Flunarizine

證據等級: L5

預測適應症: 10 個

Flunarizine: From Vertigo to Migraine Disorder

One-Sentence Summary

Flunarizine is a selective calcium channel blocker traditionally used for the prevention of vertigo and vestibular disorders across many countries, though it is not currently registered in Singapore. The TxGNN model predicts it may be effective for Migraine Disorder — a prediction strongly corroborated by existing pharmacological and clinical evidence, with 19 clinical trials and 20 publications currently supporting this direction.

Quick Overview

Item	Content
Original Indication	Vertigo (traditional use established in multiple countries; no Singapore HSA registration on file)
Predicted New Indication	Migraine Disorder
TxGNN Prediction Score	99.12%
Evidence Level	L1
Singapore Market Status	✗ Not marketed
Number of Registrations	0
Recommended Decision	Proceed with Guardrails

Why is This Prediction Reasonable?

Flunarizine is a disubstituted piperazine selective calcium channel blocker with a rich multi-target pharmacological profile. Its primary mechanism involves blocking voltage-gated calcium channels — particularly T-type channels — which suppresses cortical spreading depression (CSD), the electrophysiological cascade underlying migraine aura and the key trigger for headache onset. By preventing CSD propagation, Flunarizine simultaneously reduces neurogenic inflammation at trigeminal nerve terminals, including the release of substance P and CGRP that drive the characteristic throbbing pain of migraine attacks. Additional mechanisms amplify this benefit: its H1 receptor antagonism inhibits mast cell degranulation within the trigeminal vascular system, its weak D2 antagonism modulates central pain gating circuits, and its cerebrovascular effects improve ischaemic components of the migraine cycle.

These converging mechanisms make the connection between Flunarizine's known use in vertigo and its efficacy in migraine biologically coherent. Vertigo and migraine share considerable overlapping pathophysiology — both involve abnormal calcium-dependent neuronal hyperexcitability and trigeminal vascular dysregulation. This mechanistic overlap is clinically expressed in vestibular migraine, one of the most common causes of episodic vertigo, which is effectively treated by Flunarizine in clinical practice. The TxGNN model's high prediction score (99.12%) thus reflects genuine mechanistic plausibility rather than coincidence.

Critically, this is not a speculative prediction: Flunarizine already carries the designation of first- or second-line migraine prophylactic in multiple authoritative international guidelines. The Canadian Headache Society (2012), the American Academy of Neurology and American Headache Society joint pediatric guideline (2019), and the European Headache Federation's 2023 meta-analysis all endorse Flunarizine for migraine prevention. The EHF analysis explicitly characterises it as "a repurposed, first- or second-line treatment for migraine prophylaxis," reflecting decades of accumulated evidence. Singapore's lack of registration represents a market access gap rather than any deficiency in the underlying evidence base.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT02639598	Phase 4	Completed	62	Head-to-head RCT: Flunarizine 10 mg/day vs. Topiramate 50 mg/day for chronic migraine prophylaxis; explored efficacy of Flunarizine as a direct alternative to Topiramate in a difficult-to-treat population
NCT03712917	N/A	Completed	120	Three-arm parallel RCT comparing Greater Occipital Nerve Block, Topiramate, and Flunarizine in episodic migraine; directly measured post-treatment VAS scores and attack frequency reduction with a dedicated Flunarizine arm
NCT07354126	N/A	Recruiting	44	Head-to-head Flunarizine vs. Propranolol in children aged 8–15 with migraine, using the PedMIDAS disability scale; designed to address the evidence gap in the paediatric population
NCT04064814	Phase 4	Completed	60	Add-on alpha-lipoic acid versus Flunarizine monotherapy for adolescent migraine prophylaxis; Flunarizine served as the active comparator backbone, providing extractable single-agent efficacy data in adolescents
NCT07203248	N/A	Not Yet Recruiting	2,000	Large real-world study comparing CGRP-targeted medications vs. traditional preventives (including Flunarizine) for vestibular migraine in Chinese patients; expected to provide comparative effectiveness data highly relevant to Asian populations
NCT00752466	Phase 1	Completed	75	Open-label pharmacokinetic drug interaction study of Flunarizine and Topiramate during mono- and concomitant therapy; confirmed no clinically significant PK interaction and characterised safety profile in a migraine-relevant population
NCT06499116	Phase 4	Not Yet Recruiting	460	PREMI Study: pragmatic multicentre RCT comparing amitriptyline, Flunarizine, topiramate, and propranolol as first-line migraine preventives in primary care; will provide head-to-head comparative effectiveness in a real-world setting
NCT06162819	N/A	Unknown	84	Flunarizine vs. Amitriptyline for migraine prophylaxis; comparing attack frequency and VAS pain scores in patients with ≥3 attacks/month at a tertiary care hospital in Pakistan
NCT00740259	Phase 4	Completed	70	Flunarizine vs. Haloperidol as antipsychotic (off-target study); incidentally provides long-term Flunarizine safety data, including incidence of extrapyramidal symptoms and weight changes relevant to risk characterisation
NCT04766762	N/A	Unknown	96	Acupuncture vs. Flunarizine hydrochloride for migraine without aura using the Regulating Ying and Wei method; Flunarizine cited as the standard-of-care pharmacological comparator for vasospasm relief

