The US Food and Drug Administration issued a second warning on Friday to highlight a possible link between suicidal behaviour and antidepressant use.

The agency said that the new warning came in response to recent scientific publications reporting the possibility of increased risk of suicidal behavior in adults treated with antidepressants. The FDA initially called for stronger labelling on antidepressants in March last year [[23/03/04a]], and later concluded that the drugs also heighten the risk of suicide and suicidal behaviour amongst children and adolescents [[17/09/04e]], [[18/10/04b]].

The FDA said that, even before the publication of the reports, it had put the wheels in motion to review available data to determine whether there actually is an increased risk of suicidal behaviour in adults taking antidepressants. It has asked manufacturers of the drugs to provide clinical trial information, but noted that this will include hundreds of studies and may take more than a year to complete.

In the meantime, the agency says that patients should be watched closely for worsening of depression and for increased suicidal thinking or behaviour, and “close observation of adults may be especially important when antidepressant medications are started for the first time or when doses for the specific drugs prescribed have been changed.”

- Meanwhile, the FDA said it was also investigating a higher than expected rate of suicide attempts in clinical trials of Eli Lilly’s Cymbalta (duloxetine) in the treatment of women with stress urinary incontinence. It notes that an increased rate of suicidality was not seen in controlled trials of Cymbalta for treatment of depression or diabetic neuropathic pain – the approved indications for Cymbalta [[05/08/04b]], [[08/09/04a]] – but is evaluating additional data to determine the relationship, if any, between suicidality and Cymbalta use.

Although the drug is not approved for the treatment of SUI in the USA – Lilly pulled the US filing in this indication earlier in the year after regulators had said they could not approve the product based on the data package submitted [[31/01/05b]].