Sinusitis

New generation antihistamines are the most effective drugs in the treatment of allergies. Antihistamines for children of different ages Fenkarol generation

There are three (according to some authors - four) generations of antihistamines. The first includes drugs that, in addition to antiallergic, also have a sedative/hypnotic effect. The second includes drugs with a minimally pronounced sedation effect and a powerful antiallergic effect, but in some cases causing serious, life-threatening arrhythmias. Antihistamine drugs of the new - third - generation are metabolic products (metabolites) of second-generation drugs, and their effectiveness is 2-4 times higher than that of their predecessors. They have a number of unique positive properties and do not cause side effects such as drowsiness and negative effects on the heart. It is the third generation drugs that will be discussed in this article.

New (third) generation antihistamines: mechanism of action and effects

Medicines in this group act exclusively on H1-histamine receptors, that is, they have selectivity of action. Their antiallergic effect is also ensured due to the following mechanisms of action. So, these drugs:

inhibit the synthesis of mediators of systemic allergic inflammation, including chemokines and cytokines;
reduce the number and disrupt the functions of adhesion molecules;
inhibit chemotaxis (the process of release of leukocytes from the vascular bed into damaged tissue);
inhibit the activation of allergy cells and eosinophils;
inhibit the formation of superoxide radical;
reduce increased reactivity (hyperreactivity) of the bronchi.

All of the above mechanisms of action provide powerful antiallergic and, to a certain extent, anti-inflammatory effects: eliminate itching, reduce the permeability of the capillary wall, swelling and hyperemia of tissues. Do not cause drowsiness, do not have a toxic effect on the heart. They do not bind to cholinergic receptors, therefore, do not cause side effects such as blurred vision and. They have a high safety profile. It is thanks to these properties that new generation antihistamines can be recommended for long-term treatment of a number of.

Side effects

As a rule, these drugs are well tolerated by patients. However, occasionally, while taking them, the following undesirable effects may develop:

fatigue;
dry mouth (extremely rare);
hallucinations;
drowsiness, insomnia, agitation;
, heartbeat;
nausea, vomiting, epigastric discomfort, in isolated cases -;
muscle pain;
allergic reactions: skin rashes, accompanied or not, shortness of breath, Quincke's edema, anaphylactic reactions.

Indications and contraindications for the use of third generation antihistamines

Food can cause food allergies and cause illness.

Indications for the use of drugs in this group are:

allergic rhinitis (both year-round and seasonal);
(also seasonal and year-round);
chronic;
allergic;

New generation antihistamines are contraindicated only in cases of individual hypersensitivity of the patient's body to them.

Representatives of new generation antihistamines

This group of medicines includes:

Fexofenadine;
Cetirizine;
Levocetirizine;
Desloratadine.

Let's look at each of them in more detail.

Fexofenadine (Altiva, Telfast, Tigofast, Fexofast, Fexofen-Sanovel)

Release form: film-coated tablets of 120 and 180 mg.

Pharmacologically active metabolite of the second generation drug, terfenadine.

After oral administration, it is quickly absorbed in the digestive tract, reaching a maximum concentration in the blood after 1-3 hours. It almost does not bind to blood proteins and does not penetrate the blood-brain barrier. The half-life is 11-15 hours. It is excreted mainly in bile.

The antiallergic effect of the drug develops within 60 minutes after a single dose; within 6 hours the effect increases and persists throughout the day.

Adults and children over 12 years of age are recommended to take 120-180 mg (1 tablet) once a day, before meals. The tablet should be swallowed without chewing with 200 ml of water. The course of treatment is determined individually depending on the characteristics of the disease. Even after regular use of fexofenadine for 28 days, there were no signs of intolerance.

For patients suffering from severe or severe symptoms, the drug should be used with caution.

It should not be used during pregnancy, since clinical studies have not been conducted on this category of patients.

The drug passes into breast milk, so nursing mothers should not take it either.

Cetirizine (Allertek, Rolinoz, Cetrin, Amertil, Zodak, Cetrinal)

While taking antihistamines, you should avoid alcohol.

Release form: film-coated tablets, solution and drops for oral use, syrup.

Metabolite of hydroxyzine. The strongest antagonist of H1-histamine receptors.

The use of this drug in average therapeutic doses significantly improves the quality of life of patients suffering from seasonal and chronic allergic rhinitis.

After oral administration, the effect appears after 2 hours and lasts for a day or more.

In patients with impaired renal function, the dose of cetirizine should be adjusted depending on the value of creatinine clearance: for mild renal failure, 10 mg of an antihistamine is prescribed 1 time per day, which is the full dose; moderate degree – 5 mg 1 time per day (half dose); if the creatinine clearance rate corresponds to a severe degree of renal failure, it is recommended to take 5 mg of cetirizine every other day, and for patients on hemodialysis with end-stage renal failure, taking the drug is completely contraindicated.

Contraindications to the use of cetirizine are also individual hypersensitivity to it and congenital pathology of carbohydrate metabolism (glucose-galactose malabsorption syndrome and others).

Cetirizine, taken in normal doses, may cause temporary adverse reactions such as fatigue, drowsiness, central nervous system stimulation, dizziness and headache. In some cases, while taking it, dry mouth, impaired accommodation of the eye, difficulty urinating and increased activity of liver enzymes are noted. As a rule, after discontinuation of the drug, these symptoms disappear on their own.

During the treatment period, you should stop taking it.

Persons suffering from convulsive syndrome and epilepsy should take the drug with extreme caution due to the increased risk of occurrence.

During pregnancy, use if absolutely necessary. Do not take during lactation, as it is excreted in breast milk.

Levocetirizine (L-cet, Alerzin, Aleron, Zilola, Cetrilev, Aleron neo, Glencet, Xyzal)

Release form: film-coated tablets, drops for oral administration, syrup (dosage form for children).

Cetirizine derivative. The affinity for H1-histamine receptors of this drug is several times higher than that of its predecessor.
When taken orally, it is quickly and completely absorbed, and the degree of absorption does not depend on food intake, but its speed decreases in the presence of food in the stomach. In some patients, the effect of the drug begins within 12-15 minutes after administration, but in the majority it develops later, after 30-60 minutes. The maximum concentration in the blood is determined after 50 minutes and persists for 48 hours. The half-life is from 6 to 10 hours. Excreted by the kidneys.

In persons suffering from severe renal failure, the half-life of the drug is prolonged.

Excreted in breast milk.

Adults and children over 6 years of age are recommended to use the tablet form of the drug. 1 tablet (5 mg) is taken orally, without chewing, with a sufficient amount of water. Frequency of administration – 1 time per day. If levocetirizine is prescribed in the form of drops, the dose for adult patients and children 6 years of age and older is 20 drops once a day. Children under 6 years of age are prescribed in the form of syrup or drops, the dose of which depends on the age of the child.

Persons with severe renal impairment should have their creatinine clearance calculated before prescribing the drug. If this value indicates first-degree renal dysfunction, then the recommended dose of an antihistamine is 5 mg per day, that is, the full dose. In case of moderate renal dysfunction, it is 5 mg once every 48 hours, that is, every other day. In case of severe renal impairment, the drug should be taken 5 mg 1 time every 3 days.

The duration of treatment varies widely and is selected individually depending on the disease and the severity of its course. Thus, for hay fever, the course of treatment, as a rule, is 3-6 months, for chronic allergic diseases - up to 1 year, in case of potential contact with an allergen - 1 week.

Contraindications to the use of levocetirizine, in addition to individual intolerance and severe chronic renal failure, are congenital (galactose intolerance, lactase deficiency and others), as well as pregnancy and lactation.

