Triprolidine
| Evidence Level: L4 | Predicted Indications: 10 |
Table of Contents
Triprolidine: From Allergic Rhinitis to Allergic Urticaria
One-Sentence Summary
Triprolidine is a first-generation H1-receptor antihistamine, originally used for allergic and vasomotor rhinitis, the common cold, allergic conjunctivitis and urticaria. The TxGNN model predicts it may be effective for allergic urticaria, but there are 0 clinical trials and only 2 indirect publications supporting this direction. Allergic urticaria largely overlaps with an indication triprolidine already has, so this is arguably not a true repurposing.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Allergic rhinitis (other listed indications: vasomotor rhinitis, common cold, atopic/papillary/vernal conjunctivitis, urticaria, angioedema) |
| Predicted New Indication | Allergic urticaria |
| TxGNN Prediction Score | 99.99% |
| Evidence Level | L4 |
| Singapore Market Status | ✓ Marketed |
| Number of Registrations | 11 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism of action data is not available. Based on known information, triprolidine is a first-generation H1-receptor antagonist. Its efficacy in allergic rhinitis and other histamine-driven conditions is established, and mechanistically it may be applicable to allergic urticaria.
Histamine release from activated mast cells is the core driver of wheal and itch in allergic urticaria. Blocking H1 receptors is therefore a rational approach. Triprolidine's existing indications already include urticaria, so the high prediction score (99.99%) probably reflects this close overlap rather than a new therapeutic discovery.
Other top predictions follow a similar pattern. Cold urticaria, autoimmune urticaria and aquagenic urticaria are urticaria subtypes where H1 antagonism is plausible. Nasal cavity disease, pharyngitis and acute laryngopharyngitis overlap with existing upper-airway indications. Predictions such as rosacea conjunctivitis, recalcitrant atopic dermatitis and atopic IgE responsiveness have weak mechanistic fit, because histamine is not the main driver of these conditions.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 2568212 | 1989 | Review | Clinical Pharmacy | Reviews nonsedating H1 antagonists (terfenadine, astemizole, loratadine, acrivastine). Acrivastine is a metabolite-derived relative of triprolidine. This is class-level information with no triprolidine-specific data. |
| 14283425 | 1965 | Experimental study | British Journal of Dermatology | Examines the skin response to ultraviolet radiation with triprolidine. It is not a trial in allergic urticaria. |
Literature for other predicted indications is also indirect:
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 2901993 | 1988 | RCT | Dermatologica | Double-blind crossover trial in 18 patients with cold urticaria. Acrivastine (a triprolidine derivative) and cyproheptadine reduced wheal area versus placebo, and acrivastine was more effective. Triprolidine itself was not tested. |
| 6377256 | 1984 | RCT | Pediatric Infectious Disease | 142 children with purulent nasopharyngitis received cephalexin alone or with pseudoephedrine/triprolidine. Its relevance to triprolidine efficacy in pharyngitis is uncertain. |
Singapore Market Information
Eleven valid single-ingredient registrations are on file. The approved indication text is not recorded for any of them. The five main ones are listed below.
| Authorization Number | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| SIN09453P | DECONDINE TABLET | Film-coated tablet | Not recorded |
| SIN03116P | FEDAC TABLET | Tablet | Not recorded |
| SIN03927P | ACTIMIN TABLET | Tablet | Not recorded |
| SIN10474P | ACTIHIST SYRUP | Syrup | Not recorded |
| SIN03181P | DECONDINE SYRUP | Syrup | Not recorded |
Other registrations include syrups (BEACTAFED, PEACEF, FEDAC, BEACTAFED CO) and elixir-type linctuses (FEDAC COMPOUND, COUGH-EN). Available forms are oral tablets, syrups and elixirs.
Safety Considerations
- Contraindications flagged by the knowledge graph (not label text): Hypertension, epilepsy, kidney disease, liver disease, pancreatitis, gallbladder disease, hypothyroidism, peptic ulcer disease, inflammatory bowel disease, diabetes mellitus and diabetic ketoacidosis, benign prostatic hyperplasia, ocular hypertension, coronary artery disease, myocardial infarction, atherosclerosis, heart conduction disease and sudden cardiac arrest, among others. Some of these likely reflect combination products containing decongestants.
- Drug Interactions: 100 interactions were found in total. The most significant are Major interactions with potassium citrate and potassium chloride. Many Moderate interactions involve anticholinergic agents (atropine, hyoscyamine, scopolamine, glycopyrronium, dicyclomine, trospium and others), opioids and related agents (morphine, loperamide, eluxadoline), cannabinoids (dronabinol, nabilone) and metoclopramide. These reflect additive anticholinergic and sedative effects.
Please refer to the package insert for label warnings and contraindications.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction is biologically plausible, but allergic urticaria substantially overlaps with an existing indication, so it adds little new. No clinical trials exist, and the available literature is indirect (a class review and an unrelated skin study), giving an evidence level of L4. The package insert safety review is incomplete.
To proceed, the following is needed:
- HSA package insert warnings and contraindications (a blocking gap for safety screening)
- Detailed mechanism of action data from DrugBank
- Approved indication text for the Singapore registrations, to confirm whether urticaria is already on-label
- Direct clinical evidence of triprolidine in urticaria, or a decision that the prediction is already covered by the existing indication
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.