Low dose lopinavir/ritonavir tablet achieves adequate pharmacokinetic parameters in HIV-infected Thai adolescents

Pharmacokinetics of pediatric lopinavir/ritonavir tablets in children when administered twice daily according to FDA weight bands

BACKGROUND

Lopinavir/ritonavir (LPV/r) pediatric tablets (100/25 mg) are approved by the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) as part of combination antiretroviral therapy. Dosing is based on body weight bands or body surface area under FDA approval and only body surface area by the EMA. This can lead to a different recommended dose. In addition, weight band-based dosing has not been formally studied in the target population. We evaluated the pharmacokinetics (PK) of LPV/r in children, administered twice daily according to the FDA weight bands, using pediatric tablets.

METHODS

Fifty-three HIV-infected children were included in the PK substudy of the Paediatric European Network for the Treatment of AIDS 18 trial (KONCERT). In this study, children were randomized to receive LPV/r twice or once daily, according to FDA weight bands. A PK assessment was performed in 17, 16 and 20 children in the 15-25 kg, ≥ 25-35 kg and >35 kg weight band, respectively, while children took the tablets twice daily. Rich sampling was performed, and PK parameters were calculated by noncompartmental analysis. Given the high percentage of Asian children, it was also tested whether there was a difference in PK parameters between Asian and non-Asian children.

RESULTS

For the total group, LPV geometric mean AUC0-12, Cmax and C12 were 106.9 h × mg/L, 12.0 mg/L and 4.9 mg/L, respectively. There were no significant differences in LPV PK parameters between the weight bands. In addition, weight was not found to be associated with variability in Cmax, C12 or AUC0-12 for the LPV PK parameters.

CONCLUSIONS

FDA weight band-based dosing recommendations provide adequate exposure to LPV when using LPV/r pediatric tablets.

Once- versus twice-daily lopinavir/ritonavir tablets in virologically suppressed, HIV-infected, treatment-experienced children: comparative pharmacokinetics and virological outcome after switching to once-daily lopinavir/ritonavir

OBJECTIVES

Data on lopinavir/ritonavir tablets administered once daily in children are limited. We compared the pharmacokinetics (PK) of lopinavir/ritonavir twice daily versus once daily in virologically suppressed, HIV-infected children, and assessed the virological outcome, at 48 weeks, in children receiving the regimen of lopinavir/ritonavir once daily.

PATIENTS AND METHODS

HIV-infected children receiving a twice-daily lopinavir/ritonavir-based regimen and with an HIV-1 RNA viral load (VL) <40 copies/mL for at least 3 months were enrolled. Intensive steady-state 12 h blood sampling for PK assessment was performed at enrolment. Immediately afterwards, the lopinavir/ritonavir dose was changed to once daily with the equivalent daily dose, and intensive steady-state 24 h blood sampling was repeated 2 weeks later. If the lopinavir C(trough) was <1.0 μg/mL, the lopinavir/ritonavir dose was increased by 20%-30% and C(trough) measurement repeated. CD4 cell counts and VL were determined at baseline and at 12, 24 and 48 weeks.

RESULTS

Twelve children were enrolled. The median age was 13.1 years. Lopinavir AUC(0-24) following twice-daily and once-daily dosing was 169.7 (124.0-200.8) and 167.1 (95.1-228.1) μg · h/mL, respectively. Seven children, including all six concomitantly receiving efavirenz, had a C(trough) <1.0 μg/mL with once-daily lopinavir/ritonavir dosing, and four of seven children had a C(trough) <1.0 μg/mL after dose adjustment. All children maintained virological suppression throughout the 48 week period.

CONCLUSIONS

Lopinavir/ritonavir-based once-daily regimens could simplify therapy in children/adolescents with virological control, but a lower lopinavir C(trough) was evident. Further efficacy studies of lopinavir/ritonavir once daily in children are necessary before routinely recommending this dosing strategy.