Side effects are similar to those of other drugs in this group.

While taking levocetirizine, drinking alcoholic beverages is strictly contraindicated.

Desloratadine (Alersis, Lordes, Trexil neo, Erius, Eden, Alergomax, Allergostop, DS-Lor, Fribris, Eridez)

Release form: film-coated tablets, 5 mg each and an oral solution containing 0.5 mg of active substance per ml (dosage form for children). Some drugs, in particular Allergomax, are also available in the form of a nasal spray.

Criteria for choosing antihistamines:
*
*
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In recent years, the number of patients with atopic asthma, allergic rhinitis, and atopic dermatitis has been increasing. These conditions are generally not life-threatening, but require active therapeutic intervention that is effective, safe and well tolerated by patients.

The advisability of using antihistamines for various allergic diseases (urticaria, atopic dermatitis, allergic rhinitis and conjunctivitis, allergic gastropathy) is due to the wide range of histamine effects. The first drugs that competitively block histamine receptors were introduced into clinical practice in 1947. Antihistamines suppress symptoms associated with the endogenous release of histamine, but do not affect the sensitizing effect of allergens. In the case of late prescription of antihistamines, when the allergic reaction is already significantly expressed and the clinical effectiveness of these drugs is low.

Criteria for choosing antihistamines

The need to choose a drug that has an additional antiallergic effect:

year-round allergic rhinitis;
seasonal allergic rhinitis (conjunctivitis) with seasonal exacerbations lasting up to 2 weeks;
chronic urticaria;
atopic dermatitis;
allergic contact dermatitis;
early atopic syndrome in children.

Indicated for use in children:

children under 12 years old:

loratadine ( Claritine)
cetirizine ( Zyrtec)
terfenadine ( Trexyl)
astemizole ( Hismanal)
dimethindene ( Fenistil)

children 1-4 years old with early atopic syndrome:

cetirizine ( Zyrtec)
loratadine ( Claritine)
desloratadine ( Erius)

Indicated for use by women during pregnancy and lactation:

loratadine ( Claritine)
cetirizine ( Zyrtec)
desloratadine ( Alergostop, Delot, Dezal, Claramax, Clarinex, Larinex, Loratek, Lordestin, NeoClaritin, Eridez, Erius, Eslotin, Ezlor)
fexofenadine ( Telfast, Allegra)
pheniramine ( Avil)

When choosing antihistamines (or any other medications) during lactation, it is better to be guided by the data on the website http://www.e-lactancia.org/en/, where you just need to search for the English or Latin name of the drug or the main substance. On the website you can find information and the degree of risk of taking the drug for a woman and child during lactation (breastfeeding). Since manufacturers often play it safe and do not recommend using the drug during pregnancy and lactation (who will allow them to conduct research on the effect of the drug on pregnant and lactating women, but no research means no permission).

The patient has specific problems:

patients with renal failure:

loratadine ( Claritine)
astemizole ( Hismanal)
terfenadine ( Trexyl)

patients with liver dysfunction:

loratadine ( Claritine)
cetirizine ( Zytrec)
fexofenadine ( Telfast)

Authors: I.V. Smolenov, N.A. Smirnov
Department of Clinical Pharmacology, Volgograd Medical Academy

1st generation antihistamines

Based on their chemical structure, these drugs are divided into the following groups:

Diphenhydramine(diphenhydramine, alphadril, etc.) has a fairly high antihistamine activity, has a local anesthetic effect (numbness of the mucous membranes), reduces spasm of smooth muscles, is lipophilic and penetrates the blood-brain barrier, therefore has a pronounced sedative effect, similar to the action of antipsychotic drugs, in large doses has a hypnotic effect. This drug and its analogs inhibit the conduction of nervous excitation in the autonomic ganglia and have a central anticholinergic effect, and therefore increase the dryness of the mucous membranes and the viscosity of secretions, and can cause agitation, headache, trembling, dry mouth, urinary retention, tachycardia, and constipation. Prescribed orally 2-3 times a day, intramuscularly.

Suprastin(chloropyramine) has a pronounced antihistamine and M-anticholinergic effect, penetrates the blood-brain barrier, causes drowsiness, general weakness, dry mucous membranes and increases the viscosity of secretions, irritation of the gastrointestinal mucosa, headache, dry mouth, urinary retention, tachycardia, glaucoma. Prescribed orally 2-3 times a day, intramuscularly.

Promethazine(pipolfen, diprazine) has strong antihistamine activity, is well absorbed and, with different routes of administration, easily penetrates the blood-brain barrier, and therefore has significant sedative activity, enhances the effect of narcotic, hypnotics, analgesics and local anesthetics, lowers body temperature, warns and calms vomiting It has a moderate central and peripheral anticholinergic effect. When administered intravenously, it can cause a drop in systemic blood pressure and collapse. Prescribed orally and intramuscularly.

Clemastine(tavegil) is one of the most common and effective 1st generation antihistamines, selectively and actively blocks H1 receptors, acts longer (8-12 hours), weakly penetrates the blood-brain barrier, therefore does not have sedative activity and does not causes a drop in blood pressure. Recommended for use in acute allergic reactions parenterally (anaphylactic shock, severe forms of allergic dermatoses).

Diazolin(omeril) has less antihistamine activity, but practically does not penetrate the blood-brain barrier and does not cause sedative and hypnotic effects, and is well tolerated.

Fenkarol(quifenadine) is an original antihistamine, moderately blocks H1 receptors and reduces the content of histamine in tissues, has low lipophilicity, does not penetrate the blood-brain barrier and does not have sedative and hypnotic effects, does not have adrenolytic and anticholinergic activity, and has an antiarrhythmic effect. Children under 3 years of age are prescribed 0.005 g, from 3 to 12 years - 0.01 g, over 12 years - 0.025 g 2-3 times a day.

Peritol(cyproheptadine) moderately blocks H1 receptors, has strong antiserotonin activity, as well as an M-cholinergic effect, penetrates the blood-brain barrier and has a pronounced sedative effect, reduces the hypersecretion of ACTH and somatotropin, increases appetite, and reduces the secretion of gastric juice. Prescribed for children from 2 to 6 years old - 6 mg in three doses, over 6 years old - 4 mg 3 times a day.

Comparative characteristics of the most common 1st generation antihistamines are presented in Table. 3.

Table 3. 1st generation antihistamines recommended for the treatment of allergic pathology in children

Options/Actions	Diphenhydramine	Tavegil	Suprastin	Fenkarol	Diazolin	Peritol	Pipolfen
Sedative effect	++	+/-	+	--	--	-	+++
M-cholinergic. Effect	+	+	+	--	+	+/-	+
Start of action	2 hours	2 hours	2 hours	2 hours	2 hours	2 hours	20 minutes.
Half-life	4-6 hours	1-2 hours	6-8 hours	4-6 hours	6-8 hours	4-6 hours	8-12 hours
Frequency of intake per day	3-4 times	2 times	2-3 times	3-4 times	1-3 times	3-4 times	2-3 times
Application time	after meal	after meal	while eating	after meal	after meal	after meal	after meal
Interaction with other drugs	enhances the effect of hypnotics, neuroleptics, anticonvulsants	enhances the effect of hypnotics and MAO inhibitors	moderately enhances the effect of hypnotics and antipsychotics	reduces histamine content in tissues, has an anti-arrhythmic effect	-	has an anti-serotonin effect, reduces ACTH secretion	enhances the effect of narcotic, sleeping pills, local anesthetics
Side effects	agitation, drop in blood pressure, dry mouth, difficulty breathing	not prescribed before 1 year of age, bronchospasm, urinary obstruction, constipation	dry mouth, increased transaminase levels, irritation of the gastric mucosa and duodenum. guts	dry mouth, sometimes nausea	dry mouth, irritation of the gastric mucosa and 12 fingers. guts	dry mouth, drowsiness, nausea	short-term drop in blood pressure, increased transaminase levels, photosensitizing effect

