NEW YORK (AP) — Fears over shaky credit markets are baked into Merck & Co. Inc.’s $41.1 billion agreement to buy rival drugmaker Schering-Plough Corp., with the cost for a breakup of the deal is much higher if Merck’s financing doesn’t come through. Under most circumstances, the cost for either company to back out of the deal, announced Monday, is $1.25 billion plus expenses. But the agreement says Merck & Co. Inc. would have to pay Schering-Plough Corp. $2.5 billion if the deal falls through because Merck can’t complete the financing. The breakup fees are smaller than those for fellow drugmaker Pfizer Inc.’s planned acquisition of Wyeth. In that deal, Pfizer would pay $4.5 billion and Wyeth $1.5 billion to $2 billion to get out of the deal. The credit crisis has put the brakes on the market for mergers and acquisitions because of difficulties for companies seeking financing. But the drug industry has been an exception because most companies have large hoards of cash and sterling credit ratings. Whitehouse Station, N.J.-based Merck’s $8.5 billion in financing through JPMorgan Chase & Co. consists of $7 billion in new loans and an amendment to an existing $1.5 billion credit line. The merger agreement and details on the financing were disclosed Tuesday in a filing with the Securities and Exchange Commission. The agreement also calls for Schering-Plough to appoint three members to the board of the combined company. Merck now has 14 board members. Under the deal, Schering-Plough shareholders will get $10.50 in cash and 0.5767 Merck shares for each Schering-Plough share they own.