Fig. 5.

In vitro to in vivo prediction of P450 induction using in vitro mRNA expression (A) or enzymatic activity (B). The GMR and 90% CI of the observed in vivo induction of CYP1A2, CYP2B6, and CYP2C9 are shown in gray bars and error bars, respectively. Prediction of the in vivo P450 induction without using RIF in vitro to in vivo scaling (○) generally resulted in minimal to no predicted in vivo induction. In contrast, incorporating the RIF in vitro to in vivo induction scaling factor (●) generally resulted in predicted in vivo P450 induction within the 90% CI of that observed. The RIF scaling factors vary across enzymes and whether mRNA expression or enzymatic activity is used for scaling (C).