Features of the pharmacological effects of 1st generation antihistamines

As shown in table. 3, first-generation antihistamines, non-competitively and reversibly inhibiting H1 receptors, block other receptor formations, in particular, cholinergic muscarinic receptors and thus have an M1-cholinergic effect. Their atropine-like effect can cause dry mucous membranes and aggravate bronchial obstruction. To achieve a pronounced antihistamine effect, high concentrations of these drugs in the blood are required, which requires the administration of large doses. In addition, these compounds act quickly after administration, but for a short time, which requires their repeated use (4-6 times) during the day. It is important to note that antihistamines act on the central nervous system by penetrating the blood-brain barrier and can cause blockade of H1 receptors in cells of the central nervous system, which causes their undesirable sedative effect.

The most important property of these drugs, which determines the ease of penetration through the blood-brain barrier, is their lipophilicity. The sedative effects of these drugs, ranging from mild drowsiness to deep sleep, can often occur even at normal therapeutic doses. Essentially, all 1st generation antihistamines have a pronounced sedative effect to one degree or another, most noticeable in phenothiazines (pipolfen), ethanolamines (diphenhydramine), piperidines (peritol), ethylenediamines (suprastin), to a lesser extent in alkylamines and benzhydryl ether derivatives (clemastine, tavegil). The sedative effect is practically absent from quinuclidine derivatives (fenkarol).

Another undesirable manifestation of the effect of these drugs on the central nervous system is impaired coordination, dizziness, a feeling of lethargy, and decreased ability to concentrate. Some 1st generation antihistamines exhibit the properties of local anesthetics, have the ability to stabilize biomembranes and, by prolonging the refractory phase, can cause cardiac arrhythmias. Some drugs in this group (pipolfen), potentiating the effects of catecholamines, cause fluctuations in blood pressure (Table 3).

Among the undesirable effects of these drugs, one should also note an increase in appetite, most pronounced with piperidines (peritol) and the occurrence of functional disorders of the gastrointestinal tract (nausea, vomiting, discomfort in the epigastric region), more often manifested when taking ethylenediamines (suprastin, diazolin). Most 1st generation antihistamines reach peak concentrations after 2 hours. However, a negative characteristic of 1st generation H1 antagonists is the fairly frequent development of tachyphylaxis - a decrease in therapeutic effectiveness with prolonged use (Table 4).

Table 4. Undesirable side effects of first generation antihistamines:

1. Pronounced sedative and hypnotic effect
2. Negative effect on the central nervous system - loss of coordination, dizziness, decreased concentration
3. M-cholinergic (atropine-like) effect
4. Development of tachyphylaxis
5. Short duration of action and repeated use

Due to the peculiarities of the pharmacological action of 1st generation antihistamines, certain restrictions on their use have now been established (Table 5). Therefore, in order to prevent tachyphylaxis, when prescribing these drugs, they should be alternated every 7-10 days.

Table 5. Limitations of the clinical use of first generation antihistamines:

astheno-depressive syndrome;
bronchial asthma, glaucoma;
spastic phenomena in the pyloric or duodenal areas;
atony of the intestines and bladder;
all types of activities requiring active attention and quick reaction

Thus, the undesirable effects of 1st generation antihistamines limit their use in medical practice, especially in recent years. However, the relatively low cost of these drugs and their rapid action make it possible to recommend these drugs for the treatment of the acute period of allergic diseases in children in a short course (7 days). In the acute period and especially in severe forms of allergic dermatoses in children, when parenteral administration of antihistamines is required and taking into account the fact that to date there are no such 2nd generation drugs, the most effective is tavegil, which lasts longer (8-12 hours) , has a slight sedative effect and does not cause a drop in blood pressure. For anaphylactic shock, tavegil is also the drug of choice. Suprastin is less effective in such cases. In the subacute course of allergic dermatoses and especially in their itchy forms (atopic dermatitis, acute and chronic urticaria). in children with astheno-depressive syndrome, 1st generation antihistamines can be used, mainly without sedation - fenkarol and diazolin, which should be prescribed in a short course - 7-10 days. For allergic rhinitis (seasonal and year-round) and hay fever, the use of 1st generation antihistamines is undesirable, since they, having an M-cholinergic effect, can cause dry mucous membranes, increase the viscosity of secretions and contribute to the development of sinusitis and sinusitis, and in bronchial asthma - cause or intensify bronchospasm. Due to its pronounced cardiovascular effect, the use of pipolfen in various forms of allergic diseases is currently very limited.

2nd generation antihistamines

Antihistamines of the 2nd generation have been widely used in allergy practice in recent years. These drugs have a number of advantages over 1st generation drugs (Table 6)

Table 6. Effects of second generation antihistamines

1. They have very high specificity and affinity for H1 receptors
2. Do not cause blockade of other types of receptors
3. They do not have an M-anticholinergic effect
4. In therapeutic doses, they do not penetrate the blood-brain barrier and do not have sedative and hypnotic effects
5. Have a rapid onset of action and a pronounced duration of the main effect (up to 24 hours)
6. Well absorbed from the gastrointestinal tract
7. No connection has been established between drug absorption and food intake
8. Can be used at any time
9. Does not cause tachyphylaxis
10. Easy to use (once a day)

It is obvious that these drugs meet the basic requirements for ideal antihistamines, which should quickly show effect, have a long-lasting effect (up to 24 hours) and be safe for patients. These requirements are largely met by 2nd generation antihistamines: Claritin (loratadine), Zyrtec (cetirizine), Kestine (ebastine) (Table 7).

Table 7. 2nd generation antihistamines recommended for the treatment of allergic pathology in children

Options actions	Terfenadine (terphen)	Astemizole (gismanal)	Claritin (loratadine)	Zyrtec (cytirizine)	Kestin (ebastine)
Sedative effect	No	May be	No	May be	No
M-cholinergic. Effect	There is	There is	No	No	No
Start of action	1-3 hours	2-5 days	30 minutes	30 minutes	30 minutes
Half-life	4-6 hours	8-10 days	12-20 hours	7-9 hours	24 hours
Frequency of intake per day	1-2 times	1-2 times	1 time	1 time	1 time
Related to food intake	No	Yes	No	No	No
Application time	any time, better on an empty stomach	on an empty stomach or 1 hour before meals	Anytime	in the 2nd half of the day, preferably before bedtime	Anytime
Pharmacological incompatibility with other drugs		Erythromycin, oleandomycin, clarithromycin, mycozolon			Erythromycin, Kenolone
Side effects	Ventricular arrhythmias, QT interval prolongation, bradycardia, syncope, bronchospasm, hypokalemia, hypomagnesemia, increased transaminase activity	Ventricular arrhythmias, bradycardia, fainting, bronchospasm, increased transaminase activity, not indicated for children under 12 years of age	Dry mouth (rare)	Dry mouth (sometimes)	Dry mouth (rare), abdominal pain (rare)
Efficiency of use when
atopic dermatitis:	+/-	+/-	++	++	++
for urticaria	+/-	+/-	+++	++	+++
Weight gain	No	up to 5-8 kg in 2 months	No	No	No

Claritin (loratadine) is the most common antihistamine, it has a specific blocking effect on H1 receptors, for which it has a very high affinity, does not have anticholinergic activity and therefore does not cause dry mucous membranes and bronchospasm.

