(2005; 15 pages)
Thioridazine - Sale discontinued in Canada
Canada. According to Health Canda, thioridazine sales have been discontinued in Canada by 30 September 2005 due to the lack of convincing safety information that supports the continued safe use of the drug as an antipsychotic. The Agency says that thioridazine is associated with QT prolongation that predisposes to potentially fatal cardiac arrhythmia including sudden death and torsade de pointes. The Agency states that it has received three reports of death, between 2000 and 2005, that were possibly related to thioridazine. The innovator preparation of thioridazine (Novartis' Mellaril) was voluntarily withdrawn from the Canadian market in July 2001 due to safety concerns, but several other generic thioridazine products continued to be marketed in Canada, says the agency(1).
Health Canada advises (2):
• patients using thioridazine to not stop taking the drug, and to see their health care provider as soon as possible to be switched to an alternative treatment;
• health professionals to switch patients from thioridazine to an alternative therapy at the earliest medically feasible point, individualize the switching strategy for each patient, and gradually reduce the thioridazine dosage over several weeks to prevent cholinergic rebound and the recurrence of symptoms of the underlying condition;
• prescribers to monitor for any potentially occurring phenomena of major relevance, including pharmacokinetic interactions, rebound symptoms, extrapyramidal features (in particular involuntary movement disorders) and cardiac arrhythmia associated with QT prolongation, when switching to an alternate anti-psychotic medications.
Health Canada states that pharmacies will be permitted to continue dispensing remaining thioridazine supplies after 30 September 2005 to allow patients time to switch to another antipsychotic medication. Thioridazine will also be available through the Special Access Programme for patients who can not be adequately managed on alternative therapies, says the agency.
1. Advisories/Warnings. Health Canada, 8 September 2005 (http://www.hc-sc.gc.ca).
2. 'Dear Health-care Professional' letter from Health Canada, 31 August 2005 (http://www.hc-sc.gc.ca).