Pulmonary hypertension is different from hypertension, the common condition of high blood pressure. The pulmonary disease involves extremely high pressure in the artery that carries blood from the heart to the lungs to pick up oxygen. The disease, also called pulmonary arterial hypertension, can make even routine tasks an ordeal.
Viagra the blue pill that treats erectile dysfunction, a common but less than fatal male malady, may have a new role in treating pulmonary hypertension, a rare but deadly disease that afflicts mainly women.
Results of a clinical trial in India, showed that Viagra increased the ability of patients to exercise by about 40 percent. The authors said that was greater than the effect seen with other drugs in different trials. Although the trial involved only 22 patients, it was the first randomized test to compare Viagra against a placebo for pulmonary hypertension. The drug is even being given to babies, surprising but true .
Some doctors and insurance companies say they have concerns about this use of Viagra, saying it has not been proved effective in rigorous clinical trials, whereas other drugs have. Patients with pulmonary hypertension use the drug every day and in higher doses than men who use it before sex, potentially raising new risks.
Though only about 100,000 people in the United States and Europe have pulmonary hypertension, three drugs have already been approved for the condition and several others are on the way. Researchers say the patient population might grow because doctors, who often miss the condition, are looking more carefully now that treatments are available. Though far from cures for pulmonary hypertension, the new drugs have helped improve the outlook for patients.
Drug manufacturers say they would sell a pulmonary hypertension drug under a different name and in a different form from Viagra to prevent prescription errors. Investigators in the clinical trials said the drug was being provided as a round white pill, not a blue diamond-shaped one, and in doses different from those used for erectile dysfunction.
Given the small patient population, sales of Viagra for pulmonary hypertension are not expected to be that big, the company is pursuing the lung disease treatment because there is an unmet medical need and because the company had been urged to do so by doctors, who had begun testing the drug on their own.
The first drug approved for pulmonary hypertension, in 1995, was Flolan, a version of a natural hormone called prostacyclin, which dilates constricted blood vessels. Flolan, disappears from the body so fast that it must be pumped in 24 hours a day. The catheter used poses a risk of infection, and users must carry a small pump and mix a fresh batch of the drug every day.
Another of the new drugs, Remodulin, is a form of prostacyclin infused under the skin rather than through a catheter. That method lowers the infection risk, but many patients complain of pain. The drug was approved in 2002.
The first oral drug, approved in 2001, was Tracleer from Actelion; it inhibits endothelin, a hormone that helps constrict blood vessels. Though much cheaper than the two other approved drugs, Tracleer can cause liver problems, so users must have their liver enzymes checked every month.
Viagra works by yet another mechanism, inhibiting an enzyme called phosphodiesterase 5. The drug relaxes blood vessels, allowing blood to flow into the penis - or, it is hoped, into the lungs.
However specialists say , approved drugs typically allow someone who cannot climb even one flight of stairs to climb a flight or more, but don't return anybody to what they would perceive as normal health.