Viagra tested on Everest
Agent may treat PHT
Sildenafil, an active agent used in the impotence drug Viagra, has been administered to seven young mountaineers on an Everest expedition, to test its effect on the lungs. Seven other men on the expedition are receiving a placebo.
Leading the research, Friedrich Grimminger, from the Centre for Internal Medicine, University of Giessen, Germany, was at the base camp to carry out heart, lung and blood tests on the volunteers. He explained that sildenafil might improve the quality of life of pulmonary hypertension (PHT) patients significantly.
In PHT patients blood vessels in the lung constrict, and they suffer breathlessness and cardiac strain during strenuous activities. If the condition is not diagnosed, heart failure (HF) can result. Current therapies are said to be risky, because they reduce general blood pressure and this can lead to circulatory collapse. Dr Ardeschir Ghofrani, another Geissen study team member, reported that the drug reduced PHT without causing a dangerous reduction in blood pressure elsewhere. Because a biochemical similarity exists between the penis and lungs - both contain large amounts of the enzyme phosphodiesterase - it limits penis erection and has been found to constrict blood vessels around lungs. Sildenafil blocks that enzyme, which then allows sustained erection. Similarly, in the lung walls, it appears to improve blood circulation.
In 2003, the healthy young mountaineers were chosen for this test because their lungs undergo rapid change in a matter of weeks when staying at high altitudes. Professor Grimminger explained that they suffer pulmonary hypertension due to a lack of oxygen, which is only partly resolved by acclimatisation. ‘A stay at heights above 5,500 metres cannot be survived in the long run. In the death zone, at levels of above 7,000 metres, survival without an additional oxygen supply is only possible for a few hours to a few days. Changes caused by lack of oxygen can serve as a model for numerous heart and pulmonary diseases. While the process in the mountaineers’ systems is reversible this is not the case for the disease process in patients,’ he added.
Although the study results, published in the Annals of Internal Medicine, concluded that sildenafil reduced arterial pressure and improved oxygen transport, Professor Grimminger has stressed that the drug would not receive regulatory approval as a treatment for PHT until worldwide tests are completed.
Viagra was invented to treat a range cardiovascular problems but is only licensed to treat impotence. This possible new use is early stage research, said a spokesman for Pfizer, the manufacturer of Viagra, adding, by the by, that this year marks the 50th anniversary of the conquest of Everest, and it is five years since Viagra was launched.
01.07.2004
