Centrally acting muscle relaxant:
Ref. Oxford textbook of anesthesia. Page. 309
 
Chlorzoxazone

It’s a centrally acting muscle relaxant
Chlorzoxazone may act by inhibiting calcium and potassium influx which would lead to neuronal inhibition and muscle relaxation.
Chlorzoxazone inhibits degranulation of mast cells, subsequently preventing the release of histamine and slow-reacting substance of anaphylaxis (SRS-A), mediators of type I allergic reactions.
Chlorzoxazone also may reduce the release of inflammatory leukotrienes.
Chlorzoxazone
Scoline
Atracurium
Vecuronium