Dalfampridine: A Medication to Improve Walking in Patients with Multiple Sclerosis

Abstract

OBJECTIVE: To review the pharmacology, pharmacokinetics, efficacy, and safety of dalfampridine. DATA SOURCES: A search of PubMed (1966-March 2012) was conducted using the words dalfampridine and Ampyra. Bibliographies of retrieved articles were reviewed to identify additional references. STUDY SELECTION AND DATA EXTRACTION: All identified studies published in English involving the efficacy and safety of dalfampridine were reviewed. DATA SYNTHESIS: Dalfampridine (Ampyra) is a broad-spectrum potassium channel blocker that is indicated as a treatment to improve walking in patients with multiple sclerosis (MS). Dalfampridine is the only medication approved for this indication. Efficacy has been demonstrated in 2 Phase 3 trials involving patients with MS. Dalfampridine 10 mg twice daily improved walking, as shown by a higher proportion of timed walk responders in the dalfampridine-treated group (42.9% and 35%) versus the placebo-treated group (9.3% and 8%) during the 2 studies (p < 0.001). The maximum recommended dose of dalfampridine is 10 mg twice daily; higher doses are associated with an increased risk of seizures. At doses greater than 10 mg twice daily, the frequency of other adverse reactions and discontinuations was greater and showed no additional benefit. The average wholesale price of a 10-mg dalfampridine tablet is $21.12, which would make a 1-month supply of therapy cost $1267.20. CONCLUSIONS: In clinical trials, dalfampridine improved walking speed in approximately one third of patients with MS. The risk of seizures appears to be dose-related and the incidence is low at doses of 10 mg twice daily. Because of the cost, dalfampridine should be reserved for patients who meet criteria for the drug and continued only if they have an adequate response.