Viagra Ingredient OK'd for Lung Problem

June 8, 2005 -- The FDA has approved Viagra's active ingredient to treat pulmonary hypertension, a rare, life-shortening lung disorder that causes high blood pressure in the lungs.

Viagra's maker, Pfizer, a WebMD sponsor, announced the approval in a news release. Pfizer will repackage Viagra's key ingredient (sildenafil) and market it as Revatio.

Revatio would be used to improve exercise ability in patients with pulmonary hypertension, says Pfizer. The approved dose is limited to 20 milligrams three times daily. The white, round pills will look different from Viagra's blue diamonds and should be available by mid-July, says Pfizer.

Rare Condition

Pulmonary hypertension involves dangerously high pressure in the blood vessels that lead from the heart to the lungs. It affects an estimated 100,000 people worldwide, says Pfizer.

Most cases of pulmonary hypertension are due to some underlying condition, such as chronic lung or heart disease. Nearly 300 cases, mostly women in their 30s, are diagnosed per year, says the National Heart, Lung, and Blood Institute (NHLBI). There is no known cause.

Symptoms include difficulty breathing, dizziness, and fatigue. Without treatment, patients live less than three years from the time of diagnosis, on average, says Pfizer.

Another oral drug, Tracleer, is also used to treat the condition. Revatio's effectiveness hasn't been evaluated in patients taking Tracleer, says Pfizer. The drug company says Revatio is the first oral treatment approved for patients with an early stage of the progressive condition.

Study's Results

The FDA's approval was based on a study of 277 people with pulmonary hypertension, says Pfizer. Patients were randomly assigned to get a placebo or 20, 40, or 80 milligrams of Revatio three times daily.

After 12 weeks, all three Revatio groups showed "highly significant improvements" in the distance they could walk in six minutes, compared with the placebo group, says Pfizer. Average pressure in the lung arteries and other heart functions also improved with Revatio, and in a year-long trial, 94% of patients taking Revatio were still alive, says Pfizer.

No particular dose had an advantage, and the lowest dose was approved.

Side Effects

Pfizer says Revatio was generally well tolerated, with side effects similar to those seen with Viagra.

The most common side effects for Revatio were headache, indigestion, flushing, insomnia, and nosebleeds. Viagra's most common side effects are headache, facial flushing, and upset stomach; less common (and brief) side effects are bluish vision, blurred vision, or sensitivity to light, says Pfizer.

Pfizer also recently said it is talking with the FDA about possible label changes to Viagra regarding extremely rare reports of vision loss. rare reports of vision loss. The drug company says there is no evidence that those rare cases occurred more often in men taking Viagra. Pfizer says no such problems were seen in clinical trials of Viagra, and no cases were noted in the Revatio news release.

Ongoing Care Needed

It's important to get ongoing medical care for pulmonary hypertension, says the NHLBI. The NHBLI also recommends walking for patients who can do so, as well as eating healthfully, getting enough rest, and not smoking. Relaxation exercises, stress reduction, and a positive attitude may also help patients stay active for as long as possible, says the NHLBI.