Clozapine
| Evidence Level: L5 | Predicted Indications: 10 |
Table of Contents
Clozapine: From Treatment-Resistant Psychosis to Manic Bipolar Affective Disorder
One-Sentence Summary
Clozapine is an atypical antipsychotic marketed in Singapore as tablets, and it is established for treatment-resistant psychotic illness. The TxGNN model predicts it may be effective for manic bipolar affective disorder. The data compiled for this report show 1 completed Phase 2 trial specific to treatment-resistant mania, a completed Phase 3 trial in the broader bipolar disorder group, and 20 publications (including a systematic review and meta-analysis) supporting this direction.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not stated in the Singapore licence records (approved indication text is blank for all 4 registrations). Clozapine is known clinically as a treatment for treatment-resistant schizophrenia |
| Predicted New Indication | Manic bipolar affective disorder |
| TxGNN Prediction Score | 99.95% |
| Evidence Level | L2 (one completed Phase 2 RCT for mania; the broader bipolar disorder group reaches L1) |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 4 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available in the compiled data. Based on the known pharmacology, clozapine blocks several receptors: dopamine D2/D4, serotonin 5-HT2A, muscarinic, adrenergic and histamine receptors. This broad profile is what makes it effective in treatment-resistant psychosis.
Mania and psychosis share dopaminergic and serotonergic pathways, and many patients with bipolar disorder do not respond to first-line mood stabilisers or cannot tolerate them. Clozapine's multi-receptor activity plausibly explains antimanic and mood-stabilising effects in refractory cases. The high TxGNN score is consistent with the clinical literature, which supports use in treatment-refractory bipolar illness.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrollment | Key Findings |
|---|---|---|---|---|
| NCT00029458 | Phase 2 | Completed | 42 | Double-blind study of clozapine in treatment-resistant mania; results not summarised in the data compiled |
| NCT00036582 | Phase 3 | Completed | 116 | Clozapine vs placebo in treatment-refractory bipolar disorder in children and adolescents (bipolar disorder group) |
| NCT02562287 | Phase 4 | Unknown | 54 | Clozapine vs olanzapine, quetiapine or risperidone in treatment-resistant bipolar disorder |
| NCT04580134 | Phase 4 | Recruiting | 524 | Randomised, double-blind study of clozapine response in B-SNIP Biotype-1 psychosis, biomarker-oriented |
| NCT05603104 | Phase 3 | Recruiting | 1254 | Intensified pharmacological treatment after first-line failure in schizophrenia, depression and bipolar depression; no results yet |
| NCT06011460 | N/A | Enrolling by invitation | 30 | Observational registry of clozapine adverse events in bipolar disorder |
| NCT07047651 | Phase 4 | Active, not recruiting | 84 | Recovery-oriented programmes added to pharmacotherapy in treatment-resistant bipolar disorder (indirect) |
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 32182485 | 2020 | Systematic review/meta-analysis | J Psychiatr Res | Assessed clinical efficacy and adverse effects of clozapine in bipolar disorder |
| 25346322 | 2015 | Systematic review | Bipolar Disord | Efficacy and safety of clozapine in treatment-resistant bipolar disorder |
| 41192460 | 2025 | Cohort and meta-analysis | Lancet Psychiatry | Transdiagnostic effectiveness and safety of clozapine versus other antipsychotics across psychiatric disorders |
| 33719158 | 2021 | Review | Bipolar Disord | Summary of what is known about clozapine in bipolar disorder and next steps |
| 33460070 | 2020 | Review | Acta Psychiatr Scand | Evidence-based options for managing bipolar mania |
| 16432528 | 2006 | Review | Mol Psychiatry | Treatment-resistant bipolar disorder: gaps in response to first-line treatments |
| 11280956 | 2001 | Review | Bull Menninger Clin | Newer treatments for bipolar disorder rest mostly on case reports and case series |
