Effect of age on lopinavir concentrations
Polly Clayden, HIV i-Base
Advancing age and its effect on CYP3A4 and in turn lopinavir concentrations was also the subject of a poster from Teresa Parsons and colleagues. 
This study examined the effects of age on the pharmacokinetics of lopinavir by comparing patients enrolled in the ACTG 5010 in two age groups, Group A: 18 to 30 years (median 26 years) and Group B: 45 years and above (median 50 years), n=22 in each group. Plasma concentrations were measured 10 to 14 hours post dose.
The authors reported marginally higher overall trough concentrations in Group B at 24, 36 and 96 weeks (p=0.056). At week 24 this correlation between age and plasma concentration was highly significant (p=0.002) but this did not persist. In multivariate analysis only age (p=0.0047) correlated with lopinavir concentrations. Hours since last dose, week of blood draw and gender, were not significantly correlated.
The authors noted: Although there was significant overlap in concentrations of young and old subjects, most of the high outliers were in the old age group; the highest recorded lopinavir was taken from the oldest subject who was 79. They also explained that the clinical significance of these findings are unclear, as toxicity was infrequent and did not seem to relate to age in this study.
Parsons T, Spritzler J, Stocker V, et al. The effect of age on lopinavir concentrations. 6th International Workshop on Clinical Pharmacology of HIV Therapy. 28-30 April 2005. Quebec. Abstract 40.