Chlorpheniramine
| Evidence Level: L5 | Predicted Indications: 1 |
Table of Contents
- Chlorpheniramine
- Pharmacist Assessment Report
- Chlorpheniramine: Histamine H1 receptor antagonist → nasal cavity disease
- One-Sentence Summary
- Quick Overview
- Why is This Prediction Reasonable?
- Clinical Trial Evidence
- Literature Evidence
- Canada Market Information
- Safety Considerations
- Conclusion and Next Steps
- Disclaimer
Chlorpheniramine: Histamine H1 receptor antagonist → nasal cavity disease
One-Sentence Summary
Chlorpheniramine is an antihistamine (histamine H1 receptor blocker) that is marketed in Canada, mostly in cold, sinus and allergy products. The TxGNN model predicts it may be effective for nasal cavity disease, but the supporting evidence is limited to 8 publications, all preclinical or mechanistic, and no registered clinical trials.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not recorded in the local data |
| Predicted New Indication | nasal cavity disease |
| TxGNN Prediction Score | 0.9953 |
| Evidence Level | L5 |
| Canada Market Status | Marketed (marketed DINs on record: at least 20) |
| Number of DINs | at least 20 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Detailed mechanism-of-action data are not available in the data compiled for this report. Chlorpheniramine is a first-generation H1 antihistamine. Blocking H1 receptors reduces histamine-driven responses in the nasal mucosa, such as runny nose, sneezing and increased vascular permeability. This is the plausible link to nasal conditions.
However, “nasal cavity disease” is a very broad term and does not define a specific repurposing question. Much of what it covers (allergic and vasomotor rhinitis) overlaps with uses chlorpheniramine already has, so it adds little as a new indication.
The retrieved studies are animal models (cat, dog, rat) of nasal congestion and allergic rhinitis. Most of them test H1/H3 antagonists in general rather than chlorpheniramine alone. One cat study suggests that relieving nasal congestion may need H3 co-blockade together with H1 blockade, so H1 antagonism alone is unlikely to address congestion. None of the studies directly examines “nasal cavity disease” in patients, so the evidence level is L5.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 10582118 | 1999 | Animal study | Am J Rhinol | In cats, combined H1 (chlorpheniramine) and H3 receptor blockade reduced the rise in nasal airway resistance caused by a mast cell degranulator |
| 10582116 | 1999 | Animal study | Am J Rhinol | Cat model of nasal congestion characterised with pressure and acoustic rhinometry |
| 12962193 | 2003 | Animal study | Am J Rhinol | Model of allergic nasal congestion in ragweed-sensitised dogs, using acoustic rhinometry |
| 12387934 | 2002 | Animal study | J Pharmacol Toxicol Methods | Non-invasive chronic dog model of nasal congestion for studying decongestant mechanisms |
| 11895194 | 2002 | Animal study | Am J Rhinol | Dog acoustic rhinometry model; nasal congestion induced by mast cell degranulation |
| 10822083 | 2000 | Animal study | Immunopharmacology | New rat model of chronic allergic rhinitis used to evaluate H1 antagonists |
| 1705288 | 1990 | Animal study | J Pharmacobio-Dyn | Brown Norway rat model of allergic rhinitis used to test antiallergic drugs |
| 2923378 | 1989 | Mechanistic study | Am Rev Respir Dis | Sources of protein in histamine-induced nasal secretions in atopic and non-atopic people |
Canada Market Information
At least 20 valid single-ingredient licences were found, and this list may be partial. The main ones are below.
| DIN | Product Name | Dosage Form | Approved Indication |
|---|---|---|---|
| 00021288 | TEVA-PHENIRAM | Not recorded | Not recorded |
| 02309440 | COLDASIDE COUGH & COLD | Not recorded | Not recorded |
| 02273330 | NYQUIL KIDS COUGH & COLD | Not recorded | Not recorded |
| 02399733 | ADVIL COLD & SINUS CONVENIENCE PACK | Not recorded | Not recorded |
| 02551667 | NYQUIL COLD & FLU ALCOHOL FREE | Not recorded | Not recorded |
Safety Considerations
- Drug Interactions: 100 interactions were found in total. Two are rated Major: potassium chloride and potassium citrate. Most others are rated Moderate, including anticholinergic drugs (atropine, dicyclomine, glycopyrronium, methscopolamine, mepenzolate), opioids and related drugs (morphine, opium, loperamide, eluxadoline), cannabinoids (dronabinol, nabilone), and bupropion, eliglustat, lorcaserin and metoclopramide.
Please refer to the package insert for warnings and contraindications.
Conclusion and Next Steps
Decision: Hold
Rationale: The prediction score is high (0.9953), but the supporting studies are animal and mechanistic work, with no clinical trials. The predicted term is too broad to define a testable question, and it largely overlaps with existing allergic and vasomotor rhinitis use.
To proceed, the following is needed:
- A narrower, clinically defined target condition in place of “nasal cavity disease”
- Human clinical data on chlorpheniramine itself for that condition
- Mechanism-of-action data for chlorpheniramine
- Package insert warnings and contraindications from Health Canada
- Review of the Major interactions (potassium salts) and the anticholinergic and CNS-depressant interactions
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.