A legal dispute between Mayne Pharma and private equity suitor Cosette, which has terminated its $672 million takeover offer for the Adelaide-based target, may drag on in the courts for years unless the bidding parties settle their dispute ahead of a shareholder vote on the deal in two weeks.

Shareholders and sources close to the transaction, who were not authorised to speak publicly, said there was no legal precedent in Australia for Cosette’s termination based on its claim that there has been a material adverse change in Mayne Pharma’s financial position.