Original: Its mechanism of action is via multiple effects , including actions as a nonselective serotonin reuptake inhibitor and a sigma-1 receptor agonist and the action of its major metabolite dextrorphan as an NMDA receptor antagonist , producing effects similar to those of the controlled substances ketamine and phencyclidine ( PCP ) , as well as the active metabolite 3-methoxymorphinan which produces anesthetic effects in rats with a potency above dextrorphan but below dextromethorphan itself .
Simplified: Its mechanism of action ( how it works ) is as an NMDA receptor antagonist ( blocks a chemical in the brain ) , producing effects similar to those of the controlled substances ketamine and phencyclidine ( PCP ) .