Azelastine

證據等級: L5

預測適應症: 10 個

Azelastine: From Allergic Rhinitis to Allergic Urticaria

One-Sentence Summary

Azelastine is a potent second-generation H1 antihistamine, approved internationally for allergic rhinitis (nasal spray) and allergic conjunctivitis (eye drops), but currently not registered with SAHPRA in South Africa. The TxGNN model predicts it may be effective for Allergic Urticaria, with 10 clinical trials and 11 publications currently supporting this direction — primarily as indirect class-effect evidence drawn from large Phase 3 allergic rhinitis programmes.

Quick Overview

Item	Content
Original Indication	Allergic rhinitis, seasonal and perennial (internationally established; not SAHPRA-registered)
Predicted New Indication	Allergic Urticaria
TxGNN Prediction Score	96.23%
Evidence Level	L3
South Africa Market Status	Not marketed
Number of SAHPRA Registrations	0
Recommended Decision	Proceed with Guardrails

Why Is This Prediction Reasonable?

Azelastine acts as a potent, selective histamine H1 receptor antagonist. Beyond simple receptor blockade, it stabilises mast cells and suppresses the release of multiple inflammatory mediators — including leukotrienes, prostaglandins, and platelet-activating factor — providing both rapid symptom relief and a degree of downstream anti-inflammatory benefit. This dual mechanism is well-documented in a body of Phase 3 rhinitis trials involving over 7,000 patients and is supported by multiple pharmacological reviews included in the current evidence pack.

Allergic urticaria and allergic rhinitis share the same core immunological cascade: IgE-mediated mast cell and basophil activation leading to histamine release and the characteristic wheal-and-flare response. H1 antihistamines are recommended as first-line therapy for urticaria in all major international guidelines (EAACI/GA²LEN, AAAAI, BSACI). Since azelastine is mechanistically equivalent to second-generation H1 antihistamines that are directly indicated for urticaria — cetirizine, loratadine, fexofenadine — the class-effect extrapolation is pharmacologically well supported.

Detailed mechanism of action data was not available in the current Evidence Pack. The rationale above is based on published pharmacological class information and the literature identified in the evidence search. No direct randomised trials studying azelastine specifically in urticaria were found. Evidence is currently indirect.

Clinical Trial Evidence

None of the trials below were conducted specifically for allergic urticaria. They establish azelastine’s H1-blocking clinical efficacy and safety across a large allergic patient population, providing the class-effect foundation for urticaria extrapolation.

Trial Number	Phase	Status	Enrollment	Key Findings
NCT00883168	Phase 3	Completed	1,791	Large multicentre RCT comparing azelastine monotherapy, fluticasone propionate, MP29-02 combination, and placebo in seasonal allergic rhinitis; establishes H1-blocking efficacy baseline
NCT00651118	Phase 3	Completed	832	Azelastine vs. fluticasone vs. combination vs. placebo in seasonal allergic rhinitis; confirms clinical H1 antagonism potency — primary class-effect indirect evidence for urticaria
NCT02230696	Phase 3	Completed	951	Comparative safety and efficacy of steroid formulation vs. azelastine in seasonal allergic rhinitis
NCT00740792	Phase 3	Completed	776	Confirms azelastine monotherapy antihistamine efficacy in seasonal allergic rhinitis; validates H1-blocking mechanism
NCT00720382	Phase 3	Completed	703	16-month active-controlled safety study of Astepro® (azelastine 0.15%) vs. mometasone; long-term safety well established
NCT00712920	Phase 3	Completed	581	Dose optimisation of azelastine 0.1% vs. 0.15% in perennial allergic rhinitis
NCT00720278	Phase 3	Completed	526	Perennial allergic rhinitis trial; long-term safety in a chronic, year-round allergic state established
NCT01915823	Phase 3	Completed	348	Dymista® (azelastine + fluticasone) in paediatric seasonal allergic rhinitis; combined antihistamine and anti-inflammatory mechanisms confirmed in children ≥4 years
NCT01794741	Phase 3	Completed	405	Three-month paediatric safety study (ages 4–11 years); azelastine safety profile in children established
NCT01880840	Phase 4	Completed	191	Post-marketing safety surveillance in children aged 6 months to <6 years; lower age limit safety data confirmed