Claritin quickly acts on both phases of the allergic reaction, inhibits the production of a large number of cytokines, directly inhibits the expression of cell adhesion molecules (ICAM-1, VCAM-1, LFA-3, P-selectins and E-selectins), reduces the formation of leukotriene C4, thromboxane A2 , factors of eosinophil chemotaxis and platelet activation. Thus, claritin effectively prevents the formation of allergic inflammation and has a pronounced antiallergic effect (Leung D., 1997). These properties of claritin were the basis for its use as a basic remedy in the treatment of allergic diseases such as allergic rhinitis, conjunctivitis and hay fever.

Claritin also helps to reduce bronchial hyperreactivity, increases forced expiratory volume (FEV1) and peak expiratory flow, which determines its beneficial effect on bronchial asthma in children.

Claritin is effective and can currently be used as an alternative anti-inflammatory therapy, especially for mild persistent bronchial asthma, as well as for the so-called cough variant of bronchial asthma. In addition, this drug does not penetrate the blood-brain barrier, does not affect the activity of the NCS and does not potentiate the effect of sedatives and alcohol. The sedative effect of Claritin is no more than 4%, that is, it is detected at the placebo level.

Claritin does not have a negative effect on the cardiovascular system even in concentrations exceeding the therapeutic dose by 16 times. Apparently, this is determined by the presence of several pathways of its metabolism (the main pathway is through the oxygenase activity of the CYP3A4 isoenzyme of the cytochrome P-450 system and the alternative pathway is through the CYP2D6 isoenzyme), therefore Claritin is compatible with macrolides and antifungal drugs imidazole derivatives (ketoconazole, etc.) , as well as with a number of other medications, which is crucial when using these medications simultaneously.

Claritin is available in tablets of 10 mg and in syrup, 5 ml of which contain 5 mg of the drug.

Claritin tablets are prescribed to children over the age of 2 years in the appropriate dosage for their age. The maximum level of the drug in plasma is achieved within 1 hour after oral administration, which ensures a rapid onset of effect. Food intake, liver and kidney dysfunction do not affect the pharmacokinetics of Claritin. Claritin is released after 24 hours, which allows you to take it once a day. Long-term use of Claritin does not cause tachyphylaxis and addiction, which is especially important in the treatment of itchy forms of allergic dermatoses (atopic dermatitis, acute and chronic urticaria and strophulus) in children. We studied the effectiveness of Claritin in 147 patients with various forms of allergic dermatoses with a good therapeutic effect in 88.4% of cases. The best effect was obtained in the treatment of acute and especially chronic urticaria (92.2%), as well as in atopic dermatitis and strophulus (76.5%). Considering the high effectiveness of claritin in the treatment of allergic dermatoses and its ability to inhibit the production of leukotrienes, we investigated its effect on the activity of eicosanoid biosynthesis in peripheral blood granulocytes of patients with atopic dermatitis. The biosynthesis of prostanoids by peripheral blood leukocytes was studied by the radioisotope method using labeled arachidonic acid in vitro.

During treatment with claritin in patients with atopic dermatitis, a decrease in the biosynthesis of the studied eicosanoids was found. At the same time, the biosynthesis of PgE2 decreased most significantly - by 54.4%. The production of PgF2a, TxB2 and LTB4 decreased by an average of 30.3%, and prostacyclin biosynthesis decreased by 17.2% compared to pre-treatment levels. These data indicate a significant effect of claritin on the mechanisms of formation of atopic dermatitis in children. Obviously, a decrease in the formation of pro-inflammatory LTB4 and pro-aggregate TxB2 against the background of relatively unchanged prostacyclin biosynthesis is an important contribution of claritin to the normalization of microcirculation and a decrease in the intensity of inflammation in the treatment of atopic dermatitis. Consequently, the revealed patterns of the effects of claritin on the mediator functions of eicosanoids should be taken into account in the complex therapy of allergic dermatoses in children. Our data allows us to conclude that the use of Claritin is especially appropriate for allergic skin diseases in children. For dermorespiratory syndrome in children, Claritin is also an effective drug, as it can simultaneously affect skin and respiratory manifestations of allergies. The use of Claritin for dermorespiratory syndrome for 6-8 weeks helps to improve the course of atopic dermatitis, reduce asthma symptoms, optimize external respiration, reduce bronchial hyperreactivity and reduce the symptoms of allergic rhinitis.

Zyrtec(Cetirizine) is a pharmacologically active non-metabolized product that has a specific blocking effect on H1 receptors. The drug has a pronounced antiallergic effect, as it inhibits the histamine-dependent (early) phase of the allergic reaction, reduces the migration of inflammatory cells and inhibits the release of mediators involved in the late phase of the allergic reaction.

Zyrtec reduces the hyperreactivity of the bronchial tree, does not have an M-cholinergic effect, therefore it is widely used in the treatment of allergic rhinitis, conjunctivitis, hay fever, as well as in their combination with bronchial asthma. The drug does not have a negative effect on the heart.

Zyrtec is available in tablets of 10 mg and drops (1 ml = 20 drops = 10 mg), characterized by the rapid onset of the clinical effect and prolonged action due to its insignificant metabolism. Prescribed to children from the age of two: from 2 to 6 years, 0.5 tablets or 10 drops 1-2 times a day, for children 6-12 years old - 1 tablet or 20 drops 1-2 times a day.

The drug does not cause tachyphylaxis and can be used for a long time, which is important in the treatment of allergic skin lesions in children. Despite instructions about the absence of a pronounced sedative effect when taking Zyrtec, in 18.3% of observations we found that the drug, even in therapeutic doses, caused a sedative effect. In this regard, caution should be exercised when using Zyrtec together with sedatives due to the possible potentiation of their action, as well as in cases of liver and kidney pathology. We obtained a positive therapeutic effect of using Zyrtec in 83.2% of cases of treatment of allergic dermatoses in children. This effect was especially pronounced in itchy forms of allergic dermatoses.

Kestin(Ebastine) has a pronounced selective H1-blocking effect, without causing anticholinergic and sedative effects, is rapidly absorbed and almost completely metabolized in the liver and intestines, turning into the active metabolite carebastine. Taking kestin along with fatty foods increases its absorption and formation of carebastine by 50%, which, however, does not affect the clinical effect. The drug is available in 10 mg tablets and is used in children over 12 years of age. A pronounced antihistamine effect occurs 1 hour after administration and lasts 48 hours.

Kestin is effective in the treatment of allergic rhinitis, conjunctivitis, hay fever, as well as in complex therapy of various forms of allergic dermatoses - especially chronic recurrent urticaria and atopic dermatitis.

Kestin does not cause tachyphylaxis and can be used long-term. However, it is not recommended to exceed its therapeutic doses and use caution when prescribing kestin in combination with macrolides and some antifungal drugs, as it can cause a cardiotoxic effect. Despite the proliferation of 2nd generation drugs such as terfenadine and astemizole, we do not recommend their use in the treatment of allergic diseases in children, since some time after the start of the use of these drugs (since 1986), clinical and pharmacological data appeared indicating that the damaging effect of these drugs on the cardiovascular system and liver (heart rhythm disturbances, prolongation of the QT interval, bradycardia, hepatotoxicity). Mortality was found in 20% of patients receiving these drugs. Therefore, these drugs should be used with caution, not exceeding the therapeutic dose and not used in patients with hypokalemia, cardiac arrhythmias, congenital prolongation of the QT interval, and especially in combination with macrolides and antifungal drugs.

