Cyproheptadine
| Evidence Level: L2 | Predicted Indications: 4 |
Table of Contents
Cyproheptadine: From Antihistamine Therapy to Cold Urticaria
One-Sentence Summary
Cyproheptadine (DB00434) is a first-generation antihistamine with combined H1-receptor and 5-HT2 serotonin-receptor antagonist activity. Among four TxGNN-predicted indications for this drug, Cold Urticaria stands out as the most clinically credible candidate — not the highest-scoring one, but the one backed by decades of drug-specific evidence, including a 1977 double-blind, placebo-controlled RCT. Current support consists of 0 new clinical trials (the field is old enough that trials predate ClinicalTrials.gov registration) and 20 relevant publications, several testing cyproheptadine directly.
Note on candidate selection: TxGNN’s top-ranked prediction by raw score is “allergic urticaria” (99.96%), but all supporting trials/literature for that indication concern other antihistamines (loratadine, desloratadine, rupatadine) rather than cyproheptadine itself. Cold urticaria, ranked second by score (99.76%), has direct cyproheptadine evidence and a materially stronger evidence grade (L2 vs. L4), so it is presented as the primary finding below. The remaining candidates are summarized separately.
Quick Overview
| Item | Content |
|---|---|
| Original Indication | Not documented in this evidence pack (no approved-indication text available; drug class context indicates first-generation antihistamine use) |
| Predicted New Indication | Cold Urticaria |
| TxGNN Prediction Score | 99.76% |
| Evidence Level | L2 |
| India Market Status | Not marketed |
| Number of Registrations | 0 |
| Recommended Decision | Proceed with Guardrails |
Why is This Prediction Reasonable?
Currently, no formal DrugBank-sourced mechanism-of-action summary is available for cyproheptadine at the drug level in this evidence pack (flagged as a High-severity data gap). However, the evidence assembled specifically for this prediction describes cyproheptadine as combining potent H1-histamine receptor antagonism with 5-HT2 serotonin receptor antagonism — a dual profile that distinguishes it from most other antihistamines.
Cold urticaria is a mast-cell-mediated condition in which cold exposure triggers degranulation and histamine release, producing wheals, pruritus, and occasionally angioedema. Because H1 blockade directly suppresses the histamine-driven wheal/flare response, cyproheptadine’s core pharmacology is mechanistically well matched to this indication.
This is not a purely theoretical extrapolation: cyproheptadine has a direct clinical history in this exact indication dating to the 1970s, including a randomized, double-blind, placebo-controlled trial (Wanderer et al., 1977, Archives of Dermatology) comparing it against chlorpheniramine and placebo. Subsequent comparative studies through the 1980s–1990s found cyproheptadine performing at least comparably to, and in some series better than, other conventional antihistamines — a difference some authors attribute to its additional anti-serotonergic/membrane-stabilizing activity beyond H1 blockade alone.
Clinical Trial Evidence
Currently no related clinical trials registered (the supporting evidence predates modern trial registries; see Literature Evidence below for the primary source data).
