Merck & Co has announced it will buy Idenix Pharmaceuticals for $3.85 billion. The US drugmaker plans to combine the most promising drugs in the two portfolios to produce a faster, more effective cure for hepatitis C.

The payoff could come from a triple therapy that may cure patients with all genotypes, or strains, of the hepatitis C virus in as little as four to six weeks, Merck's research chief, Roger Perlmutter, said in an interview with the news agency Reuters.

"An ideal therapy means something that works in every hepatitis C-infected patient, irrespective of which genotype," Perlmutter said. "Our goal is to cure everyone quickly using an oral regimen."

The deal comes as drugmakers aim to better compete with Gilead Sciences Inc's Sovaldi, an $84,000 treatment approved in December that generated an unprecedented $2.3 billion in sales in the first few months on the market.

The cost of Sovaldi, claimed to cure well in excess of 90% of patients in as little as 8 weeks of treatment, has drawn sharp criticism from insurers and government officials.

Idenix has three drugs in development to treat hepatitis C, most notably a pill in early-stage trials called IDX21437. Like Sovaldi, it is a nucleotide inhibitor - or "nuc" - that blocks a protein needed by the hepatitis C virus to replicate.

Merck hopes to combine IDX21437 with its two high-profile experimental oral treatments, a protease inhibitor called MK-5172 and a so-called NS5A inhibitor called MK-8742 that together received a "breakthrough therapy" designation from the U.S. Food and Drug Administration.