Lambert-Eaton myasthenic syndrome (LEMS)
LEMS is an autoimmune disorder in which the neuromuscular junctions are attacked. The amount of acetylcholine release from terminal neurons causes exhibition of muscle weakness in proximal muscles and autonomic nervous symptoms. It is a complication of malignant tumor or paraneoplastic neurological syndrome that precedes a malignant tumor.
DYD-301 (amifampridine)
An orally administered channel blocker of potassium ion (K+) channel blocker, DYD-301 (amifampridine) blocks the membrane potential dependent K+ channel in the presynaptic membrane of the neuromuscular junction. In so doing, it depolarizes the cell membrane to open the membrane potential dependent calcium ion (Ca2+) channel to facilitate the inflow of CA2+ into the cells. It also improves muscle function by increasing neuromuscular transmission after triggering exocytosis of synaptic vesicles including acetylcholine (ACh) and helping the discharge from the synaptic terminal to the synaptic gap. Amifampridine has been designated as an orphan drug by the MHLW in Japan and already approved as a therapeutic drug for adult LEMS patients in the United States, Canada, and Europe.