I am on 3,4 Dap for Lems. It is only available through certain doctors who participate in research studies for particular diseases on a compassionate use basis. My local neuro referred me to a neuromuscular specialist who can prescribe it. Even though it is relatively safe and free from serious side effects, it has not been approved by the FDA for regular distribution. It has been in use for Lems and Congenital Myasthenic syndrome for over twenty years. It has been tried for other neuro muscular diseases, but apparently with not enough benefit to justify its use.