June 19 (Reuters) - Activist investor and hedge fund manager John Paulson has joined Valeant Pharmaceuticals International Inc's VRX.TO VRX.N board, a move that comes at a time when the embattled Canadian drugmaker is restructuring itself to repay debt.

Valeant's U.S.-listed shares were up 5.9 percent at $13.40 in premarket trading on Monday.

Paulson's hedge fund Paulson & Co had a 5.68 percent stake in Valeant as of March 31, making it the largest shareholder in the company, according to Reuters data.

Valeant Chief Executive Joseph Papa is working to narrow the company's focus to its dermatology, gastrointestinal and eye care businesses by pruning other assets to repay its debt of nearly $30 billion.

Paulson's addition increases the size of Valeant's board to 11 members, 10 of whom are independent.

The company has been a fancy of activist investors such as Pershing Square's William Ackman, who sold the stake after spending 18 months trying to repair the company and suffering more than $3 billion in losses.

(Reporting by Yashaswini Swamynathan in Bengaluru; Editing by Saumyadeb Chakrabarty) ((yashaswini.swamynathan@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 80 6749 2405; Reuters Messaging: yashaswini.swamynathan.thomsonreuters.com@reuters.net))