Lopinavir/Ritonavir Pharmacokinetic Profile: Impact of Sex and Other Covariates Following a Change From Twice-Daily to Once-Daily Therapy

The aim of this study was to determine the impact of sex on the pharmacokinetics of lopinavir/ritonavir. Interaction between lopinavir/ritonavir and tenofovir was also evaluated. Steady‐state plasma samples were obtained from virologically suppressed HIV‐infected patients on lopinavir/ritonavir 800/200‐mg soft gel capsule taken once daily. Drug assays were performed by high‐performance liquid chromatography. Pharmacokinetic parameters estimated by noncompartmental method were reported as 90% confidence intervals (CIs) about the geometric mean ratio (GMR). There were 9 males and 11 females. No sex differences were observed in lopinavir/ritonavir pharmacokinetics profile. The GMRsex (women compared with men) for lopinavir area under the concentration‐time curve (AUC24), maximum concentration (Cmax), and minimum concentration (Cmin) was 0.95 (90% CI, 0.70–1.29), 0.88 (90% CI, 0.67–1.15), and 1.27 (90% CI, 0.60–2.66), respectively. Similarly, the GMRsex for ritonavir AUC24, Cmax, and Cmin was 0.84 (90% CI, 0.57–1.24), 0.79 (90% CI, 0.50–1.22), and 1.02 (90% CI, 0.58–1.80), respectively. Tenofovir coadministration led to a reduction in lopinavir/ritonavir plasma exposure, giving a lopinavir GMRtenofovir for Cmax of 0.72 (90% CI, 0.57–0.93) and AUC24 of 0.74 (90% CI, 0.56–0.98), respectively. No difference in lopinavir/ritonavir plasma concentrations between sexes was demonstrated in this study. However, tenofovir coadministration lowered lopinavir/ritonavir plasma exposure.