The U.S. Federal Trade Commission on Thursday cleared Merck & Co.'s (MRK) $41 billion acquisition of Schering-Plough Corp. (SGP), but required that the companies divest assets as a condition of government approval.

Under the terms of an agreement with the FTC, Merck must sell its interest in Merial Ltd., an animal health joint venture with Sanofi-Aventis SA (SNY, SAN.FR), while Schering-Plough must sell assets in nausea drugs for humans.

Both sets of divestitures had been expected.

Merck spokeswoman Amy Rose said the company is still awaiting regulatory antitrust clearances in Canada, Mexico and China. Rose and Schering Plough spokesman Steve Galpin said the companies continue to expect the deal to close in the fourth quarter.

The FTC said the asset sales for nausea drugs were necessary to alleviate competitive concerns regarding human drugs known as NK 1 receptor antagonists.

Merck's Emend is the only such drug approved for human use to treat nausea from chemotherapy and surgery, but Schering-Plough was in the process of licensing a similar drug, rolapitant, the commission said.

The FTC said Schering-Plough must sell its rolapitant-related assets to Opko Health, Inc. (OPK) within 10 days of the merger's closing.

Opko announced the acquisition on Oct. 13.

Merck had previously announced its plan to sell its interest in the Merial animal-health joint-venture.

Merck and Schering-Plough reached their cash-and-stock deal in March.

The European Commission cleared the merger last week.

-By Brent Kendall, Dow Jones Newswires; 202-862-9222; brent.kendall@dowjones.com

(Peter Loftus contributed to this article.)