Inhibition of bufuralol 1′-hydroxylation by classic antihistamines (means ± 95% confidence intervals)
| Antihistamine | Vmax | KM | Ki | ||
|---|---|---|---|---|---|
| Competitive | Noncompetitive | Mixed | |||
| pmol/pmol CYP2D6/min | μM | μM | |||
| None (control) | 2.51 ± 0.25 | 10.0 ± 3.3 | |||
| Diphenhydramine | 1.75 ± 0.18 | 18.6 ± 5.2 | 11.7 ± 2.81-a | 49.8 ± 13.1 | 30.4 ± 6.6 |
| Chlorpheniramine | 1.84 ± 0.10 | 37.8 ± 4.7 | 5.4 ± 0.4 | 25.6 ± 6.3 | 10.8 ± 1.41-b |
| Clemastine | 0.61 ± 0.03 | 32.8 ± 8.7 | 0.8 ± 0.1 | 4.8 ± 1.1 | 2.0 ± 0.31-b |
| Tripelennamine | 1.74 ± 0.34 | 54.5 ± 20.9 | 3.1 ± 0.4 | 15.8 ± 4.1 | 5.6 ± 0.81-b |
| Promethazine | 1.05 ± 0.10 | 37.1 ± 7.8 | 1.9 ± 0.2 | 8.5 ± 2.3 | 3.8 ± 0.71-b |
| Hydroxyzine | 1.01 ± 0.21 | 36.0 ± 7.4 | 1.6 ± 0.4 | 9.3 ± 2.2 | 3.9 ± 0.51-b |