Health officials have called off a promising trial that used Viagra to treat
a complication of sickle cell anemia. The study, known as "walk-PHaSST"
(Treatment of Pulmonary Hypertension and Sickle Cell Disease with Sildenafil
Treatment), was stopped dead in its tracks this month. The drug was making
some patients worse instead of better; 38 percent of the subjects
experienced serious side effects, compared to 8 percent of those taking the
placebo.
The study seemed like a good idea on paper. Sildenafil is approved under the name Revatio to treat pulmonary hypertension, one of the major killers of sickle cell patients.
However, a high number of the patients on Revatio experienced painful "sickle cell crises", in which sickle-shaped blood cells become backed up in blood vessels.
Interestingly, Viagra has had mixed results with regard to another sickle cell complication: priapism. While Viagra has been known to precipitate priapism in men with sickle cell anemia, the drug has also been shown to relieve the condition in other sickle cell patients when given in a steady low dose.
Ultimately, Viagra may prove to have some benefit for certain patients with sickle cell anemia, perhaps when combined with other treatments, but the failure of this study is a major setback.
The study seemed like a good idea on paper. Sildenafil is approved under the name Revatio to treat pulmonary hypertension, one of the major killers of sickle cell patients.
However, a high number of the patients on Revatio experienced painful "sickle cell crises", in which sickle-shaped blood cells become backed up in blood vessels.
Interestingly, Viagra has had mixed results with regard to another sickle cell complication: priapism. While Viagra has been known to precipitate priapism in men with sickle cell anemia, the drug has also been shown to relieve the condition in other sickle cell patients when given in a steady low dose.
Ultimately, Viagra may prove to have some benefit for certain patients with sickle cell anemia, perhaps when combined with other treatments, but the failure of this study is a major setback.
