SHANGHAI: Topsun Science and Technology, the nation's leading privately owned pharmaceutical firm, will extend the time limit on a deal to sell its over-the-counter cough and cold business to Bayer.

The German firm will buy the Topsun subsidiary for 1.264 billion yuan - the biggest sum paid by a foreign company for a domestic drug maker.

Topsun signed a supplementary deal with Bayer on Feb 29 to extend the previous agreement to June 30, it told the Shanghai Stock Exchange in a statement. The terms remain the same.