Simeprevir (Olysio) is a new protease inhibitor approved to treat adults with hepatitis C viral infection; it should be prescribed as part of combination antiviral therapy. It can be used in either treatment-naive patients receiving their first regimen for hepatitis C or patients in whom other treatment has been ineffective. Simeprevir prevents the infectious hepatitis C virus from replicating and is the third protease inhibitor approved for the treatment of chronic hepatitis C viral infections.

In clinical trials, the addition of simeprevir to treatment with peginterferon-alfa and ribavirin increased the likelihood that the hepatitis C virus would not be detected in the patient's blood after 12 weeks of therapy; 80% of treatment-naive patients had a positive virologic response when simeprevir was part of their therapy, compared with 50% of those who received only peginterferon-alfa and ribavirin, and 79% of "treatment-experienced" patients (those whose infection had returned) experienced a positive virologic response, compared with 37% of those receiving only peginterferon-alfa and ribavirin.

Unfortunately, simeprevir's effectiveness is diminished in patients who have one particular strain of hepatitis C that's common in the United States: genotype 1a hepatitis C virus with the NS3 Q80K polymorphism. It's recommended that patients be screened for the strain prior to beginning therapy. Alternative drug therapy should be considered if the NS3 Q80K strain is detected.

The most common adverse effects are rash (including serious photosensitivity reactions), pruritis, and nausea. Nurses should instruct patients prescribed simeprevir to limit their sun exposure and to take protective measures (such as using sunscreen and wearing long-sleeved tops) to prevent photosensitivity reactions.

The Food and Drug Administration news release regarding the approval of simeprevir can be found at http://1.usa.gov/1hMpNUI.