TABLE 2

Summary for enzyme kinetic variables obtained in this study with the IFRMM, MDCM, or MDCM + ke enzymatic activity variable (ke) and the in vitro T1/2M

Values are shown as means with S.E.


Variable

Method

Benzyloxyresorufin

Diclofenac

Dextromethorphan

Ethylmelagatran

Ethoxyresorufin

Flutamide*

N-Hydroxymelagatran*
Km (μM) IFRMM 0.0937 ± 0.012 19.8 ± 2.1a 0.795 ± 0.13 4710 ± 2400 0.152 ± 0.016 2.48 ± 0.40 50.3 ± 5.4
19.6 ± 2.4b
MDCM 0.179 ± 0.099 17.8 ± 2.2 5.15 ± 0.95 2340 ± 800 0.174 ± 0.038 4.03 ± 0.54 428 ± 280
MDCM + ke 0.166 ± 0.082 16.4 ± 1.9 3.18 ± 0.50 2340 ± 790 0.157 ± 0.038 3.76 ± 0.40 294 ± 160
Vmax (pmol min-1 mg-1) IFRMM 12.0 ± 0.48 668 ± 20a 665 ± 17 42800 ± 17000 71.3 ± 2.0 200 ± 7.5 318 ± 9.1
473 ± 16b
MDCM 11.8 ± 6.8 784 ± 85 875 ± 140 36100 ± 12000 54.2 ± 7.5 282 ± 33 4090 ± 2300
MDCM + ke 26.9 ± 13 1060 ± 120 1210 ± 120 46900 ± 16000 56.1 ± 10 472 ± 48 8540 ± 400
CLint (ml min-1 g-1) IFRMM 128 ± 17 33.7 ± 3.8a 836 ± 130 9.10 ± 5.9 470 ± 51 82.2 ± 14 6.32 ± 1.7
24.2 ± 3.0b
MDCM 66.1 ± 7.5 44.0 ± 1.2 170 ± 5.9 15.5 ± 0.77 311 ± 28 70.1 ± 2.0 9.57 ± 1.4
MDCM + ke 162 ± 28 64.7 ± 4.4 380 ± 31 20.1 ± 3.0 358 ± 67 125 ± 7.1 29.1 ± 8.9
T1/2M1 67.6 ± 11 40.1 ± 1.2 - 16.3 ± 3.2 - 84.1 ± 4.3 8.86 ± 1.6
T1/2M2 10.9 ± 5.9 - - - 222 ± 18 55.9 ± 1.5 -
T1/2M3 - - 154 ± 3.2 - 71.5 ± 4.0 - -
ke (min-1)
MDCM + ke
0.034 ± 0.008
0.013 ± 0.002
0.025 ± 0.002
0.0094 ± 0.005
0.0061 ± 0.005
0.020 ± 0.002
0.040 ± 0.01
  • -, Estimation not performed.

  • * Variables obtained from IFRMM not included in method comparisons due to incomplete mass balance.

  • a Diclofenac 4′-hydroxylation reaction.

  • b Diclofenac 5-hydroxylation reaction.

  • 1 Estimation done at an initial concentration well below the Km value estimated by MDCM.

  • 2 Estimation done at an initial concentration close to the Km value estimated by MDCM.

  • 3 Estimation done at an initial concentration greater than the Km value estimated by MDCM.