Azelastine Hydrochloride: Salt Form of the H1 Antihistamine Azelastine
Azelastine hydrochloride is the salt form used in virtually all marketed pharmaceutical preparations of azelastine, an H1 antihistamine of the second generation from the group of phthalazinones. Well-known brand names are Allergodil (nasal spray and eye drops), Vividrin akut Azelastine (nasal spray), Pollival Azelastine and in fixed combination preparations Dymista (with fluticasone propionate). A comprehensive pillar page on the active substance itself can be found at /wirkstoff/azelastin.
Topical application of azelastine hydrochloride in nasal sprays and eye drops is standard for allergic rhinitis and conjunctivitis. Unlike oral antihistamines, the topical form works almost immediately (within 15 minutes), with minimal systemic absorption and thus fewer central nervous system adverse effects such as drowsiness. This property makes azelastine spray particularly suitable for rapid symptomatic treatment of acute pollen or pet hair allergies.
Mechanism of Action and Salt Form
The hydrochloride salt is chosen because it offers good water solubility and stability in aqueous sprays and eye drops. In the body, it dissociates immediately into azelastine and chloride, so the effect is carried solely by azelastine.
Azelastine is a selective competitive antagonist at the peripheral H1 histamine receptor. It blocks the binding of histamine and thus histamine-mediated allergic symptoms such as pruritus, sneezing, rhinorrhea and lacrimation. Unlike older H1 antagonists of the first generation, azelastine crosses the blood-brain barrier only to a limited degree and therefore causes minimal sedation.
In addition, azelastine has anti-inflammatory properties that go beyond simple H1 blockade. It inhibits the release of mediators from mast cells (mast cell stabilization), reduces the formation of leukotrienes and platelet activating factor (PAF), and modulates the activity of eosinophils. These pleiotropic effects explain why the efficacy extends beyond acute histamine blockade.
Pharmacokinetically, azelastine is minimally absorbed systemically after topical application (approximately 40 percent with nasal application), the oral form (not marketed in Germany) has a bioavailability of approximately 80 percent. Half-life approximately 22 hours, which is why twice daily application is sufficient.
Indications
- Seasonal allergic rhinitis (hay fever): Acute and maintenance therapy
- Perennial (year-round) allergic rhinitis: for pet hair, house dust mite, mold fungi
- Allergic conjunctivitis: as eye drops
- Vasomotor rhinitis: off-label, for non-allergic rhinitis forms
- Acute first-line treatment of allergy symptoms: because of rapid onset of action
Dosage and Administration
Nasal spray for adults and children from 6 years: one spray per nostril twice daily. In case of severe symptoms, the frequency can be temporarily increased.
Eye drops: one drop in each eye twice daily, if needed up to four times daily. Application possible from 4 years for seasonal and from 12 years for perennial allergic conjunctivitis.
Duration of use: can be used over weeks to months, depending on the allergenic trigger. No loss of efficacy with long-term use.
Application tips: Blow nose before spray application, insert spray vertically into the nose and inhale gently. Before eye drops, wash hands, remove contact lenses before application and reinsert after 15 minutes. After each drop application, briefly close the eyelid to promote distribution of the active substance.
Adverse Effects
Common: bitter taste after nasal application (typical adverse effect of azelastine spray, can be reduced by tilting head forward), local irritation of nasal mucosa, sneezing shortly after application, mild skin reaction at the eye after eye drops.
Occasional: dry mucous membranes, drowsiness (less than with oral antihistamines of the first generation), headache, nausea, mild sedation.
Rare: allergic reactions including anaphylaxis, skin rash, tachycardia, altered consciousness in case of overdose (especially with oral uptake).
Important: the bitter taste is the most common complaint with azelastine spray and sometimes leads to discontinuation of therapy. Tips such as tilting head forward instead of backward and application with mouth slightly open can reduce the taste.
Drug Interactions
- Other CNS depressant substances (alcohol, benzodiazepines, opioids): Theoretically additive sedation, clinically of little relevance with topical application
- QT prolonging substances: Theoretically additive QT prolongation with systemic absorption, clinically of little relevance with topical application
- Other intranasal substances (glucocorticoid sprays): Combination possible and standardized in Dymista; with separate application allow an interval of several minutes
- Cimetidine: Theoretical level increase, clinically of little relevance with topical application
Special Notes
Pregnancy and Lactation: Data on topical use in pregnancy are limited, but due to low systemic absorption, azelastine is considered relatively safe. Use is possible during lactation; alternative well-studied antihistamines (loratadine, cetirizine) can be chosen as oral alternatives.
Combination with nasal glucocorticoids: for moderate to severe allergic rhinitis, the combination antihistamine plus glucocorticoid is more effective than either substance alone. Dymista (azelastine plus fluticasone propionate) offers this combination in one spray, with better adherence than two separate sprays.
Allergen avoidance: the most effective measure for allergic rhinitis remains avoidance of the allergen (pollen calendar, house dust mite measures, pet hair avoidance). Specific immunotherapy (SIT, desensitization) can be a causal treatment for severe allergies.
Contact lenses: Allergodil eye drops with preservatives can be absorbed by soft contact lenses. Remove lenses before application and reinsert after 15 minutes, or use preservative-free single-dose preparations.
You Might Also Be Interested In
- Azelastine, comprehensive pillar page on the active substance
- Cetirizine, oral antihistamine of the second generation
- Loratadine, another oral antihistamine
- Fluticasone Propionate, ICS in Dymista combination
- Levocabastine, another topical antihistamine
Frequently Asked Questions
What is the difference between azelastine and azelastine hydrochloride?
None pharmacologically. Azelastine hydrochloride is the water-soluble salt form used in virtually all medications. In the body, it dissociates immediately into effective azelastine and chloride.
How quickly does azelastine nasal spray work?
Within 15 minutes of application, the first improvements in symptoms such as sneezing urge, pruritus, and rhinorrhea are noticeable. Full effect develops over the first few hours. This rapid onset of action makes azelastine spray particularly attractive for treating acute allergy symptoms.
What can I do about the bitter taste?
The bitter taste results from the spray flowing down into the throat and is perceived as unpleasant by many patients. Tips: tilt head forward (not backward) during application, inhale gently without deep breathing, then rinse mouth or suck a lozenge. If the taste remains unbearably unpleasant, switching to another intranasal antihistamine may be appropriate.
Can I combine azelastine with an oral antihistamine?
For severe allergy symptoms, combining a local with a systemic antihistamine may be useful without substantial additional risk. However, in most cases, the combination of azelastine plus intranasal glucocorticoid (e.g. Dymista) is more effective than doubling antihistamines.
Sources
- Gelbe Liste, Azelastine Active Substance Profile
- AWMF S2k Guideline Allergic Rhinitis
- BfArM, Federal Institute for Drugs and Medical Devices
- EMA Product Information Azelastine Preparations
Legal Notices and Disclaimer
The information provided on this page is for general information purposes only and does not constitute medical advice, diagnosis, or treatment recommendation. It does not replace the advice of a licensed physician or pharmacist. Medications should only be taken upon medical prescription or pharmacist dispensing. All information is based on product information published at the time of preparation and recognized scientific sources; the current product information of the manufacturer is always authoritative. Sanoliste assumes no liability for completeness, timeliness, or accuracy of the information presented. In case of a medical emergency, call the emergency number 112.