New Antiviral Agents and New Treatments on the Horizon for the Management of Viral Hepatitis

Transfusion dependant patients are at risk of acquiring transfusiontransmitted viral infections including Hepatitis B virus (HBV) and Hepatitis C (HCV). These infections can lead to cirrhosis and hepatic cancer. Standard treatment, although with improved therapeutic results still exhibits resistance and relapses. New antiviral agents have been developed to further improve results and reduce adverse events. For hepatitis B, along with pegylated interferon α-2α, other drugs that have been approved include lamivudine, adefovir, entecavir, telbivudine and tenofovir, while emtricitabine and clevudine are awaiting FDA approval. Possible combination drug therapy may improve efficacy without engendering resistance. For hepatitis C, standard therapy has been the combination of Peg-IFN/Ribavarin. Genotype 1 of the virus, which is widespread in the USA and Europe, can be resistant to treatment especially with high viral load. Directly acting antiviral agents (DAAs), are being developed. These are: (i) HCV NS3 protease inhibitors, such as telaprevir and boceprevir, which are currently approved by the FDA. Several other compounds are in phase I-II development; (ii) NS5B polymerase inhibitors, which target HCV replication. These include mericitabine (a nucleoside analogue inhibitor) currently in phase III trials, and nonnucleiside inhibitors; (iii) New intreferons such as pgylated interferonl λ, which are also on trial. Triple therapy using pegylated IFNa/ Ribavarin along with telaprevir or boceprevir are also under trial.