Mepyramine
| 證據等級: L5 | 預測適應症: 4 個 |
目錄
Mepyramine: From First-Generation Antihistamine to Allergic Urticaria
One-Sentence Summary
Mepyramine (DrugBank ID: DB06691) is a classical first-generation H1-antihistamine; a formally documented original indication was not available in this evidence pack, though the drug class is long known for treating allergic conditions. The TxGNN model predicts it may be effective for Allergic Urticaria, with a prediction score of 99.92%, but this direction is currently supported only by 5 preclinical/mechanistic publications and no registered clinical trials. Mepyramine is not currently registered with SAHPRA in South Africa.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not formally documented in this evidence pack; classically used as a first-generation H1-antihistamine for allergic conditions (rhinitis, pruritus) |
| Predicted New Indication | Allergic Urticaria |
| TxGNN Prediction Score | 99.92% |
| Evidence Level | L4 (preclinical/mechanistic studies) |
| South Africa Market Status | Not marketed (no SAHPRA registration) |
| Number of SAHPRA Registrations | 0 |
| Recommended Decision | Hold |
Why is This Prediction Reasonable?
Currently, detailed mechanism of action data is not available in this evidence pack. Based on known pharmacology, mepyramine (pyrilamine) is a first-generation H1-receptor antagonist of the ethylenediamine class. Its ability to relieve histamine-mediated allergic reactions has been established through decades of clinical and pharmacological use, and mechanistically it may be applicable to histamine-driven conditions such as allergic urticaria.
Allergic urticaria is pathophysiologically driven by mast cell degranulation and histamine release, which activates H1 receptors to increase vascular permeability and trigger neurogenic pruritus — the same receptor pathway mepyramine classically blocks. This provides a direct mechanistic rationale for the TxGNN prediction, even though allergic urticaria overlaps substantially with the antihistamine drug class’s traditional use rather than representing a novel therapeutic area.
The supporting literature, however, is largely basic pharmacology rather than clinical confirmation. Two publications characterize mepyramine’s direct effects on ion channels (KCNQ/M potassium channels and nociceptor sodium channels) that are relevant to its neurotoxicity in overdose and to non-H1-mediated analgesic effects, rather than to urticaria efficacy directly. One veterinary cohort study in dogs with angioedema (a histamine-related condition in the same disease spectrum as urticaria) showed a treatment benefit, offering the closest available evidence to a clinical outcome, but this is an animal study and cannot be extrapolated directly to human efficacy.
Clinical Trial Evidence
Currently no related clinical trials registered.
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 21033572 | 2010 | Cohort (Veterinary) | Polish Journal of Veterinary Sciences | Mepyramine maleate showed potential benefit in 15 dogs with angioedema versus 12 untreated controls — the closest available evidence to a clinical outcome, though non-human |
| 34387278 | 2021 | Review | Current Opinion in Allergy and Clinical Immunology | Review of receptor affinity profiles of ophthalmic and systemic agents (including H1-antagonists) used in allergic/dry eye disease |
| 18222495 | 2008 | Basic Pharmacology | Neuropharmacology | Mepyramine directly inhibits KCNQ/M potassium channels and depolarizes neurons — relevant to neurotoxicity seen in antihistamine overdose |
| 34758144 | 2021 | Basic Pharmacology | FASEB Journal | Mepyramine directly blocks nociceptor voltage-gated sodium channels, producing topical pain relief independent of H1-receptor blockade |
| 29371669 | 2018 | Methodology (In vitro) | Scientific Reports | Development of fluorescent H1-receptor antagonist probes (mepyramine-based) to study receptor-ligand binding kinetics in living cells |
South Africa Market Information
Mepyramine currently has no SAHPRA registration (market status: Not marketed, 0 licenses on record). No product registration, dosage form, or approved indication text is available for South Africa at this time.
Safety Considerations
Please refer to the SAHPRA-approved Professional Information (PI) for safety information. Report adverse drug reactions to SAHPRA.
Note: TFDA/SAHPRA label warnings and contraindications for mepyramine were not retrievable in this evidence pack (flagged as a Blocking data gap), so no drug-specific warnings, contraindications, or DDI data could be reported here.
Conclusion and Next Steps
Decision: Hold
Rationale: Mepyramine is not currently registered with SAHPRA in South Africa, and the evidence supporting its use in allergic urticaria consists solely of mechanistic/preclinical studies with no human clinical trials. A blocking data gap on TFDA/SAHPRA label warnings and contraindications also prevents a preliminary safety assessment (S1 stage) from being completed.
To proceed, the following is needed:
- SAHPRA/TFDA-approved Professional Information (warnings, contraindications) to resolve the Blocking data gap (DG001)
- Confirmed mechanism of action data from DrugBank or primary literature (DG002)
- At least one human clinical study or trial evaluating mepyramine specifically in allergic urticaria
- A regulatory pathway assessment for SAHPRA registration, since the drug is not currently marketed in South Africa
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.