Suboptimal lopinavir exposure in infants on rifampicin treatment receiving double-dosed or semi-superboosted lopinavir/ritonavir: time for a change

BACKGROUND

While super-boosted lopinavir/ritonavir (LPV/r; ratio 4:4 instead of 4:1) is recommended for infants living with HIV and receiving concomitant rifampicin, in clinical practice many different LPV/r dosing strategies are applied due to poor availability of paediatric separate ritonavir formulations needed to super-boost. We evaluated LPV pharmacokinetics in infants with HIV receiving LPV/r dosed according to local guidelines in various sub-Saharan African countries with or without rifampicin-based tuberculosis (TB)-treatment.

METHODS

This was a 2-arm pharmacokinetic sub-study nested within the EMPIRICAL trial (#NCT03915366). Infants aged 1-12 months recruited into the main study were administered LPV/r according to local guidelines and drug availability either with or without rifampicin-based TB-treatment; during rifampicin co-treatment they received double-dosed (ratio 8:2) or semi-superboosted LPV/r (adding a ritonavir 100mg crushed tablet to the evening LPV/r dose). Six blood samples were taken over 12 hours after intake of LPV/r.

RESULTS

In total, 14/16 included infants had evaluable pharmacokinetic curves; 9/14 had rifampicin co-treatment (5 received double-dosed and 4 semi-superboosted LPV/r). The median (IQR) age was 6.4 months (5.4-9.8), weight 6.0kg (5.2-6.8) and 10/14 were male. Of those receiving rifampicin, 6/9 (67%) infants had LPV C trough <1.0mg/L compared to 1/5 (20%) in the control arm. LPV apparent oral clearance was 3.3-fold higher for infants receiving rifampicin.

CONCLUSION

Double-dosed or semi-superboosted LPV/r for infants aged 1-12 months receiving rifampicin resulted in substantial proportions of subtherapeutic LPV levels. There is an urgent need for data on alternative antiretroviral regimens in infants with HIV/TB co-infection, including twice-daily dolutegravir.