This means that only one quarter of patients given this regimen have long-term remission or cure. Attempts to improve the sustained response rate have included increasing the dosage, the dose frequency, and the duration of treatment. Increased duration of therapy significantly increases the sustained response rate, but the long-term results of increased dosage and dose frequency have been disappointing. Other agents have been used for the treatment of hepatitis C infection, although none as successfully as interferon a . Amantadine and rimantadine are both oral drugs that are used to treat influenza A. Trials using these drugs have had some success in producing sustained responses in patients infected with hepatitis C virus.
Ribavirin is an oral drug that has been effective against a range of viruses.
The limited efficacy of using one drug alone led to studies assessing combination therapies. Multiple agents given simultaneously may block viral replication by acting at different target sites. Combinations of 2 and 3 different drugs have been studied. The most commonly used involves standard interferon a plus ribavirin. Triple therapy using interferon a , ribavirin, and amantadine was recently studied in a small pilot study.