Teva, the Israeli generic drugs company, is to acquire Barr of the US in a $7.5bn deal that will sharply reinforce its position as the largest seller of off-patent medicines.

The agreed takeover, at a 32 per cent premium to the US company’s average share price over the past year, will create a group with $12bn in annual sales, 500 marketed products, and more than 200 applications for new drugs filed with US regulators alone.