The leader of the Food and Drug Administration division responsible for regulating prescription and over-the-counter drugs is leaving her post, a senior FDA official confirmed to CBS News, marking the latest high-level shake-up at the FDA. 

Dr. Tracy Beth Høeg had served as acting director of the FDA's Center for Drug Evaluation and Research (CDER) since December, helming an office that reviews applications for new drugs. She previously advised former FDA Commissioner Dr. Marty Makary.

A Health and Human Services spokesperson did not immediately respond to a request for comment. The news of Høeg's departure was first reported by Reuters.

Høeg is leaving her job three days after Makary resigned as FDA commissioner following a flood of news reports about internal tensions within the agency, including disagreements over a recent decision to approve flavored e-cigarettes. A source familiar with the matter told CBS News that Makary left due to the e-cigarette dispute, adding that the commissioner didn't want to approve flavored products but had been forced to do so by other members of the administration.

The former head of the FDA office responsible for vaccine approvals, Dr. Vinay Prasad, also departed the agency last month. Prasad briefly left the agency last summer, but was reinstated less than two weeks later. 

Høeg's appointment as the head of CDER had drawn controversy and sparked alarm among senior FDA officials due to her history of vaccine skepticism, CBS News previously reported. She helped write a memo last year linking several children's deaths to the COVID-19 vaccine, without providing data to back up the claim, and she was involved in a controversial effort to reduce the number of recommended childhood vaccines.

"Putting Tracy Beth in charge is like dropping an atom bomb," one agency source told CBS News in December.

Høeg has acknowledged the effectiveness of some vaccines, including the measles vaccine. She said when she was confirmed that she was "committed to transparency, honesty, and decisions based on rigorous science and ensuring important changes happen efficiently."