Thus, in recent years, the pharmacotherapy of allergic diseases in children has been replenished with a new group of effective H1 receptor antagonists, devoid of a number of negative properties of first-generation drugs. According to modern concepts, an ideal antihistamine should quickly exhibit an effect, have a long-lasting effect (up to 24 hours) and be safe for patients. The choice of such a drug should be made taking into account the individuality of the patient and the characteristics of the clinical manifestations of allergic pathology, as well as taking into account the patterns of pharmacokinetics of the drug. Along with this, when assessing the priority of prescribing modern H1 receptor antagonists, special attention should be paid to the clinical effectiveness and safety of such drugs for the patient. Criteria for selecting second-generation antihistamines are shown in Table 8.

Table 8. Criteria for choosing second generation antihistamines

	Claritin	Zyrtec	Astemizole	Terfenadine	Kestin
Clinical effectiveness
Year-round allergic rhinitis	++	++	++	++	++
Seeonny	+++	+++	+++	+++	+++
Atopic dermatitis	++	++	++	++	++
Hives	+++	+++	+++	+++	+++
Strophulus	+++	+++	+++	+++	+++
Toxidermy	+++	+++	+++	+++	+++
Safety
Sedative effect	No	Yes	No	No	No
Strengthening the effect of sedatives	No	Yes	No	No	No
Cardiotoxic effect: QT prolongation, hypokalemia	No	No	Yes	Yes	at a dose of more than 20 mg
Combined use with macrolides and some antifungal drugs	does not cause side effects	does not cause side effects	cardiotoxic effect	cardiotoxic effect	at a dose of more than 20 mg, an effect on blood circulation is possible
Interaction with food	No	No	Yes	No	No
Anticholinergic effect	No	No	No	No	No

Our research and clinical observations indicate that such a second-generation antihistamine, meeting the above conditions, is clinically effective and safe in the treatment of allergic diseases in children. Claritin, and then - Zyrtec.

– these are substances that suppress the action of free histamine. When an allergen enters the body, histamine is released from connective tissue mast cells, which are part of the body's immune system. It begins to interact with specific receptors and cause itching, swelling, rash and other allergic manifestations. Antihistamines are responsible for blocking these receptors. There are three generations of these drugs.

1st generation antihistamines

They appeared in 1936 and continue to be used. These drugs bind reversibly to H1 receptors, which explains the need for large dosages and high frequency of administration.

1st generation antihistamines are characterized by the following pharmacological properties:

reduce muscle tone;

have a sedative, hypnotic and anticholinergic effect;

potentiate the effects of alcohol;

have a local anesthetic effect;

give a quick and strong, but short-term (4-8 hours) therapeutic effect;

long-term use reduces antihistamine activity, so the drugs are changed every 2-3 weeks.

The bulk of 1st generation antihistamines are fat-soluble, can cross the blood-brain barrier and bind to H1 receptors in the brain, which explains the sedative effect of these drugs, which increases after taking alcohol or psychotropic drugs. When taking moderate therapeutic doses in children and high toxic doses in adults, psychomotor agitation may occur. Due to the sedative effect, 1st generation antihistamines are not prescribed to persons whose activities require increased attention.

The anticholinergic properties of these drugs cause atropine-like reactions, such as dryness of the nasopharynx and oral cavity, urinary retention, and blurred vision. These features can be beneficial for, but can increase airway obstruction caused by bronchial inflammation (the viscosity of sputum increases), contribute to the exacerbation of prostate adenoma, glaucoma and other diseases. At the same time, these drugs have an antiemetic and anti-sickness effect, reducing the manifestation of parkinsonism.

A number of these antihistamines are included in combination drugs that are used for colds, motion sickness, or have a sedative or hypnotic effect.

The extensive list of side effects from taking these antihistamines forces them to be used less frequently in the treatment of allergic diseases. Many developed countries have banned their implementation.

Diphenhydramine is prescribed for hay fever, urticaria, seasickness, air sickness, vasomotor, bronchial asthma, allergic reactions caused by the administration of drugs (for example, antibiotics), in the treatment of peptic ulcers, dermatoses, etc.

Advantages: high antihistamine activity, reduced severity of allergic and pseudo-allergic reactions. Diphenhydramine has an antiemetic and antitussive effect, has a local anesthetic effect, making it an alternative to Novocaine and Lidocaine if they are intolerant.

Cons: unpredictability of the consequences of taking the drug, its effect on the central nervous system. It can cause urinary retention and dry mucous membranes. Side effects include sedative and hypnotic effects.

Diazolin

Diazoline has the same indications for use as other antihistamines, but differs from them in the characteristics of their effects.

Advantages: the mild sedative effect allows it to be used where it is undesirable to have a depressant effect on the central nervous system.

Cons: irritates the mucous membranes of the gastrointestinal tract, causes dizziness, difficulty urinating, drowsiness, slows down mental and motor reactions. There is information about the toxic effect of the drug on nerve cells.

Suprastin

Suprastin is prescribed for the treatment of seasonal and chronic allergic conjunctivitis, urticaria, atopic, angioedema, itching of various etiologies,. It is used in parenteral form for acute allergic conditions requiring emergency care.

Advantages: it does not accumulate in the blood serum, therefore, even with prolonged use it does not cause an overdose. Due to its high antihistamine activity, a rapid therapeutic effect is observed.

Cons: side effects - drowsiness, dizziness, inhibition of reactions, etc. - are present, although less pronounced. The therapeutic effect is short-term, in order to prolong it, Suprastin is combined with H1-blockers that do not have sedative properties.

in the form of injections, they are used for angioedema, as well as anaphylactic shock, as a preventive and therapeutic agent for allergic and pseudoallergic reactions.

Advantages: has a longer and stronger antihistamine effect than Diphenhydramine, and has a more moderate sedative effect.

Disadvantages: it can cause an allergic reaction itself, has some inhibitory effects.

Fenkarol

Fenkarol is prescribed when addiction to other antihistamines occurs.

Advantages: it has mild sedative properties, does not have a pronounced inhibitory effect on the central nervous system, is low-toxic, blocks H1 receptors, and is able to reduce the content of histamine in tissues.

Cons: less antihistamine activity compared to Diphenhydramine. Fenkarol is used with caution in the presence of diseases of the gastrointestinal tract, cardiovascular system and liver.

Antihistamines 2nd generation

They have advantages compared to first generation drugs:

there is no sedative and anticholinergic effect, since these drugs do not cross the blood-brain barrier, only some individuals experience moderate drowsiness;

mental activity and physical activity are not affected;

the effect of the drugs reaches 24 hours, so they are taken once a day;

they are not addictive, which allows them to be prescribed for a long time (3-12 months);

when you stop taking the drugs, the therapeutic effect lasts about a week;

drugs are not adsorbed from food in the gastrointestinal tract.

But 2nd generation antihistamines have a cardiotoxic effect of varying degrees, so when taking them, cardiac activity is monitored. They are contraindicated in elderly patients and patients suffering from disorders of the cardiovascular system.

The occurrence of cardiotoxic effects is explained by the ability of 2nd generation antihistamines to block potassium channels of the heart. The risk increases when these drugs are combined with antifungal drugs, macrolides, antidepressants, from drinking grapefruit juice, and if the patient has severe liver dysfunction.

Claridol and Clarisens

used for the treatment of seasonal and cyclical allergic rhinitis, allergic rhinitis, Quincke's edema and a number of other diseases of allergic origin. It copes with pseudoallergic syndromes and allergies to insect bites. Included in comprehensive measures for the treatment of itchy dermatoses.

