Study had to be withdrawn because financial support was cancelled.

Prospective, longitudinal multi-center study performed in 15 participating substitution centers in Germany.

Aims:

- Primary objective: To compare the impact of the different substitution drugs (methadone, buprenorphine, and suboxone) on the neurocognitive, emotional, and quality-of-life-related tolerability in opioid dependent patients under HCV treatment.

- Secondary objective: To investigate if IFN therapy impairs efficacy (with respect to e.g. retention rates, concomitant drug use and in particular neurocognitive function) and tolerability of agonist maintenance treatment with methadone, buprenorphine, or suboxone

Inclusion Criteria:

• Opioid-dependent patients on current stable agonist maintenance therapy (for at least 6 months prior to study enrolment) with methadone, buprenorphine, or suboxone.
• Patients need to be infected with chronic hepatitis C and must have indication for therapy with peginterferon alfa and ribavirin.
• Patients with informed written consent with respect to a follow-up of psychiatric side effects and in particular neurocognitive performance.
• Patients with baseline monitoring of emotional state and neurocognitive performance.

Exclusion Criteria:

• According to SPC
• According to legal requirements reg. drug substitution therapy (BTMVV)
• Insufficient knowledge of the German language or cognitive impairment (due to the indispensable application of questionnaires and the TAP, Test Battery of Attentional Performance).
• Age under 18 years or over 65 years
• coinfections such as hepatitis B virus or human immunodeficiency virus

Outpatients with chronic hepatitis C infection and drug substitution therapy (methadone, burpenorphine, suboxone)