In order to add a much-needed nucleotide analogue to its pipeline of drug candidates for chronic hepatitis C virus (HCV) infection, Merck & Co. has agreed to buy Idenix Pharmaceuticals for approximately US$3.85 B in cash. Idenix’s principal asset is IDX21437, a next-generation uridine-based nucleotide prodrug that Merck plans to study in combination with the NS3/4A protease inhibitor MK-5172 and the NS5A inhibitor MK-8742, with the aim of developing a pan-genotypic oral treatment regimen capable of curing patients in as little as 4 to 6 weeks, substantially quicker than current treatments.