Thioridazine (Melleril, Rideril) should now only be used for second-line treatment of schizophrenia in adults, as the risk of cardiotoxicity caused by the drug outweighs its benefits, the Committee on Safety of Medicines (CSM) says.
In a letter issued to health care professionals on December 11, the committee said that it had considered new evidence on the risk of QTc prolongation and life-threatening ventricular arrhythmias caused by thioridazine and had decided that the risks outweighed the benefits of the drug. Thus, the CSM has recommended that thioridazine, in all its formulations, should no longer be used for other indications and that a consultant psychiatrist should supervise treatment with the drug.
Patients taking thioridazine should be re-evaluated and, if the decision is made to stop using the drug, the dose should be reduced gradually over one to two weeks, the committee says.
Further information and the newly revised product information for thioridazine can be obtained from the Medicines Control Agency website www.open.gov.uk/mca/mcahome.htm or by telephoning 020 7273 0000.
A number of new precautions for safe use of the drug are listed in the revised product information. They include recommendations that patients should be checked for potentially interacting drugs (especially those that also cause QTc interval prolongation or those that are metabolised by or are inhibitors of cytochrome P450 2D6), concomitant use of drugs that can cause electrolyte imbalance or other risk factors for cardiac disease.
Novartis, the United Kingdom manufacturer of Melleril, has written to prescribers informing them of the changes to the summary of product characteristics. It says that an updated version of the patient information leaflet for Melleril is now available from the electronic compendium website www.emc.vhn.net.