Table 3

Mean enzyme kinetic parameters ± S.D. of the formation of metabolites from S-omeprazole and R-omeprazole in human liver microsomes

MetaboliteS-OmeprazoleR-Omeprazole
% of Sum % of Sum
Sulfone V max 0.18  ± 0.090.05  ± 0.02
K m 47.9  ± 16.158.4  ± 14.7
CLint 3.87  ± 1.66270.84  ± 0.172.0
5-O-desmethyl V max 0.09  ± 0.020.05  ± 0.01
K m 16.5  ± 8.3126.3  ± 10.1
CLint 6.73  ± 4.32461.80  ± 0.564.2
Hydroxy V max 0.11  ± 0.010.28  ± 0.04
K m 31.7  ± 12.27.93  ± 2.79
CLint 4.00  ± 1.592739.9  ± 22.594
Sum CLint 14.610042.5100

Km expressed as micromoles per liter,Vmax as nanomoles per minute per milligram of protein, and CLint as microliters per minute per milligram of microsomal protein. Trivial names of the metabolites given in Fig. 2are used. Microsomes prepared from liver tissue from three different donors were used.