NCT00208143.

Methods	Open (no masking), randomised, parallel assignment, superiority trial
Participants	Adults age 19 to 65 years with a diagnosis of schizophrenia or schizoaffective disorder and co‐occurring cocaine or methamphetamine abuse or dependence as diagnosed by Structured Clinical Interview for DSM‐IV.
Interventions	quetiapine or risperidone oral formulation
Outcomes	Primary: 50% or greater decrease in the drug use determined by the Time Line Follow Back (TLFB) method versus baseline Secondary: psychiatric symptoms assessed with the CGI, PANSS, BPRS, HAM‐D, and HAM‐A. Safety and tolerability assessed by patient‐ and physician‐reported adverse events and AIMS. Quality of life assessed with QoLI.
Notes	Authors were contacted via e‐mail but no response received.