A Phase 4 interventional study of Clozapine in Schizophrenia and Schizoaffective Disorder, sponsored by Centre for Addiction and Mental Health. Recruiting at 1 site in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-25.
Sponsored by Centre for Addiction and Mental Health · Phase 4, Interventional, and Treatment
Among 37 studies testing clozapine in Schizophrenia — 6 open to participants now, 6 under way, none of them phase 3. Clozapine · Schizophrenia.
Among the 37 studies testing clozapine in Schizophrenia, this one is the 25th largest by planned enrollment, is one of 2 that started in 2016, is one of 21 in phase 4, and was the 24th registered.
3,563 studies on the registry are indexed under Schizophrenia; 491 are open to participants now.
Browse Schizophrenia studies →6 of the 37 studies testing clozapine in Schizophrenia are open now, in 8 countries. Recruiting first, the newest first:
Northwell Health · Sites in United States, Canada
Dr. Inge Winter · Sites in Austria, Germany, Italy and 2 more countries
New York State Psychiatric Institute · Sites in United States
University of Texas Southwestern Medical Center · Sites in United States
Jimmi Nielsen · Sites in Denmark
By country, each count listing its studies:
Clozapine: first FDA approval 1989 (CLOZARIL). What it is approved for, and how studies give it, is on its page →
Of the 331 Schizophrenia studies recruiting now, 63 (19%) set no upper age limit and 257 (78%) stop at 75 or younger; 42 take children under 18; 83 take healthy volunteers.
This study: 18 Years and older · all sexes · no healthy volunteers.
The full table on the hub →This tab as a report to print or save as PDF → With an account.
37 studies; the count open now beside each. This study's row is marked.
First in 1994; this study’s year is marked. 2 started in 2016.
This study's planned enrollment of 30 is below the median of 71 across 2,944 interventional studies indexed under Schizophrenia.
Median enrollment 41 across the 37 interventional studies. Of the 24 that completed or were terminated, 6 (25%) have results posted.
This tab as a report to print or save as PDF → With an account.
4 of 37 have an industry lead sponsor. The 10 most frequent:
Centre for Addiction and Mental Health is the lead sponsor of 339 studies on the registry; 51 are open to participants now.
57 studies in Schizophrenia by Centre for Addiction and Mental Health: 4 open now, 10 under way, none of them phase 3. Of 42 finished, 6 (14%) have results posted.
Among the 57 studies in Schizophrenia by Centre for Addiction and Mental Health, this one is the 34th largest by planned enrollment of the 51 interventional ones that give a count, is one of 6 that started in 2016, is one of 5 in phase 4, and was the 30th registered.
Centre for Addiction and Mental Health’s Schizophrenia studies by the year they started, since 1999.
2 of the studies testing clozapine in Schizophrenia that are under way reach primary completion within a year, 0 of them phase 3. Phase 3 first, then by date:
| Study | Primary completion |
|---|---|
| NCT04580134University of Texas Southwestern Medical CenterCLOZAPINE Response in Biotype-1 | 2027-04-30 |
| NCT02639702Centre for Addiction and Mental HealthSwitching From Twice-Daily to Once-Daily Clozapine Dosing in Schizophrenia | 2027-09-30 |
Among the 37 studies testing clozapine in Schizophrenia, from their registry updates:
Among Centre for Addiction and Mental Health’s 57 in Schizophrenia:
This tab as a report to print or save as PDF → With an account.
Plasma half-life has routinely been used to establish the dosing schedule of antipsychotics; for example, it is recommended that agents with a short plasma half-life be administered multiple times per day. However, to date, several randomized controlled trials (RCTs) have shown no differences in clinical outcomes between once- and twice-daily dosing of various antipsychotics, suggesting that once-daily dosing of antipsychotics is a viable option regardless of plasma half-life. This would apply to clozapine as well; however, there have been no studies comparing once-daily vs. twice-daily dosing regimens of clozapine in terms of efficacy and tolerability. To address this gap in the literature, the investigators shall conduct a pilot, double-blind, RCT to examine efficacy and tolerability following a switch to once-daily dosing regimen of clozapine in patients with schizophrenia receiving clozapine twice a day.
Plasma half-life has routinely been used to establish the dosing schedule of antipsychotics; for example, it is recommended that agents with a short plasma half-life be administered multiple times per day. To date, however, several randomized controlled trials (RCTs) have shown that once-daily dosing of antipsychotics including perphenazine, risperidone, olanzapine, quetiapine, and asenapine is comparable to twice-daily dosing in terms of efficacy and tolerability, suggesting that once-daily dosing of antipsychotics is a viable option regardless of plasma half-life.