Literature Evidence
| PMID | Year | Type | Journal | Key Findings |
|---|---|---|---|---|
| 334082 | 1977 | RCT (double-blind) | Archives of Dermatology | Double-blind comparison of cyproheptadine, chlorpheniramine, and placebo in 8 patients with primary acquired cold urticaria; cyproheptadine significantly increased the minimum cold-stimulus time needed to provoke urtication |
| 6102102 | 1980 | Clinical study | J Allergy Clin Immunol | Cyproheptadine normalized ice-cube test results and reduced cold-induced histamine release in cold urticaria patients |
| 6480953 | 1984 | Comparative trial | J Am Acad Dermatol | Randomized comparison of cinnarizine, cyproheptadine, doxepin, and hydroxyzine in idiopathic cold urticaria; doxepin preferred but cyproheptadine among effective conventional options |
| 7488341 | 1995 | Comparative trial | Asian Pac J Allergy Immunol | Double-blind crossover in 6 Thai children with cold urticaria; cyproheptadine and ketotifen both effective |
| 1364168 | 1992 | Comparative crossover trial | J Investig Allergol Clin Immunol | Compared loratadine, cetirizine, cyproheptadine, and ketotifen in 7 patients with acquired cold urticaria; cyproheptadine included among effective classical agents |
| 5287036 | 1971 | Case series/early trial | J Allergy Clin Immunol | Early report establishing cyproheptadine as an effective treatment for cold urticaria |
| 8447871 | 1993 | Review | Am J Emerg Med | Reviews diagnosis and management of cold-induced urticaria/angioedema, including antihistamine therapy |
| 3760401 | 1986 | Cohort study | J Allergy Clin Immunol | Characterizes cold-induced systemic reactions across 50 patients with acquired cold urticaria syndromes; informs risk stratification for antihistamine-treated patients |
| 20609144 | 2010 | Case report | Pediatric Dermatology | Case report and literature review of localized facial cold urticaria in a child |
| 26038847 | 2016 | RCT (other drug, indirect) | Acta Derm Venereol | Up-dosed rupatadine reduces chronic cold urticaria symptoms — supportive class-level evidence for H1-antagonism in this disease |
Other Predicted Indications Considered (Lower Priority)
| Rank | Predicted Indication | TxGNN Score | Evidence Level | Recommendation | Note |
|---|---|---|---|---|---|
| 1 | Allergic urticaria | 99.96% | L4 | Research Question | Highest model score, but all supporting trials/literature concern loratadine, desloratadine, rupatadine, and bilastine — no cyproheptadine-specific evidence |
| 3 | Nasal cavity disease | 99.21% | L4 | Hold | Vague disease category; evidence base is a herbal-remedy trial and other-antihistamine studies, none involving cyproheptadine |
| 4 | Acute laryngopharyngitis | 99.13% | L5 | Hold | Model prediction only — no clinical trials or literature; weak mechanistic rationale given the largely infectious etiology of this condition |
Safety Considerations
Drug Interactions: 308 documented interactions on file (ddinter). Two are flagged as Major: Potassium citrate and Potassium chloride. Numerous Moderate-level interactions involve other anticholinergic/CNS-depressant agents, including Hyoscyamine, Atropine, Glycopyrronium, Dicyclomine, Trospium, Mepenzolate, Methscopolamine, Propantheline, Scopolamine, Loperamide, Morphine, Opium, Metoclopramide, Dronabinol, Nabilone, Eluxadoline, and Fenfluramine — consistent with cyproheptadine’s combined antihistamine/anticholinergic/antiserotonergic pharmacology.
Formal key warnings and contraindications are not available in this evidence pack (blocking data gap — see Conclusion).
Conclusion and Next Steps
Decision: Proceed with Guardrails
Rationale: Cold urticaria has the strongest evidentiary support (L2) among all TxGNN-predicted indications for cyproheptadine, backed by a historical double-blind RCT and multiple direct comparative studies with a mechanistically coherent rationale (H1 blockade against mast-cell-mediated histamine release). However, the drug is currently unregistered in this jurisdiction and a Blocking-severity data gap (missing label warnings/contraindications) prevents a full safety assessment.
To proceed, the following is needed:
- Official label warnings and contraindications (Blocking gap DG001) — required before any Stage-1 safety screen can be completed
- A formal DrugBank/regulatory MOA record (High-severity gap DG002) to support the mechanistic rationale beyond the repurposing-analysis text used here
- A regulatory pathway assessment, since the drug currently has zero registrations in this jurisdiction
- Consideration of a contemporary confirmatory trial, since the existing direct evidence dates from 1971–1995 and predates current cold urticaria treatment guidelines (which favor up-dosed second-generation antihistamines)
Disclaimer
This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.