Table 4

Inhibition of testosterone hydroxylation in rat and human liver microsomes by MOM and its metabolites

IC50 (μM)4-a
Rat liver microsomesHuman liver microsomes
2 α (CYP2C11)2 β (CYP3A2)6 β (CYP3A2)7 α (CYP2A1/2)16 α (CYP2C11)16 β (CYP2B1)6 β (CYP3A4/5)
Testosterone hydroxylation nmol/min/mg protein
 MOM−4-b −−−−−11.6
 Mb-2−−−−−>1000330
 Mb-6−−−−−−1107
 Mb-12−−−−−−320
Ketoconazole>100.42  ± 0.030.44 ± 0.04−>103.4 ± 0.90.038
Cimetidine1902 ± 196254 ± 34289 ± 52−1955 ± 2691688 ± 386260
Terfenadine40.3 ± 3.024.7 ± 2.828.7 ± 0.2106 ± 2143.6 ± 0.723.3 ± 1.19.1

Each value was expressed as the mean ± S.D. (rat;n = 3, human: duplicate).

  • ↵4-a The activity was measured at a final testosterone concentration of 100 μM.

  • ↵4-b −; no inhibition.