Inhibitor constants for phenylbutazone and quinine inhibition of 4-methylumbelliferone glucuronidation by human UGTs
UGT | Kia,b | ||
|---|---|---|---|
| Phenylbutazone | Quinine | ||
| μM | |||
| 1A1 | 272 ± 8.6 | 384 ± 6.8 | |
| 1A6 | N.F. | N.D. | |
| 1A7 | 3.9 ± 0.3 | 784 ± 3.5 | |
| 1A9 | 5.7 ± 0.2 | N.D. | |
| 1A10 | 12 ± 0.4 | 492 ± 31 | |
N.D., not determined due to low degree of inhibition (IC50 > 1 mM); N.F., data were not consistent with competitive, noncompetitive, or mixed inhibition models.
↵ a Noncompetitive inhibition, except for phenylbutazone inhibition of UGT1A1 (competitive inhibition) and quinine inhibition of UGT 1A1 and 1A10 (competitive inhibition).
↵ b Values are Ki ± standard error of parameter fit.