Inhibition of diclofenac metabolism in incubations with human liver microsomes or recombinant CYP3A42-a
| CYP Source | IgG | Quinidine | Diclofenac | 5-Hydroxydiclofenac |
|---|---|---|---|---|
| mg/nmol | μM | % control2-b | ||
| HLM2-c | 2.5 | 0 | 100 | 43 |
| HLM | 2.5 | 100 | 100 | 10 (31) |
| HLM | 10 | 0 | 100 | 22 |
| HLM | 10 | 100 | 100 | 6 (17) |
| CYP3A4 | 10 | 0 | 100 | 11 |
| CYP3A4 | 10 | 10 | 100 | 9 (26) |
| CYP3A4 | 40 | 0 | 100 | 7 |
| CYP3A4 | 40 | 10 | 100 | 6 (16) |
↵2-a Diclofenac and glutathione in phosphate buffer were added to human liver microsomes or recombinant CYP3A4+OR+b5 suspended in phosphate buffer (0.1 M, pH 7.4) containing EDTA. Microsomes were preincubated with anti-CYP IgG for 15 min at room temperature. Reactions were initiated by adding NADPH and proceeded for an additional 5 min. Incubations were performed in duplicate.
↵2-b Test incubations were compared with their respective controls containing preimmune IgG. For example, incubations containing IgG and 0 μM quinidine were compared with incubations containing preimmune IgG and 0 μM quinidine, whereas incubations containing IgG and 2.5 μM quinidine were compared with incubations containing preimmune IgG and 2.5 μM quinidine. % Control was therefore calculated. Numbers in parentheses, however, represent percentage of metabolite formed in incubations containing IgG and quinidine in comparison to controls containing preimmune IgG but no quinidine.
↵2-c HLM, human liver microsomes.