AZELASTINE HYDROCHLORIDE ALLERGY
Clinical safety rating: caution
Comprehensive clinical and safety monograph for AZELASTINE HYDROCHLORIDE ALLERGY (AZELASTINE HYDROCHLORIDE ALLERGY).
Antihistamine with mast cell stabilizing properties; selectively antagonizes histamine H1 receptors, reducing nasal pruritus, sneezing, rhinorrhea, and ocular symptoms.
| Metabolism | Hepatic metabolism via CYP450 enzymes (primarily CYP3A4 and CYP2D6) to active metabolite desmethylazelastine; also undergoes oxidation and conjugation. |
| Excretion | Azelastine is primarily eliminated via renal excretion (approximately 75% as metabolites, <10% unchanged) and fecal excretion (approximately 25%) after oral administration. Biliary excretion is minimal. |
| Half-life | The terminal elimination half-life is approximately 22 hours (range 16-26 hours) at steady state, supporting twice-daily dosing. The half-life may be prolonged in elderly patients or those with hepatic impairment. |
| Protein binding | Approximately 88-90% bound to plasma proteins, primarily to albumin. |
| Volume of Distribution | The apparent volume of distribution is approximately 14.5 L/kg (range 5-20 L/kg), indicating extensive extravascular distribution into tissues. |
| Bioavailability | Intranasal: systemic bioavailability is approximately 40% due to absorption across nasal mucosa and first-pass metabolism. Ophthalmic: negligible systemic absorption (<0.1%). Oral: bioavailability is approximately 60% after oral administration, with extensive first-pass metabolism to desmethylazelastine. |
| Onset of Action | Intranasal: onset within 15-30 minutes for allergic rhinitis symptoms. Ophthalmic: onset within 3-5 minutes for allergic conjunctivitis. Oral: clinical effect may be noted within 1 hour. |
| Duration of Action | Intranasal: duration up to 12 hours with twice-daily dosing. Ophthalmic: duration approximately 8-12 hours. Oral: symptom relief lasts approximately 12 hours. |
One spray (137 mcg) per nostril twice daily (total 548 mcg/day). Intranasal route.
| Dosage form | SPRAY, METERED |
| Renal impairment | No dose adjustment required for GFR >30 mL/min. For GFR <30 mL/min, avoid use due to lack of data. |
| Liver impairment | No dose adjustment required in mild-to-moderate hepatic impairment (Child-Pugh A or B). Not studied in severe impairment (Child-Pugh C); use with caution or avoid. |
| Pediatric use | Children 6-11 years: One spray per nostril twice daily (total 548 mcg/day). Children ≥12 years: Same as adult. |
| Geriatric use | No specific dose adjustment recommended; use with caution due to potential increased sensitivity and comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for AZELASTINE HYDROCHLORIDE ALLERGY (AZELASTINE HYDROCHLORIDE ALLERGY).
| Breastfeeding | Excretion in human milk: Unknown. M/P ratio: Not established. Caution advised; consider risk-benefit. |
| Teratogenic Risk | Animal studies: No evidence of teratogenicity in rats or rabbits at up to 68.7 times the maximum recommended human daily intranasal dose. Human data: Limited; no well-controlled studies in pregnant women. Risk cannot be ruled out; use only if clearly needed. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypersensitivity to azelastine or any component of the formulation."]
| Precautions | ["Somnolence: may impair mental alertness; avoid driving or operating hazardous machinery until effects are known.","Avoid concurrent use with alcohol or other CNS depressants.","Use with caution in patients with renal impairment (CrCl < 25 mL/min) or hepatic disease."] |
| Food/Dietary | No significant food interactions. Avoid alcohol as it may increase the risk of drowsiness. Grapefruit juice does not significantly affect azelastine metabolism. |
| Clinical Pearls |
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| Monitor for maternal adverse effects: somnolence, headache, bitter taste. No specific fetal monitoring required. |
| Fertility Effects | No human data. Animal studies showed no impairment of fertility at doses up to 68.7 times MRHDID. |
| Azelastine is an intranasal antihistamine that provides rapid relief of allergic rhinitis symptoms within 15-30 minutes. It can be used concomitantly with intranasal corticosteroids for additive effect. Bitter taste (dysgeusia) is a common side effect, occurring in up to 20% of patients; this can be minimized by tilting the head forward and sniffing gently during administration, and avoiding leaning back. Azelastine is metabolized by CYP450, but significant drug interactions are rare. It does not cause significant sedation at recommended doses due to low systemic absorption. In pediatric patients, use is approved from 6 years of age for allergic rhinitis. |
| Patient Advice | Use the spray regularly for maximum benefit; do not skip doses even if symptoms improve. · Prime the pump after a period of non-use (4 sprays or until a fine mist appears). · Blow your nose gently before use to clear the nasal passages. · Insert the nozzle into one nostril while closing the other, tilt head slightly forward, and sniff gently while spraying. · Do not spray directly onto the nasal septum (middle partition of the nose). · After spraying, avoid leaning the head back to prevent the medication from dripping down the throat and causing a bitter taste. · Clean the spray tip once a week with warm water and dry with a clean cloth. · If you experience drowsiness, avoid driving or operating heavy machinery. · Inform your doctor if you are pregnant, planning to become pregnant, or breastfeeding. · Store at room temperature, away from moisture and heat. |