3,4-diaminopyridine (3,4-DAP, amifampridine) is the leading treatment for Lambert–Eaton myasthenic syndrome (LEMS), an autoimmune disorder with impaired neuromuscular transmission, for which few effective medications are currently available. 3,4-DAP has been available as a therapy for LEMS in special treatment programmes for approximately 25 years. As an unlicensed drug, doses for oral administration are required to be compounded by local, hospital or other compounding pharmacies from the base chemical. Administering the correct dose of 3,4-DAP is critical; overdosing can increase the risk of seizures and other adverse events, while underdosing can result in a substantial loss of efficacy or even treatment failure. Two recent studies, have shown a wide variation in the 3,4-DAP content of compounded preparations (22.2–125.2 %, n=9) and (53.5–128.5 %, n=21), thereby reflecting the possibility of patients receiving dosages that might be above safety limits or even markedly below efficacy limits. This inconsistency results from the variable quality and instability of the base chemical and compounding errors. A formulation of 3,4-DAP phosphate salt has now been licensed in Europe and the US with orphan medicinal product status and appears to be as efficacious as the base in relieving the symptoms of LEMS.
Acknowledgements: Editorial assistance was provided by Touch Briefings and funded by BioMarin Europe Limited.
Keywords: Amifampridine, compounded drugs, Lambert–Eaton myasthenic syndrome, potassium ion channel blockers, neuromuscular transmission, myasthenia gravis
Disclosure: Jörn Peter Sieb has received honoraria or consultation fees from BioMarin, Temmler and Valeant.
Citation European Neurological Review, 2012;7(1):56–61
Correspondence: Jörn Peter Sieb, Department of Neurology, Grosse Parower Strasse, 18437 Stralsund, Germany. E: firstname.lastname@example.org
Support: The publication of this article was funded by BioMarin Europe Limited. The views and opinions expressed are those of the author and not necessarily those of BioMarin Europe Limited.
bid is 1.52 (1400) ask 1.64 (800) 1.82 is the last price some moron just paid, ignore that. expect gap down tomorrow at 1.3s then drift down at 1.05 rally back to 1.5s then down and flat until official press release from CPRX Regarding recent stock devaluation. if they refute AF claims stock will rally imminently to sub 4$. hold on your seats, road ahead is bumpy