Cyclizine
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Cyclizine: From First-Generation Antihistamine to Allergic Urticaria
One-Sentence Summary
Cyclizine is a first-generation H1 antihistamine, and the SAHPRA registration data supplied here do not record an approved indication. The TxGNN model predicts it may be effective for allergic urticaria, but there are 0 clinical trials and only 1 indirectly related publication (on solar urticaria), so this is a research question, not a treatment recommendation.
Quick Overview
| Item | Content |
|---|---|
| Predicted New Indication | Allergic urticaria |
| TxGNN Prediction Score | 99.98% |
| Evidence Level | L4 |
| South Africa Market Status | Marketed |
| Number of SAHPRA Registrations | 1 |
| Recommended Decision | Hold (research question only) |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not currently available from DrugBank. Based on general class pharmacology, cyclizine is a first-generation H1 antihistamine. H1 receptor blockade is the standard mechanism for controlling urticaria, so the prediction is biologically coherent.
The retrieved evidence is weak, however. The only paper found concerns solar urticaria, a different subtype, and supports the prediction only indirectly. No trials exist for cyclizine itself. Second-generation antihistamines are already the better-studied standard, and they cause less sedation and anticholinergic burden. That makes cyclizine an unlikely first choice even if H1 blockade is relevant.
The other nine predictions are weaker. Rhinitis is biologically coherent but has no cyclizine-specific evidence. Headache disorder has five papers, but all are indirect, and cyclizine appears mainly as an antiemetic component of ergotamine combination products. The remaining seven are either too broad, mechanistically unsupported, or not treatable indications (for example, “IgE responsiveness, atopic” is a trait).
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 8573923 | 1995 | Photobiology / diagnostic study | Dermatology (Basel) | Action spectra in solar urticaria vary between patients, and light outside the activating wavelengths can influence wheal formation. This is not a cyclizine treatment study. |
South Africa Market Information
| Registration Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| Reg. No. B769 (ACT 101) | Cyclimorph 1ml | Injection | Not stated in the available data |
Only an injectable product is registered. Urticaria is usually managed with oral agents, so route compatibility has not been assessed.
Safety Considerations
Please refer to the SAHPRA-approved Professional Information (PI) for safety information. Report adverse drug reactions to SAHPRA.
Two general concerns were noted in the evidence review. First-generation antihistamines carry sedation and anticholinergic burden. Ergot toxicity reported with ergotamine-containing migraine combinations is a concern for those products, not for cyclizine alone.
Conclusion and Next Steps
Decision: Hold (research question only)
Rationale: The 99.98% model score and the H1-antagonist mechanism make the prediction plausible. But there are no trials, the single publication is indirect, and better-tolerated antihistamines are already standard for urticaria. The evidence does not support a clinical recommendation.
To proceed, the following is needed:
- SAHPRA Professional Information, to confirm the approved indication, warnings and contraindications
- Mechanism of action data from DrugBank
- A targeted literature review of cyclizine or first-generation H1 antihistamines in chronic and allergic urticaria
- A comparison against second-generation antihistamines on efficacy, sedation and anticholinergic burden
- A route and formulation assessment, since the only registered product is an injection
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.