Idenix Pharmaceuticals, Inc. has announced that after discussions with the United States Food and Drug Administration (FDA) the development programme of valopicitabine (NM283) for the treatment of hepatitis C has been placed on clinical hold in the United States based on the overall risk/benefit profile observed to date in clinical testing.

"We are disappointed with the FDA's perspective on the programme and are working with Novartis to evaluate our options for valopicitabine," said Jean- Pierre Sommadossi, PhD, chairman and chief executive officer of Idenix. "We remain committed to building a leading antiviral franchise and will continue to focus on ensuring a successful launch of Tyzeka /Sebivo and on advancing our pipeline. We have a novel non-nucleoside reverse transcriptase inhibitor being evaluated in phase I clinical testing for the treatment of HIV. Additionally, we have a comprehensive HCV discovery effort, which includes a second-generation nucleoside polymerase inhibitor that is being evaluated in IND-enabling preclinical testing and novel HCV non-nucleoside polymerase inhibitor and HCV protease inhibitor programmes."