PHARMACOKINETIC EXPOSURE AND VIROLOGIC RESPONSE IN HIV-1 INFECTED PREGNANT WOMEN TREATED WITH LOPINAVIR/RITONAVIR: AIDS CLINICAL TRIALS GROUP PROTOCOL A5153S: A SUBSTUDY TO A5150.

Objective: We studied the pharmacokinetics and pharmacodynamics of boosted soft-gel lopinavir/ritonavir to assess if the area under the plasma concentration versus time curve (AUC) is altered in pregnancy and whether changes in AUC impacted HIV-1 control.

Methods: We enrolled pregnant women ≥13 years of age between 22 to 30 weeks gestation who expected to be on stable lopinavir/ritonavir for ≥8 weeks pre-delivery and ≥24 weeks post-delivery. Pharmacokinetic evaluations for lopinavir and ritonavir occurred at 36 weeks gestation and 6 and 24 weeks postpartum.

Results: Ten women underwent intensive pharmacokinetic evaluations for lopinavir and ritonavir at 36 weeks gestation and at 6 and 24 weeks postpartum. Estimated geometric mean (GM) AUC 0-6h (95% CI) for lopinavir were not significantly different at 26.5 (17.0, 41.4) and 41.9 (26.1, 67.5) mcg*hr/mL at 36 weeks gestation and 6 weeks postpartum, respectively (within-subject GM ratio 0.60 (0.25, 1.43); p=0.19). At 36 weeks gestation, 5 of 10 women had viral load <50 copies/mL and at 6 weeks postpartum 5 of 9 had viral load <50 copies/mL. Nine of ten infants for whom data were available were HIV negative.

Conclusion: Despite below target lopinavir levels (< 52 mcg*hr/mL except at 2 postpartum measurements), women maintained virologic control postpartum. Higher doses of lopinavir/ritonavir during pregnancy may not be necessary in all women.