Recruiting

Clozapine

Sponsor:

Centre for Addiction and Mental Health

Code:

NCT02639702

Conditions

Schizophrenia

Schizoaffective Disorder

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Interventions

Clozapine

Study Details

Brief summary:

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.

Conditions

Schizophrenia

Schizoaffective Disorder

Study ID

NCT02639702

Start date

Oct 15, 2016

Status verified date

Aug, 2026

Completion date

Dec 31, 2027

Anticipated

Primary completion date

Sep 30, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18+

Healthy Volunteers: Not accepted

Inclusion Criteria:

  • Diagnosed with schizophrenia or schizoaffective disorder based on DSM-IV criteria
  • Outpatient status
  • Ages 18 years or older
  • Has received clozapine twice a day, one of which is in the evening/bedtime, at the same dose and dosing regimen for at least 3 months
  • Fluent in English and competent to provide written informed consent

Exclusion Criteria:

  • Having significant medical or neurological illnesses
  • Pregnant or lactating

Study Design

Enrollment

30 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Treatment

Interventions and Outcome Measures

Arms

experimental: Switch group

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.

no intervention: Maintenance group

Participants will continue to take clozapine twice daily throughout the study period.

Interventions

Clozapine

Switching from twice-daily to once-daily clozapine dosing regimen

Primary outcome measure

  • Brief Psychiatric Rating 18 item Scale (BPRS 18 item scale) [ Time Frame: 0 and 12 weeks ]

Central Contacts and Locations

Central contacts

Locations

Centre for Addiction and Mental Health

Recruiting

Toronto, Ontario, Canada, M5T 1R8

Contacts

Principal Investigator:

Gary Remington, MD, PhD

More Information

Sponsor

Centre for Addiction and Mental Health

Last update posted

Aug 25, 2026

Last verified

Aug, 2026

Keywords

  • Clozapine
  • Dosing
  • Once daily
  • Regimen
  • Schizophrenia

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by Centre for Addiction and Mental Health on 2026-08-25.