3,4-diaminopyridine or amifampridine (Firdapse®) is already indicated in some myasthenic syndromes, congenital or autoimmune (Lambert-Eaton). In the past, case reports had alerted to the possible efficacy of this drug in myasthenia gravis as well. The results of an open-label clinical trial conducted in Italy in 15 adults with anti-acetylcholine receptor (AChR) myasthenia gravis support these publications. They show that taking a single tablet of Firdapse® 10 mg :
- leads to a significant clinical (QMG score, vital capacity) and electrophysiological (repetitive nerve stimulation) improvement within one hour in participants with severe myasthenia, benefits that are not linked to a direct effect on the functioning of the AChRs as demonstrated by the same team using in vitro tests;
- is well tolerated, the only notable side effects being transient paresthesias in 60% of participants.
Firdapse® could be an adjunct therapeutic solution, particularly in the most severe patients, when immune-based treatment has not yet achieved its full effect or in cases of poor tolerance to anticholinesterase drugs.
Voir aussi « Myasthénie : le Firdapse®, un traitement d’appoint possible »