Dalfampridine for the treatment of ambulatory impairment in multiple sclerosis

Dalfampridine is a potassium-channel blocker that is approved by the US FDA as 10 mg extended-release tablets to improve walking in patients with multiple sclerosis. Approval is currently pending in Europe. This is the first pharmacological symptomatic treatment approved for multiple sclerosis patients of any type with walking difficulties. Relative to an immediate-release formulation, the extended-release formulation of dalfampridine lowers peak serum concentrations that contribute to toxicity while maintaining a comparable amount of total drug exposure. Several studies show the efficacy and tolerability of dalfampridine. The pivotal published clinical trial demonstrated a treatment-responder rate of 35% compared with an 8% placebo-responder rate (p < 0.0001). The subjects who responded to treatment had an average improvement in their 25-foot walking test time of 25.2% (95% CI: 21.5-28.8) compared with an average improvement of 4.7% (95% CI: 1.0-8.4) in subjects who responded to placebo. Seizures are the most serious adverse effect of dalfampridine with a probable dose-dependent likelihood of occurrence.