Allergy medications: what are they?

Allergy medications are histamine blockers or, as they are more commonly called, antihistamines. Before they are prescribed, differential diagnostics are carried out to identify a specific allergen or allergy complexes. In addition, it is mandatory to neutralize the identified allergen and minimize contact with it.

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Antihistamines for allergies

The most common and effective are antihistamines, which have undergone several stages of improvement over the past decades. These are the drugs that are designed to block histamine, a mediator of inflammatory allergic processes. Anti-allergy drugs of this type effectively cope with H2-histamine receptors, moreover, antihistamines are successfully used in gastroenterology as antiulcer therapy. Antipruritic action, neutralization of spasms, anti-edematous and local anesthetic properties allow these drugs to be widely used in the fight against the enemy of the 21st century - allergies.

Antihistamines are divided into generations - I, II, III. The first generation of antihistamines has a clearly expressed sedative effect, these drugs are called sedative antihistamines. The second generation is more advanced and is called non-sedative antihistamines. Completely new in the mechanism of penetration, pharmacokinetics and bioavailability - these are third-generation drugs, called active metabolites.

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Allergy medications – first generation, sedating antihistamines

These drugs are capable of connecting with H1 receptors, they act as anticholinergics (breaking the connection of neurotransmitters, preventing the transmission of impulses to the nervous system), have a sedative property. The antihistamine effect lasts up to 8 hours, then the drug must be taken again. The sedative effect is explained by the fat solubility of first-generation antihistamines and the excellent ability to overcome the blood-brain protective barrier of the brain. Due to the sedative property, antihistamines of this generation are limited in prescriptions, as well as have limitations in combination with combination therapy. Such drugs are not prescribed together with some types of analgesics, anti-inflammatory drugs. First-generation antihistamines can give atropine-like manifestations - urinary retention, dry mouth, tachycardia, bowel disorder, visual impairment. Among the positive properties of first-generation antihistamines are the antiemetic effect and the tremor-reducing property, which makes it possible to prescribe such therapy for Parkinsonism. These antihistamines can also have a local anesthetic effect. The downside is that over time (2-3 weeks) the body becomes tolerant to the drug and it must be changed. The therapeutic effect occurs quickly enough, but it is short-lived and unstable. In the group of drugs of this generation, diphenhydramine can be considered the leader in popularity and fame. The second position in the ranking is occupied by diazolin, followed by suprastin and tavegil. Pipolfen and fenkarol are less known among the people, but are well known to clinicians, especially those who have worked in the medical field for more than thirty years.

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Allergy medications: second generation antihistamines

It is not by chance that these drugs are called non-sedative antihistamines. They penetrate the blood-brain barrier minimally, therefore the sedative effect is very insignificant. However, second-generation antihistamines perform their main function - blocking H1 receptors - perfectly. Among the disadvantages of these drugs, their cardiotoxicity should be noted. If they are prescribed, constant monitoring of the patient's cardiac activity and additional supportive therapy are necessary. Cardiotoxicity is associated with the blocking of not only H1 receptors, but also potassium channels of the heart muscle. Toxicity may increase in combination therapy with antifungal agents and antidepressants. It is also necessary to exclude drugs and food containing vitamin C and citrus fruits.

It is not recommended to prescribe antihistamines of this generation to elderly people and pregnant women. The therapeutic effect is visible immediately, lasts more than 10 hours, often up to 14 hours, which allows using the drugs less often, and therefore minimizing side effects. Long-term use is possible without addiction and withdrawal syndrome. Among the second-generation antihistamines, one can name Trexil, Astemizole, Semprex, the more popular Fenistil, the even more famous Claritin or Loratadine.

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Allergy medications: third generation antihistamines

These are active metabolites that do not have a sedative effect and are absolutely safe for cardiac activity. They can be prescribed even if the patient's activity is associated with active functions and the need to concentrate. They also cope well with blocking H1 receptors, act for 24 hours, and do not depend on meal time, meaning that the drugs can be taken whenever convenient, but daily. The list of third-generation antihistamines includes Telfast, Erius, and Levocetirizine hydrochloride, better known as Xyzal. These drugs can be released in tablet form, but active metabolites are often released in syrups, which is very attractive in the case of antiallergic therapy for children.

Anti-allergy medications are not limited to antihistamines, the treatment complex also includes nasal sprays, eye drops and even glucocorticoids. Also, sometimes a "veteran" among medications is prescribed - calcium chloride. In any case, medications should be prescribed by an allergist, because the choice of drug directly depends on the type of allergy, allergen and general condition of the person.