Federal health officials will begin monitoring prescription drug usage by Medicare participants in an effort to identify potential safety problems. New regulations will enable the FDA, states and academic researchers to screen the Medicare claims data. The FDA primarily relies on physicians and patients to report suspected adverse events, and it often takes a number of cases before someone at the agency detects a pattern that's worth investigating. But now at the first hint of trouble, the FDA now will be able to query databases involving tens of millions of patients.