Once-daily lopinavir/ritonavir for children may offer advantages

A once-daily dosing schedule for HIV-positive children may offer an advantage to families and healthcare workers in terms of convenience and adherence. The currently approved paediatric dose of lopinavir/ritonavir (LPV/r, Kaletra) is 230/57.5 mg/m2 taken twice daily with food. Gwenda Verweel and colleagues evaluated the pharmacokinetics, tolerability, and efficacy of once-daily dosing of LPV/r in children.

In this study children on stable treatment with a viral load < 50 copies/mL for at least 6 months received LPV/r 460/115 mg/m2 once daily with AZT and 3TC. LPV/r was taken with food in the morning. Intensive pharmacokinetic studies were performed after observed drug intake during steady state at two weeks. Target for Cmin was 1.0mg/L. After this period the time of dosing could be changed to the evening meal.

Single sample plasma levels were collected at day 28 and months 2, 3, and 6. Clinical assessment included plasma RNA levels, lymphocyte counts, biochemistry, haematology, and side effects monitoring.

Six-month follow up results were available for 14 children (7 boys and 7 girls) with a median age of 4.5 (range 3.3 to 9.5) years. The dose of LPV/r 460/115 mg/m2 once daily, resulted in comparable LPV plasma levels to those in adults after an 800/200 mg once-daily regimen.

The authors report that: 3/14 children had a C trough that was considered to be too low (< 1.0 mg/L) and a dose increase was necessary; 11 children took LPV/r with their evening meal; and 44% (17 of 39) of the LPV/r plasma levels were higher than their corresponding values on day 14. 2/3 children taking LPV/r with breakfast had lower plasma levels than those on day 14.

All 14 children had viral load < 50 copies/mL after 6 months of treatment. CD4 cell counts did not change significantly during the study.

This once-daily regimen of LPV/r was generally well tolerated. Of the 14 children, 6 experienced mild gastrointestinal side effects but all were resolved after 2 months. Cholesterol and triglyceride levels were stable during 6 months of follow-up.

The authors concluded that LPV/r 460/115 mg/m2 once daily led to LPV plasma levels comparable to adult data. In 3 of 14 children dose increase to 600mg/m2 or 798mg/m2 was necessary because of low Cmin (24hr). Intake with a large meal (like dinner) is important to obtain adequate plasma levels when LPV/r is dosed once daily in children. They also noted that because of interpatient variability in plasma levels, TDM might be useful to guide the correct dose for children.