The present invention includes salts and polymorphs of flupirtine including, but not limited to carboxylic acid salts and sulfonic acid salts and their polymorphs. The present invention also includes pharmaceutical compositions comprising the salts and polymorphs of flupirtine. The invention also relates to the therapeutic use of the flupirtine salts and polymorphs to treat nervous system disorders, pain disorders, musculoskeletal disorders, and other diseases and conditions.
