FDA questions wider approval of Cymbalta

Eli Lilly has submitted data to the FDA ahead of an advisory panel meeting to support approval of its antidepressant Cymbalta (duloxetine) for chronic pain, but scientists have questioned some of the statistical methodologies used to study the drug and liver side-effects.

The advisory panel meeting was originally scheduled for January 2010, but it was delayed so the FDA could review additional information it said was "relevant to the benefit risk balance for the proposed new indication." The application is for a range of pain ailments, including lower back pain.

Cymbalta is currently approved in the US for depression, diabetic nerve pain and fibromyalgia. But FDA reviewers appeared cautious about expanding the use of the drug already used by nearly 15m patients.

The drugmaker has been trying to gain approval for the new indication for more than two years. It withdrew its application in November 2008 after the FDA questioned the method and design of the trials. The application was resubmitted last year.

Three studies showed Cymbalta lowered patient-reported pain score significantly more than a placebo after three months, but reviewers noted that positive feedback from patients who later dropped out of one of the studies, possibly due to side-effects, was included.

According to reviewers, this practice could "potentially assign good pain scores to subjects who could not tolerate the drug."