TABLE 1.
Km values and concentrations of P450-specific probe substrates, and the MS/MS selected reaction monitoring (SRM) transitions and collision energies (CEs) for substrate metabolites and stable isotope-labeled internal standards used in the cocktail assays
| Enzyme | Substrate | Km | Concentration | Metabolite | SRM Transition (Polarity) | CE | Internal Standard | SRM Transition (Polarity) | CE |
|---|---|---|---|---|---|---|---|---|---|
| µM | µM | V | V | ||||||
| CYP1A2 | Phenacetin | 112.7 ± 10.9 | 100 | Acetaminophen | 152.2 > 110.0 (+) | −17 | [d4]-Acetaminophen | 156.2 > 114.1 (+) | −19 |
| CYP2A6 | Coumarin | 1.5 ± 0.2 | 1.5 | 7-Hydroxycoumarin | 161.1 > 133.1 (−) | 23 | [d5]-7-Hydroxycoumarin | 166.1 > 138.1 (−) | 22 |
| CYP2B6 | Bupropion | 125.2 ± 14.0 | 12 | Hydroxybupropion | 256.2 > 139.1 (+) | −26 | [d6]-Hydroxybupropion | 262.2 > 139.0 (+) | −26 |
| CYP2C8 | Amodiaquine | 1.0 ± 0.1 | 1 | N-desethylamodiaquine | 328.1 > 283.0 (+) | −21 | [d5]-N-desethylamodiaquine | 333.1 > 283.1 (+) | −29 |
| CYP2C9 | Tolbutamide | 110.7 ± 11.6 | 100 | Hydroxytolbutamide | 285.1 > 186.0 (−) | 18 | [d9]-Hydroxytolbutamide | 294.2 > 186.0 (−) | 18 |
| CYP2C19 | (S)-mephenytoin | 52.5 ± 10.6 | 50 | (±)-4′-Hydroxymephenytoin | 235.1 > 133.1 (+) | −18 | [d3]-(±)-4′-Hydroxymephenytoin | 238.1 > 133.1 (+) | −22 |
| CYP2D6 | Dextromethorphan | 2.9 ± 0.5 | 2.5 | Dextrorphan | 258.1 > 157.0 (+) | −37 | [d3]-Dextrorphan | 261.2 > 157.1 (+) | −40 |
| CYP2E1 | Chlorzoxazone | 149.8 ± 12.6 | 15 | 6-Hydroxychlorzoxazone | 184.0 > 120.0 (−) | 18 | [d2]-6-Hydroxychlorzoxazone | 186.2 > 122.0 (−) | 18 |
| CYP3A4/5 | Midazolam | 2.7 ± 0.1 | 2.5 | 1′-Hydroxymidazolam | 342.1 > 324.0 (+) | −21 | [13C3]-1′-hydroxymidazolam | 347.2 > 329.0 (+) | −22 |
| Testosterone | 50.5 ± 5.6 | 50 | 6β-Hydroxytestosterone | 305.2 > 269.2 (+) | −18 | [d7]-6β-Hydroxytestosterone | 312.2 > 276.2 (+) | −16 |