Background:  Transient elastometry (Fibroscan) is a reproducible method allowing evaluation of liver fibrosis by measurement of liver stiffness. The aim of this study was to evaluate ART pharmacokinetics in HIV patients with chronic hepatitis C virus (HCV) and to determine a relationship between ART concentrations and liver fibrosis.

Methods:  A total of 113 HCV/HIV-co-infected patients receiving HAART containing boosted protease inhibitor (PI) or non-nucleoside reverse transcriptase inhibitors (NNRTI) were included in the study. A liver stiffness cut-off defined 2 groups, over or under 12 kPa. Boosted PI plasma concentrations (C_min and C_max), such as lopinavir (n = 52), atazanavir (n = 37), and fosamprenavir (n = 9), and NNRTI, such as efavirenz (EFV) (n = 19) and nevirapine (NVP) (n = 6), were compared in these 2 groups by using a Mann Whitney test with p <0.05. In case of difference, a relationship between ART concentrations and liver stiffness was determined by using a Spearmann test.

Results:  Considered to have a cirrhosis were 42 patients (37%) whose liver stiffness exceeded 12 kPa. There was no statistical difference for C_min and C_max between the 2 groups for all boosted PI. The average of observed concentrations did not differ from HIV-infected patients without HCV infection. There was a difference for NNRTI C12h : 2.87±1.75 vs 7.27±2.41 mg/L (p = 0.017) and 3.64±2.05 vs 7.10±0.71 mg/L (p = 0.008), respectively, for EFV and NVP and for <12 kPa and >12 kPa. A relationship between NNRTI’s C12h and liver stiffness was found r = 0.464 and 0.763 for EFV and NVP, respectively.

Conclusions:  These preliminary findings suggest that only NNRTI’s C12h may be elevated in HCV/HIV-co-infected patients and correlated with liver stiffness. Further investigations will be necessary to confirm these results. Therapeutic drug monitoring will be helpful to identify co-infected patients at risk for toxicity.