From the FDA Drug Label
DOSAGE AND ADMINISTRATION Starting Dose: 12.5 mg once daily or twice daily. (2.2) Use cautious titration and divided dosage schedule. (2.2,5. 3) Titration: increase the total daily dosage in increments of 25 mg to 50 mg per day, if well-tolerated. (2.2) Target dose: 300 mg to 450 mg per day, in divided doses, by the end of 2 weeks. (2.2) Subsequent increases: increase in increments of 100 mg or less, once or twice weekly. (2.2) Maximum daily dose: 900 mg (2. 2)
The appropriate dosing of Clozapine (Clozaril) for schizoaffective disorder is:
- Starting dose: 12.5 mg once daily or twice daily
- Target dose: 300 mg to 450 mg per day, in divided doses, by the end of 2 weeks
- Maximum daily dose: 900 mg
- Titration: increase the total daily dosage in increments of 25 mg to 50 mg per day, if well-tolerated, with subsequent increases in increments of 100 mg or less, once or twice weekly 1
From the Research
Dosing Regimens for Clozapine in Schizoaffective Disorder
The appropriate dosing of Clozapine (Clozaril) for schizoaffective disorder can be considered based on the following evidence:
- A study published in 2024 2 found that clozapine significantly reduced symptoms of mania and depression in patients with refractory schizoaffective disorder, with a mean daily dose not specified.
- Another study from 2024 3 compared once-daily and divided dosing regimens of clozapine in patients with treatment-resistant schizophrenia or schizoaffective disorder, and found that once-daily dosing was associated with lower clinical symptom severity and better functioning.
- A 2023 study 4 explored the impact of clozapine dosing frequency, dose level, and pharmacological augmentation on clinical, social, and cognitive outcomes in patients with treatment-resistant schizophrenia, and found that patients receiving a lower daily dose (≤300 mg/day) had better cognitive functions.
Comparison of Different Dose Regimens
Comparing different dose regimens of clozapine:
- A 2017 systematic review 5 found no evidence of effect on mental state between standard, low, and very low dose regimes, but noted that the evidence available was generally of low or very low quality.
- A 2008 randomized, double-blind study 6 compared the efficacy and tolerability of high-dose olanzapine and clozapine in patients with treatment-resistant schizophrenia or schizoaffective disorder, and found that clozapine (mean dose, 564 mg/day) was equivalent to high-dose olanzapine in terms of psychopathology improvement.
Key Findings
Key findings related to clozapine dosing in schizoaffective disorder include:
- Once-daily dosing regimens may be a viable option for selected patients 3.
- Lower daily doses (≤300 mg/day) may be associated with better cognitive functions 4.
- The evidence for optimal dosing is generally of low or very low quality, and more studies are needed to validate findings and report on long-term outcomes 5.