Methadone and buprenorphine are medications to prevent withdrawal from, and treat dependence on, narcotics. Hepatitis C is very common among people on opioid substitution treatment (OST) with methadone or buprenorphine.

OST increases adherence to HIV treatment by stabilizing people; the same is true for hepatitis C treatment. HCV has been safely treated—and cured—in people on buprenorphine and methadone. In fact, methadone clinics are an ideal place for HCV support groups and directly observed, multidisciplinary hepatitis C treatment programs, since people must show up regularly to get their methadone.

People on OST should be carefully monitored during hepatitis C treatment. Methadone dosing may need to be adjusted, even in the absence of a known or suspected drug-drug interaction. This is because some people experience similar side effects from pegylated interferon and drug withdrawal; increasing the dose of methadone has helped manage these side effects.

Drug-drug interactions between HCV protease inhibitors and methadone or buprenorphine may complicate hepatitis C treatment.