Viagra helps mountain climbers breathe easier

Researchers may have found a new use for Viagra, after conducting tests on mountain climbers scaling Mt. Everest, the world’s tallest summit.

The drug, which promotes erections by opening the tiny veins and arteries leading to the penis, performs similarly in the lungs of men and women at high altitudes, a new study has found.

German medical researchers reported that sildenafil (the generic name for Viagra) enabled 14 experienced Swiss and German climbers to better tolerate hypoxia, or lack of oxygen, while scaling the Himalayan peak. Hypoxia causes altitude sickness and hinders exercise by constricting lung blood vessels, as well as triggering other changes in the heart and lungs.

The drug is believed to be the first shown to increase exercise capacity during severe hypoxia at high altitudes. The researchers also found that it had a similar effect at sea level, where hypoxia-like conditions were induced on volunteers to produce an effect akin to what is experienced by patients suffering from lung disease or obstructions.

The study results, published in the August issue of the Annals of Internal Medicine, could have wide implications, not only for mountain climbers and athletes working out in higher altitudes but also for patients suffering from lung diseases as well as pulmonary hypertension, Dr. Hossein A. Ghofrani, assistant professor at the University of Giessen in Germany and research team co-leader, said in a phone interview.

It could potentially also be seen as a performance-enhancer in competitive as well as noncompetitive sports, though it remains to be seen whether sildenafil can increase cardiopulmonary exercise capacity in healthy athletes operating at sea level. (At present, it is not banned for use by Olympic athletes.)

Ghofrani says he doesn’t think it would improve lung function in healthy athletes in normal conditions because their lung and blood vessels are dilated already, and dilate more with exercise. However, he notes that it has been shown to improve performance in horses. Racehorses sometimes suffer lung bleeding and edema after races due to severe pulmonary hypertension that sildenafil appears to alleviate.

For those who “perform a demanding workout in a condition of hypoxia,” however, Ghofrani says sildenafil might have benefits, though he says more extensive studies are needed to confirm it. He does not recommend its use for the majority of people in any setting, however. For one thing, it seemed to exacerbate headaches that occur often at high altitudes.

The 12 men and two women mountain climbers were a median age of 36 1/2 years. All had often climbed to altitudes over 3,500 meters (eight had repeatedly climbed peaks of 6,000 meters). Half of the volunteers took 50 milligrams of sildenafil and half took the placebo pill on random days. The researchers measured exercise capacity at the low altitudes while breathing a mixture of air that contained little oxygen and also at the high altitude of the Mt. Everest base camp, perched at 5,245 meters.

The study reported that the sildenafil reduced high pressure in the lungs’ blood vessels and increased maximum exercise capacity at sea level and at high altitude. The researchers chose to do the study at Mt. Everest because subjects needed to be exposed to long-term hypoxia for more than a few days or weeks. The base camp at Everest’s infrastructure also enabled 1 ton of medical monitoring equipment to be brought in.

The study, done in early 2003, was funded by the German Research Foundation, a government agency that provided about two-thirds of the $150,000 cost, while Pfizer Inc., maker of Viagra, paid for the other third.

Since observing the drug’s efficacy on the climbers, the research physicians -- all from the University of Giessen Lung Center -- now treat about 300 to 400 previously bedridden patients with severe pulmonary problems -- such as lung fibrosis, obstruction and cancer -- using Viagra, Ghofrani said, with good results. Many resumed exercise and daily activities or returned to work after taking the drug daily.