Switching clozapine dosing from twice daily to once daily for schizophrenia

Switching From Twice-Daily to Once-Daily Clozapine Dosing in Schizophrenia: A Pilot, Double-Blind, Randomized Controlled Trial

Phase 4 Interventional Centre for Addiction and Mental Health · NCT02639702

This study is testing if switching people with schizophrenia from taking clozapine twice a day to once a day can still be effective and easier for them to manage.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment30 (estimated)
Ages18 Years and up
SexAll
SponsorCentre for Addiction and Mental Health Academic / other
Locations1 site (Toronto, Ontario)
Trial IDNCT02639702 on ClinicalTrials.gov

What this trial studies

This clinical trial aims to evaluate the efficacy and tolerability of switching patients with schizophrenia from a twice-daily to a once-daily dosing regimen of clozapine. The study will be a pilot, double-blind, randomized controlled trial involving patients who have been on a stable twice-daily clozapine regimen for at least three months. By comparing the outcomes of the two dosing schedules, the trial seeks to determine if once-daily dosing is a viable alternative without compromising treatment effectiveness. The findings could provide insights into optimizing clozapine administration for better patient adherence and comfort.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18 and older diagnosed with schizophrenia or schizoaffective disorder who have been stable on a twice-daily clozapine regimen for at least three months.

Not a fit: Patients with significant medical or neurological illnesses, or those who are pregnant or lactating, may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to a more convenient dosing schedule for patients, potentially improving adherence and quality of life.

How similar studies have performed: Previous studies have shown that once-daily dosing of other antipsychotics is effective, suggesting potential for success in this novel approach with clozapine.

Eligibility criteria

Show full inclusion / exclusion criteria
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

Where this trial is running

Toronto, Ontario

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions SchizophreniaSchizoaffective DisorderClozapineDosingOnce dailyRegimen
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.