Literature Evidence

PMID	Year	Type	Journal	Key Findings
37723437	2023	Meta-Analysis	Journal of Headache and Pain	European Headache Federation critical re-appraisal and meta-analysis of Flunarizine for migraine prophylaxis; concluded Flunarizine is a repurposed first- or second-line preventive with established efficacy supported by pooled RCT data
40553594	2025	Systematic Review + Meta-Analysis	Journal of the Association of Physicians of India	Comparative systematic review and meta-analysis of amitriptyline vs. propranolol vs. Flunarizine for migraine prophylaxis; assessed relative efficacy and safety across three commonly used preventive agents
39388181	2024	Network Meta-Analysis	JAMA Network Open	Network meta-analysis of preventive medications in paediatric migraine; evaluated comparative efficacy and safety of pharmacological interventions, including Flunarizine, across children and adolescents
31413170	2019	Practice Guideline	Neurology	AAN and American Headache Society updated practice guideline for pharmacologic migraine prevention in the paediatric population; evidence-based recommendations with and without cognitive behavioural therapy
22683887	2012	Clinical Guideline	Canadian Journal of Neurological Sciences	Canadian Headache Society guideline for episodic migraine prophylaxis; assists practitioners in selecting appropriate preventive medication based on current evidence and expert consensus
39365169	2024	Systematic Review	Health Technology Assessment	Systematic review with economic modelling comparing clinical effectiveness and cost-effectiveness of preventive drugs for chronic migraine in adults; provides timely context against expensive CGRP monoclonal antibodies
33350223	2020	Systematic Review + Meta-Analysis	China Journal of Chinese Materia Medica	Systematic review and meta-analysis of RCTs comparing acupuncture vs. Flunarizine hydrochloride in migraine treatment; searched 7 major databases (CNKI, VIP, WanFang, CBM, Cochrane, EMbase, MEDLINE) up to January 2020
30428122	2019	RCT	Acta Neurologica Scandinavica	RCT evaluating efficacy and safety of Flunarizine combined with transcutaneous supraorbital neurostimulation (tSNS) vs. either treatment alone; demonstrated additive benefit of combination approach for migraine prophylaxis
39324692	2024	Review	Expert Review of Neurotherapeutics	Overview of current and emerging treatments for vestibular migraine, including Flunarizine; particularly relevant given mechanistic and clinical overlap between vestibular disorders and migraine
25676133	2015	Review	Expert Opinion on Drug Safety	Comprehensive review of drug safety and tolerability in prophylactic migraine treatment; characterises Flunarizine's adverse effect profile including extrapyramidal effects, weight gain, and depression risk relevant to long-term use

Singapore Market Information

Flunarizine currently has no HSA registration in Singapore. There are no approved product licences on file, and the drug is not commercially marketed.

Flunarizine is registered and widely used in Japan, across European Union member states, Canada, Taiwan, Hong Kong, and multiple other Asian markets for migraine prophylaxis and/or vertigo. Its absence from the Singapore market represents a regulatory gap rather than a safety or efficacy concern, and a registration application based on existing international dossiers (e.g., EMA or TGA approval packages) would be the appropriate next step.

Safety Considerations

Please refer to the package insert for safety information.

The broader literature highlights several well-characterised safety signals that should inform any Singapore registration application: sedation and somnolence (common, particularly at treatment initiation), weight gain, depressive episodes (requiring monitoring in patients with a history of depression), and extrapyramidal symptoms including drug-induced parkinsonism (primarily with prolonged use or in elderly patients). These findings are documented in NCT00740259, PMID 25676133, and the EHF meta-analysis (PMID 37723437). Formal safety data — including package insert warnings and contraindications from registered markets — should be retrieved and reviewed before proceeding.

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: Flunarizine has an exceptionally robust evidence base for migraine prophylaxis, including multiple completed head-to-head RCTs against established agents (Topiramate, Propranolol, Amitriptyline), endorsement in three major international guideline bodies (Canadian Headache Society, AAN, EHF), and a TxGNN L1 prediction score reflecting mechanistic consistency. The primary barrier is regulatory — the drug is unregistered in Singapore — rather than any deficiency in clinical evidence.

To proceed, the following is needed:

Initiate HSA registration pathway using existing international approval dossiers (EMA, TGA, or Health Canada) as the basis for a Drug Registration submission
Retrieve formal package insert documents from registered markets to characterise key warnings, contraindications, and drug interaction profiles (currently data gaps DG001 and DG002)
Obtain formal mechanism of action documentation from DrugBank or published pharmacology literature to complete the evidence dossier
Develop a Risk Management Plan addressing extrapyramidal symptom monitoring, weight management, and depression screening for Singapore patients
Map the competitive landscape: assess positioning of Flunarizine against currently registered Singapore migraine prophylactics (propranolol, topiramate, amitriptyline, CGRP inhibitors) to define the target patient population
Monitor outcomes from NCT07354126 (paediatric) and NCT07203248 (vestibular migraine, Asian cohort) for population-specific evidence directly applicable to Singapore
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.