June 26, 2014

Low dose Ampyra does not improve walking speed in MS: results from a post-marketing study in the US

Acorda Therapeutics Inc. reported that post-marketing study results for Ampyra (Fampyra in Canada) have failed to show an improvement in the walking speed of people with MS in the United States.

Following approval of Ampyra 10 mg in 2010, the FDA requested that Acorda conduct a clinical trial to assess the safety and efficacy of a lower dose, 5mg taken twice daily as compared with the approved 10 mg dose twice daily, and placebo. Both the 5 mg and 10 mg treatment groups failed to show improvement in walking speed when compared with placebo. When investigators analyzed the data using methods similar to the previous studies, the 10-mg dose significantly improved walking speed compared with placebo in responders, but the 5-mg dose did not. In addition there were significantly more responders (average improvement in walking speed of at least 20% from baseline) in the 10-mg group compared to the placebo group.

Acorda reported that two trial participants, each from the 5 mg and 10 mg treatment group, experienced serious adverse events, including the loss of consciousness in the 10 mg group. This follows the recent safety warning issued in July by the FDA about the increased risk of seizures from the drug in people with kidney impairment in July.

What do these findings mean for Canadians currently being treated with Fampyra?

At this point, Health Canada has not made a formal statement related to these findings and it is not clear what the FDA plans on doing with this new data. It is possible that the most recent findings will be included in the product information (monograph) for physicians to prescribe appropriately.

Health Canada approved fampridine, (PrFAMPYRA™) on February 10, 2012 for the symptomatic improvement of walking in adults with multiple sclerosis (MS) with walking disability. Health Canada labeling for Fampyra currently recommends assessing kidney function prior to treatment as well as ongoing monitoring during treatment. Individuals who miss a dose are advised not to take an additional dose of Ampyra as it may increase the risk of seizures. Individuals are strongly advised to follow the prescribing instructions for taking FAMPYRA and to report any worrying side-effects to their doctor immediately.