Sofosbuvir in the treatment of chronic hepatitis C: new dog, new tricks

The existing standard of care for chronic hepatitis C virus (HCV) infection includes the use of pegylated interferon and ribavirin as primary components of treatment, with the addition of a direct-acting antiviral for genotype 1 infection. Sofosbuvir, an oral nucleotide inhibitor of the HCV nonstructural protein 5B RNA-dependent RNA polymerase enzyme, was recently approved for use in combination with ribavirin and/or pegylated interferon for chronic HCV infection, depending on the genotype. Sofosbuvir is orally administered, and peak plasma concentrations are not affected by food. The drug is renally eliminated and does not require adjustment in mild to moderate renal insufficiency or in any degree of hepatic impairment. Sofosbuvir is not metabolized by cytochrome P450 isoenzymes, nor does it induce or inhibit the metabolism of agents that are substrates of these enzymes. Sofosbuvir demonstrates a high barrier to resistance and was well tolerated by patients in clinical trials. Overall efficacy rates vary between 70% and 90%.