Azelastine, sold under the brand name Astelin among others, is a H₁ receptor-blocking medication primarily used as a

nasal spray Nasal sprays are used to deliver medications Route of administration#Local, locally in the nasal cavities or systemic administration, systemically. They are used locally for conditions such as nasal congestion and allergic rhinitis. In some sit ...

to treat

allergic rhinitis Allergic rhinitis, of which the seasonal type is called hay fever, is a type of inflammation in the nose that occurs when the immune system overreacts to allergens in the air. It is classified as a type I hypersensitivity reaction. Signs a ...

(hay fever) and as eye drops for

allergic conjunctivitis Allergic conjunctivitis (AC) is Allergic Inflammation, inflammation of the conjunctiva (the membrane covering the white part of the eye) due to allergy. Although allergens differ among patients, the most common cause is hay fever. Symptoms consist ...

. Other uses may include

asthma Asthma is a common long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wh ...

and

skin rashes A rash is a change of the skin that affects its color, appearance, or texture. A rash may be localized in one part of the body, or affect all the skin. Rashes may cause the skin to change color, itch, become warm, bumpy, chapped, dry, cracke ...

for which it is taken by mouth. Onset of effects is 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, sleepiness, change in taste, and sore throat. It is unclear if use is safe during

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

breastfeeding Breastfeeding, also known as nursing, is the process where breast milk is fed to a child. Infants may suck the milk directly from the breast, or milk may be extracted with a Breast pump, pump and then fed to the infant. The World Health Orga ...

. It is a second-generation

antihistamine Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides ...

and works by blocking the release of a number of inflammatory mediators including

histamine Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 19 ...

. Azelastine was patented in 1971 and came into medical use in 1986. It is available as a

generic medication A generic drug is a pharmaceutical drug that contains the same chemical substance as a drug that was originally protected by chemical patents. Generic drugs are allowed for sale after the patents on the original drugs expire. Because the active ch ...

. In 2022, it was the 124th most commonly prescribed medication in the United States, with more than 5million prescriptions.

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 Rhinorrhea (American English), also spelled rhinorrhoea or rhinorrhœa (British English), or informally runny nose is the free discharge of a thin mucus fluid from the nose; it is an extremely common condition. It is a common symptom of allergie ...

, sneezing and nasal pruritus in people five 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 eye drops are indicated for the local treatment of seasonal and perennial

Side effects

Azelastine is safe and well tolerated in both adults and children with

. Bitter taste, headache, nasal burning and

somnolence Somnolence (alternatively sleepiness or drowsiness) is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia). It has distinct meanings and causes. It can refer to the usual state preceding falling aslee ...

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

(approx. 2%) compared with placebo treatment. The most common side effect is a bitter taste (about 20% of people). Due to this, the manufacturer has produced another formulation of azelastine with

sucralose Sucralose is an artificial sweetener and sugar substitute. In the European Union, it is also known under the E number E955. It is produced by chlorination of sucrose, selectively replacing three of the hydroxy groups—in the C1 a ...

. The problem of bitter taste may also 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. In addition,

anosmia Anosmia, also known as smell blindness, is the lack of ability to detect one or more smells. Anosmia may be temporary or permanent. It differs from hyposmia, which is a decreased sensitivity to some or all smells. Anosmia can be categorized int ...

(loss in the ability to smell) can occur with nasal spray antihistamines (including both formulations of azelastine).

Pharmacology

Pharmacodynamics

Azelastine has a triple mode of action: # Anti-histamine effect, # Mast-cell stabilizing effect and #

Anti-inflammatory Anti-inflammatory is the property of a substance or treatment that reduces inflammation, fever or swelling. Anti-inflammatory drugs, also called anti-inflammatories, make up about half of analgesics. These drugs reduce pain by inhibiting mechan ...

effect.

Pharmacokinetics

The systemic

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...

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). Approximately 75% of an oral dose is excreted in feces.

Pharmacokinetics Pharmacokinetics (from Ancient Greek ''pharmakon'' "drug" and ''kinetikos'' "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to describing how the body affects a specific su ...

of orally administered azelastine is not affected by age, gender, or hepatic impairment.

Metabolism

Azelastine is oxidatively metabolized by the

cytochrome P450 Cytochromes P450 (P450s or CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for examp ...

family into its active metabolite, desmethylazelastine, and two inactive carboxylic acid metabolites.

Chemical properties

The chemical nomenclature of azelastine is (±)-1-(2H)-phthalazinone, 4- 4-chlorophenyl) methyl2-(hexahydro-1-methyl-1H-azepin-4-yl)-monohydrochloride. It is white, almost odorless with a bitter taste.drugs.co
Azelastine
Page accessed 28 June 2015

References

{{Authority control Azepanes 4-Chlorophenyl compounds H1 receptor antagonists Lactams Mast cell stabilizers Phthalazines Wikipedia medicine articles ready to translate