Shire's Xiidra has been approved by US regulators to treat the signs and symptoms of dry eye disease, giving patients access to the first prescription eye drop specifically approved for the condition.

Around 16 million adults in the US are diagnosed with dry eye disease, which is associated with inflammation that may eventually lead to damage to the surface of the eye.

Approval of Xiidra (liftegrast) came on the back of four placebo-controlled 12-week trials, which showed a significant drop in the reported eye dryness score in patients treated with Shire's drug.

"The approval of Xiidra marks a new day in treatment options for patients with dry eye disease, with the only prescription eye drop approved in the US specifically to treat both the signs and symptoms of the condition," said Flemming Ornskov, Shire's chief executive.

"As Shire's first FDA-approved medicine in ophthalmics, this significant milestone advances our goal of becoming the global leader in this category, where there are unmet patient needs. We have a robust ophthalmics pipeline, and we look forward to leveraging Xiidra as our entrée into the space as we continue to develop additional innovative eye care treatment options."

Shire will launch Xiidra - which it acquired through its $160-million take-over of US group SARcode Bioscience in 2013 - during the third quarter of this year, and is expecting peak sales in excess of $1 billion.