Treatment of Schizophrenia and Comorbid Cannabis Use Disorder: Comparing Clozapine to Treatment-as-Usual

Schizophrenia Clinical Trial

Official title:

Cannabis and Schizophrenia: Effects of Clozapine

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00498550
• Other study ID #: NCT00149955
• Secondary ID: R01DA013196DPMCD
• Status: Completed
• Phase: Phase 4
• Start date: October 2000
• Est. completion date: March 2009

Study information

• Verified date: February 2019
• Source: Dartmouth-Hitchcock Medical Center
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

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, vs. treatment-as-usual with other oral antipsychotics at reducing marijuana use in schizophrenic individuals.

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 as compared to other oral antipsychotic treatment, including combinations of up to two antipsychotics, in reducing marijuana use in schizophrenic individuals.

This study will enroll individuals with schizophrenia who are currently taking any oral antipsychotic other than clozapine, including those taking up to two oral antipsychotic, 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 their prestudy antipsychotic for 12 weeks. Participants remaining on their prestudy antipsychotic treatment 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.

Other known NCT identifiers

• NCT00149955

Recruitment information / eligibility

• Status: Completed
• Enrollment: 31
• Est. completion date: March 2009
• Est. primary completion date: March 2009
• Accepts healthy volunteers: No
• Gender: All
• Age group: 18 Years to 65 Years

Eligibility

Inclusion Criteria:

• Meets Diagnostic and Statical Manual of Mental Disorders IV (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 any oral antipsychotic other than clozapine in the month prior to study entry. (Patients may take a second oral antipsychotic medication, if approved by the Medication Adjustment Group)

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

Exclusion Criteria:

• Unable to take clozapine 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 other psychotropic medications for the treatment of substance use (e.g., disulfiram, naltrexone, acamprosate, inderol, tegretol, topiramate, and pramipexole)

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

• Currently participating in a psychosocial intervention clinical trial

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

• 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

Related Conditions & MeSH terms

• Cannabis Abuse
• Disease
• Dual Diagnosis
• Marijuana Abuse
• Mental Disorders
• Psychotic Disorder
• Psychotic Disorders
• Schizoaffective Disorder
• Schizophrenia

Intervention

Drug:
• Clozapine
Clozapine up to 550mg per day
• Treatment as usual
Remain on pre-study antipsychotic treatment

Locations

Country	Name	City	State
United States	University South Carolina	Columbia	South Carolina
United States	University Missouri	Kansas City	Missouri
United States	West LA VAHCS	Los Angeles	California
United States	Mental Health Center of Greater Manchester	Manchester	New Hampshire

Sponsors (5)

Lead Sponsor	Collaborator
Dartmouth-Hitchcock Medical Center	National Institute on Drug Abuse (NIDA), University of Missouri, Kansas City, University of South Carolina, VA Medical Center-West Los Angeles

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Average Over Time of Intensity of Cannabis Use (Used to Evaluate Treatment Efficacy)	Intensity of cannabis use is obtained for each week retrospectively as the number of joints smoked during the prior week (assessed by the Timeline Followback Scale). Mixed models are used to obtain estimates of efficacy from the partial data provided by each subject while adherent to assigned treatment (under the 'missing at random' assumption). The 'explanatory' estimands (target of the mixed model estimation) are defined in terms of population quantities that would have occurred had all subjects remained on assigned treatment throughout the study. The point estimate for each arm is reported under Number.	Week 1 to week 12