Swiss drugmaker Roche Holding AG announced Monday it is paying $230 million to take over Anadys Pharmaceuticals Inc., a U.S.-based specialist in the development of hepatitis C treatments.

The offer amounts to $3.70 per share, a premium of more than 250 percent on Anadys's closing price Friday, Roche said.

The board of San Diego-based Anadys approved the deal, which analysts said could boost the company's chances of getting approval for Setrobuvir, an oral drug currently being tested for treatment of chronic infections with hepatitis C virus, or HCV.

"With Roche's considerable capabilities and experience in HCV, this acquisition provides the best chance of success for the new potential treatments our team has been dedicated to developing," Anadys CEO Steve Worland was quoted as saying in a statement.

Roche said the acquisition would boost its portfolio of hepatitis C drugs, which include Pegasys and Copegus.

Last week, the Basel-based company reported third-quarter sales of 9.82 billion Swiss francs ($10.98 billion).

Roche shares were down 0.6 percent at 141.90 francs ($158.00) on the Zurich exchange.