How azelastine works
In allergies, for example to grass pollen or animal hair, substances that are actually harmless (allergens) trigger an excessive immune reaction in the body. Experts have not yet conclusively clarified why this happens in some people. However, the course of an allergic reaction is now very well understood and has enabled the development of anti-allergic agents.
H1 antihistamines such as azelastine
Some of these belong to the class of H1 antihistamines. In the case of an allergy, certain defense cells (mast cells) in tissue interstices secrete large amounts of the inflammatory messenger histamine. This binds to specific docking sites of the tissue cells (histamine receptors) and signals to them that an immune reaction has just been triggered.
As a result, the mucous membranes of the nasopharynx and the eyes, for example, are better supplied with blood in order to transport further immune cells there. The tissue reddens, swells, and itching occurs in order to remove any foreign bodies that may be present. In addition, tissue fluid escapes to wash away foreign bodies and pathogens – the nose runs and the eyes water.
The special feature of azelastine is its “combination effect”: in addition to the antihistamine effect, it also stabilizes the mast cells, causing them to release less histamine when irritated.
Absorption, degradation and excretion
When azelastine nasal spray and eye drops are used, very little active ingredient enters the systemic circulation. When azelastine tablets are taken, azelastine is rapidly absorbed into the blood through the intestines and then rapidly distributed throughout the body tissues.
After about 20 hours, the level of active ingredient in the blood has dropped by half. The degradation product desmethyl azelastine, which is also effective and is formed in the liver, is half degraded or excreted after about 50 hours.
Approximately three quarters of the active ingredient and its degradation products are excreted in the stool, the rest leaves the body in the urine.
When is azelastine used?
The anti-allergic drug azelastine is approved for the treatment of seasonal and year-round allergic rhinitis (such as hay fever) and allergic conjunctivitis.
For the duration of use, always follow the instructions of your doctor or pharmacist or the information in the package leaflet of the preparation used.
How to use azelastine
Eye drops
Unless otherwise stated or prescribed, adults may use azelastine eye drops twice daily (1 drop per eye). In case of severe symptoms, the administration may be increased to four times a day.
The eye drops can also be used in children – the age at which they should be used may depend on the particular preparation. It is best to ask the pediatrician or pharmacist about this.
When using azelastine eye drops, strict hygiene must be observed (washing hands beforehand, not touching the eye with the opening of the vial, observing the shelf life of the preparation after opening – this is usually four weeks).
Nasal spray
Unless otherwise indicated or prescribed, adults use azelastine nasal spray twice daily with one spray per nostril. Before first use, the spray should be actuated several times to fill the pump mechanism.
Another tip for the use of the nose drops in children: If the child keeps his or her head tilted slightly forward during administration, less of the bitter-tasting solution will run down the throat and be tasted in the mouth.
Tablets
Azelastine tablets are generally taken twice daily with a glass of water, independent of food. Patients over 65 years of age and those with liver or kidney dysfunction should begin treatment with one tablet daily in the evening – more specific instructions will be provided by the treating physician. According to a doctor’s prescription, some of the tablets are approved for use in children as young as six years of age.
What are the side effects of azelastine?
When using azelastine, the bitter taste can lead to nausea if the nasal spray is not used properly (head tilted back when spraying).
One in one hundred to one thousand people treated complain of mild irritation of the eye and nasal mucosa, as well as sneezing and nosebleeds.
What should I be aware of when using azelastine?
Interactions
To date, interactions between azelastine and other active ingredients are only known when taken as a tablet. Nasal spray and eye drops do not show any interactions due to negligible absorption.
Azelastine is degraded by the liver enzyme cytochrome 2D6 (CYP2D6). Drugs that inhibit this enzyme may increase azelastine blood levels. This can increase the rate of side effects.
Examples include anti-depression agents (such as citalopram, fluoxetine, moclobemide, paroxetine, venlafaxine, sertraline), anti-cancer agents (such as vinblastine, vincristine, doxorubicin, lomustine), and certain HIV agents (such as delavirdine, ritonavir).
Sedatives, sleeping pills, anti-psychotic medications, other allergy medications and also alcohol may unpredictably increase the depressant effect of azelastine.
Age restriction
The age at which azelastine preparations are approved depends on the preparation in question. The package leaflet as well as the doctor and pharmacist provide more detailed information on this.
Pregnancy and breastfeeding
Eye drops and nasal spray can be used both during pregnancy and breastfeeding.
How to obtain medication with azelastine
Azelastine nasal spray and eye drops do not require a prescription in Germany, Austria, and Switzerland and can be purchased at any pharmacy.
Azelastine tablets or nasal sprays in combination with a glucocorticoid (“cortisone”) require a prescription in all three countries. However, azelastine tablets are currently not on the market in Germany, Austria, or Switzerland (as of November 2021).
Since when is azelastine known?
Azelastine already belongs to the second generation of H1 antihistamines and is thus a further development of the first available allergy agents. Compared to its predecessors, it has fewer side effects and is better tolerated. Azelastine nasal spray and tablets were approved in 1991, followed by eye drops containing the active ingredient azelastine in 1998.