Fluoxetine
| Evidence Level: L3 | Predicted Indications: 10 |
Table of Contents
Fluoxetine: From Depression and Anxiety Disorders to Schizotypal Personality Disorder
One-Sentence Summary
Fluoxetine is a selective serotonin reuptake inhibitor (SSRI), originally used for depression, anxiety disorders, obsessive-compulsive disorder and bulimia nervosa. The TxGNN model predicts it may be effective for schizotypal personality disorder, but there are currently no registered clinical trials and only a small body of directly relevant literature (one 22-patient open-label study from 1991 plus reviews), so the evidence is limited.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Anxiety disorder, neurotic disorder, dysthymic disorder, bipolar disorder, unipolar and endogenous depression, major depressive disorder, bulimia nervosa, obsessive-compulsive disorder (from the knowledge graph; the Singapore licence records contain no indication text) |
| Predicted New Indication | Schizotypal personality disorder |
| TxGNN Prediction Score | 99.92% |
| Evidence Level | L3 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 7 |
| Recommended Decision | Hold (research question only) |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available. Based on known information, fluoxetine is an SSRI whose efficacy in depression, anxiety and obsessive-compulsive disorder is well established. Mechanistically, serotonergic modulation may reduce affective instability and the obsessive and anxious features that overlap with schizotypal traits.
The strongest direct support is a 1991 prospective, non-blind 12-week study of 22 patients with borderline or schizotypal personality disorder. It reported significant reductions in self-injury and in Hopkins Symptom Checklist scores, and the authors called for controlled trials. A 1998 review of psychopharmacologic treatment in these disorders concluded that there is no agent of choice, and that different drug classes may help selected patients depending on symptom presentation.
There is also a safety signal: a 1998 case report describes transient psychosis with psychogenic polydipsia in a schizotypal patient taking fluoxetine. The high TxGNN score therefore remains a hypothesis rather than confirmed efficacy.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 1853957 | 1991 | Open-label study | Am J Psychiatry | 22 borderline/schizotypal patients on fluoxetine for 12 weeks; significant reductions in self-injury and symptom scores; controlled trials recommended |
| 9448667 | 1998 | Clinical outcome review | J Clin Psychiatry | No agent of choice for borderline or schizotypal personality disorder; benefit depends on symptom presentation |
| 29955451 | 2016 | Review | Ment Health Clin | Pharmacologic treatment of cluster A personality disorders |
| 8227492 | 1993 | Review | J Clin Psychopharmacol | Conceptual framework and efficacy data for medications in personality disorders |
| 12214786 | 2002 | Review | Psychol Med | Personality disorder diagnoses in depressed outpatients before and after fluoxetine treatment (indirect) |
| 15209835 | 2004 | Cohort | Aust N Z J Psychiatry | Personality traits and treatment outcome in bipolar II disorder versus major depression (indirect) |
| 9664779 | 1998 | Case report | Psychosomatics | Transient psychosis with psychogenic polydipsia in a schizotypal patient taking fluoxetine (safety signal) |
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN03027P | PROZAC CAPSULE 20 mg | Capsule | Not stated in the available records |
| SIN09317P | APO-FLUOXETINE CAPSULE 10 mg | Capsule | Not stated in the available records |
| SIN09318P | APO-FLUOXETINE CAPSULE 20 mg | Capsule | Not stated in the available records |
| SIN12311P | FLUOXETINE-TEVA 20 MG CAPSULES | Capsule | Not stated in the available records |
| SIN11954P | PROCTIN CAPSULE 20 mg | Capsule | Not stated in the available records |
Seven valid single-ingredient licences are registered in total, all oral capsules.
Safety Considerations
- Disease-level contraindication signals (knowledge graph, not label text): Conditions linked to fluoxetine include bipolar disorder and major affective disorder, epilepsy, liver failure/liver disease and cirrhosis, diabetes and diabetic ketoacidosis, hyperglycemia, neutropenia and agranulocytosis, blood coagulation disease, orthostatic and other hypotensive disorders, benign prostatic hyperplasia, hyperlipidemia and hypertriglyceridemia, obesity, stroke and cerebrovascular disorders, and myocardial infarction. These should be verified against the package insert.
- Drug Interactions: 100 interactions were found. Major-level examples include bupropion, lorcaserin, diethylpropion, dolasetron, palonosetron, eliglustat and cisapride. Moderate-level examples include famotidine, loperamide, morphine, acetylsalicylic acid, clarithromycin and chlorpropamide.
- Literature safety signal: Transient psychosis with polydipsia in a schizotypal patient on fluoxetine (1998 case report).
Please refer to the package insert for warnings and contraindications.
Conclusion and Next Steps
Decision: Hold (research question only)
Rationale: The TxGNN score is very high, but direct evidence for schizotypal personality disorder is limited to one small, non-blind study from 1991 and general reviews that identify no agent of choice. There are no registered trials, and a case report raises a psychosis-related safety signal in this population.
To proceed, the following is needed:
- A randomized, placebo-controlled trial of fluoxetine in schizotypal personality disorder
- Package insert warnings and contraindications from HSA
- Mechanism of action data
- Safety review for psychotic-spectrum patients, including the polydipsia/psychosis case report
Other predicted indications (for reference):
- Phobic disorder (L1, Proceed with Guardrails): a completed Phase 3 trial in childhood social phobia (NCT00043537, n=139) plus reviews and meta-analyses support SSRI use. Whether fluoxetine was the pharmacologic arm needs verification, pediatric suicidality warnings apply, and novelty is limited because anxiety disorders are already an indication.
- Agoraphobia, manic bipolar affective disorder, melancholia (L2, Research Question): these overlap with existing indications. Evidence for agoraphobia is mostly panic disorder studies. The bipolar evidence concerns the depressive phase, not mania, and antidepressant monotherapy in mania carries a switching risk. Melancholia lacks subtype-specific data.
- Schizoid, paranoid and histrionic personality disorders, benign paroxysmal torticollis of infancy, Ohdo syndrome (L4–L5, Hold): prediction only, with no relevant fluoxetine-specific evidence.
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.