Salix Pharmaceuticals will buy Santarus for about $2.12 billion to add to its roster of drugs.
Salix will pay $32 per share for Santarus' stock, the drugmakers said Thursday. They say the deal values Santarus at $2.6 billion.
Salix Pharmaceuticals Ltd., based in Raleigh, N.C., is paying a 38 percent premium to Santarus Inc.'s closing price of $23.22 Thursday.
The boards of both companies have approved the deal and say they expect the sale to close during the first quarter.
Salix sells Xifaxan, a treatment for traveler's diarrhea and neurological problems associated with liver failure, the ulcerative colitis drug Apriso, and constipation drug Relistor.
San Diego-based Santarus, whose stock price has more than doubled this year, sells Glumetza for diabetes, Zegerid for acid reflux, and Uceris for ulcerative colitis.