A randomized controlled trial of amantadine in fatigue associated with multiple sclerosis. The Canadian MS Research Group.

One hundred and fifteen patients with definite multiple sclerosis (M.S.) and chronic persistent fatigue were studied. This ten-week cross-over study consisted of a 2-week baseline period and two 3-week treatment periods separated by a 2-week washout. Patients received either amantadine 100 mg bid or matching placebo capsules. Fatigue, the effect of fatigue on an individually pre-selected activity and its effect on activities of daily living, were evaluated. Amantadine produced a small but statistically significant decrease in fatigue. An important placebo effect was noted. Mean fatigue during the washout period was lower than during the placebo run-in period, independently of which treatment had been given first. Side effects were numerous both on amantadine and on placebo. Only insomnia was significantly more common with amantadine.