A Phase 3 Trial of Extended Release Oral Dalfampridine in Multiple Sclerosis

Objective: A previous phase 3 study showed significant improvement in walking ability in multiple sclerosis (MS) patients treated with oral, extended-release dalfampridine (4-aminopyridine) 10mg twice daily. The current study was designed to confirm efficacy and further define safety and pharmacodynamics. Methods: This was a 39-center, double-blind trial in patients with definite MS of any course type. Participants were randomized to 9 weeks of treatment with dalfampridine (10mg twice daily; n = 120) or placebo (n = 119). Response was defined as consistent improvement on the Timed 25-Foot Walk, with percentage of timed walk responders (TWRs) in each treatment group as the primary outcome. The last on-treatment visit provided data from 8 to 12 hours postdose, to examine maintenance of effect. Results: One patient from each group was excluded from the modified Intention to Treat population. The proportion of TWRs was higher in the dalfampridine group (51/119 or 42.9%) compared to the placebo group (11/118 or 9.3%, p < 0.0001). The average improvement in walking speed among dalfampridine-treated TWRs during the 8-week efficacy evaluation period was 24.7% from baseline (95% confidence interval, 21.0-28.4%); the mean improvement at the last on-treatment visit was 25.7%, showing maintenance of effect over the interdosing period. There were no new safety findings. Interpretation: This interventional study provides class 1 evidence that dalfampridine extended-release tablets produce clinically meaningful improvement in walking ability in a subset of people with MS, with the effect maintained between doses. ANN NEUROL 2010;68:494-502