Pizotifen
| 證據等級: L5 | 預測適應症: 10 個 |
目錄
Pizotifen: From an Unregistered Status in Australia to Migraine Disorder (Prophylaxis)
One-Sentence Summary
Pizotifen is a serotonin (5-HT2) receptor antagonist with antihistamine and anticholinergic activity that has never been registered on Australia’s ARTG. The TxGNN model’s top-ranked prediction is Migraine Disorder (prophylaxis), supported by 1 clinical trial and 20 PubMed records — but this is not a novel hypothesis: it is pizotifen’s long-established traditional indication in other markets, and the model is effectively confirming known pharmacology rather than surfacing a new use.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not documented in this evidence pack — Pizotifen has never held an ARTG registration in Australia, so no TGA-approved indication text exists |
| Predicted New Indication | Migraine Disorder (prophylaxis) |
| TxGNN Prediction Score | 98.76% |
| Evidence Level | L2 |
| Australia Market Status | Not marketed |
| Number of ARTG Entries | 0 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Detailed formal mechanism-of-action data for pizotifen was not returned in this evidence pack (DrugBank query gap). However, the evidence collected for this candidate describes pizotifen as a 5-HT2 serotonin receptor antagonist with additional antihistamine (H1) and anticholinergic activity. This receptor profile maps directly onto the serotonin theory of migraine — cortical spreading depression and trigeminovascular sensitisation — which is the accepted rationale for 5-HT2 antagonists in migraine prophylaxis.
Importantly, the evidence pack’s own rationale for this candidate flags that migraine prophylaxis is pizotifen’s traditional, decades-old indication internationally, not a novel repurposing signal. Several of the supporting publications date from the 1970s–1990s (e.g. comparative trials against metoprolol, cyclandelate, and flunarizine), consistent with an agent whose migraine use is long-standing rather than emerging. The practical significance for Australia is different from a typical repurposing case: the open question here is not “does this mechanism plausibly extend to a new disease,” but “why is an internationally recognised migraine prophylactic absent from the ARTG,” and what would be needed to bring TGA-quality documentation (PI, safety, DDI) up to a standard suitable for local use.
Clinical Trial Evidence
| Trial Number | Phase | Status | Enrolment | Key Findings |
|---|---|---|---|---|
| NCT06158230 | Phase 2 | Unknown | 140 | Single-blind RCT comparing amitriptyline–propranolol combination vs pizotifen for migraine prophylaxis; asks whether pizotifen outperforms the combination. Status unconfirmed — completion/publication not verified. |
No ANZCTR (Australian) trial identifiers were found for this candidate.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 3986895 | 1985 | RCT | Cephalalgia | Double-blind cross-over of pizotifen (0.5mg tid) vs metoprolol (50mg bid) in 35 patients with classical/common migraine; comparable prophylactic effect. |
| 1573338 | 1992 | RCT | Journal of Medicine | Double-blind parallel trial of cyclandelate vs pizotifen in 61 evaluable migraine patients over 12 weeks; comparable efficacy and tolerance. |
| 23416816 | 2013 | RCT | Mymensingh Med J | Compared amitriptyline, pizotifen and propranolol in 90 patients; all reduced attack duration/frequency/severity with no significant between-group difference. |
| 327746 | 1977 | RCT | Acta Neurol Scand | Double-blind cross-over of placebo vs Divascan vs pizotifen (3mg/day) in 30 patients; early comparative prophylaxis data. |
| 22683887 | 2012 | Guideline | Can J Neurol Sci | Canadian Headache Society guideline for migraine prophylaxis — evidence-based medication selection framework. |
| 35190383 | 2022 | Review | Arch Dis Child | Narrative review of paediatric migraine management; notes recent large trials of propranolol, pizotifen, topiramate and amitriptyline have generally failed to show robust superiority over placebo in children. |
| 40705288 | 2025 | Cohort | Neurology India | Retrospective study of pizotifen efficacy and tolerance in children with migraine in a Brazilian Amazon cohort. |
| 25217187 | 2014 | Review | Eur J Clin Pharmacol | Review of anti-migraine drug safety in breastfeeding, including pizotifen. |
| 2891428 | 1988 | Review | CMAJ | General migraine therapy review covering beta-blockers, calcium-channel blockers and other prophylactic agents. |
| 6398056 | 1984 | Review | Aust NZ J Med | Review of serotonin antagonists across carcinoid syndrome, migraine, nociception and vascular disease. |
Note: several additional PubMed records were returned for this candidate but were not yet classified by study type (pending) in the evidence pack, so they are omitted from this table rather than guessed at.
Australia Market Information
Pizotifen is not currently registered on the ARTG (0 entries). No Australian Product Information, brand name, or approved indication text exists for this drug at this time.
Safety Considerations
No safety data (key warnings, contraindications, or drug–drug interactions) were returned for pizotifen in this evidence pack, and because it is not TGA-registered, no Australian Product Information exists to consult. Any clinical use would need to rely on reference-market documentation (e.g. UK/EU SmPC) pending formal Australian evaluation — please do not treat the absence of flagged warnings here as evidence of a clean safety profile.
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: The mechanism (5-HT2 antagonism) and a modest body of older comparative RCTs support pizotifen’s efficacy in migraine prophylaxis, and this is an internationally well-established use rather than a speculative new indication. However, the complete absence of Australian registration, PI, MOA documentation, and DDI/contraindication data means this cannot proceed without substantial regulatory and safety work.
To proceed, the following is needed:
- Formal DrugBank/manufacturer MOA documentation (currently a data gap)
- TGA/ARTG registration pathway assessment, since pizotifen has never been marketed in Australia
- Reference-market Product Information (safety, contraindications, DDI) as a stopgap pending local approval
- Confirmation of NCT06158230’s completion status and any resulting publication
- Explicit framing for stakeholders that this is a confirmatory finding of an established indication, not a novel repurposing signal
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.