US FDA warns Pfizer for not reporting side effects

WASHINGTON, June 9 (Reuters) - The U.S. Food and Drug Administration has warned Pfizer Inc (PFE.N) for failing to quickly report serious and unexpected potential side effects from its drugs already on the market, citing growing and repeated delays.

In a 12-page warning letter to Pfizer Chief Executive Jeffrey Kindler, the FDA cited numerous examples involving some of the company's top-known brands, including impotence drug Viagra, cholesterol pill Lipitor and seizure medicine Lyrica.

The problems date back as as far as 2004, according to the FDA's letter, released by Pfizer on Wednesday.

Ronald Pace, director of the FDA's New York office, told Pfizer in the letter dated May 26 that it had not properly documented or investigated reported problems in patients after the drugs were approved for use.

"FDA expects drug manufacturers to establish and implement reasonable mechanisms to assure that all serious and unexpected experiences are promptly recorded and investigated," Pace wrote. (Reporting by Susan Heavey, additional reporting by Lisa Richwine; Editing by Tim Dobbyn)