Ampyra Aids More Than Walking in MS, But Side Effects May Be of Concern
But the investigators caution the therapy should be taken only under expert medical guidance, due to its higher rate of potential side effects.
The study, “Dalfampridine in the treatment of multiple sclerosis: a meta-analysis of randomised controlled trials,” was published in the Orphanet Journal of Rare Diseases.
Ampyra, by Acorda Therapeutics, is an extended-release tablet that aids walking in MS patients by restoring nerve signal conduction in the central nervous system (CNS), consisting of the brain and spinal cord.
The treatment is approved — sold under the brand name Fampyra in the EU, with generics also available — to help with walking in adults with MS. But despite Ampyra’s well-documented benefits in walking abilities, less is known regarding how it affects other symptoms, such as hand use and cognition.
Researchers at Peking University, in China, reviewed published studies of randomized clinical trials comparing Ampyra to a placebo in adults with MS.
A total of nine trials were included, with patient groups ranging from 21 participants to 633, and ages varying between 39.5 to 54. These patients took Ampyra tablets twice daily at doses between 5 and 10 mg, over periods ranging from four to 24 weeks.
Four trials reported changes in the Multiple Sclerosis Walking Scale, a patient self-assessment survey of MS-based walking limitations, in which higher scores represent greater difficulties. These trials showed significant differences between groups, with those on Ampyra experiencing a 3.68 point greater reduction in their scores, compared with patients on placebo.
Ampyra significantly improved mobility and leg function over short and long distances, as measured by the timed 25-foot walk and the six-minute walk test. The medication was similarly associated with better manual dexterity, with significant differences appearing between Ampyra and placebo groups on the nine-hole peg test.
Finally, Ampyra use correlated with greater cognitive improvements than placebo, as measured by the symbol digit modalities test. Out of three trials, patients taking Ampyra scored an average of 5.5, compared to 4.4 among those on placebo.
From six trials, adverse side effects were reported in 67.6% of the 596 patients taking Ampyra, and in 61.4% of 427 patients receiving placebo. These included urinary tract infections, falls, insomnia, headache, dizziness, nausea, back pain, balance issues, upper respiratory tract infections, spasticity, mood alterations, gastric pain, vertigo, and hand tremor.
Ampyra carries a known risk of adverse reactions that include seizures and allergic shock, which increases with dose exposure, the researchers noted. Post-marketing data in the United States has shown that 23.9% of around 107,000 Ampyra users experienced at least one undesirable side effect, with the 657 seizure cases reported (324 confirmed medically) occurring anywhere from a single dose to more than four years of treatment.
Overall, the study found that Ampyra had a net positive effect on walking, hand use, and cognition. But “with a slightly higher incidence of [adverse side effects], dalfampridine requires administration under the guidance of a physician or pharmacist,” the researchers concluded.
“Additional high-quality [randomized, controlled] trials are needed to verify the results, and equally, long-term studies to evaluate the safety of dalfampridine more completely are needed,” they concluded.