AstraZeneca’s bid to get another approval for Seroquel XR has been hit by news that US regulators require additional information on the drug as a treatment for anxiety.

The Anglo-Swedish has received a complete response letter from the US Food and Drug Administration asking for “additional information” for the supplemental New Drug Application for Seroquel XR (quetiapine fumarate) extended-release tablets for the treatment of generalised anxiety disorder (GAD) in adults. AstraZeneca gave out no other details about the agency’s request and commented that it is evaluating the contents of the CRL and “proposed labelling revisions”.

The company had been advised by the FDA that the latter’s Psychopharmacologic Drugs Advisory Committee is tentatively scheduled to meet on April 8 to discuss the safety and efficacy of sNDAs for Seroquel XR proposed for the treatment of major depressive disorder and GAD.

Seroquel XR is the slow-release version of the company's antipsychotic Seroquel, which was launched in 1997 and had sales of $4.5 billion in 2008. The extended-release drug was approved in the USA in 2007 for the treatment of schizophrenia in adult patients and in October last year for bipolar disorder.

Stock down, documents released to US court
The letter from the FDA has led to a slide in AstraZeneca shares this morning and the stock was down 6.4% to £22.06 at 11.20 UK time. The decline was exacerbated by news from an ongoing court case in Florida which is the result of a number of consolidated cases from the 9,000 lawsuits the company is facing from plaintiffs who claim that taking Seroquel caused their diabetes.

AstraZeneca has released over 100 documents to the court and one of them refers to a voicemail message addressed to US sales representatives in 2005 from an employee, Christine Ney, saying that “our objective is to neutralise customer objections to Seroquel's weight and diabetes profile".

AstraZeneca is vehement that it has acted "responsibly and appropriately as it developed and marketed Seroquel," according to spokesman Tony Jewell and reported by Bloomberg. He added that "from the time it was first approved, the Seroquel labeling alerted physicians that diabetes mellitus, hyperglycemia and weight gain had been observed in clinical trials. We've continued to update the label as the findings have developed."

The company had argued that the documents should not be disclosed because they contained information that could hurt the company if it was revealed to competitors and could harm the public if interpreted out of context. However AstraZeneca then agreed to make public most of the documents following negotiations with plaintiffs' attorneys, though Mr Jewell said the firm believes that “communications from the FDA to doctors is the appropriate way to notify patients and the public about a medicine's benefits and risks, not a court proceeding".