AstraZeneca is to buy U.S. respiratory drug specialist Pearl Therapeutics for up to $1.15 billion as Britain's second biggest drugmaker steps up a drive to rebuild its product pipeline via deal-making.

AstraZeneca said on Monday it would pay $560 million upfront, plus up to $450 million if certain development milestones are hit and sales-related payments of up to a further $140 million.

Pearl's lead product, PT003, is a fixed dose combination of formoterol fumarate, a long-acting beta-2-agonist (LABA) and glycopyrrolate, a long-acting muscarinic antagonist (LAMA). It is in final-stage Phase III clinical trials.

(Reporting by Ben Hirschler; Editing by Paul Sandle)