NIH stops study in sickle cell patients

[July 29, 2009]  WASHINGTON (AP) -- The government has stopped a study of a potential treatment for certain sickle cell disease sufferers a year early because of a big increase in serious side effects.

At issue is whether the same ingredient that powers the impotence pill Viagra could treat a leading killer of sickle cell patients, a kind of lung damage called pulmonary hypertension.

A particular dose of sildenafil, sold under the brand name Revatio, is approved to treat general pulmonary hypertension, but not in sickle cell patients, because doctors didn't know how it would react in them. The National Institutes of Health was sponsoring a study at nine U.S. hospitals and one in London to try to answer that question.

An early safety review found more than a third of sildenafil users had serious side effects compared with 8 percent of patients given a dummy pill, the NIH announced Tuesday.

Most of the side effects were episodes of severe pain called sickle cell crises, bad enough for hospitalization. NIH said no deaths were associated with the drug.

The NIH stopped the study on July 7, and notified participants before making a public announcement.

The side effects are specific to sickle cell patients, stressed Dr. Elizabeth Nabel, chief of NIH's National Heart, Lung and Blood Institute. Sildenafil has been proven safe and effective for other people with pulmonary hypertension.

[Associated Press]

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