A form of Pfizer Inc.’s erection drug Viagra, sold as the blood-pressure treatment called Revatio in adults, may be used for children with a rare lung disorder if U.S. regulators can agree on how to test it.
The condition, called pulmonary arterial hypertension, affects only 600 children a year, New York-based Pfizer said. It causes high blood pressure in arteries in the lungs, making the right side of the heart work harder than normal and causing chest pain, dizziness and fatigue. Outside advisers to the Food and Drug Administration are set to meet July 29 to evaluate whether Pfizer’s study of Revatio is sufficient to determine its effectiveness in children, the agency said today.
The FDA in 2001 asked Pfizer, the world’s biggest drugmaker, to study the medicine in children with the lung disorder. If the New York-based company meets the FDA study requirements, the drug would get an extra six months on the market without generic competition. Patents on the drug, with 2009 sales of $1.89 billion as Viagra and $450 million as Revatio, are expected to expire in 2012. Some doctors are already using the treatment in kids with the lung condition.
“It’s a good option in pediatric patients because it is well-tolerated, in that it doesn’t have as many side effects as some of the other options,” said Chad Knoderer, a pediatric clinical pharmacist at Riley Hospital for Children in Indianapolis, who has used Viagra in kids with the disorder.
FDA Request
Sildenafil, the chemical name for both Viagra and Revatio, blocks an enzyme found in the lungs and penis that regulates blood flow. Pfizer is considering whether to seek approval for Revatio, a lower-dose form of sildenafil, in children, said Colin Ewen, an executive director at the company, in a July 23 telephone interview.
Pfizer shares rose 25 cents, or 1.7 percent, to $15.27 at 4 p.m. in New York Stock Exchange composite trading.
The FDA is asking its panel of advisers to decide what is the best measurement to use in determining if the drug is effective in children with pulmonary hypertension.
In adults, researchers typically use an exercise test to determine if the drug is having a benefit. Because that test was difficult to perform in young children, Pfizer has asked the FDA to consider an alternative test that measures blood flow by inserting a catheter through the arteries.
In Pfizer’s study of 234 children, the drug failed to show a benefit when the children’s exercise ability was measured. However, it did show a significant benefit when researchers used an alternative measure of blood flow.
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