Lopinavir/ritonavir Once Daily May Be a Suitable Regimen for Antiretroviral-naive Children

Lopinavir/ritonavir (Kaletra) is approved for treatment of HIV-infected children at a dosage regimen of 230/57.5 mg/m(2) twice daily. However, once daily administration could increase convenience and patient adherence.

In the current study, Italian researchers aimed to evaluate whether inhibitory concentrations are maintained in plasma following administration of lopinavir/ritonavir once daily.

Lopinavir/ritonavir was administered at the standard twice daily regimen to 21 HIV-infected children, as a component of their antiretroviral treatment. Following at least 1 month of administration, seven patients received a dose of 460/115 mg/m(2) once daily for three consecutive days.

After the third dose of once daily administration, blood samples were drawn at the following times: 0 (pre-dose), 1, 2 and 4 h following administration. The pre-dose (Cmin) and the peak (Cmax) concentrations were compared with the values obtained following twice daily administration in all the study patients.

Results

Median (interquartile range) Cmin with the once daily regimen was 1.59 (0.77-6.85) mg/L versus 7.90 (5.45-9.77) mg/L with the twice daily regimen (P < 0.05).

Cmin was considered inhibitory for wild-type virus (>1.0 mg/L) in four out of seven patients.

Cmax did not differ significantly between the once daily and twice daily regimens.

In conclusion, the authors write, “Our small pilot study suggests that lopinavir/ritonavir once daily may be a suitable regimen for antiretroviral-naive children. However, due to the high inter-individual variability and low concentrations in some patients, therapeutic drug monitoring may be necessary to ensure that concentrations are adequate to inhibit viral replication.”

“A formal clinical study of lopinavir/ritonavir once daily in treatment-naive children is warranted.”

Department of Infectious Diseases, San Martino Hospital and University of Genoa, Genoa, Italy.

04/18/06

Reference
R Rosso, A Di Biago, C Dentone, and others.Lopinavir/ritonavir exposure in treatment-naive HIV-infected children following twice or once daily administration. The Journal of Antimicrobial Chemotherapy [Epub ahead of print: April 10, 2006].