Merck & Co has been boosted by the news that regulators in the USA have given the green light to its new hepatitis C drug Victrelis.

Victrelis (boceprevir) has been approved by the US Food and Drug Administration for the treatment of chronic hepatitis C genotype 1 infection, in combination with peginterferon alfa and ribavirin. It will be available for adults with compensated liver disease, including cirrhosis, who are previously untreated or who have failed previous interferon and ribavirin therapy.

The green light for Victrelis came as no surprise given that the FDA's Antiviral Drugs Advisory Committee voted 18-0 that the protease inhibitor is safe and effective at the end of last month. Some agency staffers had expressed concerns about the side effect profile of the drug, notably anaemia, but Edward Cox, director at the Office of Antimicrobial Products in the FDA’s Center for Drug Evaluation and Research, noted that "this new medication provides an effective treatment for a serious disease, and offers a greater chance of cure for some patients’ hepatitis C infection compared to currently available therapy.”

The approval is based on two Phase III trials with 1,500 adults. In both studies, two-thirds of patients receiving Victrelis and the aforementioned combo experienced a significantly increased sustained virologic response (ie, the hep C virus was no longer detected in the blood 24 weeks after stopping treatment), compared to pegylated interferon and ribavirin alone, the current standard of care.

Analysts believe Victrelis will be a big seller though it will face a major battle for market share with Vertex Pharmaceuticals' telaprevir.The latter was also unanimously backed by the FDA's ADAC in April and full approval is expected shortly.

Inspire acquisition a done deal

Meantime, Merck will complete its $430 million takeover of Inspire Pharmaceuticals later today.

The New Jersey-headquartered drugs giant noted that some 75.4% of shares in the ophthalmology specialist have been tendered and it will now exercise a top-up option to acquire enough shares at $5 each. It will then own at least 90% of Inspire's outstanding stock.