NEW YORK - Drugmakers Merck and Co. and Schering-Plough Corp., which are in the process of a $41.1 billion tie-up, said today that the Federal Trade Commission has asked for more information about the deal.

The companies said that they expected the request, which was made under federal antitrust law, and that they intend to cooperate with the request.

Merck agreed to buy Schering-Plough in March, and the companies still expect the deal to close in the fourth quarter. The transaction also requires approval by Merck and Schering-Plough shareholders.

The combined company would be the world's second-largest drugmaker by revenue, with products including the asthma drug Singulair, Nasonex for allergies, and the heart drugs Zetia and Vytorin.

Merck is based in Whitehouse Station, N.J., and has major operations in the Philadelphia region, including headquarters for its vaccine operations in West Point, Montgomery County. Schering-Plough is based in Kenilworth, N.J.