U.S. health regulators have warned drugmaker Bayer over quality control issues at a plant that makes the key ingredient in Yaz and other popular birth control drugs.
In a warning letter posted online Tuesday, the Food and Drug Administration said its inspectors uncovered testing problems at the company’s plant in Berghamen, Germany, during a March visit.
FDA inspectors said the company measured the quality of its drug ingredients based on an average of several samples, instead of reporting individual tests results.