The US Food and Drug Administration has hired a management consultancy firm to check that it is consistent in its handling of post-marketing studies across all its medical centres.

Post-marketing studies – sometimes known as Phase IV testing – are designed to provide additional information on the safety, efficacy or optimal use of a product that has otherwise been cleared to reach the market.

“Even the largest and best designed pre-market studies cannot reasonably answer all of the important questions that may arise about medicines,” said Steven Galson, director of the FDA’s Center for Drug Evaluation and Research.

That said, concerns have grown that the FDA was being inconsistent in its demand for post-marketing studies, so the agency has contracted consultancy firm Booz Allen Hamilton to investigate how it demands, requests and reviews the studies. The probe is expected to take around a year to complete.

The move comes on the heels of an FDA report released last month showing that two thirds of 1,231 Phase 4 studies drugmakers had agreed to conduct were still pending, although only 2% were officially delayed.

At present, the FDA has no authority in law to force companies to complete post-marketing studies, but a bill that would give it this power has been introduced in the US Congress by Senators Chuck Grassley and Christopher Dodd. This bill would give the FDA the power to order drugs off the market, require changes to warning labels without a lengthy negotiation process, and create a new department focused on drug safety and post-marketing surveillance of the new medicines.