Abstract
Background
Lopinavir/ritonavir (LPV/r) is an effective and commonly used protease inhibitor in HIV-infected adolescents. Previous data showed high plasma concentrations of LPV in Thai patients. This study determined the phar-macokinetic (PK) parameters of a low-dose LPV/r tablet (70% of standard dose) in HIV-infected Thai adolescents.
Methods
A total of 24 adolescents on LPV/r- containing HAART regimens with HIV RNA<50 copies/ml were included. Standard and low doses for two different weight bands using LPV/r 100/25 mg tablet formulation twice daily were prescribed as follows: 3 and 2 tablets for adolescents weighing 25–35 kg, and 4 and 3 tablets for those weighing >35 kg, respectively. On the fourth week of treatment, PK was performed for all doses at 0 (pre-dose), 2, 4, 6, 8, 10 and 12 h. LPV and ritonavir concentrations were measured using the HPLC method.
Results
The median (IQR) age was 13.5 (12–15) years. The median LPV doses of standard and low doses were 290 and 208 mg/m2. The mean (sd) area under the concentration– time curve at 0–12 h, maximum concentration and plasma concentration at 12 h for the standard dose were 97.6 (25.7) mg•h/l, 11.1 (2.6) mg/l and 4.1 (2.0) mg/l, and for the low dose were 87.4 (29.0) mg•h/l, 11.0 (3.1) mg/l and 3.2 (1.9) mg/l, respectively. No significant differences were detected between the groups. One child had plasma concentration at 12 h <1.0 mg/l while on low-dose LPV/r but HIV RNA was undetectable.
Conclusions
The low-dose LPV/r tablet provides adequate PK parameters in HIV-infected Thai adolescents. A randomized study to assess the efficacy of low and standard doses of LPV/r among Thai HIV-infected adolescents should be explored.