Kinetic analysis of biotransformation of citalopram and desmethycitalopram enantiomers by heterologously expressed human cytochromes
| Transformation Reaction | Cytochromes | ||
|---|---|---|---|
| CYP2C19 | CYP2D6 | CYP3A4 | |
| R-CT to DCT | |||
| V max | 1.65 (±0.09) | 2.18 (±0.11) | 2.15 (±0.21) |
| K m | 77 (±15) | 47 (±8) | 454 (±103) |
| V max/K m | 2.13 | 4.63 | 0.47 |
| Abundance-adjusted relative V max/K m | 32.9% | 20.7% | 46.3% |
| S-CT to DCT | |||
| V max | 2.52 (±0.08) | 2.73 (±0.17) | 3.19 (±0.22) |
| K m | 69 (±6) | 29 (±7) | 588 (±86) |
| V max/K m | 3.63 | 9.54 | 0.54 |
| Abundance-adjusted relative V max/K m | 36.9% | 28.1% | 34.9% |
| R-DCT to DDCT | |||
| V max | 0.62 (±0.02) | ||
| K m | 12.4 (±1.8) | ||
| V max/K m | 5.04 | ||
| S-DCT to DDCT | |||
| V max | 0.58 (±0.02) | ||
| K m | 16.8 (±2.2) | ||
| V max/K m | 3.44 | ||
Units are: Vmax, picomoles per minute per picomole of P450; Km, micromolar concentration;Vmax/Km, nanoliters per minute per picomole of P450; RelativeVmax/Km, percentage of total. Table entries are parameter estimates with asymtotic standard errors in parenthesis.