Pfizer has announced it will acquire exclusive global rights to the over-the-counter (OTC) version of AstraZeneca's Nexium, a heartburn treatment, for $250m.

AstraZeneca will retain the rights to manufacture and market the prescription version of the drug and will also be eligible to receive milestone and royalty payments from Pfizer, based upon the launch and sales of the OTC version.

Pfizer has confirmed it expects to market the OTV version of Nexium in 2014, coinciding with the prescription version of the drug losing its patent protection. The company also confirmed that a marketing application for the pill was filed with European regulators in June 2012, and a similar application will be filed with the US Food and Drug Administration in the first half of 2013.

Despite being AstraZeneca's second-largest seller in Q2 2012, Nexium has been hit by generic competition that has seen its revenue fall. Revenue from the acid reflux medication fell 13% to $949m during the quarter.

As per the terms of the agreement, AstraZeneca will supply Pfizer with OTC Nexium upon regulatory approval, and both companies will consider similar partnerships for other AstraZeneca prescription drugs for which OTC versions could be made available.

AstraZeneca Global Commercial Organisation executive vice president Tony Zook said; "AstraZeneca has long been a leader in the gastrointestinal sector, and we believe that an OTC version of Nexium will complement this globally successful prescription medicine and help bring relief to more patients around the world."

"This agreement will help AstraZeneca realise the substantial, long-term value of this brand and potentially other brands in our portfolio," added Zook.