Health professionals are advised that the Product Information for quetiapine has been updated to include additional information regarding risks of QT prolongation.
Postmarketing reports of QT prolongation associated with quetiapine treatment have occurred not only in the context of overdose, but also with concomitant illness and in patients taking other drugs known to cause electrolyte imbalances or increase the QT interval.
Quetiapine, which is marketed as Seroquel and multiple generics, is an atypical antipsychotic drug indicated for the treatment of schizophrenia and bipolar disorder.
TGA investigations found that, while the Australian Product Information (PI) had a precaution for use with cardiovascular disease, family history of QT prolongation, congenital long QT syndrome, congestive heart failure, heart hypertrophy, hypokalaemia and hypomagnesaemia, it did not specifically state the need to avoid use in circumstances that may increase the occurrence of torsades de pointes and/or sudden death.
New information
The PI for quetiapine products now advises, particularly in elderly patients, to avoid concomitant treatment with antipsychotics and other drugs that are known to prolong the QT interval. These include:
- Class IA antiarrhythmics (such as disopyramide)
- Class III antiarrhythmics (such as amiodarone and sotalol)
- antipsychotics (such as ziprasidone, chlorpromazine and haloperidol)
- antibiotics (such as erythromycin)
- others (such as citalopram, pentamidine and methadone).
The updated information also advises that quetiapine should be avoided in circumstances that may increase the risk of torsades de pointes and/or sudden death, including a history of cardiac arrhythmias, hypokalaemia or hypomagnesaemia, and congenital prolongation of the QT interval.
Additionally, the PI has also been updated to include further information about the risk of:
- venous thromboembolism (VTE)
- akathisia
- neutropenia.
Adverse event reports in Australia
Over the 13 years that quetiapine has been registered in Australia, from March 2000 to August 2013, there have been a total of 807 adverse event reports made to the TGA relating to its use. Of those reports, 23 involved QT prolongation. More than half involved concomitant drugs that can increase the QT interval.
There were two reports of cardiac arrest in which QT prolongation was also noted, and another report of fatal cardiac arrest in which QT prolongation was not reported. Meanwhile there was one report of torsades de pointes, associated with hypokalaemia and hypomagnesaemia.
Information for health professionals
Health professionals are encouraged to review the latest PI for quetiapine and particularly the updated information regarding QT prolongation, VTE, akathisia and neutropenia in the precautions section.
Quetiapine treatment in combination with antipsychotics and other drugs that are known to prolong the QT interval should be avoided, particularly in elderly patients.