Azelastine and its medical uses

Azelastine marketed under brands such as Optivar, is an H1 receptor blocking drug used primarily as a nasal spray to treat allergic rhinitis (hay fever) and as an eye drop to treat allergic conjunctivitis.Other uses may include oral treatment of asthma and rashes.Effects appear within minutes when used in the eyes and within an hour when used in the nose.Effects last for up to 12 hours.Common side effects include headache, drowsiness, altered taste, and sore throat.It is not known if it is safe to use during pregnancy or breastfeeding.It is a second-generation antihistamine that works by blocking the release of various inflammatory mediators, including histamine. Azelastine was patented in 1971 and became available for medical use in 1986.It is available as a generic drug in the United States.In 2020, it was the 173rd most prescribed drug in the U.S. with over 3 million prescriptions.

Medical uses

Azelastine Nasal Spray is indicated for the topical treatment of symptoms of seasonal allergic rhinitis and perennial allergic rhinitis, such as runny nose, sneezing, and nasal itching in people 5 years of age and older.In some countries, it is also indicated for the treatment of vasomotor rhinitis in adults and children over 12 years of age.Azelastine eye drops are indicated for topical treatment of seasonal and perennial allergic conjunctivitis.

Side effects

Azelastine was safe and well tolerated in both adults and children with allergic rhinitis.Bitter taste, headache, nasal burning, and drowsiness were the most frequently reported adverse events.Prescribing recommendations in the United States warn against concomitant use of alcohol and/or other CNS depressants, but to date no studies have evaluated the effects of azelastine nasal spray on the CNS in humans.Recent studies showed similar levels of sleepiness (approximately 2%) compared to placebo treatment.The most common side effect was a bitter taste (about 20% of people).Therefore, the manufacturer produced another formulation of azelastine that contained sucralose.The problem of bitter taste can also be reduced by using nasal sprays correctly (i.e. tilting the head slightly forward and not inhaling the drug too deeply) or using azelastine/sucralose formulations.In addition, nasal spray antihistamines (including both formulations of azelastine) may cause anosmia (anosmia).

Pharmacokinetics

The systemic bioavailability of azelastine is approximately 40% when administered intranasally.Maximum plasma concentration (Cmax) is observed within 2-3 hours.The elimination half-life, steady-state volume of distribution, and plasma clearance were 22 hours, 14.5 L/kg, and 0.5 L/h/kg, respectively (based on data from intravenous and oral administration).Approximately 75% of an oral dose is excreted in feces.The pharmacokinetics of oral azelastine are not affected by age, sex or hepatic impairment.

Metabolism

Azelastine is oxidatively metabolized by the cytochrome P450 family to its active metabolite, desmethylazelastine, and two inactive carboxylic acid metabolites.

Chemical properties

The chemical name of azelastine is (±)-1-(2H)-phthalazinone, 4-[(4-chlorophenyl)methyl]-2-(hexahydro-1-methyl-1H-azepin-4-yl)-monohydrochloride.It is white, almost odorless, and has a bitter taste.