Trial · NCT01639872

Clozapine for Cannabis Use in Schizophrenia

NCT01639872, Phase 4, Completed, Dartmouth-Hitchcock Medical Center; results first posted 2019-12-26

3 sourcestrials-2026-11-12-0.5.0

Cite this record

ConductScience Library. Clozapine for Cannabis Use in Schizophrenia. Trials, record NCT01639872. Release trials-2026-11-12-0.5.0, 12 Nov 2026. https://conductscience.org/library/trials/NCT01639872

On this page

Trial

As registered on ClinicalTrials.gov, in the graph's capture of the registry.

Title: Clozapine for Cannabis Use in Schizophrenia
NCT number: NCT01639872
Status: Completed
Phases: Phase 4
Enrollment: 49 participants, actual
Lead sponsor: Dartmouth-Hitchcock Medical Center
Conditions: Schizophrenia, Cannabis Abuse, Cannabis Dependence, Dual Diagnosis
Interventions: Clozapine, Risperidone
First posted: 2012-07-13
Last updated: 2020-05-05
Results first posted: 2019-12-26

Source ClinicalTrials.gov

Registered outcomes2

Each outcome the trial registered, primary first, in ClinicalTrials.gov's words.

List	Outcome	Time frame	Description
Primary	Average Over Time of Intensity of Cannabis Use (Used to Evaluate Treatment Efficacy)	12 weeks	Intensity of cannabis use is obtained each week retrospectively as the number of joints smoked during the prior week (assessed using the Timeline Followback). 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.
Primary	Average Over Time of Frequency of Cannabis Use	12 weeks	Frequency of cannabis use is obtained each week retrospectively as the number of days of cannabis use during the prior week (assessed using the Timeline Followback). 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.

Source ClinicalTrials.gov

Outcomes2

Each outcome the trial posted results for, in ClinicalTrials.gov's words.

Type	Outcome	Time frame	Population	Units	Measured as
PRIMARY	Average Over Time of Intensity of Cannabis Use (Used to Evaluate Treatment Efficacy)	12 weeks	Average number of joints Over Time was calculated using the midpoint of 6.5 weeks. NOTE: Outlying data for a CLOZ and RISP subject were removed from the analyses . Additionally, two subjects were excluded from the study due to unreliability (1 CLOZ, 1 RISP).	joints smoked during the prior week	NUMBER
PRIMARY	Average Over Time of Frequency of Cannabis Use	12 weeks	Average number of days of cannabis use over time was calculated using the midpoint 6.5 weeks. NOTE: Outlying data for a CLOZ and RISP subject were removed from the analyses. Additionally, two subjects and their data were excluded from the study due to unreliability (1 CLOZ, 1 RISP).	days of cannabis use during prior week	NUMBER

Source ClinicalTrials.gov

Results by group4

Each measurement the trial posted, group by group, in the words and numbers it posted.

Outcome	Group	Value	Spread	Units
Average Over Time of Intensity of Cannabis Use (Used to Evaluate Treatment Efficacy)	Clozapine	10.21	95% Confidence Interval 4.88 to 15.5	joints smoked during the prior week
Average Over Time of Intensity of Cannabis Use (Used to Evaluate Treatment Efficacy)	Risperidone	10.2	95% Confidence Interval 5.98 to 14.4	joints smoked during the prior week
Average Over Time of Frequency of Cannabis Use	Clozapine	4.26	95% Confidence Interval 3.40 to 5.12	days of cannabis use during prior week
Average Over Time of Frequency of Cannabis Use	Risperidone	4.58	95% Confidence Interval 3.94 to 5.22	days of cannabis use during prior week

Source ClinicalTrials.gov

Participant flow6

How many started, completed or left each group, period by period.

