Influence of quinidine on diclofenac metabolism in the presence or absence of cytochrome b54-a
| CYP | b5 | Quinidine | 5-Hydroxydiclofenac |
|---|---|---|---|
| nmol | μM | % control4-b | |
| 3A4+OR | 0 | 0 | 100 |
| 3A4+OR | 0 | 100 | 900 |
| 3A4+OR | 0.1 | 0 | 100 |
| 3A4+OR | 0.1 | 100 | 1100 |
| 3A4+OR+b 5 | 0 | 100 | |
| 3A4+OR+b 5 | 100 | 490 |
↵4-a Diclofenac and glutathione in phosphate buffer (pH 7.4) and quinidine in methanol were added to recombinant CYP3A4+OR or CYP3A4+OR+b5 suspended in phosphate buffer (0.1 M, pH 7.4) containing EDTA. Cytochromeb5 was added. Controls contained no quinidine but the same amount of methanol. Incubations were performed in duplicate.
↵4-b % Control was based on the formation of 5-hydroxydiclofenac in test incubations relative to the values in control experiments that lacked quinidine.