High rates of sustained virological response in hepatitis C virus-infected injection drug users receiving directly observed therapy with peginterferon alpha-2a (40KD) (PEGASYS) and once-daily ribavirin.

This retrospective study evaluated the efficacy and tolerability of directly observed therapy with peginterferon alfa-2a and once-daily ribavirin (RBV) for chronic hepatitis C in 49 opioid-addicted injection drug users (IDUs) participating in a drug treatment program at a specialized outpatient center. Patients also received prophylactic citalopram to minimize the risk of interferon-induced depression. Patients had daily access to and support from specialist physicians, nurses and counseling services at the center, and a 24-hour helpline. Sustained virological response was achieved by 48 of 49 patients (98%) overall, including 20 of 21 (95%) hepatitis C virus (HCV) Genotype 1/4-infected patients and 28 of 28 (100%) Genotype 2/3-infected patients. Treatment was well tolerated, and no unexpected side effects of peginterferon treatment were seen. The safety profile of once-daily RBV was not different from twice-daily dosing. Decline in hemoglobin levels was similar to those reported in clinical trials including once-daily RBV and did not lead to dose reduction or treatment withdrawal. Our data demonstrate that HCV-infected IDUs on stable L-polamidone (methadone) or buprenorphine maintenance can be successfully and safely treated with peginterferon alfa-2a and RBV in an optimal substitution setting.