Literature Evidence

PMID	Year	Type	Journal	Key Findings
7530629	1994	Review	Drugs	Urticaria review: nonsedating H1 antihistamines are the primary treatment for chronic idiopathic urticaria; establishes the therapeutic class rationale for azelastine
20476933	2005	Review	Expert Rev Clin Immunol	Comprehensive pharmacology review of azelastine; confirms H1 potency, mast cell stabilising activity, and favourable safety and tolerability profile
9951950	1999	Review	Drugs	Comparative review of second-generation antihistamines including azelastine; positions it alongside agents used for urticaria and rhinitis
1683523	1991	Review	Annals of Allergy	Comparative H1 receptor antagonist efficacy; azelastine noted to have additional antiallergic mechanisms extending beyond H1 blockade alone
1685361	1991	Review	Clin Pharmacokinetics	Pharmacokinetic optimisation of H1-receptor antagonists including azelastine; confirms suitability for chronic urticaria within the antihistamine class
10804044	2000	Review	Drugs	Ebastine comparative review covering class-wide efficacy in urticaria; supports class-effect extrapolation for azelastine
34387278	2021	Pharmacology Study	Curr Opin Allergy Clin Immunol	Receptor affinity profiling of ophthalmic and systemic agents; characterises azelastine’s multi-receptor pharmacological activity across allergic conditions
40055363	2025	Experimental	Scientific Reports	Bilastine vs. azelastine eye drop comparison; confirms H1 antihistamine class efficacy in allergic conditions, with azelastine as active comparator
19348661	2009	Case Report/Series	J Dermatology	Rare H1 antihistamine-induced urticaria reported; highlights the importance of patient monitoring and highlights that azelastine class agents are central to urticaria management
14499249	2003	Animal Study	Clin Immunol	Antihistamines evaluated in eosinophilic skin disease model; azelastine-class agents suggest skin anti-inflammatory activity relevant to allergic urticaria

South Africa Market Information

Azelastine is not currently registered with SAHPRA and has no active pharmaceutical licences in South Africa. No products are available through registered channels in any formulation.

For context, azelastine is approved in other markets for:

Allergic rhinitis: US FDA-approved as Astelin® and Astepro® (nasal spray); EMA-approved as Allergodil®
Allergic conjunctivitis: US FDA-approved as Optivar® (0.05% eye drops) — this indication also has direct Phase 3 RCT evidence (see TxGNN rank 10 below)

To make azelastine available to South African patients, a new medicine registration application to SAHPRA would be required. For patients with documented urgent need, a Section 21 authorisation for an unregistered medicine can be applied for through SAHPRA’s Regulatory Affairs division.

Safety Considerations

Detailed safety information — including specific warnings, contraindications, and drug-drug interactions — was not available in the current Evidence Pack.

Please refer to the country-of-origin Professional Information (PI) for full safety details — for example, the US FDA Prescribing Information for Astelin® or Astepro®, or the EMA Summary of Product Characteristics for Allergodil® — until a SAHPRA-approved South African PI is available. Report adverse drug reactions to SAHPRA at pharmacovigilance@sahpra.org.za.

Additional Finding: Conjunctivitis (Rank 10, L2 Evidence)

A separate TxGNN prediction for conjunctivitis (TxGNN score: 91.15%) carries stronger direct evidence than any other prediction in this pack (Evidence Level L2, Decision: Proceed with Guardrails). This is consistent with azelastine’s FDA-approved ophthalmic formulation (Optivar® 0.05% eye drops) for seasonal allergic conjunctivitis. Two directly relevant trials were identified:

Trial Number	Phase	Status	Enrollment	Key Findings
NCT06212973	Phase 3	Completed	266	Epinastine vs. azelastine eye drops as active comparator in Chinese seasonal allergic conjunctivitis; directly confirms ophthalmic azelastine efficacy
NCT06800274	Phase 4	Completed	134	NAAGA vs. azelastine 0.05% eye drops in allergic conjunctivitis with tear film dysfunction; azelastine as benchmark comparator

This represents a regulatory gap in South Africa rather than a new repurposing question — the evidence is well established globally, but no ophthalmic azelastine product is currently registered with SAHPRA.

Conclusion and Next Steps

Decision: Proceed with Guardrails

Rationale: Azelastine’s well-characterised H1-blocking mechanism directly underpins the standard-of-care treatment for allergic urticaria, and its extensive clinical safety record (>7,000 patients across Phase 3 rhinitis trials) is reassuring. The primary barrier in South Africa is regulatory — the drug is simply not registered — rather than a genuine evidence gap about its pharmacological activity. Class-effect evidence from the H1 antihistamine literature is robust.

To proceed, the following is needed:

SAHPRA registration application for at least one formulation appropriate for urticaria (oral tablets for systemic management; ophthalmic drops separately for conjunctivitis)
Full manufacturer PI review: obtain and assess warnings, contraindications, and drug-drug interaction data before clinical use
Direct clinical evidence in urticaria: a randomised controlled trial or robust comparative effectiveness meta-analysis evaluating azelastine specifically against registered H1 antihistamines in urticaria populations
Pharmacoeconomic analysis: compare azelastine to currently registered H1 antihistamines in South Africa (cetirizine, loratadine, fexofenadine) to justify formulary consideration
Oral formulation pharmacokinetics confirmation: verify systemic bioavailability data for urticaria indication, noting current South African clinical interest is in the oral route (not nasal spray)
Post-registration pharmacovigilance plan aligned with SAHPRA requirements

⚠️ This report is for research purposes only and does not constitute medical advice. Drug repurposing candidates require clinical validation before therapeutic use. All adverse drug reactions should be reported to SAHPRA.

Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.