TABLE 3

Parameters describing the in vitro induction of CYP1A2, CYP2B6, and CYP2C9 mRNA expression and activity in plated human hepatocytes by rifampin, ritonavir, or nelfinavir

Estimated value (percentage of coefficient of variation of the estimate) in four pooled hepatocyte lots.

P450ParameterRifampinRitonavirNelfinavir
mRNAActivitymRNAActivitymRNAActivity
CYP1A2Emax0.160 ± 0.034*1.7 (36)0.145 ± 0.032*1.1 (22)0.134 ± 0.034*1.6 (30)
EC50 (μM)5.4 (107)1.3 (111)5.4 (90)
CYP2B6Emax10.9 (43)9.4 (31)7.0 (16)3.7 (29)4.3 (45)3.0 (33)
EC50 (μM)11.1 (94)22.6 (55)8.0 (41)5.5 (87)11.0 (102)7.9 (84)
CYP2C9Emax0.165 ± 0.015*3.0 (34)2.9 (52)1.4 (35)2.0 (28)2.8 (43)
EC50 (μM)2.7 (133)7.5 (135)1.9 (157)1.0 (153)6.4 (119)
  • * Estimates of EC50 were above the highest tested concentration (25 μM); therefore, the slope of the line with intercept forced to 0 was used for extrapolation purposes. Reported value is mean slope ± S.D.