A Cochrane review [Abstract] 1 included 3 studies with a total of 524 subjects with sickle cell disease (aged between 12 and 65 years). One study, conducted in India, compared zinc sulphate (220 mg three times a day orally) to placebo, and 2 multicenter studies compared senicapoc to placebo. Zinc sulphate reduced painful crises compared to placebo over one and a half years (MD -2.83, 95% CI -3.51 to -2.15; 1 study, n=145). Changes to red cell parameters and blood counts were inconsistent. No serious adverse events were noted in the study.
The second study (n=90) was a Phase II dose-finding study of senicapoc (Gardos channel blocker) compared to placebo. Compared to the placebo group the high dose senicapoc showed significant improvement in change in hemoglobin level, number and proportion of dense red blood cells, red blood cell count and indices and hematocrit. The results with low-dose senicapoc were similar to the high-dose senicapoc group but of lesser magnitude. There was no difference in the frequency of painful crises between the three groups. A subsequent Phase III study (n=289) of senicapoc was terminated early since there was no difference observed between the treatment and control groups in the primary end point of painful crises.
Comment: The quality of evidence is downgraded by study limitations (unclear allocation concealment), and by imprecise results (few patients and wide confidence intervals).
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