Advantages: Claridol has antipruritic, antiallergic, antiexudative effects. The drug reduces capillary permeability, prevents the development of edema, and relieves spasm of smooth muscles. It has no effect on the central nervous system and does not have an anticholinergic or sedative effect.

Cons: occasionally, after taking Claridol, patients complain of dry mouth, nausea and vomiting.

Clarotadine

Clarotadine contains the active substance loratadine, which is a selective blocker of H1-histamine receptors, on which it has a direct effect, avoiding the undesirable effects inherent in other antihistamines. Indications for use are allergic conjunctivitis, acute chronic and idiopathic urticaria, rhinitis, pseudoallergic reactions associated with the release of histamine, allergic insect bites, itchy dermatoses.

Advantages: the drug does not have a sedative effect, is not addictive, acts quickly and for a long time.

Cons: undesirable consequences of taking Clarodin include nervous system disorders: asthenia, anxiety, drowsiness, depression, amnesia, tremor, agitation in a child. Dermatitis may appear on the skin. Frequent and painful urination, constipation and diarrhea. Weight gain due to disruption of the endocrine system. Damage to the respiratory system can be manifested by cough, bronchospasm, sinusitis and similar manifestations.

indicated for seasonal and permanent allergic rhinitis, skin rashes of allergic origin, pseudo-allergies, reactions to insect bites, allergic inflammation of the mucous membrane of the eyeball.

Advantages: Lomilan is able to relieve itching, reduce the tone of smooth muscles and the production of exudate (a special fluid that appears during the inflammatory process), and prevent tissue swelling within half an hour from the moment of taking the drug. The greatest effectiveness occurs after 8-12 hours, then subsides. Lomilan is not addictive and does not have a negative effect on the activity of the nervous system.

Disadvantages: adverse reactions occur rarely and are manifested by headache, a feeling of fatigue and drowsiness, inflammation of the gastric mucosa, and nausea.

LauraHexal

Advantages: the drug has neither anticholinergic nor central effects, its use does not affect the attention, psychomotor functions, performance and mental qualities of the patient.

Cons: LauraHexal is usually well tolerated, but occasionally it causes increased fatigue, dry mouth, headache, tachycardia, dizziness, allergic reactions, cough, vomiting, gastritis, and liver dysfunction.

Claritin

Claritin contains the active ingredient loratadine, which blocks H1-histamine receptors and prevents the release of histamine, bradycanin and serotonin. Antihistamine effectiveness lasts a day, and therapeutic effectiveness occurs after 8-12 hours. Claritin is prescribed for the treatment of rhinitis of allergic etiology, allergic skin reactions, food allergies and mild bronchial asthma.

Advantages: highly effective in the treatment of allergic diseases, the drug does not cause addiction or drowsiness.

Cons: cases of side effects are rare, they are manifested by nausea, headache, gastritis, agitation, allergic reactions, drowsiness.

Rupafin

Rupafin has a unique active component - rupatadine, characterized by antihistamine activity and a selective effect on H1-histamine peripheral receptors. It is prescribed for chronic idiopathic urticaria and allergic rhinitis.

Advantages: Rupafin effectively copes with the symptoms of the allergic diseases listed above and does not affect the functioning of the central nervous system.

Cons: undesirable consequences of taking the drug - asthenia, dizziness, fatigue, headache, drowsiness, dry mouth. It can affect the respiratory, nervous, musculoskeletal and digestive systems, as well as metabolism and skin.

Zyrtec

Zyrtec is a competitive antagonist of the hydroxyzine metabolite, histamine. The drug facilitates the course and sometimes prevents the development of allergic reactions. Zyrtec limits the release of mediators, reduces the migration of eosinophils, basophils, and neutrophils. The drug is used for allergic rhinitis, bronchial asthma, urticaria, conjunctivitis, dermatitis, fever, skin edema, angioedema.

Advantages: effectively prevents the occurrence of edema, reduces capillary permeability, relieves spasm of smooth muscles. Zyrtec does not have anticholinergic or antiserotonin effects.

Cons: improper use of the drug can lead to migraines, drowsiness, and allergic reactions.

blocks histamine receptors, which increase vascular permeability, causing muscle spasms, leading to an allergic reaction. Used to treat allergic conjunctivitis, rhinitis and chronic idiopathic urticaria.

Advantages: the drug acts within an hour after use, the therapeutic effect lasts for 2 days. A five-day intake of Kestin allows you to maintain the antihistamine effect for about 6 days. Sedative effects are practically non-existent.

Cons: the use of Kestin can cause insomnia, abdominal pain, nausea, drowsiness, asthenia, headache, sinusitis, dry mouth.

New, 3rd generation antihistamines

These substances are prodrugs, which means that when they enter the body, they are converted from their original form into pharmacologically active metabolites.

All 3rd generation antihistamines do not have cardiotoxic or sedative effects, so they can be used by people whose activities involve high concentration.

These drugs block H1 receptors and also have an additional effect on allergic manifestations. They are highly selective, do not cross the blood-brain barrier, therefore they are not characterized by negative consequences from the central nervous system, and there is no side effect on.

The presence of additional effects promotes the use of 3rd generation antihistamines for long-term treatment of most allergic manifestations.

prescribed as a therapeutic and prophylactic agent for hay fever, allergic skin reactions, including urticaria, allergic rhinitis. The effect of the drug develops over 24 hours and reaches its maximum after 9-12 days. Its duration depends on previous therapy.

Advantages: the drug has virtually no sedative effect and does not enhance the effect of taking sleeping pills or alcohol. It also does not affect driving ability or mental performance.

Cons: Gismanal can cause increased appetite, dry mucous membranes, tachycardia, drowsiness, prolongation of the QT interval, palpitations, collapse.

is a fast-acting, selectively active H1 receptor antagonist, a derivative of buterophenol, which differs in chemical structure from its analogues. Used for allergic rhinitis to relieve its symptoms, allergic dermatological manifestations (dermatographism, contact dermatitis, urticaria, atonic eczema), asthma, atonic and provoked physical activity, as well as in connection with acute allergic reactions to various irritants.

Advantages: lack of sedative and anticholinergic effect, no effect on psychomotor activity and human well-being. The drug is safe to use by patients with glaucoma and those suffering from prostate disorders.

– a highly effective antihistamine, which is a metabolite of terfenadine, and therefore has great similarity with histamine H1 receptors. Telfast binds to them and blocks them, preventing their biological manifestations as allergic symptoms. The membranes of mast cells are stabilized and the release of histamine from them is reduced. Indications for use include angioedema, urticaria, and hay fever.

Advantages: does not exhibit sedative properties, does not affect the speed of reactions and concentration, heart function, is not addictive, highly effective against the symptoms and causes of allergic diseases.

Disadvantages: rare consequences of taking the drug are headache, nausea, dizziness, shortness of breath, anaphylactic reaction, and skin flushing are extremely rare.

The drug is used for the treatment of seasonal allergic rhinitis with the following manifestations of hay fever: skin itching, sneezing, rhinitis, redness of the mucous membrane of the eyes, as well as for the treatment of chronic idiopathic urticaria and its symptoms: skin itching, redness.

Advantages– when taking the drug, there are no side effects characteristic of antihistamines: blurred vision, constipation, dry mouth, weight gain, negative effect on the functioning of the heart muscle. The drug can be purchased at a pharmacy without a prescription; no dose adjustment is required for the elderly, patients with renal and hepatic insufficiency. The drug acts quickly, maintaining its effect throughout the day. The price of the drug is not too high, it is available to many people suffering from.

