Pyridostigmine and amifampridine evaluated versus placebo in myasthenia gravis

Almost a century after Dr Mary Walker first used pyridostigmine to treat autoimmune myasthenia gravis:

• the randomised, randomised, double-blind IMPACT-MG trial in the Netherlands compared the anticholinesterase alone (in 19 patients), then in combination with amifampridine (20 patients), versus placebo, in 5-day periods separated by 2-day washout periods;
• the investigators concluded that pyridostigmine was superior in terms of efficacy (MGII, QMG, MG-ADL, MG-QoL15r) and lower annual societal costs for pyridostigmine compared with placebo.
• Amifampridine (30 or 60 mg) added to pyridostigmine was not shown to be more effective than pyridostigmine alone;
• however, it was associated with a higher incidence of adverse effects (paraesthesia, dizziness, sleep disturbances, etc.).

 

Efficacy of Pyridostigmine in Myasthenia Gravis: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial. Remijn-Nelissen L, Bakker WR, van den Hout WB et al. Neurology. 2026 Apr 28;106(8):e214865.

 

Efficacy and Safety of Amifampridine in Myasthenia Gravis: A Randomized, Double-Blind, Placebo-Controlled Crossover Trial. Remijn-Nelissen L, Bakker WR, van Gelder T et al. Neurology. 2026 Apr 28;106(8):e214715.