About Chlorzoxazone A benzoxazolone derivative, Centrally acting Muscle relaxant and mild sedative. Mechanism of Action of Chlorzoxazone This muscle relaxant works by blocking nerve impulses (or pain sensations) that are sent to your brain. It 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. It may also reduce the release of inflammatory leukotrienes. Chlorzoxazone may act by inhibiting calcium influx.