NIH Halts Viagra Trial In Sickle Cell Patients

Chrissie Cole

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A trial of sildenafil intended to determine if the drug could be used to treat pulmonary hypertension in some patients with sickle cell disease has been halted a year early by the National Institutes of Health (NIH).

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. The NIH was sponsoring a study at nine U.S. hospitals and one in London.

The researchers found that 38 percent of patients taking Revatio had serious adverse effects, compared to 8 percent of patients getting a placebo.

Most episodes involved severe pain called sickle cell crises requiring hospitalization. No deaths have been linked with the drug.

Dr. Elizabeth Nabel, chief of NIH’s National Heart, Lung and Blood Institute (NHLBI) stresses that the side effects are specific to sickle cell patients and advises patients to talk to their doctors.

Sildenafil treats pulmonary hypertension by relaxing blood vessels in the lungs to allow blood to flow easier.

Nearly 30 percent of people with sickle cell disease are affected by pulmonary hypertension.