Four year double-blind controlled study of levamisole in multiple sclerosis.

41 patients with definite multiple sclerosis (MS) in the stationary phase entered this four year double-blind levamisole-placebo controlled study. 22 patients were treated with levamisole, 150 or 200 mg once a week for a 4 year period, and other 19 with placebo with the same schedule. Patients were put in one of the two groups at random. The treatment was then stopped for those patients who presented a clear exacerbation before the end of the 4 year trial period, and these cases have been considered as negative. Of the group treated with levamisole 8 patients presented an exacerbation during the observation period, and 14 did not. The group treated with placebo presented 14 subjects who had exacerbations and 5 patients who did not. The difference between the two groups was statistically significant. This study demonstrates that levamisole significantly reduced the number of MS patients with acute relapse during the 4 year period of treatment. Nevertheless, not all patients were free from relapse: that could probably suggest that different immunopathological backgrounds may underlie what we usually call MS.