Published: June 2005
MARC prescriber advice

Thioridazine Prescribing Reminder

Prescriber Update 26(1): 9
June 2005

Medsafe Pharmacovigilance Team

Prescribers are reminded that thioridazine is a third-line antipsychotic agent and should only be prescribed in patients for whom the therapeutic benefits clearly outweigh the risk of arrhythmia from QT-prolongation.

Thioridazine (Aldazine®, Melleril®*) increases the risk of arrhythmia from QT-prolongation.  Consequently, the Medicines Adverse Reactions Committee (MARC) recommended changes to how thioridazine is prescribed in New Zealand.  The following advice was issued in June 2001 (see, which the MARC would like to reiterate.

Thioridazine is contraindicated in the following circumstances, all of which are risk factors for arrhythmia:

Thioridazine should be initiated only by a specialist and only as third-line therapy.  In addition, the following precautions should be observed for new patients:

For all patients currently taking thioridazine:

Any children taking thioridazine should also have their therapy reviewed by a specialist.  If thioridazine discontinuation is necessary, gradually reduce the dose over a period of one month and concurrently introduce alternative medication.  Specialist supervision may be advisable for the withdrawal process.

* Novartis has advised that from 1 July 2005 supplies of Melleril will no longer be available.

Competing interests (authors): none declared.