Allergy is the most common chronic disease of adolescents and young people in developing and developed countries. This disease is a reaction of the body’s immune system to certain substances (allergens), which can be food, chemicals, dust, pollen, etc. The prevalence of seasonal allergies is higher in spring and summer due to pollen. Clinical symptoms of allergies include runny nose, congestion, eczema, asthma, itching and hives. According to WHO statistics, hundreds of millions of people in the world suffer from a runny nose and 235 million people also suffer from asthma. Ways to treat allergies include: avoiding allergens, drug therapy and immunotherapy. <br>The drugs used for allergies are mostly antihistamines, decongestants and corticosteroids.
In this article, we will review two drugs used in allergies, hydroxyzine and montelukast.
Hydroxyzine: First choice for severe itching
Hydroxyzine is an H1 receptor antagonist that has antihistamine (moderate), anticholinergic, and antiemetic (high) properties. Hydroxyzine is used to treat and control allergic reactions such as itching, runny nose, watery eyes, and sneezing. It also has hypnotic, antianxiety, anti-anxiety, and anti-nausea and vomiting effects. The onset of action of the drug is 15 to 30 minutes after oral administration, and hypnotic effects are seen in 4 to 6 hours and antipruritic effects in 1 to 12 hours. This drug is metabolized in the liver and the elimination half-life of the drug is 20 hours and is excreted in the urine. The drug is used in anxiety (high doses, 50 to 100 mg), histamine-related itching (25 mg), and nausea and vomiting (25 to 100 mg).
Hydroxyzine is considered a first-generation antihistamine. Later generations of antihistamines such as levostrizine, fexofenadine, loratadine, etc. have more advantages than the first generation; however, hydroxyzine has unique capabilities that are not seen in the later generation, such as:
Hydroxyzine has very strong antipruritic effects compared to other antihistamines and is considered the first choice for severe itching.
In children with atopic dermatitis who are very itchy, using an antihistamine that has sedative and hypnotic effects in addition to antipruritic effects, such as hydroxyzine, is considered an advantage.
Montelukast: Prevents Asthma Attacks
Montelukast is a leukotriene receptor antagonist and is used to prevent asthma, exercise-induced bronchospasm, allergic rhinitis, relieve symptoms of hay fever (sneezing, nasal congestion, runny and itchy nose), and seasonal allergies. Using Montelukast reduces the need to use a respiratory spray. Since the drug has a preventive role, it is not used during asthma or bronchospasm attacks. This drug relieves respiratory problems by blocking leukotriene receptors (a factor that causes or worsens asthma or allergies) and also by reducing inflammation in the airways. Montelukast is well absorbed after oral administration and reaches peak plasma concentrations within 3 to 4 hours (oral tablet) and 2 to 2.5 hours (chewable), and provides a bioavailability of 64%. This drug is metabolized in the liver and has an elimination half-life of 5.5 hours. Montelukast should be taken at specific times of the day; the timing of taking the medication is as follows:
To prevent asthma: In the evening
To prevent allergies: In the morning or evening
To prevent breathing problems during physical activity: 2 hours before starting the activity
Advantages of Montelukast:
Montelukast is effective as a monotherapy in improving symptoms of nocturnal and daytime runny nose.
Combination therapy with antihistamines, especially levostrizine or desloratadine, is more effective and improves symptoms better.
In allergic rhinitis, the effectiveness of montelukast is similar to antihistamines and less than inhaled corticosteroids.
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Martin K Church and Diana S Church, Pharmacology of Antihistamines, Indian J Dermatol. 2013 May-Jun; 58(3): 219–224.
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