(Adds the European Commission declines comment, Novo and Catalent did not immediately respond to request for comments, details)

By Foo Yun Chee and Maggie Fick

BRUSSELS/LONDON, Nov 22 (Reuters) - Novo Holdings is set to gain unconditional EU antitrust approval for its planned $16.5 billion takeover of U.S. contract drug maker Catalent

, a person with direct knowledge of the matter said on Friday, clearing a key hurdle.

Another source said Catalent is preparing senior management for the deal to go through.

Novo Holdings is the controlling shareholder of Danish drugmaker Novo Nordisk , whose profit from blockbuster weight-loss drug Wegovy has made it Europe's most valuable company by market value.

The deal would help Novo Nordisk boost output of Wegovy, a once-weekly injection.

The European Commission, which acts as the EU competition watchdog and has set a Dec. 6 deadline for its decision, declined to comment.

Novo Holdings, Novo Nordisk and Catalent did not immediately respond to requests for comment.

In May, the companies said they had received a second request from the U.S. Federal Trade Commission $(FTC.UK)$ for more information on the deal. However, there has been no update from the U.S. antitrust agency since then.

(Reporting by Foo Yun Chee in Brussels and Maggie Fick in London; Editing by Louise Heavens)

((foo.yunchee@thomsonreuters.com; +32 2 585 2866; Reuters Messaging: foo.yunchee.thomsonreuters.com@reuters.net))