Increased bilirubin levels when atazanavir is dosed twice-daily

The changes in total, conjugated and unconjugated bilirubin were studied in 10 HIV+ subjects who switched from atazanavir 400 mg once daily to atazanavir 200 mg twice daily.

Total bilirubin at Ctrough and AUC24 were slightly increased after switch (31% and 15%, respectively), while maximum total bilirubin was unchanged.  Similar increases were observed for unconjugated bilirubin at Ctrough and AUC24, while maximum unconjugated bilirubin was unchanged.

The increases in bilirubin levels related to the switch from once to twice daily dosing were not clinically significant and the data suggest that the increase in unconjugated bilirubin associated with atazanavir  administration is rapidly reversible.

Ref: Gonzalez de Requena D et al. Bilirubin levels in HIV+ patients switching from atazanavir (ATV) 400 mg QD to ATV 200 mg BID. 11th PK Workshop, 2010. Abstract 42.

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