Two researchers say that expedited review of new drugs may have exposed some patients to safety risks that had not been well characterized.

Writing online for JAMA Internal Medicine, the Institute for Safe Medication Practices’s Thomas Moore and Wake Forest University School of Medicine’s Curt D. Furberg say that further systematic assessment of the standards and procedures for testing new drugs is needed.

The two studied 20 drugs approved by FDA in 2008, eight with expedited review and 12 with standard review. By 2013, Moore and Furberg found, five drugs have received a new or expanded Boxed Warning.

They note that testing of new drugs has shifted from a situation in which most testing was done before marketing approval was granted to a situation in which many innovative drugs are more rapidly approved after a small trial, with much testing done after approval. “Our findings suggest that the shift has made it more difficult to balance the benefits and risks of new drugs,” they conclude.