Table 2

Summary of probe substrate metabolic reactions used in in vitro drug metabolism studies

P450Preferred Substrate ReactionKmRecommended Organic Solvent2-a
μM <1%, v/v
1A2PhenancetinO-deethylation10–50DMSO, methanol
2A6Coumarin 7-hydroxylation0.5–2DMSO, methanol
2B6 S-mephenytoinN-demethylation1900N.R.
2C9Tolbutamine 4′-hydroxylation100–200Acetonitrile
S-Warfarin 7′-hydroxylation1–5N.R.
2C19 S-mephenytoin 4′-hydroxylation31–340Acetonitrile, methanol
2D6Bufuralol 1′-hydroxylation4–10Acetonitrile
DextromethorphanO-demethylation2–10DMSO, acetonitrile, methanol
2E1Chlorzoxazone 6-hydroxylation40Acetonitrile
3A4/5Testosterone 6β-hydroxylation50–100Acetonitrile, methanol
Midazolam 1′-hydroxylation3–5N.R.
  • N.R., not reported.

  • 2-a  Effect less than 20% is deemed acceptable. Recommendation is based on at least two consistent experimental results available in the studies by Draper et al., (1997), Chauret et al., (1998), Hickman et al., (1998), Busby et al., (1999), orTang et al., (2000), with the exception of bufuralol 1′-hydroxylation in incubation with acetonitrile, which is only reported by Busby et al. (1999) in cDNA-expressed enzymes.