In a new study entitled “Repurposing of the antihistamine chlorcyclizine and related compounds for treatment of hepatitis C virus infection” researchers report to have identified that an antihistamine medication to treat allergies, chlorcyclizine HCl (CCZ), has potent antiviral-effects in hepatitis C virus infection. The study was published in the journal Science Translational Medicine.

Hepatitis C virus (HCV) targets the liver, causing both acute and chronic hepatitis infection, which often progresses to liver cirrhosis and hepatocellular carcinoma. In fact, more than 50% of liver cancer cases have HCV as an underlying cause. According to the WHO, 130 to 150 million people are infected with HCV worldwide. While antiviral treatment is available, the cost associated with these therapies is extremely high and there is currently no vaccine for HCV is available.

Here, researchers at the National Institutes of Health (NIH), in Bethesda, Maryland screened already FDA-approved drugs that might have an antiviral activity against HCV infection. The authors screened a library of compounds available at the NIH (the library was built by the NIH Chemical Genomics Center, NCGC) with their previously established cell-based quantitative high-thoroughput screening (qHTS) platform. In total, they screened approximately 3,800 small-molecule compounds available in the NCGC collection. The team identified that multiple drugs belonging to the multiple H1-antihistamines family exhibited anti-HCV activity. The team identified specifically the agent chlorcyclizine HCl (CCZ), an antihistamine medication used for allergies, as a potent inhibitor of HCV infection in both human hepatoma cells and primary human hepatocytes. Furthermore, in in vitro studies with other anti-HCV drugs, including ribavirin, interferon-a, telaprevir, boceprevir, sofosbuvir, daclatasvir, and cyclosporin A, CCZ exhibited a synergistic capacity to act with these drugs and enhance anti-viral activity. Notably, in mice studies, CCZ preferentially targeted the liver and significantly inhibited HCV infection, without signs of cytotoxicity.

The authors claim their results show that CCZ, an already FDA-approved drug with an established clinical safety profile as a medication for allergies, is a promising drug candidate for anti-HCV treatments, offering affordable prices and with a chemical structure that allows further optimization and improve HCV anti-viral efficacy.

Jake Liang, M.D., senior investigator at NIH’s National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and study lead author commented in a press release, “Although hepatitis C is curable, there is an unmet need for effective and affordable medication. CCZ is a promising candidate for part of a treatment regimen for this potentially life-threatening disease.”