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Clozapine to Reduce Marijuana Use in Schizophrenic Individuals

Information source: National Institute on Drug Abuse (NIDA)
Information obtained from ClinicalTrials.gov on June 20, 2008
Link to the current ClinicalTrials.gov record.

Condition(s) targeted: Marijuana Abuse; Substance-Related Disorders; Schizophrenia; Psychotic Disorders

Intervention: Clozapine (Drug); Risperidone (Drug); Olanzapine (Drug)

Phase: N/A

Status: Recruiting

Sponsored by: National Institute on Drug Abuse (NIDA)

Official(s) and/or principal investigator(s):
Alan I. Green, MD, Principal Investigator, Affiliation: Dartmouth-Hitchcock Medical Center

Overall contact:
Christopher O'Keefe, MA, Phone: 603-271-5747, Email: christopher.okeefe@dartmouth.edu


Many individuals with schizophrenia also suffer from marijuana addiction. Clozapine, an atypical antipsychotic medication, may prove useful at preventing drug relapse in schizophrenic individuals who are seeking treatment for marijuana addiction. The purpose of this study is to compare the effectiveness of clozapine, risperidone, and olanzapine at reducing marijuana use in schizophrenic individuals.

Clinical Details

Official title: Cannabis and Schizophrenia: Effects of Clozapine

Study design: Treatment, Randomized, Open Label, Active Control, Parallel Assignment, Efficacy Study

Primary outcome: Marijuana use (measured by Timeline Followback, urine tests, collateral reports, and clinician ratings at Week 12)

Secondary outcome:

Psychiatric clinical symptoms (measured by the Brief Psychiatric Rating Scale, Clinical Global Inventory, and Schedule for the Assessment of Negative Symptoms at Week 12)

Quality of life (measured by the Quality of Life Scale and the subjective section of the Quality of Life Interview at Week 12)

Detailed description: Individuals with schizophrenia have a high risk of becoming addicted to drugs; between 13 to 42% of schizophrenics are addicted to marijuana. These individuals often have difficulties adhering to a substance abuse treatment program, and have an increased chance of marijuana relapse. Marijuana use by schizophrenics has also been associated with clinical exacerbations, noncompliance with antipsychotic medications, poor global functioning, and increased rehospitalization rates. While antipsychotic medications are often effective in controlling symptoms of schizophrenia, they are not always effective in preventing substance abuse. Clozapine, an atypical antipsychotic drug, is currently used to treat schizophrenia. Preliminary research has shown that clozapine is more successful at reducing drug relapse rates in individuals with schizophrenia, as compared to other antipsychotic medications, including olanzapine and risperidone. The purpose of this study is to compare the effectiveness of clozapine, olanzapine, and risperidone in reducing marijuana use in schizophrenic individuals.

This study will enroll individuals with schizophrenia who are currently taking olanzapine or risperidone and who are also addicted to marijuana. The study will begin with a 1-week assessment phase, during which all participants will continue taking olanzapine or risperidone. Participants will undergo a physical examination and have blood drawn for laboratory tests. Information pertaining to their medical, psychiatric, and substance use history will also be collected. Urine tests and breathalyzers will be used to screen for the presence of alcohol and drugs. Following the assessment phase, participants will be randomly assigned to switch to clozapine or remain on either olanzapine or risperidone for 12 weeks. Participants taking olanzapine or risperidone will continue to receive the same dose for the entire study. Participants taking clozapine will initially receive a daily dose of 12. 5 mg, which will be increased to a maximum of 400 mg per day, as tolerated. Study visits will take place once a week. At each visit, medication side effects, physical and psychological symptoms, substance use, treatment services received, and living situation will be assessed. Blood will be drawn for laboratory tests. Drug and alcohol levels will be monitored three times a week through urine and breathalyzer tests. Quality of life questionnaires will be administered once a month.


Minimum age: 18 Years. Maximum age: 65 Years. Gender(s): Both.


