Lower Ribavirin Plasma Concentrations in HCV/HIV-Coinfected Patients Than in HCV-Monoinfected Patients Despite Similar Dosage.

BACKGROUND: Hepatitis C virus (HCV)/HIV-coinfected patients respond worse to dual therapy with ribavirin (RBV)/peginterferon compared with HCV-monoinfected patients. Several trials found that lower RBV plasma concentrations are associated with impaired virological response rates. The aim of this study was to determine RBV plasma concentrations in a cohort of HCV-monoinfected and HCV/HIV-coinfected patients. Our hypothesis is that HCV/HIV-coinfected patients have lower RBV plasma concentrations, which may in part explain their inferior response to dual therapy. METHODS: A retrospective cohort study was performed in chronic HCV-monoinfected and HCV/HIV-coinfected patients who received peginterferon and weight-based RBV. Plasma RBV concentrations were determined at weeks 4 and 12 by a validated high-performance liquid chromatography assay. RBV concentrations were compared between monoinfected and coinfected patients. We calculated the proportion of patients with a subtherapeutic RBV plasma concentration defined as <2.0 mg/L. RESULTS: A total of 61 HCV-infected patients were included, of whom 21 (34%) were coinfected with HIV. Although there was no difference in the weight-based dose of RBV between monoinfected and coinfected patients, RBV exposure was significantly lower in HCV/HIV-coinfected patients than in HCV-monoinfected patients: the mean ± SD RBV plasma concentrations were 1.82 ± 0.63 mg/L versus 2.25 ± 0.80 mg/L (P = 0.04) at week 4 and 2.14 ± 0.65 mg/L versus 2.62 ± 0.81 mg/L (P = 0.05) at week 12, respectively. The percentage of patients with subtherapeutic plasma concentrations of RBV in coinfected patients versus monoinfected patients was 62% versus 46% (P = 0.240) at week 4 and 50% versus 16% (P = 0.01) at week 12 of treatment, respectively. CONCLUSIONS: HIV/HCV-coinfected patients yield significantly lower plasma concentrations of RBV than HCV-monoinfected patients. This puts them at an increased risk of not achieving sustained virological response.

The ARRIBA concept: adequate resorption of ribavirin.

BACKGROUND: Adequate ribavirin exposure is essential for optimal sustained virological response (SVR) rates in chronic HCV treatment. It has been proposed that the area under the concentration-time curve up to 4 h after intake of ribavirin (AUC0-4 h) of the first weight-based ribavirin dose should be ≥1.755 mg•h/l to guarantee the highest chance of SVR. Our ARRIBA concept comprises a test dose of ribavirin to select the optimal starting dose to achieve adequate exposure. This study aims to evaluate whether adequate exposure can be achieved after dose advice based on the AUC0-4 h of a single weight-based ribavirin test dose. METHODS: (Formerly) HCV-infected subjects received a single weight-based ribavirin test dose (<75 kg: 400 mg; ≥75 kg: 600 mg) and the AUC0-4 h was calculated. If ribavirin AUC0-4 h was ≥1.755 mg•h/l, subjects received the same dose 4 weeks later; if the AUC0-4 h was <1.755 mg•h/l, an adjusted dose was administered. The ribavirin AUC0-4 h was recorded again. The primary outcome was the proportion of subjects with an AUC0-4 h ≥1.755 mg•h/l after the second dose. RESULTS: A total of 26 subjects were included. The geometric mean (95% CI) ribavirin AUC0-4 h was 1.67 (1.44-1.92) mg•h/l with 9 subjects (35%) reaching the target AUC on day 1. Thus, on day 29, 17 subjects (65%) received an adjusted dose. The geometric mean (95% CI) AUC0-4 h increased to 1.90 (1.62-2.21) mg•h/l and then 16 subjects (62%) had an AUC0-4 h ≥1.755 mg•h/l, which is significantly higher than day 1 (P<0.05). CONCLUSIONS: Our ARRIBA concept of a ribavirin test dose, with dose adjustment if necessary, leads to an increased proportion of patients with an AUC≥1.755 mg•h/l compared to traditional weight-based ribavirin dosing.