Amifampridine is a New Treatment for Patients with Lambert-Eaton Myasthenic Syndrome


AmifampridineAmifampridine, CAS# 54-96-6, is the first and only approved drug thus far for the symptomatic treatment of Lambert-Eaton Myasthenic Syndrome in adults. As a rare autoimmune disease, Lambert-Eaton Myasthenic Syndrome, also called LEMS, is typically caused by autoantibodies to voltage gated calcium channels, leading to a reduction in the amount of acetylcholine released from nerve terminals in patients. The predominant symptom of LEMS is muscle weakness, with this weakness usually concentrated in the proximal muscles of the legs and trunk. Additional, devastating symptoms of this rare disease include extreme fatigue, reduced reflexes, drooping of the eyelids, problems with swallowing,  facial weakness, overwhelming dry mouth, impotence, feelings of light headedness or faintness upon on standing and constipation.

Approved in the EU, Amifampridine is known as the brand name Firdapse. The prevalence of Lambert-Eaton Myasthenic Syndrome is estimated at about 2,000 to 5,000 patients in the EU and 1,200 to 3,100 patients in the United States. In addition, approximately 50 percent of LEMS patients are also diagnosed alongside small cell lung cancer, which exacerbates the weakness of their respiratory muscles. The diagnosis of patients with LEMS is based on not only clinical symptoms, but also on electromyographic testing and the presence of autoantibodies against voltage gated calcium channels.

Acetylcholine
Acetylcholine (often abbreviated ACh) is an organic, polyatomic cation that acts as a neurotransmitter in both the peripheral nervous system (PNS) and central nervous system (CNS) in many organisms including humans.

Patients suffering from this uncommon condition have not seen treatment options until the advent of Amifampridine. Treatments consisting of immunosuppressive agents are limited due to their toxicity. The consistent therapy of 3,4-DAP treatment has proven helpful to many patients, but the limited availability of this treatment is not promising for extensive use. Amifampridine phosphate is effective as it works by blocking potassium channel efflux in nerve terminals, which in turn causes the action potential duration to be increased.

The Phase 3 studies of Amifampridine began in June of 2011, and are set to continue until completion in August of 2016. Preliminary findings are expected to be released in June of 2014. This multicenter, placebo-controlled, randomized and double-blind trial is specifically designed to evaluate the efficacy and safety of Amifampridine Phosphate in patients with Lambert-Eaton Myasthenic Syndrome.  The recommended starting dose of Amifampridine is 15 milligrams per day, which can be increased in 5 milligram increments every 4 to 5 days. The maximum dose of Amifampridine is 60 milligrams  daily. No single or individual dose should exceed 20 milligrams as well. Side effects have thus far proven to be mild, with the most frequently reported adverse effect being paresthesias. LGM Pharma provides Amifampridine for research and development, and offers clients continued support throughout the R&D process.


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