Inclusion Criteria:

- Meets DSM-IV diagnostic criteria for schizophrenia or schizoaffective disorder

- Meets diagnostic criteria for marijuana use disorder, as determined by a rating of 3

or higher on the Drug Use Scale (Abuse or Dependence)

- Used marijuana on 5 or more days during the 3 weeks prior to study entry

- Taking olanzapine or risperidone in the month prior to study entry (may take a second

antipsychotic medication at a low dose, if approved by the Medication Adjustment Group)

- If female, willing to use effective contraception throughout the study

Exclusion Criteria:

- Unable to take clozapine, risperidone, or olanzapine for medical reasons, including

previous clozapine-induced granulocytopenia, myeloproliferative disorder, white blood cell count less than 3500/mm3, or history of seizures

- Currently taking clozapine

- Currently taking a second antipsychotic medication at a dose higher than what is

approved by the Medication Adjustment Group

- Currently taking a combination of olanzapine and risperidone

- Currently taking other psychotropic medications for the treatment of substance use

(e. g., disulfiram, naltrexone, acamprosate, inderol, tegretal, topiramate, and pramipexole)

- Participated in a clinical trial of an investigational drug within 30 days of study


- Currently participating in a psychosocial intervention clinical trial

- Has medical or legal problems that may entail a jail or hospital stay during the


- Has a developmental disability that would make study participation difficult

- Currently enrolled in a live-in treatment program for substance use disorders

- Pregnant or plans to become pregnant during the study

Locations and Contacts

Christopher O'Keefe, MA, Phone: 603-271-5747, Email: christopher.okeefe@dartmouth.edu

Mental Health Center of Greater Manchester, Manchester, New Hampshire 03101, United States; Recruiting
Margaret Almeida, BS, BSN, RN, BC, MBA, Phone: 603-668-4111, Ext: 5301, Email: almeidam@mhcgm.org
Christopher O'Keefe, MA, Phone: 603-271-5747, Email: christopher.okeefe@dartmouth.edu

West Central Behavioral Health, Lebanon, New Hampshire 03766, United States; Recruiting
Kimberly Southworth, MA, Phone: 603-448-5610, Email: Kimberly.Mae.Southworth@Hitchcock.ORG
Christopher O'Keefe, MA, Phone: 603-271-5747, Email: christopher.okeefe@dartmouth.edu

Riverbend, Concord, New Hampshire 03301, United States; Recruiting
Sarah Davis, MA, Phone: 603-228-1551, Email: sdavis@riverbendcmhc.org
Christopher O'Keefe, MA, Phone: 603-271-5747, Email: christopher.okeefe@dartmouth.edu

Institute for Clinical Research, Nashua, New Hampshire 03060, United States; Recruiting
Jody Stephens, MEd, Phone: 603-594-0374, Email: jody.stephens@snhmc.org
Christopher O'Keefe, MA, Phone: 603-271-5747, Email: christopher.okeefe@dartmouth.edu

Additional Information

Related publications:

Dixon L, Haas G, Weiden PJ, Sweeney J, Frances AJ. Drug abuse in schizophrenic patients: clinical correlates and reasons for use. Am J Psychiatry. 1991 Feb;148(2):224-30.

DeQuardo JR, Carpenter CF, Tandon R. Patterns of substance abuse in schizophrenia: nature and significance. J Psychiatr Res. 1994 May-Jun;28(3):267-75.

Albanese MJ, Khantzian EJ, Murphy SL, Green AI. Decreased substance use in chronically psychotic patients treated with clozapine. Am J Psychiatry. 1994 May;151(5):780-1. No abstract available.

Drake RE, Xie H, McHugo GJ, Green AI. The effects of clozapine on alcohol and drug use disorders among patients with schizophrenia. Schizophr Bull. 2000;26(2):441-9.

Zimmet SV, Strous RD, Burgess ES, Kohnstamm S, Green AI. Effects of clozapine on substance use in patients with schizophrenia and schizoaffective disorder: a retrospective survey. J Clin Psychopharmacol. 2000 Feb;20(1):94-8.

Starting date: March 2004
Last updated: November 29, 2006

Page last updated: June 20, 2008

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