| 10682225 | 2000 | Case series/review | Clin Neuropharmacol | 36 patients on ECT plus clozapine; 67% benefited, with adverse reactions in 16.6% |
| 41262335 | 2025 | Modelling study | Drug Des Devel Ther | Clozapine drug interactions and individualised dosing in bipolar disorder |
| 31567198 | 2021 | Observational | Am J Ther | Rapid clozapine titration in schizophrenia and bipolar disorder |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN11384P | CLOZAPINE TABLET 100 mg | Tablet | Not stated in licence records |
| SIN11497P | CLOZAPINE TABLET 25 mg | Tablet | Not stated in licence records |
| SIN07235P | CLOZARIL TABLET 100 mg | Tablet, film coated | Not stated in licence records |
| SIN07234P | CLOZARIL TABLET 25 mg | Tablet, film coated | Not stated in licence records |
Safety Considerations
- Disease associations flagged in the knowledge graph (not label text): neutropenia, agranulocytosis, leukopenia, epilepsy, liver and gallbladder disease, diabetes mellitus, hyperglycaemia, diabetic ketoacidosis, hyperlipidaemia, obesity, coronary artery disease, stroke and cerebrovascular disorders, pulmonary embolism, sudden cardiac arrest, heart conduction disease, orthostatic and other hypotensive disorders, respiratory failure, angle-closure glaucoma, paralytic ileus and benign prostatic hyperplasia.
- Drug Interactions: 100 interactions were recorded. Major-level examples include bupropion, morphine and potassium citrate. Moderate-level examples include antidiabetic drugs (metformin, pioglitazone, acarbose, alogliptin, canagliflozin, chlorpropamide, albiglutide), anticholinergic agents (atropine, hyoscyamine, glycopyrronium), famotidine, cimetidine, omeprazole, epinephrine, loperamide, bisacodyl and lorcaserin.
- Literature-reported risks: myocarditis and cardiomyopathy, seizures, metabolic syndrome and weight gain, and somnolence. Blood monitoring for agranulocytosis is a central requirement.
Please also refer to the package insert, as label warnings and contraindications were not available in the data compiled.
Other Predicted Indications (Summary)
| Predicted Indication | TxGNN Score | Evidence Level | Recommendation |
|---|---|---|---|
| Tourette syndrome | 99.91% | L4 | Hold (case-level reports only; weak mechanistic fit) |
| Trichotillomania | 99.90% | L5 | Hold (no studies retrieved) |
| Schizophreniform disorder | 99.69% | L2 | Proceed with Guardrails (trials mostly broader schizophrenia studies) |
| Bipolar disorder | 99.62% | L1 | Proceed with Guardrails |
| Major affective disorder | 99.48% | L2 | Research Question (indirect support only) |
| ADHD | 99.31% | L4 | Hold (indirect and preclinical data only) |
| ADHD, inattentive type | 99.21% | L5 | Hold (no studies retrieved) |
| Psychotic disorder | 99.12% | L1 | Proceed with Guardrails |
| Malan overgrowth syndrome | 99.02% | L5 | Hold (no studies retrieved) |
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: A completed double-blind Phase 2 trial in treatment-resistant mania, a completed Phase 3 trial in treatment-refractory bipolar disorder (paediatric), and a systematic review with meta-analysis support clozapine in refractory bipolar illness. The mania-specific trial is small and its results are not summarised in the data compiled, and clozapine carries serious known risks, so use should be restricted to treatment-refractory patients under strict monitoring.
To proceed, the following is needed:
- Package insert warnings, contraindications and approved indications for the Singapore-registered products (not available in the data compiled; this is a blocking gap for safety screening)
- Detailed mechanism of action data
- Published results of NCT00029458 and the adult bipolar trials (for example NCT02562287)
- A monitoring plan covering absolute neutrophil count, cardiac (myocarditis), metabolic and seizure risk
- A drug-interaction management plan for common co-medications
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.