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Viagra treats erectile dysfuntion by widening arteries. Viagra’s active ingredient also has been approved, under the name Revatio, to treat pulmonary hypertension, the condition raising blood pressure in the lungs. And that’s why researchers were studying whether Revatio might also work in patients with sickle-cell disease, a genetic blood disorder.

Until today, that is, when the National Heart, Lung and Blood Institute announced it had stopped the study a year early “due to safety problems.”

The trigger, the institute said in a news release, was an interim review of safety data from 33 study participants who had completed 16 weeks of treatment. Compared with those taking a placebo, the 33 study subjects taking Revatio were “significantly more likely” to suffer serious side effects, including painful episodes called “sickle cell crises” that can lead to hospitalization.

The NHLBI, a part of the National Institutes of Health that conducted the study, emphasized that the findings were specific to sickle-cell patients and therefore “should not be applied to other groups of patients with pulmonary hypertension where the drug has been found to be safe and effective.” It said that sickle-cell patients taking Revatio should consult their doctors.

Revatio isn’t approved for use by sickle-cell patients, according to this Dow Jones Newswires story. About 30% of sickle-cell disease patients develop pulmonary hypertension, which can lead to heart failure and death. There are no established guidelines for treating sickle-cell patients with pulmonary hypertension, NHLBI said.

Viagra maker Pfizer said the safety of Viagra and Revatio is “well-established.” The company also said it would be a mistake to compare the safety of sildenafil, the active ingredient in Viagra and Revatio, in patients coping with erectile dysfunction to its safety in those suffering from pulmonary hypertension because of differences in the two conditions.

Excerpt from: 
Study Using Viagra Ingredient to Treat Sickle Cell Cut Short