Table 4

Inhibition of human liver microsomal oxazaphosphorine activation by P-450 form-specific inhibitors

HLS#Drug SubstrateActivity 4-a % Inhibition 4-b
TAO (30 μM)MAB-2B6 (50 μg/100 μg)Sulfaphenazole (20 μM)
2CPA2.62<1052  ± 4<10
IFA0.8240  ± 513  ± 513  ± 3
9CPA1.8520  ± 345  ± 3<10
IFA0.9075  ± 40<10
36CPA1.53<1033  ± 717  ± 6
IFA0.5865  ± 4027  ± 3
  • 4-a Data are in units of nmol 4-hydroxy CPA (or IFA)/min/mg protein assayed at 2 mM drug substrate in the absence of inhibitor.

  • 4-b Data are expressed as mean ± 1/2 range of duplicate determinations.