NEW YORK (The Deal) -- Dublin-based Mallinckrodt on Tuesday agreed to buy pain-fighting rival Cadence Pharmaceuticals  (CADX) for $1.3 billion to tap growing interest in the target's acetaminophen treatment to relieve pain.

Mallinckrodt, which operates out of Hazelwood, Mo., said it would pay $14 per Cadence share, a 26% premium to the target's Monday close.

"We have been impressed with the strong relationships that Cadence's commercial organizations have established with customers in the hospital channel and are excited by the opportunity to build on these relationships to expand our platform in this area," said Mallinckrodt CEO and president Mark Trudeau in a statement.

The buyer is working to beef up its specialty pharmaceutical portfolio after being spun off last June by Dublin medical devices manufacturer Covidien. Mallinckrodt hopes it got in early on the development of Cadence's Ofirmev injectable acetaminophen, its only product.

San Diego-based Cadence said the drug had estimated sales $110.5 million in 2013, more than double the $50.1 million in 2012. That number is expected to grow further since the drug only recently won approval for use in Canada.

Mallinckrodt also hopes the drug's position on the list of approved medications in 2,350 U.S. hospitals will give it leverage to sell its other treatments. The deal will immediately add to earnings, Mallinckrodt said.

Cadence had been seen as a potential acquisition target since it only offers a single product - most drug companies offer complete portfolios.

The deal is expected to close in March and Mallinckrodt said it would use loans from Deutsche Bank Securities and available cash for the purchase. Both boards are recommending the offer to shareholders and Mallinckrodt said it already has commitments from investors holding 13% of the target's stock.