Watson Pharmaceuticals has won U.S. antitrust approval to buy Swiss peer Actavis on the condition that it sell a number of their current and future products to two other companies, the Federal Trade Commission said on Monday.

The $5.9 billion deal won approval in Europe on Oct. 5.

New Jersey-based Watson is one of the world's biggest suppliers of generic drugs.

The FTC said it would require the two companies to sell the rights and assets of 18 drugs to Sandoz International and Par Pharmaceuticals.

The FTC required the companies to divest drugs such as the generic version of the anti-smoking drug Zyban, the generic version of the high blood pressure drug Cardizem CD, and the generic version of the fentanyl patch system for chronic pain. It also has drugs in the pipeline that it must divest, such as the generic version of the attention deficit drug Adderall XR.

Fourteen of the drugs are being sold to Par Pharmaceuticals and four are being sold to Sandoz.

Watson said the U.S. approval was the last one needed. It said it expected the transaction to close in late October or early November.