Azelastine

Azelastine is a selective histamine H1 receptor antagonist with mast cell stabilizing properties used to treat symptoms of allergic rhinitis and allergic conjunctivitis. It is formulated as a nasal spray (azelastine hydrochloride) and as an ophthalmic solution. The nasal spray reduces symptoms such as nasal itching, sneezing, and rhinorrhea; the eye drops relieve conjunctival itching. It is applied topically, and onset of relief is typically within minutes for nasal or ocular formulations, with effects lasting several hours.

Mechanism and pharmacology: Azelastine blocks histamine at H1 receptors and stabilizes mast cells, which helps prevent the release of inflammatory mediators such as histamine and leukotrienes. This dual action contributes to relief from itching and other allergic symptoms.

Pharmacokinetics and formulation: When used topically, systemic exposure is limited. The drug is metabolized by the liver and excreted in urine and feces. It is available in nasal spray and ophthalmic forms, and there are combination nasal products that pair azelastine with corticosteroids for enhanced control of nasal symptoms.

Clinical use and safety: Contraindications include known hypersensitivity to azelastine or any ingredients. Use with caution in pregnancy or breastfeeding and avoid driving or operating machinery if drowsiness occurs. Because of potential CNS effects, avoid alcohol or other sedatives with prominent drowsiness. Common adverse effects include a bitter taste after nasal administration, nasal irritation or burning, headache, and drowsiness. Less commonly, systemic reactions or hypersensitivity may occur; seek medical advice if unusual symptoms appear.

Interactions and guidance: Patients should inform clinicians about all medications, as interactions with alcohol or CNS depressants can increase sedation. Azelastine is typically used as directed on labeling or by a clinician.