Table 2

Effects of phenytoin administration on the oxidation activities of phenytoin and its primary metabolites in rat liver microsomes

SubstrateμMMetaboliteUntreatedPhenytoin-Treated
pmol/min/mg protein
Phenytoin1004′-HPPH95  ± 456  ± 62-160
3′-HPPH1.0  ± 0.13.3  ± 0.62-160
3′,4′-diHPPH11  ± 36  ± 12-160
3′,4′-dihydrodiol<0.1<0.1
4′-HPPH13′,4′-diHPPH10  ± 39  ± 1
1003′,4′-diHPPH375  ± 68353  ± 54
3′-HPPH13′,4′-diHPPH16  ± 312  ± 2
1003′,4′-diHPPH992  ± 158704  ± 189

Data are mean ± S.D. for four male rats treated with oral administration of phenytoin (300 mg/kg/day) for 20 days.

  • 2-160  Significantly different from untreated male rats (p < 0.01).