A day after signing a $1.24 billion antidepressant deal with Targacept, AstraZeneca has been boosted by news that regulators in the USA have granted an approval for Seroquel XR for major depressive disorder.

Specifically, the US Food and Drug Administration has approved once-daily Seroquel XR (quetiapine fumarate) extended-release tablets as adjunctive treatment to antidepressants in adults with MDD. The company noted that the drug is the only medication in its class approved by the agency to treat both MDD as add-on therapy and acute depressive episodes associated with bipolar disorder as monotherapy.

However the FDA has issued a complete response letter asking AstraZeneca for additional information before Seroquel XR can be used as acute and maintenance monotherapy for MDD. The company said it is evaluating the contents of the letter and will provide a response to the agency “in due course”.

Also the FDA has required that AstraZeneca implement a risk evaluation and mitigation strategy for Seroquel XR, which will involve “periodic assessments”, that will include a survey of patients' understanding of the potential risks of the drug. The REMS applies to all approved indications, including schizophrenia and bipolar disorder.

However the partial approval is good news for AstraZeneca given that the Seroquel franchise is expected to start suffering from generic competition after September 2011. A further boost came from the announcement that the FDA has approved standard Seroquel for the treatment of schizophrenia in adolescents (13-17 years of age) as monotherapy, and for the acute treatment of manic episodes associated with bipolar I disorder in children and adolescents (10-17), both as monotherapy and as an adjunct to lithium or divalproex.

The approvals come after AstraZeneca signed a deal to licence Targacept’s late-stage investigational product for MDD, TC-5214, which recently completed a Phase IIb trial.