Objectives: To determine the relationship between erythrocyte and plasma ribavirin concentrations in hepatitis C virus (HCV)/HIV-coinfected patients, and to correlate ribavirin exposure with early and sustained virological response (EVR and SVR) and haemoglobin level reductions.
Methods: Clinical and biological data from 68 HCV/HIV-coinfected patients were recorded at baseline, week 4 (W4), week 12 and at 24 weeks after completion of treatment. Plasma and erythrocyte ribavirin concentrations were determined 12 h after the final ribavirin dose (C(min)).
Results: Erythrocyte ribavirin concentrations were 100-fold higher than plasma concentrations, with a significant relationship between them (P < 0.05). In patients with HCV genotype 1 or 4, a plasma ribavirin C(min) threshold of 1.95 mg/L at W4 tended to predict EVR [sensitivity 44%; specificity 87%; AUC 0.67 (95% CI 0.50-0.84)] and was predictive of SVR [sensitivity 58%; specificity 84%; AUC 0.71 (95% CI 0.51-0.90)]. Among patients with these HCV genotypes, an erythrocyte ribavirin C(min) threshold of 146 mg/L at W4 was found to be the best value for discriminating between responders and non-responders for both EVR [sensitivity 67%; specificity 75%; AUC 0.58 (95% CI 0.24-0.93)] and SVR [sensitivity 50%; specificity 80%; AUC 0.70 (95% CI 0.39-1.01)]. We also demonstrated a significant relationship between reduced haemoglobin levels and plasma ribavirin C(min) at W4 (P = 0.05).
Conclusions: Therapeutic drug monitoring may be useful for the management of anti-HCV treatment in HCV/HIV-coinfected patients.