Also available in 10 mg 50 mg 100 mg 500 mg 1 mL 10 mM (in DMSO) and bulk. Please contact Fisher for quotes. Flupirtine maleate (Katadolon maleate) a centrally acting non-opioid analgesia is the salt form of Flupirtine. It is an NMDA receptor antagonist and also a specific neuronal potassium channel opener. purity: 99%