The FDA has placed a “precautionary” clinical hold on Idenix Pharmaceuticals’ next-generation nucleotide polymerase inhibitor, IDX19368, being developed to treat hepatitis C (HCV) infection.

This is the second clinical hold in a month for Idenix’s hep C program, as the FDA just put a partial hold on IDX184, which was already in clinical trials. No patients have received IDX19368.

Both holds follow adverse heart events seen in Bristol-Myers Squibb (BMS) trials of a similar drug, BMS-986094.

“We understand the clinical hold is a precautionary decision,” Idenix President and CEO Ron Renaud said. Although the Idenix and BMS drugs share the same active metabolite, “there are many attributes of our compounds … that we believe favorably differentiate the toxicity profiles,” he added.

BMS has agreed to share relevant information on its drug with Idenix, “and we hope this helps us to resolve this issue quickly,” Renaud said. Idenix had planned to begin clinical trials in the third quarter of 2012.

In response to major safety-related drug withdrawals, Congress has given FDA greater authority in pharmaceutical safety regulation. Add in the soon-to-be-implemented pharmacovigilance measures in the EU and sponsors’ jobs have never been tougher.

Even if you think you know the FDA’s latest thinking on clinical trial safety, postmarketing pharmacovigilance, adverse event reporting and REMS, you could be working under false assumptions — using outdated practices that could set you up for serious penalties.

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