What you need to know about ASIT therapy: drugs, possibilities, contraindications

Various allergic reactions in our age are not at all a rare occurrence. Moreover, they occur with the same frequency in both adults and children.

Desensitizing drugs (antiallergic and antihistamine) are drugs that are widely used in the treatment of allergic manifestations. The mechanism of action of such drugs is determined by blocking H1-histamine receptors. This means that the drug suppresses the effects of histamine, which is a mediator substance that contributes to the occurrence of most allergic manifestations. This article will provide a detailed list of desensitizing drugs.

Histamine was first identified in animals at the beginning of the 20th century, and by the mid-thirties of the 20th century, scientists had invented the first drugs that inhibited the effects of such a substance. Repeated studies confirm the fact that histamines act on histamine receptors in the skin, respiratory system and eyes, which is responsible for the occurrence of typical allergic symptoms. It is precisely this reaction that antihistamines can suppress.

Desensitizing drugs are classified according to the mechanism of their effect on various types of allergies:

• Remedies that affect allergies immediately.
• Drugs that have a slow effect on allergies.

Immediate antiallergic agents

This category can also be classified into:

1. Drugs that inhibit the release of allergic mediators from basophilic and smooth muscle cells. In this case, the cytotoxic cascade characteristic of an allergic reaction slows down. These include glucocorticoids and β1-adrenomimetic agents, as well as those having an antispasmodic myotropic effect.
2. Drugs that stabilize cell membranes.
3. Drugs that block H1-histamine cellular receptors.
4. Desensitizing drugs.
5. Drugs that are inhibitors of the complementary system.

What other desensitizing drugs are there?

What are the side effects of allergy vaccination?

The ASIT technique is used in the treatment of millions of patients of different ages. Provided that the optimal dose is correctly calculated and the procedure is carried out correctly, the treatment is tolerated quite well. However, no one is immune from side effects.

When it comes to subcutaneous injection of allergens, many patients experience symptoms such as redness, slight swelling and itching at the injection site. This is a temporary reaction that goes away in 1–3 days. When the drug is absorbed under the tongue, similar symptoms (burning, itching, swelling of the mouth) can sometimes occur, but they occur much less frequently.

In addition to local side effects, some patients complain of more serious systemic manifestations: headache, nasal congestion, urticaria, swelling (Quincke's edema). In most cases, such a reaction indicates improper treatment.

The response usually manifests itself within 30–60 minutes, so this time must be spent in a clinic (hospital), where professional assistance can be provided in a timely manner.

Pathogenesis of allergic reaction

In the pathogenetic formation of an allergic reaction, a decisive role is played by histamine, which is synthesized from histidine and deposited in basophils (so-called mast cells) present in the connective tissue of the body (not excluding blood), as well as in eosinophils, platelets, biofluids, and lymphocytes. In cells, histamine is present in the inactive phase and is associated with polysaccharides and proteins. Its release occurs as a result of a mechanical defect in the cell, an immune reaction, or exposure to drugs or chemicals. Its inactivation is possible through histaminase from mucosal tissues. Histamine activates H1 receptors, and as a result, membrane phospholipids are excited. Due to chemical reactions, conditions arise that allow calcium to enter the cell. It is he who influences the contraction reactions of smooth muscles. Desensitizing agents are aimed at suppressing the effects of histamine.

This substance, acting on H2-histamine receptors, activates adenylate cyclase and also increases the production of cAMP in cells. As a result, gastric secretion increases. Accordingly, some of the desensitizing agents can be used to reduce the secretion of HCI.

Histamine causes dilation of capillaries, increases the permeability of vascular walls, provokes edema and reduces plasma volume. In combination, such disorders lead to thickening of the blood and a decrease in blood pressure, the smooth muscle layer of the bronchi contracts, the release of adrenaline increases, and the heart rate increases.

As a result of this effect on the H1 receptors of the endothelium of the capillary walls, prostacyclin is released, which contributes to the process of expanding the lumen of venules and small vessels. Blood is deposited in them, and the volume of circulating fluid decreases. As a result, plasma, proteins and blood cells are released through the dilated interendothelial wall spaces.

From the mid-twentieth century to the present day, desensitizing drugs have been constantly changing. Scientists have been able to synthesize new drugs that have fewer side effects and are more effective. At the moment, experts distinguish three main groups of anti-allergy drugs: from the first to the third generation.

How is ASIT performed?

Preparation

The decision on the advisability of specific immunotherapy is made jointly by the patient and the doctor. Before starting treatment, a person suffering from allergies will have to undergo training, which involves conducting research - their results are necessary to draw up an individual treatment regimen.

Mandatory examinations include blood and urine tests, as well as allergy tests. Additionally, the doctor may order an electrocardiogram and spirography (the list of necessary examinations depends on the characteristics of the disease and the patient’s condition).

A week before the procedure, the patient should stop taking antihistamines. During the treatment course, it is important to create such conditions to avoid contact with the provoking allergen (or at least reduce it to a minimum).

