Table 5.
In vitro inhibition of CYP activities by sildenafil. The values are mean ± s.d. of triplicate determinations in microsomes prepared from a pool of four human livers.
Isozyme | Activity measured | IC50 (µm) |
---|---|---|
CYP1A2 | Phenacetin O-deethylase | > 300 |
CYP2C9 | Phenytoin 4-hydroxylase | 150 ± 23 |
CYP2C19 | (S)-mephenytoin 4-hydroxylase | > 300 |
CYP2D6 | Bufuralol 1′-hydroxylase | > 300 |
CYP2E1 | Chlorzoxazone 6-hydroxylase | > 300 |
CYP3A4 | Felodipine oxidase | > 300 |
Testosterone 6β-hydroxylase | > 300 | |
Terfenadine hydroxylase | 105 ± 7 |