Safety and exposure of once-daily ritonavir-boosted atazanavir in HIV-infected pregnant women

Objective There are limited antiretroviral options for use in the treatment of HIV infection during pregnancy. The purpose of this study was to assess the safety, efficacy and appropriate dosing regimen for ritonavir (RTV)-boosted atazanavir in HIV-1-infected pregnant women. Methods In this nonrandomized, open-label study, HIV-infected pregnant women were dosed with either 300/100mg (n = 20) or 400/100 mg (n = 21) atazanavir/RTV once-daily (qd) in combination with zidovudine (300 mg) and lamivudine (150 mg) twice daily in the third trimester. Pharmacokinetic parameters [maximum observed plasma concentration (C(max)), trough observed plasma concentration 24 hour post dose (C(min)) and area under concentration-time curve in one dosing interval (AUC(tau))] were determined and compared with historical values (300/100 mg atazanavir/RTV) for HIV-infected nonpregnant adults (n = 23). Results At or before delivery, all mothers achieved HIV RNA <50 HIV-1 RNA copies/mL and all infants were HIV DNA negative at 6 months of age. The third trimester AUC(tau) for atazanavir/RTV 300/100mg was 21% lower than historical data, but the C(min) values were comparable. The C(min) value for atazanavir/RTV 400/100mg was 39% higher than the C(min) for atazanavir/RTV 300/100mg in historical controls, but the AUC(tau) values were comparable. Twice as many patients in the 400/100mg group (62%) had an increase in total bilirubin (>2.5 times the upper limit of normal) as in the 300/100mg group (30%). Atazanavir (ATV) was well tolerated with no unanticipated adverse events. Conclusions In this study, use of atazanavir/RTV 300/100 mg qd produced C(min) comparable to historical data in nonpregnant HIV-infected adults. When used in combination with zidovudine/lamivudine, it suppressed HIV RNA in all mothers and prevented mother-to-child transmission of HIV-1 infection. During pregnancy, the pharmacokinetics, safety and efficacy demonstrated that a dose adjustment is not required for ATV.