This issue applies to clozapine as well, in that it has a relatively short plasma half-life of 12-16 hours; of note, the product monographs recommends that clozapine be administered more than once daily if the dose exceeds 200 mg/day in Canada. Despite this, in clinical practice clozapine is frequently administered once daily because of convenience and side effects such as a daytime sedation or somnolence, In support of this, a cross-sectional survey done at the investigators' own centre has revealed that clozapine was prescribed once daily in 75.1% of 676 patients, even though >200 mg/day was administered in 88.6%. However, there have been no studies comparing once-daily vs. twice-daily dosing regimens of clozapine in terms of efficacy and tolerability. To address this gap in the literature, the investigators shall conduct a pilot, double-blind, RCT to examine efficacy and tolerability following a switch to once-daily dosing regimen of clozapine in patients with schizophrenia receiving clozapine twice a day.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
DSM diagnostic criteria
The American Psychiatric Association’s manual of mental health diagnoses. DSM-5 (2013, revised as DSM-5-TR in 2022) replaced DSM-IV, and some studies still name the older edition. “Meets DSM criteria for …” means diagnosed by that edition’s diagnostic criteria, usually by a clinician in an interview.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive clozapine once daily at evening or bedtime throughout the study period. If a participant takes ≥200 mg of clozapine at a time other than evening/bedtime, half of this dose will be switched to an evening/bedtime regimen on day 0 (baseline), then another half dose will be switched on day 7 (week 1). Participants will receive placebo in place of the clozapine dose that was switched to evening/bedtime.
Drug: Clozapine
Participants will continue to take clozapine twice daily throughout the study period.
Switching from twice-daily to once-daily clozapine dosing regimen
Also known as: Clozaril
Brief Psychiatric Rating 18 item Scale (BPRS 18 item scale)
Change in BPRS total scores from baseline to 12 weeks Total scores range from 18-126, higher scores represent worse clinical outcomes: \<31 = Illness not significant \>=31 = Mildly ill \>41 = Moderately ill \>53 = Markedly ill.
Time frame: 0 and 12 weeks
Glasgow Antipsychotic Side-effect Scale for Clozapine (GASS-C)
Detect side effects related to Clozapine from baseline to 12 weeks Higher Scores indicating worse side-effects: 0-16 (absent/mild side-effects) 17-32 (moderate side-effects) 33-48 (severe side-effects)
Time frame: 0 and 12 weeks
Brief Evaluation of Psychosis Symptom Domains (BE-PSD)
Assess the overall severity of five symptom domains of BE-PSD with a total score in each domain scoring from absent to very severe (i.e. 0-6 with higher scores with worse outcomes)
Time frame: 0 and 12 weeks
Personal and Social Performance scale (PSP)
Change in patients social functioning scores from baseline to 12 weeks The PSP is a 100-point single item rating scale from 1-100, subdivided into 10 equal intervals with higher scores indicating better outcomes. The ratings are based on patient's functioning in four main areas: 1) socially useful activities, 2) personal and social relationships, 3) self-care; and 4) disturbing and aggressive behaviours.
Time frame: 0 and 12 weeks
Clinical Global Impression - Severity of Illness (CGI-S)
Assess severity of Illness in Schizophrenia CGI scores from baseline to 12 weeks Scores ranging from normal to the most ill (i.e., scores ranging from 1-7 with higher scores with illness worsening)
Time frame: 0 and 12 weeks
Brief Neurocognitive Assessment (BNA)
The BNA is a brief neurocognitive assessment that measures global cognitive impairment in patients with schizophrenia from baseline to 12 weeks. Negative Z scores (i.e., -0.5 to -2.0 ) indicate mild to severe cognitive impairment.
Time frame: 0 and 12 weeks
Subjective Well-being under Neuroleptics scale - Short form (SWNS)
Self report scale to measure well being. Study assess changes in subjective wellbeing in patients on a neuroleptic from baseline to Week 12. Higher total score indicating better outcomes
Time frame: 0 and 12 weeks
Change in the Visual Analogue Scale for Distress Associated with Symptoms (VAS-DAS) scores from baseline to 12 weeks
Assess changes in level of distress associated with symptoms from no distress to worst distress (i.e., 0-100)
Time frame: 0 and 12 weeks
Plan to share: No
Started Oct 2016 (actual). Primary completion is estimated for Sep 2027, 131 months after the start.
Of 71 non-industry phase 4 interventional studies under Schizophrenia, half reached primary completion within 48 months of starting (the median), counting those still running; a quarter within 27 and three quarters within 64. This study's planned 131 months is above that.
Counting every sponsor, half of 88 studies reached it within 39 months; a quarter within 20 and three quarters within 63.
How these figures are worked out, and which studies are left out of them.
Eligibility is decided by the study team. Share this record with your doctor or contact the team directly.
Contact study teamGet an email when the registry record changes — status, dates, results — or when someone posts here.
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Studies of the drug tested here: Clozapine
Centre for Addiction and Mental Health →