Flaws– after some time, it is possible to get used to the action of the drug; it has side effects: dyspepsia, dysmenorrhea, tachycardia, headache and dizziness, anaphylactic reactions, taste perversion. A dependence on the drug may develop.

The drug is prescribed for the occurrence of seasonal allergic rhinitis, as well as for chronic.

Advantages– the drug is quickly absorbed, reaching the desired level within an hour after administration, this effect continues throughout the day. Its use does not require restrictions for people operating complex mechanisms, driving vehicles, and does not cause a sedative effect. Fexofast is available without a prescription, has an affordable price, and is highly effective.

Flaws– for some patients, the drug brings only temporary relief, without bringing complete recovery from allergy symptoms. It has side effects: swelling, increased drowsiness, nervousness, insomnia, weakness, increased allergy symptoms in the form of itchy skin, skin rash.

The drug is prescribed for the symptomatic treatment of hay fever (hay fever), urticaria, allergic and allergic conjunctivitis with itching, lacrimation, conjunctival hyperemia, dermatosis with rashes and rashes, angioedema.

Advantages– Levocytirizine-Teva quickly demonstrates its effectiveness (after 12-60 minutes) and throughout the day prevents the occurrence and weakens the course of allergic reactions. The drug is quickly absorbed, showing 100% bioavailability. Can be used for long-term treatment and for emergency assistance with seasonal exacerbations of allergies. Available for treatment of children from 6 years of age.

Flaws– has side effects such as drowsiness, irritability, nausea, headache, weight gain, tachycardia, abdominal pain, migraine. The price of the medicine is quite high.

The drug is used for the symptomatic treatment of such manifestations of hay fever and urticaria as itching, sneezing, inflammation of the conjunctiva, rhinorrhea, Quincke's edema, and allergic dermatoses.

Advantages– Xyzal has a pronounced anti-allergic effect, being a very effective remedy. It prevents the onset of allergy symptoms, alleviates their course, and has no sedative effect. The drug acts very quickly, maintaining its effect for a day from the moment of administration. Xyzal can be used to treat children from 2 years of age; it is available in two dosage forms (tablets, drops) acceptable for use in pediatrics. It eliminates nasal congestion, symptoms of chronic allergies are quickly relieved, and does not have a toxic effect on the heart or central nervous system.

Flaws– the product may exhibit the following side effects: dry mouth, fatigue, abdominal pain, itching, hallucinations, shortness of breath, cramps, muscle pain.

The drug is indicated for the treatment of seasonal hay fever, allergic rhinitis, chronic idiopathic urticaria with symptoms such as lacrimation, cough, itching, swelling of the nasopharyngeal mucosa.

Advantages– Erius acts exceptionally quickly on allergy symptoms; it can be used to treat children from one year old, as it has a high degree of safety. It is well tolerated by both adults and children; it is available in several dosage forms (tablets, syrup), which is very convenient for use in pediatrics. It can be taken for a long period of time (up to a year) without causing addiction (resistance to it). Reliably stops the manifestations of the initial phase of the allergic response. After a course of treatment, the effect lasts for 10-14 days. Overdose symptoms were not noted even with a fivefold increase in the dose of Erius.

Flaws– side effects may occur (nausea and headache, tachycardia, local allergic symptoms, diarrhea, hyperthermia). Children usually experience insomnia, headaches, and fever.

The drug is intended for the treatment of such manifestations of allergies as allergic rhinitis and urticaria, marked by itching and skin rashes. The drug relieves symptoms of allergic rhinitis such as sneezing, itching in the nose and palate, and lacrimation.

Advantages– Desal prevents the appearance of edema, muscle spasm, and reduces capillary permeability. The effect of taking the drug can be noticed after 20 minutes, it persists throughout the day. A single dose of the medicine is very convenient; it comes in two forms – syrup and tablets, the intake of which does not depend on food. Since Dezal is taken to treat children starting from 12 months, the syrup form of the drug is in demand. The drug is so safe that even a 9-fold dose does not lead to negative symptoms.

Flaws– occasionally, symptoms of side effects such as increased fatigue, headache, dry mouth may occur. Additionally, side effects such as insomnia, tachycardia, hallucinations, diarrhea, and hyperactivity occur. Allergic manifestations of side effects are possible: itching, urticaria, angioedema.

4th generation antihistamines – do they exist?

All statements by advertising creators positioning drug brands as “fourth generation antihistamines” are nothing more than an advertising gimmick. This pharmacological group does not exist, although marketers include in it not only newly created drugs, but also second-generation drugs.

The official classification indicates only two groups of antihistamines - first and second generation drugs. The third group of pharmacologically active metabolites is positioned in pharmaceuticals as “third generation H 1 histamine blockers.”

To treat allergic manifestations in children, antihistamines of all three generations are used.

1st generation antihistamines are distinguished by the fact that they quickly exhibit their healing properties and are eliminated from the body. They are in demand for the treatment of acute manifestations of allergic reactions. They are prescribed in short courses. The most effective of this group are Tavegil, Suprastin, Diazolin, Fenkarol.

A significant percentage of side effects leads to a reduction in the use of these medications for childhood allergies.

2nd generation antihistamines do not cause a sedative effect, act for a longer time and are usually used once a day. Few side effects. Among the drugs in this group, Ketotifen, Fenistil, and Cetrin are used to treat manifestations of childhood allergies.

The 3rd generation of antihistamines for children includes Gismanal, Terfen and others. They are used for chronic allergic processes, since they can remain in the body for a long time. There are no side effects.

Newer drugs include Erius.

Negative consequences:

1st generation: headache, constipation, tachycardia, drowsiness, dry mouth, blurred vision, urinary retention and lack of appetite;

2nd generation: negative effect on the heart and;

Antihistamines are produced for children in the form of ointments (allergic skin reactions), drops, syrups and tablets for oral administration.

Antihistamines during pregnancy

In the first trimester of pregnancy, it is forbidden to take antihistamines. In the second, they are prescribed only in extreme cases, since none of these remedies are absolutely safe.

Natural antihistamines, which include vitamins C, B12, pantothenic, oleic and nicotinic acids, zinc, and fish oil, can help get rid of some allergic symptoms.

The safest antihistamines are Claritin, Zyrtec, Telfast, Avil, but their use must be agreed with a doctor.

4 Best Natural Antihistamines

In some cases, you can resort to the following remedies that can suppress the production of histamine in the body.

Nettle. Nettle has antihistamine properties. Freeze-dried nettle powder has been shown to help relieve allergy symptoms. 69 people took part in the experiment using this substance. Of these, 58% of patients noted a significant improvement in their health. The positive effect was achieved through daily intake of 300 mg of nettle.

Quercetin. Quercetin is an antioxidant known for its anti-inflammatory properties. It is found in some foods, such as onions and apples. Scientists became interested in quercetin's ability to reduce the severity of an allergic reaction. They conducted the experiment on rats. Based on its results, it was concluded that quercetin can reduce the intensity of the allergic and inflammatory process in the respiratory system. People with allergies can purchase quercetin in supplements, or simply eat foods that are rich in this antioxidant.

Bromelain. Bromelain is an enzyme found in large quantities in pineapples. There is evidence that it helps reduce the intensity of allergy symptoms. To have a positive effect, it is recommended to take 400-500 mg of this substance 3 times a day. Alternatively, you can simply enrich your diet with pineapples, which are record holders for the content of this substance.

Vitamin C. Vitamin C is found in various foods. This antioxidant has properties to suppress the symptoms of an allergic reaction. Vitamin C is non-toxic, and taking it in moderate dosages does not harm the human body. Therefore, it can be safely used as an antihistamine. The recommended dose of vitamin C for allergy sufferers is 2 g. This amount is contained in 3-5 citrus fruits. They need to be eaten throughout the day.