Period	Milestone	Group	Participants
Overall Study	STARTED	Clozapine	24
Overall Study	STARTED	Risperidone	25
Overall Study	COMPLETED	Clozapine	14
Overall Study	COMPLETED	Risperidone	20
Overall Study	NOT COMPLETED	Clozapine	10
Overall Study	NOT COMPLETED	Risperidone	5

Source ClinicalTrials.gov

Adverse events50

Each adverse event the trial posted, group by group: the participants affected out of those at risk.

Type	Event	Organ system	Group	Affected	At risk	Events
other	Leukopenia	Blood and lymphatic system disorders	Clozapine	0	23	0
other	Leukopenia	Blood and lymphatic system disorders	Risperidone	2	24	4
other	Tachycardia	Cardiac disorders	Clozapine	2	23	2
other	Tachycardia	Cardiac disorders	Risperidone	0	24	0
other	Abdominal pain	Gastrointestinal disorders	Clozapine	2	23	2
other	Abdominal pain	Gastrointestinal disorders	Risperidone	0	24	0
other	Constipation	Gastrointestinal disorders	Clozapine	4	23	4
other	Constipation	Gastrointestinal disorders	Risperidone	1	24	1
other	Vomiting	Gastrointestinal disorders	Clozapine	3	23	4
other	Vomiting	Gastrointestinal disorders	Risperidone	3	24	3

1 to 10 of 50Source ClinicalTrials.gov

See all 50 adverse events

Adverse event totals6

The totals the trial posted for each group.

Total	Group	Affected	At risk
Total, all-cause mortality	Clozapine	0	23
Total, all-cause mortality	Risperidone	0	24
Total, other adverse events	Clozapine	23	23
Total, other adverse events	Risperidone	21	24
Total, serious adverse events	Clozapine	3	23
Total, serious adverse events	Risperidone	3	24

Source ClinicalTrials.gov

Papers0

The papers the trial lists on ClinicalTrials.gov.

None in this release.

Grants1

The grants NIH RePORTER links to the trial, newest funded first: NIH's, and some of AHRQ's, CDC's, FDA's and VA's. Each shows its title, principal investigators, organization and funder in its newest year.

Project	Title	Principal investigators	Organization	Funder	Fiscal years
R01DA032533	Clozapine for Cannabis Use Disorder in Schizophrenia	GREEN, ALAN I	DARTMOUTH COLLEGE	NATIONAL INSTITUTE ON DRUG ABUSE	2012 to 2017

Source NIH RePORTER

Trial comparisons2

Comparisons of the trial's two groups, calculated by ConductScience from the counts it posted.

Comparison	Source
Clozapine vs Risperidone: deaths from any cause	Trial comparisons
Clozapine vs Risperidone: serious adverse events	Trial comparisons

Tests0

The ConductCognition tests this trial's registered outcomes name, as ScienceGraph matched them in trial-tests-2026-11-12-0.2.1.

None in this release.

Data dates

The day each source was copied for this release.

ClinicalTrials.gov: 2026-11-12; ClinicalTrials.gov
Results, from AACT: 2026-03-23; AACT
NIH grant links: 2026-11-13; NIH RePORTER

Sources 3

ClinicalTrials.gov's posted results, through CTTI's AACTFreely available. Acknowledgement requested
ClinicalTrials.govNo license stated
NIH RePORTER's clinical studies and project filesPublic domain

Each source's terms

ClinicalTrials.gov's posted results, through CTTI's AACTClinicalTrials.gov data via Aggregate Analysis of ClinicalTrials.gov (AACT), CTTI. CTTI makes its materials freely available and requests acknowledgement. https://aact.ctti-clinicaltrials.org/documentation/299
ClinicalTrials.govnone stated
NIH RePORTER's clinical studies and project filesPublic domain (NIH RePORTER)

ClinicalTrials.gov's data carry an international copyright outside the United States: https://clinicaltrials.gov/about-site/terms-conditions.

For software

Read this trial from software.

The record and each of its lists are JSON, twenty rows a page. No key.

GET https://conductscience.org/api/trials/v1/NCT01639872

GET https://conductscience.org/api/trials/v1/NCT01639872/events?page=2

API reference For AI assistants