PR-Fampridine (4-aminopyridine), a potassium channel blocker, is licensed for improving walking speed in pwMS who have a motor disability.   Benefits have been reported in relation to diplopia, cognitive functioning, visual improvement and upper limb functioning. Data supporting these off-label uses remain limited.

We conducted a single-centre, randomised, double-blind, placebo-controlled, crossover group trial (NCT02208050).  PwMS were randomised to receive PR-Fampridine 10mg tablets or placebo. Each treatment period lasted eight weeks with a two-week washout. Outcome measures were assessed at screening, weeks 1, 2 (baseline), 6, 10 (on-treatment period), 12 (washout), 16, 20 (on-treatment), 22 (end of study).   Performance measures: 9 Hole Peg Test (9HPT), Timed 25Foot Walk Test (T25FW), Jensen-Taylor Hand Function Test (JTT). Self-reported questionnaires: Disabilities of the Arm, Shoulder and Hand (DASH), Arms Function in MS Questionnaire (AMSQ), Multiple Sclerosis (MSIS-29), Multiple Sclerosis Walking Scale - 12 (MSWS-12).

Primary Outcome: Difference in number of upper limb responders to treatment as defined as improvement by 20% in both 9-HPT assessments compared to the average of baseline. 

Secondary Outcomes: Difference in number of upper limb responders to treatment as defined as improvement by 20% in both on-treatment JTT assessments.

64 pwMS (60% female, median age 55 (range 29-69)) were enrolled. Treatment with PR-Fampridine was not associated with significant change in the primary outcome.  11% of the PR-Fampridine group demonstrated ≥20% improvement in the JTT on both visits compared to 3% of the placebo group. Questionnaire assessments did not differ.

PR-Fampridine did not significantly improve upper limb function as measured by 9HPT compared to placebo but a trend to benefit on the JTT, a more practical measure of upper limb function was seen and merits further investigation.