The U.S. Food and Drug Administration is shuffling its top drug and biologics regulators, according to a memo seen by CNBC, days after the departure of former commissioner Marty Makary. Acting director of the FDA's Center for Drug Evaluation and Research Tracy Beth Høeg and acting director of the Center for Biologics Evaluation and Research Katherine Szarama will leave their roles, according to the memo. The two divisions are responsible for regulating prescription drugs, including pills and