Fig. 1.

Fold increase in hepatic CYP3A4 abundance upon initiation and discontinuation of a rifampicin (600 mg once daily), b efavirenz (600 mg once daily), and c rifabutin (300 mg once daily). Fold increase in hepatic UGT1A1 abundance upon initiation and discontinuation of d rifampicin (600 mg once daily), e efavirenz (600 mg once daily), and f rifabutin (300 mg once daily). In all the figures, the solid line, the shaded area, and the dashed line represent the mean, the 90% normal range, and the 1.25-fold cut-off threshold above which the AUC ratio (i.e., in the presence vs. the absence of an inducer) is below 0.8. CYP cytochrome P450; UGT uridine diphosphate glucuronosyltransferase; AUC area under the concentration–time curve