text: We examined the N-demethylation of individual << ketamine >> enantiomers using human liver microsomes (HLMs) genotyped for the [[ CYP2B6*6 ]] allele, insect cell expressed recombinant CYP2B6 and CYP3A4 enzymes and COS-1 cell expressed recombinant CYP2B6.1 and CYP2B6.6 protein variant.