WASHINGTON - The Food and Drug Administration is working hard to speed up reviews of new drugs, yet often fails to keep track of safety issues with those medicines once they reach patients, according to government investigators.

A new Government Accountability Office report outlines a host of shortcomings in FDA's system for tracking drug safety, including incomplete, outdated and inaccurate information.

The new findings are significant because FDA leadership have stressed the speed and efficiency with which agency scientists approve experimental drugs. Last year the agency approved 45 first-of-a-kind drugs, the highest number in 19 years. More than half received some form of specialized review to speed or streamline their review.

But the GAO says the agency often fails to keep track the follow-up studies required for these high-priority drugs.