Table 4 Pharmacokinetic indices for plasma drug binding at eight and 12 hours after methadone dosing

Methadone

C_{free, 8 h} (ng/mL)

1.40

1.43

1.36

3.18

C_{bound, 8 h} (ng/mL)

8.45

8.22

8.72

78.0

C_{free, 12 h} (ng/mL)

1.18

1.10

1.38

2.61

C_{bound, 12 h} (ng/mL)

6.86

6.74

7.40

58.8

Mean f _u

0.14

0.14

0.15

0.04

f _u ratio (A/B or C/D)

1.0

3.7

V_{d (extrap)} ratio

0.93

4.2

V_{d (area)} ratio

0.91

5.9

EDDP

C_{free, 8 h} (ng/mL)

0.38

0.39

0.35

0.75

C_{bound, 8 h} (ng/mL)

0.72

0.75

0.61

6.56

C_{free, 12 h} (ng/mL)

0.36

0.36

0.38

0.77

C_{bound, 12 h} (ng/mL)

0.71

0.66

0.69

7.37

Mean f _u

0.34

0.35

0.36

0.10

f _u ratio (A/B or C/D)

1.0

3.6