Options

Allergen immunotherapy can be performed on an outpatient or inpatient basis. In the first case, one treatment course lasts up to six months (such courses are repeated for several years in a row). If the patient is in a hospital, vaccination is carried out for 3–4 weeks, after which another 2–3 months of procedures are carried out on an outpatient basis.

Scheme

There are several schemes of hyposensitizing therapy. The best option is the classic scheme, which is suitable for various forms of allergies - both at an early stage and with a long-term illness. As an alternative, the patient may be offered a shortened version that takes less time. Accelerated courses carry more risks, so they can only be carried out in mild forms and in a hospital setting, under constant medical supervision.

Without exception, all schemes consist of two stages:

1. At the first stage, the introduction of minimal doses of allergens begins with their gradual increase to the maximum permissible dose (this is the so-called optimal dose, the maximum tolerated volume of the allergen). In the classic version, this stage, called the initiating stage, usually lasts 4 months.
2. The second stage is the maintenance stage (according to the classical scheme, it lasts from 6 months to several years). All this time, the patient receives an optimal dose of purified allergen - this allows the achieved effect to be consolidated.

Methods of administration

To deliver the allergen into the body, ASIT therapy provides injection and non-injection methods of administration:

• Using subcutaneous injections (shots);
• orally (in the form of tablets, drops, capsules);
• sublingual (absorption under the tongue);
• intranasally (instillation into the nose).

The most convenient and safest method is sublingual administration, which can be used in both adult patients and children.

Subcutaneous injection

ASIT treatment - drugs

The patient may be offered different forms of drugs. Initially, therapy using this method involved the use of water-salt extracts (for example, a water-salt preparation of birch pollen).

Later, in addition to natural allergens found in nature, modified polymerized analogs appeared - allergoids for injection and resorption.

In the arsenal of domestic allergists there are drugs of Russian and imported origin (medicinal allergens Stallerzhen, Alustal, Oralair, Staloral, etc. have proven themselves well).

Therapy

The most effective and safest are depot preparations (long-acting allergy vaccines). Their peculiarity is that the release of the allergen occurs directly in the body (this reduces the risk of side effects), and the effect of the drug lasts for a longer time, due to which fewer procedures are needed.

First generation of children's products

This generation of drugs includes:

• "Fenistil" - it is recommended for children older than one month. Prescribed in the form of drops.
• "Suprastin" - for children over one year old. If the child is under one year old, the medicine is prescribed by injection and only under the close supervision of a pediatrician.
• Diphenhydramine can be used for children over seven months of age.
• "Fenkarol" - for children over three years old.
• "Clemastine" can be used to treat children who have reached the age of six years.
• "Diazolin" - only older than two years.
• "Tavegil" - for children over six years old.

Desensitizing treatment should only be prescribed by a pediatrician.

Who is it suitable for and how does ASIT work?

ASIT is used in cases where allergens are substances that cannot be avoided (for example, pollen). This method is used if an IgE-dependent allergic disease is diagnosed.

The technique helps with:

• allergic rhinitis and/or rhinoconjunctivitis;
• insect allergies (reaction to dust mites, allergy to insect bites);
• hay fever (seasonal rhinitis);
• atopic bronchial asthma.

Seasonal allergies

The key participants in the body's allergic reaction are antibodies and immunoglobulins lgE. Upon contact with an allergen, immunoglobulins cause an increased reaction, which manifests itself in the form of unpleasant symptoms (nasal congestion, sneezing, coughing, rash, etc.). Allergy vaccination (ASIT) allows you to rebuild the immune system: such treatment is designed to normalize the level of specific E-immunoglobulins.

Second generation of children's products

The most common drugs of this generation include:

• Claritin is prescribed to children over two years of age.
• Zyrtec is prescribed in the form of drops for children over six months old, and in tablets for those over six years old.
• “Erius” is prescribed by the attending physician in the form of syrup for children over one year of age and in tablets for those over twelve years of age.

What are the contraindications?

This treatment method is not universal: it has both limitations and contraindications.

Reviews

Few people know that antihistamines and antiallergic drugs are called desensitizing drugs. But reviews about them are mostly positive. Consumers prefer the latest generation of medicines, considering them more effective. They practically do not cause drowsiness or other side effects.

It should be remembered that before you start taking such desensitizing drugs, you must consult a specialist and carefully study the attached instructions for use. This will avoid possible side effects.

How do you know that ASIT therapy is helping?

Proof that immunotherapy gives a positive result is the weakening of allergic symptoms after the next course, as well as an improvement in the patient’s general well-being. People undergoing such treatment note that the manifestations of allergies gradually decrease, and the need for taking antiallergic drugs decreases (including in the period between courses). Laboratory tests, in particular, a blood test for immunoglobulin E (the IgE level in the blood serum decreases after treatment), can objectively assess the effectiveness of therapy.

To ensure maximum effectiveness of therapy, it is important:

• start treatment as early as possible, if possible in the early stages of allergy;
• use quality vaccines;
• follow all recommendations of the attending physician.