Objective: To determine whether an association existed between lopinavir (LPV) plasma concentrations and changes in body fat composition.
Design: A prospective, non-randomized study.
Setting: HIV clinic of a University Hospital.
Subjects, participants: HIV-infected subjects who had virological failure on protease inhibitor-containing regimens. Twenty-two consecutive patients were enrolled, 19 completed 24 weeks of treatment and 16 completed the full 48-week study period.
Intervention: Patients were treated with LPV/ritonavir (LPV/r) in combination with other antiretroviral agents. LPV trough plasma concentrations were measured at baseline and weeks 4, 8, 12, 24, 36 and 48. Body fat composition was quantified by computerized tomographic scanning at baseline, and weeks 24 and 48.
Results: LPV trough concentrations correlated with absolute and proportional changes in limb fat from baseline to week 48. Significant differences were found in mean LPV trough concentrations between patients losing less than 5% of limb fat, those experiencing a limb fat loss between 5 and 20%, and those losing more than 20% at week 24 [mean (SD), 4.67 (1.67); 8.57 (1.77); 9.49 (2.67) microg/ml, respectively; P=0.013] and week 48 [mean (SD), 4.5 (2.24); 7.04 (1.77); 9.7 (2.8) microg/ml, respectively; P=0.027]. Most patients losing more than 5% of limb fat during LPV/r therapy had mean LPV trough concentrations > or = 8 microg/ml.
Conclusions: In patients receiving salvage therapy with LPV/r there was an association between LPV plasma trough concentrations and limb fat loss. The risk of peripheral limb fat loss may be greater among patients achieving higher LPV trough concentrations.