(Adds background on FDA's role, details on Sharfstein) WASHINGTON, March 27 (Reuters) - Obama appointee Joshua Sharfstein will serve as acting Food and Drug Administration commissioner starting on Monday, the agency said on Friday. President Barack Obama appointed Sharfstein earlier this month as the agency's principal deputy and nominated former New York City health commissioner Margaret Hamburg to serve as commissioner. Hamburg needs Senate confirmation before she can run the agency. Frank Torti, who has served as acting FDA commissioner since late January, told staff he would leave the agency and return to Wake Forest University on April 4. The FDA regulates prescription drugs, medical devices, most foods and other products that account for about one-quarter of the U.S. economy. Sharfstein has served as Baltimore's health commissioner for the past three years and made headlines for pushing the FDA to warn against use of over-the-counter cough and cold medicines in young children. He also did previous work for Democratic Rep. Henry Waxman, a harsh critic of drugmakers. (Reporting by Lisa Richwine; editing by Gunna Dickson and Matthew Lewis)
