Quetiapine in patients with comorbid schizophrenia-spectrum and substance use disorders: an open-label trial.
BACKGROUND
Preliminary evidence suggests that clozapine relieves the craving for psychoactive substances in schizophrenia patients. Quetiapine shares crucial pharmacological properties with clozapine. Promising results have been described with quetiapine therapy in patients with psychosis and substance use disorder.


METHODS
Based on Diagnostic and Statistical Manual of Mental Disorders - fourth edition (DSM-IV) criteria, patients were diagnosed with comorbid schizophrenia-spectrum and substance use disorders. Patients were switched to quetiapine for a 12-week open-label trial. Craving, quantities used, days of consumption, and severity of substance abuse were assessed every 3 weeks. Alcohol and Drug Use Scales were administered on baseline and end-point. Psychiatric symptoms, depressive symptoms, extrapyramidal symptoms, and cognition were also assessed at baseline, week 6 and week 12.


RESULTS
Twenty-four schizophrenia-spectrum patients were included in the last observation carried forward (LOCF) analyses, responding to one or more of the following substance use disorders: cannabis (15 patients), alcohol (10 patients), and other psychoactive substances (nine patients). Overall, severity of substance abuse improved during the study. Less weekly days were spent on drugs of abuse. A decrease in the weekly Canadian dollars spent on psychoactive substances was also observed. Cognition, psychiatric, depressive, and extrapyramidal symptoms also significantly improved (p < 0.05).


CONCLUSIONS
In this open-label, uncontrolled trial, significant improvements were noted in substance abuse, psychiatric symptoms, extrapyramidal symptoms, and cognition during quetiapine therapy. The study suffered from three main limitations: (1) the open-label design of the study; (2) the patients' poor compliance; and (3) the small sample size involved. Controlled studies on the use of quetiapine in dual diagnosis schizophrenia are warranted to confirm that the effects are drug-related.
Potvin
Stéphane
S
Centre de recherche Fernand-Seguin, Hôpital Louis-H. Lafontaine, Montreal, Canada.
Stip
Emmanuel
E
Lipp
Olivier
O
Elie
Robert
R
Mancini-Marië
Adham
A
Demers
Marie-France
MF
Roy
Marc-André
MA
Bouchard
Roch-Hugo
RH
Gendron
Alain
A
D000328:Adult; D000437:Alcoholism / Q000150:complications / Q000188:drug therapy; D003071:Cognition / Q000187:drug effects; D003987:Dibenzothiazepines / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000150:complications / Q000188:drug therapy; D000069348:Quetiapine Fumarate; D012559:Schizophrenia / Q000150:complications / Q000188:drug therapy*; D012565:Schizophrenic Psychology; D012720:Severity of Illness Index; D019966:Substance-Related Disorders / Q000150:complications / Q000188:drug therapy* / Q000523:psychology
D003987:Dibenzothiazepines; D000069348:Quetiapine Fumarate