Safety concern from side effects prompts action by U.S. government
TUESDAY, July 28 (HealthDay News) -- The first clinical trial of a treatment for pulmonary hypertension in adults with sickle cell anemia has been stopped because of severe side effects in some participants.
The trial involved sildenafil -- marketed as Viagra when it is used to treat erectile dysfunction and Revatio when used for pulmonary arterial hypertension, or high blood pressure in the lungs.
"This was a very big disappointment," said Dr. Mark Gladwin, lead investigator of the study, which was sponsored by the U.S. National Heart, Lung, and Blood Institute. "We were very excited about this drug. It has a very high safety profile and has worked in every form of pulmonary hypertension. The preliminary data showed a lowering in pulmonary hypertension in sickle cell patients."
Pulmonary hypertension affects as many as 30 percent of people with sickle cell disease. "It's the highest risk of death, so it's a very important complication," said Gladwin, who is director of the Vascular Medicine Institute at the University of Pittsburgh.
People with sickle cell disease have an average of two so-called "crises" a year, involving severe pain and often requiring hospitalization. The crises occur when red blood cells, which are misshaped in those with the disease, get jammed up in the blood vessels, blocking blood flow.
An estimated 70,000 to 100,000 people in the United States have this genetic blood disorder, most of them black.
According to the institute, there are no current guidelines for treating pulmonary hypertension in people with sickle-cell disease, although drugs known as endothelin receptor blockers are sometimes used. The condition can lead to heart failure and death.
A small pilot trial using Revatio and involving just 12 people with sickle cell anemia had found a decrease in pulmonary hypertension.
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