Pheniramine
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Pheniramine: From Allergic and Upper Respiratory Conditions to Allergic Urticaria
One-Sentence Summary
Pheniramine is a first-generation H1-antihistamine, originally used for allergic rhinitis, the common cold, allergic conjunctivitis, urticaria and angioedema. The TxGNN model predicts it may be effective for allergic urticaria, but this largely restates an existing indication, and 0 clinical trials and 4 publications (none providing efficacy evidence for pheniramine) are currently available.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Allergic rhinitis, vasomotor rhinitis, pharyngitis, common cold, allergic conjunctivitis, urticaria, angioedema (the Singapore licence has no approved indication text recorded) |
| Predicted New Indication | Allergic urticaria |
| TxGNN Prediction Score | 99.67% |
| Evidence Level | L4 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 1 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available. Based on known information, pheniramine is a first-generation H1-antihistamine, and its efficacy in histamine-mediated allergic conditions is well established. Mechanistically, it may be applicable to allergic urticaria, which is driven by histamine release from mast cells.
Urticaria and angioedema are already among pheniramine's known original indications. The prediction is therefore not a true repurposing finding but a restatement of existing use, which is consistent with the very high TxGNN score.
Other predicted indications, such as nasal cavity disease, acute laryngopharyngitis and cold urticaria, also overlap with existing uses. Others, such as faucial diphtheria, cervical disc degenerative disorder and anorectal stricture, have no plausible mechanistic link.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 2859711 | 1985 | Review | Zeitschrift fur Hautkrankheiten | Review of 39 trials of astemizole (not pheniramine) in hayfever, allergic rhinitis, conjunctivitis and chronic urticaria; pheniramine appears only as a comparator |
| 40324831 | 2025 | Case report | Indian Journal of Pharmacology | Loss of consciousness after concurrent intravenous pheniramine and hydrocortisone during treatment of an allergic reaction |
| 40125237 | 2025 | Case report | Cureus | Immediate hypersensitivity reaction to pheniramine in a patient with multiple drug hypersensitivity syndrome |
| 16854350 | 2006 | Case report | Allergologia et Immunopathologia | Life-threatening facial oedema after pine caterpillar ingestion that mimicked an allergic event; not related to pheniramine efficacy |
None of these publications provides efficacy evidence for pheniramine in allergic urticaria.
Singapore Market Information
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN04717P | NAPHCON-A STERILE OPHTHALMIC SOLUTION (Alcon Singapore Manufacturing Pte. Ltd.) | Solution | Not recorded |
Safety Considerations
- Contraindications flagged in the knowledge graph (these come from the TxGNN knowledge graph, not from package insert text, and need verification against the label): hypertension, liver failure and liver disease, epilepsy, insomnia, chronic obstructive pulmonary disease, bronchitis, gastric and peptic ulcer disease, gastritis, inflammatory bowel disease, kidney disease, pancreatitis, gallbladder disease, thrombocytopenia, diabetes mellitus and diabetic ketoacidosis, hyperglycemia, hypothyroidism and myxedema, psychotic and other mental disorders (including schizophreniform and schizoaffective disorder), benign prostatic hyperplasia, pyoureter, and dermatitis herpetiformis.
- Case reports: serious adverse events (loss of consciousness) and an immediate hypersensitivity reaction to pheniramine have been described.
Please refer to the package insert for key warnings and drug interaction information.
Conclusion and Next Steps
Decision: Hold
Rationale: Allergic urticaria is already within pheniramine's existing use, so this is not a genuine repurposing opportunity. No clinical trials were found, and the retrieved literature contains no efficacy data for pheniramine. The only registered Singapore product is an ophthalmic solution, which is not an obvious route for treating urticaria.
To proceed, the following is needed:
- The package insert warnings and contraindications from the HSA (currently missing and blocking safety screening)
- Mechanism of action data from DrugBank
- Confirmation of the approved indication and available systemic formulations in Singapore
- Pheniramine-specific efficacy evidence for urticaria, compared with the second-generation antihistamines that are the usual standard of care
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.