AstraZeneca, which will continue to manufacture and market the prescription version of Nexium, would be eligible to get milestone and royalty payments from Pfizer based on the launch and sales of the drug.
AstraZeneca would also supply Pfizer with the over-the-counter version of Nexium, upon marketing approval.
The companies said they are also exploring the potential for a strategic partnership that could include similar agreements for other AstraZeneca prescription brands for which OTC versions might be appropriate.
Pfizer lowered its full-year earnings per share forecast to between $2.12 and $2.22 from its prior forecast of between $2.14 and $2.24 to incorporate the impact from the deal.
Analysts were expecting the pharmaceutical giant to earn $2.22 per share for the year, according to Thomson Reuters I/B/E/S.