebo.)
In part two of the study, 329 men started with a 50-milligram dose of Viagra or with a placebo, and they could double or halve the dose as needed over 12 weeks. Researchers followed up with the Viagra patients for another 32 weeks. By the end of the trial, 69 percent of attempts at intercourse were successful with Viagra, vs. 22 percent with the placebo.
Results are less promising in Steers' as-yet-unpublished study of 1,418 men with the most "severe" impotence. Of those who took 50 or 100 milligrams of Viagra for eight weeks, only 46 percent were able to have intercourse at least "most of the time." For the placebo, the success rate was 8 percent.
Chronic illnesses such as hypertension, diabetes, severe kidney problems, neurological disorders, and emotional problems can lead to impotence. According to Pfizer's data, Viagra allowed sexual intercourse less than 60 percent of the time for men with spinal-cord injuries, 50 percent for diabetics, and 43 percent for men who'd had a radical prostatectomy.
Recommendations
In an editorial in the May 14 issue of The New England Journal of Medicine, Dr. Robert Utiger, a Boston endocrinologist and a deputy editor of the Journal, termed the results "promising," noting anecdotes of "nearly miraculous restoration of sexual function." But he concluded that the promise of sildenafil won't be realized until many more men are treated for prolonged periods.
If you decide to try Viagra despite the potential for side effects:
- Have your doctor give you a physical exam, take your medical history, and review medications you're taking.
- Ask your doctor how to take the pill. Steers says that taking it with milk or dairy products or on a full stomach may delay absorption.
- Find out who'll pay. Some medical insurers will cover a few pills per month.
- Consider how the drug will affect your mate or partner. Dr. Drogo Montague, director of the Center for Sexual Function at the Cleveland Clinic, tries to involve the patient's wife in choosing options.
The pills come in 25-, 50-, and 100-milligram doses. Pfizer recommends starting with 50 milligrams and increasing or decreasing the dosage as needed. Currently, the pills are selling for about $10 each, regardless of dose. (Some doctors are prescribing 100-milligram pills and telling patients to split them to save money--although a Pfizer spokesman advises against that, saying the pills aren't scored and may not split evenly.)
Don't take Viagra if you're not impotent. It's not an aphrodisiac. Nor does it improve sexual performance in men who can achieve a healthy erection.
This is great, I'm going to use it as a patient information handout when I prescribe Viagra or for patients considering it, along with the one from Pfizer.
Zebra
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