Pfizer has gained global rights to market an OTC version of AstraZeneca's blockbuster heartburn drug Nexium® (esomeprazole magnesium) for US$250 M upfront plus milestones and royalties. AstraZeneca will continue to manufacture and market the prescription version of the drug. Pfizer anticipates that it will begin to commercialise OTC Nexium in 2014, thus providing AstraZeneca with a revenue stream from the brand after the arrival of generic competition.