The commissioner’s job at the U.S. Food and Drug Administration (FDA) is coming open at the end of March. FDA Commissioner Margaret Hamburg, the 59-year-old physician who graduated from Harvard Medical School, announced Thursday that she would be leaving her post next month after serving for almost six years. Dr. Stephen Ostroff, chief scientist at FDA, will reportedly take over the job on an interim basis.

Hamburg was appointed as the 21st FDA Commissioner by President Barack Obama and took over as head of the agency on May 18, 2009. She had previously served as the commissioner of the New York City Department of Health and Mental Hygiene, where she was credited with reducing the incidence of tuberculosis. At FDA, Hamburg focused most of her attention on drugs and medical devices, leaving a team headed by Michael Taylor, Deputy Commissioner for Food and Veterinary Medicine, to implement the Food Safety Modernization Act (FSMA) passed by Congress in late 2010. With the announcement, Hamburg is getting credit for lifting the agency’s drug and medical device units out of the crisis it had been in regarding how long it was taking for approvals. By contrast, FDA approved 51 drugs in 2014, the most in 20 years. She is the second Obama administration official to depart from a food-safety agency. Dr. Elisabeth Hagen resigned more than a year ago as USDA’s Under Secretary of Agriculture for Food Safety. That position remains open. And, like the FDA Commissioner post, it requires both presidential appointment and confirmation by the U.S. Senate. Hagen left USDA to become senior food safety advisor for the business consulting firm Deloitte Touche Tohmatsu Limited, commonly referred to as Deloitte. Hamburg has not said what she’ll be doing once she leaves FDA. Reports are that the White House will make a formal announcement of her departure on Friday.