Comparative cardiac safety of low-dose thioridazine and low-dose haloperidol.
OBJECTIVE
To compare the rate of ventricular arrhythmia, sudden death and unexplained or unattended death among users of thioridazine and haloperidol.


METHODS
Observational cohort study of thioridazine and haloperidol users in the UK General Practice Research Database (GPRD) using data from 1987 through 29 June 2000. Patients were followed for 30 days following each study prescription. The event of interest was a diagnosis of ventricular arrhythmia, sudden death, or unexplained or unattended death. Cox regression was used to calculate rate ratios (RRs) and 95% confidence intervals (CIs), to examine potential confounding factors, and to examine dose-response relationships.


RESULTS
Use of thioridazine and haloperidol in the GPRD was primarily in older patients, at low dose (median daily dose 31 mg thioridazine, 1.8 mg haloperidol). There was no association between thioridazine use and the rate of ventricular arrhythmia, sudden death, and unexplained or unattended death (adjusted RR 0.9, 95% CI 0.7, 1.1). The rate did not appear to increase with dose for either drug over the range observed.


CONCLUSIONS
These results suggest that low-dose thioridazine and haloperidol have similar cardiac safety.
Hennessy
Sean
S
Center for Clinical Epidemiology & Biostatistics, Department of Biostatistics & Epidemiology, and Center for Education & Research in Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. shenness@cceb.med.upenn.edu
Bilker
Warren B
WB
Knauss
Jill S
JS
Kimmel
Stephen E
SE
Margolis
David J
DJ
Morrison
Mary F
MF
Reynolds
Robert F
RF
Glasser
Dale B
DB
Strom
Brian L
BL
D000293:Adolescent; D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects*; D001145:Arrhythmias, Cardiac / Q000139:chemically induced*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D004305:Dose-Response Relationship, Drug; D006220:Haloperidol / Q000008:administration & dosage / Q000009:adverse effects*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008875:Middle Aged; D011379:Prognosis; D012044:Regression Analysis; D013881:Thioridazine / Q000008:administration & dosage / Q000009:adverse effects*
D014150:Antipsychotic Agents; D006220:Haloperidol; D013881:Thioridazine