NCT01639872.

Trial name or title	Clozapine for Cannabis Use in Schizophrenia (CLOCS)
Methods	Double blind (subject, caregiver, investigator, outcomes assessor), randomised, parallel assignment, superiority trial, comparing the efficacy of clozapine with risperidone, Estimated recruitment target N = 132
Participants	Adults 18 to 55 years, males and females, clinical diagnosis of schizophrenia and a co‐occurring cannabis use disorders (abuse or dependence)
Interventions	clozapine with target dose of 400 mg/day and maximum of 550 mg/day; risperidone with target dose of 4 mg/day and maximum of 6 mg/day
Outcomes	Primary: intensity (amount of cannabis used); frequency (number of days in past week) Secondary: symptoms of schizophrenia as measured by the BPRS, SANS, CGI; neuropsychological function by means of MATRICS Consensus Cognitive Battery; and reward responsiveness by means of a computerised Probablistic Reward Task.
Starting date	April 2013
Contact information	alan.i.green@dartmouth.edu; christopher.okeefe@dartmouth.edu
Notes	Estimated completion in Oct 2016 (recruitment); Oct 2017 (results)