Azelastine is a potent, second-generation, selective, histamine antagonist (histamine-H1-receptor antagonist) used as a first line therapy of mild intermittent, moderate/severe intermittent and mild persistent rhinitis (new classification system for rhinitis).
Azelastine has been formulated both as a nasal spray and as eye drops and are available worldwide under many brand names.
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Medical uses
Azelastine nasal spray is indicated for the local treatment of the symptoms of seasonal allergic rhinitis and perennial allergic rhinitis, such as rhinorrhea, sneezing and nasal pruritus in adults and children 5 years of age and older. In some countries, it is also indicated for the treatment of vasomotor rhinitis in adults and children >= 12 years old. Azelastine eyes drops are indicated for the local treatment of seasonal and perennial allergic conjunctivitis.
Side effects
Azelastine is safe and well tolerated in both adults and children with allergic rhinitis. Bitter taste, headache, nasal burning and somnolence are the most frequently reported adverse events. US prescribing recommendations warn against the concurrent use of alcohol and/or other central nervous system depressants, but to date there have been no studies to assess the effects of azelastine nasal spray on the CNS in humans. More recent studies have shown similar degrees of somnolence (approx. 2%) compared with placebo treatment. The problem of bitter taste may be reduced by correct application of the nasal spray (i.e. slightly tipping the head forward and not inhaling the medication too deeply), or alternatively using the azelastine/sucralose formulation.
Pharmacokinetics and metabolism
The systemic bioavailability of azelastine is approximately 40% when administered intranasally. Maximum plasma concentrations (Cmax) are observed within 2-3 hours. The elimination half life, steady-state volume of distribution and plasma clearance are 22 h, 14.5 l/kg and 0.5 l/h/kg respectively (based on intravenous and oral administration data). Azelastine is oxidatively metabolized by the cytochrome P450 family into its active metabolite, desmethylazelastine, and two inactive carboxylic acid metabolites. Approximately 75% of an oral dose is excreted in feces. Pharmacokinetics of orally administered azelastine are not affected by age, gender or hepatic impairment.
Mode of action
Azelastine has a triple mode of action:
- Anti-histamine effect,
- Mast-cell stabilizing effect and
- Anti-inflammatory effect.
Chemical properties
The chemical nomenclature of azelastine is (±)-1-(2H)-phthalazinone, 4-[(4-chlorophenyl) methyl]-2-(hexahydro-1-methyl-1H-azepin-4-yl)-monohydrochloride. It is white, almost odorless with a bitter taste.
Society and culture
Availability
Azelastine is generic and available worldwide under many brand names.
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