TABLE 1

Kinetic parameter estimates for flurbiprofen 4 ′-hydroxylation in the presence of varying concentrations of benzbromarone

Data were fit to a two-site model (see eq. 1). Parameter estimates are reported as the estimate (mean ± S.E. of the estimate) resulting from nonlinear regression of the data. Kb, the binding constant for the effector; α, the change in Km resulting from effector binding; and β, the change in Vm resulting from effector binding. An α value <1 indicates a decrease in Km. A β value >1 indicates an increase in Vm, whereas a β value <1 indicates a decrease in Vm.

Enzyme VmKmKB α β R2
pmol/min/pmol P450 μM nM
CYP2C9.1 3.98 (0.13) 16.4 (1.98) 39.9 (14.2) 5.02 (1.94) 0.50 (0.13) 0.977
CYP2C9.3 1.43 (0.09) 147 (20.6) 627 (516) 0.14 (0.08) 1.14 (0.11) 0.991