The US Food and Drug Administration has sent a warning letter to AstraZeneca over a case concerning a sales representative promoting unapproved use for the firm’s antipsychotic blockbuster Seroquel.

According to the letter, the rep made an unsolicited sales call to a doctor in January and stated that Seroquel (quetiapine fumarate) was approved for treatment of major depressive disorder. However, although AstraZeneca filed for that indication earlier this year, the FDA has not made a decision on the drug.

Seroquel is approved to treat bipolar disorder and schizophrenia and that approval includes treatment for depressive episodes but not MDD. The doctor then requested that AstraZeneca provide written information supporting the claim that Seroquel was approved for MDD and the company then sent the doctor promotional materials containing summaries of eight clinical trials of Seroquel and the extended-release version of the drug Seroquel XR in MDD.

The material provided by AstraZeneca did state that the company does not recommend the use of the drugs in any other manner than as described in the prescribing information. Nevertheless, the agency has requested that the Anglo-Swedish drugmaker immediately stop distributing the materials.

AstraZeneca said that it takes the allegations very seriously and is conducting a full investigation.