Foods that help fight allergies

To cope with allergies, you don't have to empty the pharmacy shelves. Sometimes it is enough to minimize contact with the allergen and enrich your menu with products that have antihistamine properties. A proper diet coupled with physical activity will help the immune system resist attacks from the external environment.

As for antioxidants in the form of supplements, they can only be taken after consultation with a specialist. It is best to get these substances from food. This way they will be absorbed 100%.

Natural Treatment of Perennial Allergic Rhinitis
http://www.altmedrev.com/archive/publications/5/5/448.pdf

Quercetin inhibits transcriptional up-regulation of histamine H1 receptor via suppressing protein kinase C-?/extracellular signal-regulated kinase/poly(ADP-ribose) polymerase-1 signaling pathway in HeLa cells
https://www.ncbi.nlm.nih.gov/pubmed/23333628

Anti-inflammatory activity of quercetin and isoquercitrin in experimental murine allergic asthma
https://www.ncbi.nlm.nih.gov/pubmed/18026696

About the doctor: From 2010 to 2016 practicing physician at the therapeutic hospital of the central medical unit No. 21, the city of Elektrostal. Since 2016 he has been working at diagnostic center No. 3.

Many home first aid kits contain medications whose purpose and mechanism of action people do not understand. Antihistamines are also such drugs. Most allergy sufferers choose their own medications, calculate the dosage and course of therapy, without consulting a specialist.

Antihistamines - what are they in simple words?

This term is often misunderstood. Many people think that these are just allergy drugs, but they are intended to treat other diseases. Antihistamines are a group of medications that block the immune response to external stimuli. These include not only allergens, but also viruses, fungi and bacteria (infectious agents), and toxins. The medications in question prevent the occurrence of:

swelling of the mucous membranes of the nose and throat;
redness, blisters on the skin;
itching;
excessive secretion of gastric juice;
narrowing of blood vessels;
muscle spasms;
swelling.

How do antihistamines work?

The main protective role in the human body is played by leukocytes or white blood cells. There are several types of them, one of the most important is mast cells. After maturation, they circulate through the bloodstream and are embedded in connective tissue, becoming part of the immune system. When dangerous substances enter the body, mast cells release histamine. This is a chemical substance necessary for the regulation of digestive processes, oxygen metabolism and blood circulation. Its excess leads to allergic reactions.

For histamine to provoke negative symptoms, it must be absorbed by the body. For this purpose, there are special H1 receptors located in the inner lining of blood vessels, smooth muscle cells and the nervous system. How antihistamines work: the active ingredients of these medications “deceive” H1 receptors. Their structure and structure are very similar to the substance in question. Medicines compete with histamine and are absorbed by receptors instead of it, without causing allergic reactions.

As a result, the chemical that causes the unwanted symptoms remains in an inactive state in the blood and is later eliminated naturally. The antihistamine effect depends on how many H1 receptors the drug has managed to block. For this reason, it is important to begin treatment as soon as the first allergy symptoms appear.

The duration of therapy depends on the generation of the medication and the severity of pathological signs. The doctor must decide how long to take antihistamines. Some medications can be used for no more than 6-7 days; modern pharmacological agents of the latest generation are less toxic, so their use is allowed for 1 year. Before taking it, it is important to consult a specialist. Antihistamines can accumulate in the body and cause poisoning. Some people subsequently develop allergies to these medications.

How often can you take antihistamines?

Most manufacturers of the described products produce them in a convenient dosage, suggesting use only once a day. The question of how to take antihistamines, depending on the frequency of occurrence of negative clinical manifestations, is decided with the doctor. The presented group of medications refers to symptomatic methods of therapy. They must be used every time signs of illness occur.

New antihistamines can also be used as prophylaxis. If contact with the allergen cannot be avoided (poplar fluff, ragweed, etc.), you should use the medicine in advance. Taking antihistamines in advance will not only soften negative symptoms, but eliminate their occurrence. The H1 receptors will already be blocked when the immune system tries to mount a defense response.

Antihistamines - list

The very first drug of this group was synthesized in 1942 (Phenbenzamine). From this moment on, a massive study of substances capable of blocking H1 receptors began. To date, there are 4 generations of antihistamines. Early versions of medications are rarely used due to unwanted side effects and toxic effects on the body. Modern medicines are characterized by maximum safety and quick results.

1st generation antihistamines - list

This type of pharmacological agent has a short-term effect (up to 8 hours), can be addictive, and sometimes provokes poisoning. 1st generation antihistamines remain popular only because of their low cost and pronounced sedative (calming) effect. Names:

Daedalon;
Bicarfen;
Suprastin;
Tavegil;
Diazolin;
Clemastine;
Diprazine;
Loredix;
Pipolfen;
Setastin;
Dimebon;
Cyproheptadine;
Fenkarol;
Peritol;
Quifenadine;
Dimetinden;
and others.

Antihistamines 2nd generation - list

35 years later, the first H1 receptor blocker was released without sedation or toxic effects on the body. Unlike their predecessors, 2nd generation antihistamines work much longer (12-24 hours), are not addictive and do not depend on food and alcohol intake. They provoke fewer dangerous side effects and do not block other receptors in tissues and blood vessels. New generation antihistamines - list:

Taldan;
Astemizole;
Terfenadine;
Bronal;
Allergodil;
Fexofenadine;
Rupafin;
Trexil;
Loratadine;
Histadil;
Zyrtec;
Ebastine;
Astemisan;
Clarisens;
Gistalong;
Cetrin;
Semprex;
Kestin;
Akrivastine;
Gismanal;
Cetirizine;
Levocabastine;
Azelastine;
Histimet;
Loragexal;
Claridol;
Rupatadine;
Lomilan and analogues.

Antihistamines 3rd generation

Based on previous drugs, scientists obtained stereoisomers and metabolites (derivatives). At first, these antihistamines were positioned as a new subgroup of medications or 3rd generation:

Glenceth;
Xizal;
Caeser;
Suprastinex;
Fexofast;
Zodak Express;
L-Cet;
Loratek;
Fexadine;
Erius;
Desal;
NeoClaritin;
Lordestin;
Telfast;
Fexofen;
Allegra.

Later, this classification caused controversy and controversy in the scientific community. To make a final decision on the listed funds, a group of experts was assembled for independent clinical trials. According to the evaluation criteria, third-generation allergy drugs should not affect the functioning of the central nervous system, produce a toxic effect on the heart, liver and blood vessels, and interact with other medications. According to research results, none of these drugs meets these requirements.

4th generation antihistamines - list

Some sources include Telfast, Suprastinex and Erius as this type of pharmacological agent, but this is an erroneous statement. Antihistamines of the 4th generation have not yet been developed, as well as the third. There are only improved forms and derivatives of previous versions of medications. The most modern drugs so far are 2nd generation drugs.

The selection of funds from the described group should be carried out by a specialist. Some people benefit from 1st generation allergy medications due to the sedative effect required; other patients do not need this effect. Likewise, the doctor recommends the dosage form of the medication depending on the symptoms present. Systemic drugs are prescribed for severe signs of the disease; in other cases, local remedies can be used.

Antihistamine tablets

Oral medications are necessary to quickly relieve clinical manifestations of pathology that affect several body systems. Antihistamines for internal use begin to act within an hour and effectively relieve swelling of the throat and other mucous membranes, relieve runny nose, lacrimation and skin symptoms of the disease.

Effective and safe allergy pills: