Catad_tema Allergic diseases

Antihistamines: myths and reality

"EFFICIENT PHARMACOTHERAPY"; No. 5; 2014; pp. 50-56.

T.G. Fedoskova
SSC Institute of Immunology, FMBA of Russia, Moscow

The main drugs that affect the symptoms of inflammation and control the course of diseases of allergic and non-allergic origins include antihistamines.
The article analyzes the discussion points regarding the experience of using modern antihistamines, as well as some of their main characteristics. This will allow a differentiated approach to the choice of the optimal drug during complex therapy various diseases.
Keywords: antihistamines, allergic diseases, cetirizine, Cetrin

ANTIHISTAMINES: MYTHS AND REALITY

T.G. Fedoskova
State Science Center Institute of Immunology, Federal Medical and Biological Agency, Moscow

Antihistamines belong to main drugs influencing symptoms of inflammation and controlling course of both of allergic and non-allergic diseases. In this paper debatable issues regarding experience of using current antihistamines as well as some of their characteristics are analyzed. It may let to make a differential choice to administer appropriate drugs for a combination therapy of different diseases.
key words: antihistamines, allergic diseases, cetirizine, Cetrine

Type 1 antihistamines (H1-AHP), or type 1 histamine receptor antagonists, are widely and successfully used in clinical practice for over 70 years. They are used as part of the symptomatic and basic therapy of allergic and pseudo-allergic reactions, complex treatment acute and chronic infectious diseases of various genesis, as a premedication during invasive and radiopaque studies, surgical interventions, for the prevention of side effects of vaccination, etc. In other words, H 1 -AHP is advisable to use in conditions caused by the release of active mediators of inflammation of a specific and non-specific nature, the main of which is histamine.

Histamine has a wide spectrum of biological activity, realized through the activation of cell surface specific receptors. The main depot of histamine in the tissues are mast cells, in the blood - basophils. It is also present in platelets, gastric mucosa, endothelial cells, and brain neurons. Histamine has a pronounced hypotensive effect and is an important biochemical mediator in all clinical symptoms of inflammation of various origins. That is why antagonists of this mediator remain the most popular pharmacological agents.

In 1966, the heterogeneity of histamine receptors was proven. Currently, 4 types of histamine receptors are known - H 1 , H 2 , H 3 , H 4 belonging to the superfamily of receptors associated with G-proteins (G-protein-coupled receptors -GPCRs). Stimulation of H 1 receptors leads to the release of histamine and the realization of inflammation symptoms, mainly of allergic origin. Activation of H 2 receptors increases the secretion of gastric juice and its acidity. H3 receptors are predominantly present in the organs of the central nervous system (CNS). They perform the function of histamine-sensitive presynaptic receptors in the brain, regulate the synthesis of histamine from presynaptic nerve endings. Recently, a new class of histamine receptors, expressed predominantly on monocytes and granulocytes, H 4 , has been identified. These receptors are present in the bone marrow, thymus, spleen, lungs, liver, and intestines. The mechanism of action of H 1 -AHP is based on reversible competitive inhibition of histamine H 1 receptors: they prevent or minimize inflammatory reactions, preventing the development of histamine-induced effects, and their effectiveness is due to the ability to competitively inhibit the effect of histamine on the loci of specific H 1 receptor zones in effector tissue structures.

Currently, over 150 types of antihistamines are registered in Russia. These are not only H 1 -AGP, but also drugs that increase the ability of blood serum to bind histamine, as well as drugs that inhibit the release of histamine from mast cells. Due to the variety of antihistamines, make a choice between them for their most effective and rational use in specific clinical cases It's hard enough. In this regard, there are debatable points, and often myths are born about the use of H 1 -AHP, which are widely used in clinical practice. In the domestic literature, there are many works on this topic, however, there is no consensus on the clinical use of these drugs (PM).

The myth of three generations of antihistamines
Many are mistaken in thinking that there are three generations of antihistamines. Some pharmaceutical companies present new drugs that have appeared on the pharmaceutical market as third-generation AGPs. Attempts were made to classify metabolites and stereoisomers of modern AGPs to the third generation. Currently, these drugs are considered to be second-generation antihistamines, since there is no significant difference between them and previous second-generation drugs. According to the Consensus on Antihistamines, it was decided to reserve the name "third generation" to denote future synthesized antihistamines, which are likely to differ from known compounds in a number of key characteristics.

There are many differences between first and second generation AGPs. This is primarily the presence or absence of a sedative effect. A sedative effect when taking first-generation antihistamines is subjectively noted by 40-80% of patients. Its absence in individual patients does not exclude the objective negative effect of these drugs on cognitive functions, which patients may not complain about (the ability to drive a car, learn, etc.). Dysfunction of the central nervous system is observed even with the use of minimal doses of these drugs. The effect of first-generation antihistamines on the central nervous system is the same as when using alcohol and sedatives (benzodiazepines, etc.).

Second-generation drugs practically do not penetrate the blood-brain barrier, so they do not reduce the mental and physical activity of patients. In addition, antihistamines of the first and second generations differ in the presence or absence of side effects associated with stimulation of other types of receptors, duration of action, development of addiction.

The first AGPs - phenbenzamine (Antergan), pyrilamine maleate (Neo-Antergan) began to be used as early as 1942. Subsequently, new antihistamines have appeared for use in clinical practice. Until the 1970s Dozens of compounds belonging to this group of drugs have been synthesized.

On the one hand, a large clinical experience has been accumulated in the use of first-generation antihistamines, on the other hand, these drugs have not undergone expert examination in clinical research that meet modern requirements of evidence-based medicine.

Comparative characteristics AGP of the first and second generations is presented in Table. 1 .

Table 1.

Comparative characteristics of AGP of the first and second generations

Properties	First generation	Second generation
Sedation and effects on cognition	Yes (in minimum doses)	No (in therapeutic doses)
Selectivity for H 1 receptors	No	Yes
Pharmacokinetic studies	Few	A lot of
Pharmacodynamic studies	Few	A lot of
Scientific studies of various doses	No	Yes
Studies in newborns, children, elderly patients	No	Yes
Use in pregnant women	FDA Category B (diphenhydramine, chlorpheniramine), Category C (hydroxyzine, ketotifen)	FDA Category B (loratadine, cetirizine, levocetirizine), Category C (desloratadine, azelastine, fexofenadine, olopatadine)

Note. FDA (US Food and Drug Administration) - Quality Control Administration food products And medicines(USA). Category B - no teratogenic effect of the drug was detected. Category C - studies have not been conducted.

Since 1977, the pharmaceutical market has been replenished with new H 1 -AHPs, which have clear advantages over first-generation drugs and meet modern requirements for AGPs set out in the EAACI (European Academy of Allergology and Clinical Immunology) consensus documents.

The myth about the benefits of the sedative effect of first-generation antihistamines
Even with regard to some of the side effects of first-generation antihistamines, there are misconceptions. The sedative effect of first-generation H1-HPA is associated with the myth that their use is preferable in the treatment of patients with concomitant insomnia, and if this effect is undesirable, it can be leveled by using the drug at night. At the same time, it should be remembered that first-generation antihistamines inhibit the phase of REM sleep, due to which the physiological process sleep, there is no complete processing of information in a dream. When using them, breathing and heart rhythm disturbances are possible, which increases the risk of developing sleep apnea. In addition, in some cases, the use of high doses of these drugs contributes to the development of paradoxical excitation, which also negatively affects the quality of sleep. It is necessary to take into account the difference in the duration of the preservation of the antiallergic effect (1.5-6 hours) and the sedative effect (24 hours), as well as the fact that prolonged sedation is accompanied by impaired cognitive functions.

The presence of pronounced sedative properties debunks the myth about the expediency of using H1-HPA of the first generation in elderly patients who use these drugs, guided by the prevailing stereotypes of habitual self-treatment, as well as the recommendations of doctors who are not sufficiently informed about the pharmacological properties of drugs and contraindications to their appointment. Due to the lack of selectivity of effects on alpha-adrenergic receptors, muscarinic, serotonin, bradykinin and other receptors, a contraindication to the appointment of these drugs is the presence of diseases that are quite common among the elderly patients - glaucoma, benign prostatic hyperplasia, bronchial asthma, chronic obstructive pulmonary disease, etc. . .

The myth about the absence of a place in clinical practice for first-generation antihistamines
Despite the fact that H 1 -AGP of the first generation (most of them were developed in the middle of the last century) are capable of causing known side effects They are still widely used in clinical practice today. Therefore, the myth that with the advent of the new generation of AHD there is no place left for the previous generation of AHD is invalid. The H 1 -AGP of the first generation has one indisputable advantage - the presence of injectable forms that are indispensable in providing emergency assistance, premedication before conducting certain types of diagnostic examination, surgical interventions etc. In addition, some drugs have an antiemetic effect, reduce the condition increased anxiety, effective in motion sickness. An additional anticholinergic effect of a number of drugs of this group is manifested in a significant reduction in itching and skin rashes with itchy dermatoses, acute allergic and toxic reactions to food, drugs, insect bites and stings. However, it is necessary to prescribe these drugs with strict consideration of indications, contraindications, severity clinical symptoms, age, therapeutic dosages, side effects. The presence of pronounced side effects and the imperfection of the first generation H 1 -AGP contributed to the development of new second generation antihistamine drugs. The main directions of improvement of drugs were the increase in selectivity and specificity, the elimination of sedation and tolerance to the drug (tachyphylaxis).

Modern H 1 -AGP of the second generation have the ability to selectively affect H 1 receptors, do not block them, but, being antagonists, they transfer them to an “inactive” state without violating their physiological properties, have a pronounced anti-allergic effect, a rapid clinical effect, act long (24 hours), do not cause tachyphylaxis. These drugs practically do not penetrate the blood-brain barrier, therefore, do not cause a sedative effect, cognitive impairment.

Modern H 1 -AGP of the second generation have a significant anti-allergic effect - they stabilize the membrane of mast cells, suppress the release of interleukin-8 induced by eosinophils, granulocyte-macrophage colony-stimulating factor (Granulocyte Macrophage Colony-Stimulating Factor. GM-CSF) and soluble intercellular adhesion molecule 1 (Soluble Intercellular Adhesion Molecule-1, sICAM-1) from epithelial cells, which contributes to greater efficiency compared to first-generation H1-AHP in the basic therapy of allergic diseases, in the genesis of which mediators of the late phase of allergic inflammation play a significant role.

In addition, an important characteristic of second-generation H1-AHP is their ability to provide an additional anti-inflammatory effect by inhibiting the chemotaxis of eosinophils and neutrophilic granulocytes, reducing the expression of adhesion molecules (ICAM-1) on endothelial cells, inhibiting IgE-dependent platelet activation, and releasing cytotoxic mediators. Many doctors do not pay due attention to this, however, the listed properties make it possible to use such drugs for inflammation not only of an allergic nature, but also of an infectious origin.

The myth of the same safety of all second-generation AHDs
There is a myth among physicians that all second-generation H1-HPAs are similar in their safety. However, in this group of drugs there are differences associated with the peculiarity of their metabolism. They may depend on the variability in the expression of the CYP3A4 enzyme of the liver cytochrome P 450 system. Such variability may be due to genetic factors, diseases of the hepatobiliary system, simultaneous administration of a number of drugs (macrolide antibiotics, some antimycotic, antiviral drugs, antidepressants, etc.), products (grapefruit) or alcohol that have an inhibitory effect on the oxygenase activity of the CYP3A4 cytochrome P450 system.

Among the H1-AGP of the second generation, there are:

"metabolizable" drugs that have a therapeutic effect only after undergoing metabolism in the liver with the participation of the CYP 3A4 isoenzyme of the cytochrome P450 system with the formation of active compounds (loratadine, ebastine, rupatadine);

active metabolites - drugs that enter the body immediately in the form of an active substance (cetirizine, levocetirizine, desloratadine, fexofenadine) (Fig. 1).

Rice. 1. Features of the metabolism of H 1 -AGP of the second generation

The advantages of active metabolites, the intake of which is not accompanied by an additional burden on the liver, are obvious: the speed and predictability of the development of the effect, the possibility of joint administration with various drugs and foods that are metabolized with the participation of cytochrome P450.

The myth about the higher efficiency of each new AGP
The myth that appeared in last years new H1-AGP means are obviously more effective than the previous ones, also did not find confirmation. The works of foreign authors indicate that second-generation H1-AHP, for example, cetirizine, have a more pronounced antihistamine activity than second-generation drugs that appeared much later (Fig. 2).

Rice. 2. Comparative antihistamine activity of cetirizine and desloratadine on the effect on the skin reaction caused by the administration of histamine within 24 hours

It should be noted that among the H 1 -AGP of the second generation, researchers assign a special place to cetirizine. Developed in 1987, it was the first original highly selective H1 receptor antagonist based on the pharmacologically active metabolite of the previously known first-generation antihistamine, hydroxyzine. Until now, cetirizine remains a kind of standard of antihistamine and antiallergic action, used for comparison in the development of the latest antihistamine and antiallergic drugs. There is an opinion that cetirizine is one of the most effective antihistamine H 1 drugs, it has been used more often in clinical trials, the drug is preferable for patients who respond poorly to therapy with other antihistamines.

The high antihistamine activity of cetirizine is due to the degree of its affinity for H 1 receptors, which is higher than that of loratadine. It should also be noted the significant specificity of the drug, since even at high concentrations it does not have a blocking effect on serotonin (5-HT 2), dopamine (D 2), M-cholinergic receptors and alpha-1-adrenergic receptors.

Cetirizine meets all the requirements for modern second generation antihistamines and has a number of features. Among all known antihistamines, the active metabolite cetirizine has the smallest volume of distribution (0.56 l/kg) and provides full employment of H1 receptors and the highest antihistamine effect. The drug is characterized by a high ability to penetrate the skin. 24 hours after taking a single dose, the concentration of cetirizine in the skin is equal to or exceeds the concentration of its content in the blood. At the same time, after a course of treatment, the therapeutic effect persists for up to 3 days. The pronounced antihistamine activity of cetirizine favorably distinguishes it among modern antihistamines (Fig. 3).

Rice. 3. Efficacy of a single dose of second-generation H 1 -AHP in suppressing histamine-induced whealing over 24 hours in healthy men

The myth about the high cost of all modern AGPs
Any chronic disease is not immediately amenable to even adequate therapy. It is known that insufficient control over the symptoms of any chronic inflammation leads not only to a deterioration in the patient's well-being, but also to an increase in the total cost of treatment due to an increase in the need for drug therapy. The selected drug should have the most effective therapeutic effect and be affordable. Physicians who remain committed to prescribing first-generation H1-AHP explain their choice by referring to another myth that all second-generation antihistamines are significantly more expensive than drugs first generation. However, in addition to the original drugs on the pharmaceutical market, there are generics, the cost of which is lower. For example, at present, 13 generics are registered from cetirizine drugs in addition to the original one (Zyrtec). The results of pharmacoeconomic analysis presented in Table. 2, testify to the economic feasibility of using Cetrin, a modern second-generation AGP.

Table 2.

Results of comparative pharmacoeconomic characteristics of H1-AGP of the first and second generations

A drug	Suprastin 25 mg № 20	Diazolin 100 mg №10	Tavegil 1 mg № 20	Zyrtec 10 mg No. 7	Cetrin 10 mg № 20
Average market value of 1 pack	120 rub.	50 rub.	180 rub.	225 rub.	160 rub.
Multiplicity of reception	3 r/day	2 r / day	2 r / day	1 r / day	1 r / day
The cost of 1 day of therapy	18 rub.	10 rub.	18 rub.	32 rub.	8 rub.
Cost of 10 days of therapy	180 rub.	100 rub.	180 rub.	320 rub.	80 rub.

The myth that all generics are equally effective
The question of the interchangeability of generics is relevant when choosing the optimal modern antihistamine drug. Due to the variety of generics on the pharmacological market, a myth has arisen that all generics act approximately the same, so you can choose any, focusing primarily on price.

Meanwhile, generics differ from each other, and not only pharmacoeconomic characteristics. The stability of the therapeutic effect and the therapeutic activity of the reproduced drug are determined by the features of the technology, packaging, the quality of active substances and excipients. The quality of the active substances of drugs from different manufacturers can vary significantly. Any change in the composition of excipients can contribute to a decrease in bioavailability and the occurrence of side effects, including hyperergic reactions of various nature (toxic, etc.). A generic drug must be safe to use and equivalent to the original drug. Two medicinal products are considered to be bioequivalent if they are pharmaceutically equivalent, have the same bioavailability and, when administered at the same dose, are similar, providing adequate efficacy and safety. According to the recommendations of the World Health Organization, the bioequivalence of a generic should be determined in relation to the officially registered original drug. The study of bioequivalence is one of the stages in the study of therapeutic equivalence. The FDA (Food and Drug Administration - Food and Drug Administration (USA)) annually publishes and publishes the "Orange Book" with a list of drugs that are considered therapeutically equivalent to the original. Thus, any doctor can make the optimal choice of a safe antihistamine drug, taking into account all the possible characteristics of these drugs.

One of the highly effective generics of cetirizine is Cetrin. The drug acts quickly, for a long time, has a good safety profile. Cetrin is practically not metabolized in the body, the maximum serum concentration is reached one hour after ingestion, with prolonged use it does not accumulate in the body. Cetrin is available in 10 mg tablets, indicated for adults and children from 6 years of age. Cetrin is completely bioequivalent to the original drug (Fig. 4).

Rice. 4. The average dynamics of the concentration of cetirizine after taking the compared drugs

Cetrin is successfully used as part of the basic therapy of patients with allergic rhinitis with sensitization to pollen and household allergens, allergic rhinitis associated with atopic bronchial asthma, allergic conjunctivitis, urticaria, including chronic idiopathic urticaria, pruritic allergic dermatoses, angioedema, as well as symptomatic therapy with acute viral infections in patients with atopy. When comparing the effectiveness of cetirizine generics in patients with chronic urticaria when using Cetrin, best results(Fig. 5) .

Rice. 5. Comparative evaluation of the clinical efficacy of cetirizine preparations in patients with chronic urticaria

Domestic and foreign experience in the use of Cetrin indicates its high therapeutic efficacy in clinical situations where the use of second-generation H 1 antihistamines is indicated.

Thus, when choosing the optimal H 1 -antihistamine drug from all drugs on the pharmaceutical market, one should not be based on myths, but on selection criteria that include maintaining a reasonable balance between efficacy, safety and availability, the presence of a convincing evidence base, and high quality production. .

BIBLIOGRAPHY:

1. Luss L.V. The choice of antihistamines in the treatment of allergic and pseudo-allergic reactions // Russian Allergological Journal. 2009. No. 1. S. 78-84.
2. Gushchin I.S. Potential of antiallergic activity and clinical efficacy of H1-antagonists // Allergology. 2003. No. 1. C. 78-84.
3. Takeshita K., Sakai K., Bacon K.B., Gantner F. Critical role of histamine H4 receptor in leukotriene B4 production and mast cell-dependent neutrophil recruitment induced by zymosan in vivo // J. Pharmacol. Exp. Ther. 2003 Vol. 307. No. 3. P. 1072-1078.
4. Gushchin I.S. Diversity of the antiallergic action of cetirizine // Russian Allergological Journal. 2006. No. 4. S. 33.
5. Emelyanov A.V., Kochergin N.G., Goryachkina L.A. To the 100th anniversary of the discovery of histamine. History and modern approaches to the clinical use of antihistamines // Clinical dermatology and venereology. 2010. No. 4. S. 62-70.
6. Tataurshchikova N.S. Modern aspects of the use of antihistamines in the practice of a general practitioner // Farmateka. 2011. No. 11. S. 46-50.
7. Fedoskova T.G. The use of cetirizine (Cetrin) in the treatment of patients with perennial allergic rhinitis // Russian Allergological Journal. 2006. No. 5. C. 37-41.
8. Holgate S. T., Canonica G. W., Simons F. E. et al. Consensus Group on New-Generation Antihistamines (CONGA): present status and recommendations // Clin. Exp. Allergy. 2003 Vol. 33. No. 9. P. 1305-1324.
9. Grundmann S.A., Stander S., Luger T.A., Beissert S. Antihistamine combination treatment for solar urticaria // Br. J. Dermatol. 2008 Vol. 158. No. 6. P. 1384-1386.
10. Brik A., Tashkin D.P., Gong H. Jr. et al. Effect of cetirizine, a new histamine H1 antagonist, on airway dynamics and responsiveness to inhaled histamine in mild asthma // J. Allergy. Clin. Immunol. 1987 Vol. 80. No. 1. P. 51-56.
11. Van De Venne H., Hulhoven R., Arendt C. Cetirizine in perennial atopic asthma // Eur. Resp. J. 1991. Suppl. 14. P. 525.
12. An open randomized crossover study of comparative pharmacokinetics and bioequivalence of Cetrin tablets 0.01 (Dr. Reddy's Laboratories LTD, India) and Zirtek tablets 0.01 (UCB Pharmaceutical Sector, Germany). St. Petersburg, 2008.
13. Fedoskova T.G. Features of the treatment of acute respiratory viral infections in patients with year-round allergic rhinitis // Russian Allergological Journal. 2010. No. 5. P. 100-105.
14. Medicines in Russia, Vidal's Handbook. M.: AstraPharmService, 2006.
15. Nekrasova E.E., Ponomareva A.V., Fedoskova T.G. Rational pharmacotherapy of chronic urticaria // Russian Allergological Journal. 2013. No. 6. S. 69-74.
16. Fedoskova T.G. The use of cetirizine in the treatment of patients with year-round allergic rhinitis associated with atopic bronchial asthma // Russian Allergological Journal. 2007. No. 6. C. 32-35.
17. Elisyutina O.G., Fedenko E.S. Experience with the use of cetirizine in atopic dermatitis // Russian Allergological Journal. 2007. No. 5. S. 59-63.

are substances that inhibit the action of free histamine. When an allergen enters the body, histamine is released from the mast cells of the connective tissue that are part of the body's immune system. It begins to interact with specific receptors and cause itching, swelling, rashes 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 reversibly bind to H1 receptors, which explains the need for a large dosage and high frequency of administration.

Antihistamines of the 1st generation 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 every 2-3 weeks the funds are changed.

The bulk of 1st generation antihistamines are fat-soluble, can cross the blood-brain barrier and bind to the H1 receptors of the brain, which explains the sedative effect of these drugs, which is enhanced after taking alcohol or psychotropic drugs. When taking medium therapeutic doses in children and high toxic doses in adults, psychomotor agitation may be observed. Due to the presence of a 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 mouth, urinary retention, visual impairment. These features can be beneficial when, but they can increase airway obstruction caused by bronchial (sputum viscosity increases), exacerbate prostate adenoma, glaucoma and other diseases. At the same time, these drugs have an antiemetic and anti-swaying effect, reduce the manifestation of parkinsonism.

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

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

Dimedrol is prescribed for hay, urticaria, sea, air sickness, vasomotor, bronchial asthma, with allergic reactions caused by the introduction medicinal substances(e.g. antibiotics), in the treatment peptic ulcer, dermatoses, etc.

Advantages: high antihistamine activity, reduced severity of allergic, pseudo-allergic reactions. Diphenhydramine has antiemetic and antitussive effects, has a local anesthetic effect, due to which it is an alternative to Novocaine and Lidocaine in case of their intolerance.

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

Diazolin

Diazolin has the same indications for use as other antihistamines, but differs from them in the features of the effect.

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

Cons: irritates the mucous membranes of the gastrointestinal tract, causes dizziness, impaired urination, 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, Quincke's edema, itching of various etiologies,. It is used in parenteral form for those requiring emergency care acute allergic conditions.

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

Cons: side effects - drowsiness, dizziness, inhibition of reactions, etc. - are present, although they are 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, it is used for angioedema, as well as anaphylactic shock, as a prophylactic and therapeutic agent for allergic and pseudo-allergic reactions.

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

Cons: can itself cause an allergic reaction, has some inhibitory effect.

Fenkarol

Phencarol is prescribed when addiction to other antihistamines appears.

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

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

2nd generation antihistamines

They have advantages over 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, physical activity do not suffer;

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

they are not addictive, which makes it possible to prescribe them long time(3-12 months);

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

drugs are not adsorbed with food in the gastrointestinal tract.

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

The Emergence of Cardio toxic action due to the ability of 2nd generation antihistamines to block the potassium channels of the heart. The risk is increased when these drugs are combined with antifungal drugs, macrolides, antidepressants, grapefruit juice, and if the patient has severe liver dysfunction.

Claridol and Clarisens

used to treat seasonal as well as cyclic allergic rhinitis, allergic, Quincke's edema and a number of other diseases of allergic origin. It copes with pseudo-allergic syndromes and allergies to insect bites. Included in the complex measures for the treatment of itchy dermatoses.

Benefits: Claridol has antipruritic, antiallergic, antiexudative effects. The drug reduces capillary permeability, prevents the development of edema, relieves spasm of smooth muscles. It does not affect the central nervous system, has no anticholinergic and 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, pseudo-allergic 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 disorders of the nervous system: 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 dysfunction endocrine system. The defeat of the respiratory system can be manifested by cough, bronchospasm, sinusitis and similar manifestations.

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

Benefits: 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), prevent tissue edema already half an hour after taking the drug. The greatest efficiency comes in 8-12 hours, then subsides. Lomilan is not addictive and does not negative impact on the activity of the nervous system.

Cons: adverse reactions are rare, manifested by headache, fatigue and drowsiness, inflammation of the gastric mucosa, nausea.

LauraGeksal

Advantages: the drug has neither anticholinergic nor central action, its reception does not affect the attention, psychomotor functions, working capacity and mental qualities of the patient.

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

Claritin

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

Advantages: high efficiency in the treatment of allergic diseases, the drug is not addictive, 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 ingredient- rupatadine, which is distinguished 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, neutrophils. The drug is used for allergic rhinitis, bronchial asthma, urticaria, conjunctivitis, dermatitis, fever, skin, angioedema.

Benefits: effectively prevents the occurrence of edema, reduces capillary permeability, relieves smooth muscle spasm. Zyrtec does not have anticholinergic and antiserotonin effects.

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

blocks histamine receptors that increase vascular permeability, causing muscle spasms, leading to the manifestation allergic reaction. It is used to treat allergic conjunctivitis, rhinitis and chronic idiopathic urticaria.

Advantages: the drug acts an hour after application, the therapeutic effect lasts for 2 days. A five-day intake of Kestin allows you to maintain an 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 antihistamines, 3rd generation

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 a cardiotoxic and sedative effect, so they can be used by people whose activities are associated with a high concentration of attention.

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

The presence of additional effects contributes to the use of 3rd generation antihistamines in the long-term treatment of most allergic manifestations.

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

Advantages: the drug has practically no sedative effect, does not enhance the effect of taking sleeping pills or alcohol. It also does not affect the ability to drive a car or mental activity.

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

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

Benefits: no sedative and anticholinergic effect, no effect on psychomotor activity and well-being of a person. The drug is safe to use in patients with glaucoma and prostate disorders.

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

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

Cons: rare consequences of taking the drug are headache, nausea, dizziness, very rarely there is shortness of breath, anaphylactic reaction, skin flushing.

The drug is used to treat seasonal allergic rhinitis with the following manifestations of hay fever: pruritus, 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, side effects characteristic of antihistamines do not appear: visual impairment, constipation, dryness of the oral mucosa, weight gain, a 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 and renal and hepatic insufficiency. The drug acts quickly, maintaining its effect during the day. The price of the drug is not too high, it is available to many people suffering from.

Flaws- after some time, addiction to the action of the drug is possible, it has side effects: dyspepsia, dysmenorrhea, tachycardia, headache and dizziness, anaphylactic reactions, taste perversion. Dependence on the drug may form.

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

Advantages- the drug is rapidly absorbed, reaching the desired one within an hour after ingestion, this action continues for a day. Its reception does not require restrictions for people operating complex mechanisms, driving vehicles, and does not cause a sedative effect. Fexofast is dispensed without a prescription, has affordable price, shows high efficiency.

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

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

Advantages– Levocitirizine-Teva quickly shows its effectiveness (after 12-60 minutes) and during the day it prevents the appearance and weakens the course of allergic reactions. The drug is rapidly absorbed, showing 100% bioavailability. It can be used for long-term treatment and for emergency help with seasonal exacerbations of allergies. Available for the treatment of children from 6 years.

Flaws- has such side effects 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 pollinosis and urticaria as skin itching, sneezing, inflammation of the conjunctiva, rhinorrhea, Quincke's edema, allergic dermatoses.

Advantages– Xyzal has a pronounced anti-allergic orientation, being very effective tool. It prevents the onset of allergy symptoms, facilitates 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, the symptoms of chronic allergies are quickly stopped, it does not have a toxic effect on the heart and central nervous system

Flaws- the remedy may exhibit the following side effects: dry mouth, fatigue, abdominal pain, pruritus, hallucinations, shortness of breath, convulsions, 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, can be used to treat children from one year old, as it has a high degree of safety. 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 time period (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 of it persists for 10-14 days. Overdose symptoms were not observed 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 have insomnia, headache, fever.

The drug is intended for the treatment of allergic manifestations such as allergic rhinitis, and urticaria, marked by itching and skin rashes. The drug stops such symptoms of allergic rhinitis as sneezing, itching in the nose and in the sky, watery eyes.

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

Flaws- occasionally, symptoms of side effects such as increased fatigue, headache, dryness of the oral mucosa may occur. Additionally, side effects such as insomnia, tachycardia, the appearance of hallucinations, diarrhea, and hyperactivity are manifested. Allergic manifestations of side effects are possible: itching, urticaria, angioedema.

4th generation antihistamines - do they exist?

All statements by advertisers positioning drug brands as “fourth-generation antihistamines” are nothing more than a publicity stunt. This pharmacological group does not exist, although marketers include not only newly created drugs, but also second-generation drugs.

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

For the treatment of allergic manifestations in children, antihistamines of all three generations are used.

Antihistamines of the 1st generation are distinguished by the fact that they quickly show their healing properties and are excreted 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 is Tavegil, Suprastin, Diazolin, Fenkarol.

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

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

3rd generation antihistamines for children include Gismanal, Terfen and others. They are used in chronic allergic processes, since they are able to stay in the body for a long time. There are no side effects.

Erius can be attributed to newer drugs.

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;

For children, antihistamines are produced in the form of ointments (allergic reactions on the skin), 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 is absolutely safe.

Natural antihistamines, which include vitamins C, B12, pantothenic, oleic and nicotinic acid, zinc, fish oil.

The safest antihistamines are Claritin, Zirtek, Telfast, Avil, but their use must be agreed with the doctor without fail.

4 Best Natural Antihistamines

In some cases, you can resort to the help of the following funds, which can suppress the production of histamine in the body.

Nettle. Nettle has antihistamine properties. Freeze-dried nettle powder has been proven 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 well-being. The positive effect was achieved thanks to the 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 the ability of quercetin to reduce the severity of an allergic reaction. The experiment was carried out on rats. Based on its results, it was concluded that quercetin is able to reduce the intensity of the allergic and inflammatory process in the respiratory system. People with allergies can either purchase quercetin in supplements or just eat foods that are rich in this antioxidant.

Bromelain. Bromelain is an enzyme found in high amounts in pineapples. There is evidence that it helps to 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 hold the record 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, its intake 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 found in 3-5 citrus fruits. They need to be eaten throughout the day.

Food to help fight allergies

To cope with allergies, it is not necessary 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. Proper Diet in combination with physical activity will help the immune system to resist attacks from the external environment.

As for antioxidants in the form of supplements, they should be taken only after consultation with a specialist. The best way to get these substances is from food. So they will be absorbed by 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 of the therapeutic hospital of the central medical unit No. 21, the city of Elektrostal. Since 2016 he has been working in diagnostic center №3.

Antihistamines are a pharmacological group of drugs that inhibit the action of free histamine. First, let's look at what it is from the point of view of medicine in a professional language, this will help to understand what applies to such medicines. Then we will see a simple explanation and examples.

Histamine is a mediator in the development of allergic reactions. It exerts its effect through its influence on H1, H2, H3 receptors located in smooth muscles. internal organs and vessels. The level of development of histamine actions is directly proportional to the amount of released mediator, which means that the more histamine is released, the more pronounced the allergic reaction.

The effect of drugs in the body of patients

H1 receptors are found in the muscles of the respiratory system and blood vessels. The mechanism of action of histamine on H1 receptors is mediated through a cascade of reactions associated with the stimulating effect of extracellular calcium, which, entering the cell, causes smooth muscle contraction.

Affects the lungs, causing contraction of the muscles of the bronchi. This leads to narrowing of the airway lumen up to its complete obstruction. The situation is aggravated by inflammation of the mucous membrane, which further closes the lumen of the bronchus. By affecting the cells that secrete mucus, histamine causes increased secretion of fluid and electrolytes into the bronchial lumen. This process provokes the development of pulmonary edema, which can lead to death.

According to a similar scheme, the effect of histamine on the trachea and uterus is realized, provoking contractions of its muscles and swelling.

The effect on the vessels is characterized by a dilating (expanding) direction, mediated through the activation of phospholipase A2. The enzyme increases the capillary permeability of the walls of blood vessels and causes the release of fluid from the microvasculature into the interstitial (interstitial) space with the development of edema. The arachidonic acid cascade is also activated. During the development of this process connective tissue loses its density, and interstitial edema increases even more.

Consequently, the binding of histamine to H1 receptors in most cases causes the development of allergies.

The mechanism of action of antihistamines is associated with the blocking of H1 receptors instead of histamine. This process is possible due to the biochemical similarity of histamine molecules and drugs of this group. Drugs bind to receptors tropic for histamine, and the released endogenous histamine remains unbound. Thus, the influence of the mediator is blocked, and the called processes do not develop.

Thus, it is possible to distinguish pharmacological actions. These include:

• antipruritic (swelling of tissues causes irritation of nerve endings, which is eliminated under the influence of drugs);
• decongestant;
• bronchodilator (implemented due to anticholinergic influences);
• sedative;
• local anesthetic;
• antiallergic.

Of course, most people want to know what antihistamines are. in simple words what they mean to patients.

Simply put, these are products that are aimed at combating allergies. They eliminate the symptoms of allergies and alleviate the condition of a person.

Generations of drugs for allergic insidiousness

The classification of antihistamines divides them into generations. Knowing this helps to understand what allergy medications are, which ones are the most effective.

Medicines of the 1st generation are the very first medicines of this group. They selectively bind to H1 receptors, blocking the action of free histamine. Due to their lipophilic structure, they also block serotonin and m-cholinergic receptors. This causes their undesirable effect associated with a sedative effect on the body.

List of 1st generation drugs that are used most often:

• Suprastin;
• Diphenhydramine;
• Tavegil.

Their benefit occurs within 30 minutes after ingestion, but the effect is quite short, ranging from 4 to 12 hours. This is due to their rapid excretion from the body in the urine.

Due to their good absorption from the gastrointestinal tract, many of them are available in the form of tablets. Also, medicines have the ability to penetrate the blood-brain barrier and the placenta, and can be excreted in breast milk.

This generation is called sedative because of a side symptom. Given their ability to penetrate the blood-brain barrier, antihistamines can affect serotonin receptors in the brain. Blockade of central serotonin receptors leads to inhibition processes in the central nervous system, which determines the calming effect of drugs. Depending on the strength of the agent, this effect may be dominant. Doxylamine from the group of antihistamines is used as a sedative.

Due to the severity of CNS inhibition, drugs of this group should not be used while intoxicated and together with sedative and sedative varieties, since potentiation of the effect is possible.

2nd generation drugs are newer and more advanced. They block H1 receptors more specifically and do not have m-cholinergic and serotonin effects. Therefore, there are no side effects associated with CNS inhibition. This allows patients to prescribe drugs of the 2nd group without limiting their performance. They also have a low cardiotoxic effect.

The prolonged effect of drugs is associated with their longer cumulation in the body. The effect is achieved in 1-2 hours and lasts up to 24 hours. Excretion of metabolic products occurs through the kidneys. Due to prolonged cumulation, the substance is able to accumulate in the body. Terfenadine is completely eliminated only 12 days after the last dose. This property is used in the outpatient treatment of urticaria, hay fever, rhinitis.

The list of the most popular means from 2 groups are:

• Claritin;
• Fenistil;
• Histimet;
• Allergodil.

One of the disadvantages of second-generation antihistamines is the lack of parenteral forms. Most are sold as enteral tablets and some as topical ointments.

The official classification indicates two groups of antihistamines. The third group of pharmacologically active metabolites in pharmaceuticals is presented as the 3rd generation H 1` histamine blockers.

For those who are interested the best medicines 3rd and 4th generations, as well as new drugs of the unique 5th generation, it is important to remember that this is a publicity stunt designed to attract more buyers. There are no 4th and 5th generation antihistamines. Here is a short list of group 3 drugs that may represent both the fourth and fifth generation:

• Levocetirizine;
• Desloratadine;
• Fexofenadine.

The main thing to know is that medicines that go beyond the first two generations are the best modern allergy drugs. The high bioavailability of drugs contributes to the rapid development of the therapeutic effect (within 30 minutes). The selectivity of action completely removes the effect of cardiotoxicity, which is extremely important for patients with cardiac disorders. The lack of drowsiness allows you to maintain the performance of patients taking medication. The list of drugs of the latest generation is wider, but they must also be prescribed by a doctor.

Forms of drugs with the desired result

Antihistamine drugs exist in the main pharmacological forms:

• pills;
• locally acting agents (and gels);
• parenteral agents for intravenous administration.

Application depends on the form. Tablets (Loratadin, Suprastin, Dimedrol) are prescribed to patients with allergic diseases for the prevention of relapses, the treatment of chronically occurring processes. They are prescribed in a certain dose at regular intervals to maintain the anti-allergic effect.

Parenteral antiallergic drugs are more often used in emergency situations in a hospital with the development of anaphylactic shock, Quincke's edema. Due to the rapidly onset benefit (immediate blockade of histamine receptors), antihistamines in ampoules are the first choice drugs.

Ointments and gels (Fenistil, Dermadrin) are prescribed for the relief of local inflammatory processes. Most of them are used because of the antipruritic effect. The effect is achieved by rubbing into the skin. The action occurs within an hour and lasts 3-5 hours.

Other forms are also used in pediatrics. They are designed for ease of introduction to children:

• rectal suppositories;
• eye drops (Fenistil, Zyrtec);
• syrups (Claritin);
• nasal drops.

Medicines for children from painful passions

Appointments for children are handled by a pediatrician. Do not give your child medication on their own. This is due to the large number adverse symptoms caused by a high concentration of conventional (adult) drugs.

Suprastin and Diphenhydramine are prescribed:

• injection to children under 1 year old only for health reasons, the concentration of the drug is chosen by the pediatrician;
• 1-6 years - a quarter of a tablet 3 times a day;
• 6-10 years - half a tablet 3 times a day;
• 10+ - 1 tablet is prescribed 3 times a day.

Claritin:

• children weighing less than 30 kg - 1 scoop;
• more than 30 kg - 2 measuring spoons;
• tablets are allowed from 4 years.

• one of the most safe drugs for the treatment of allergies;
• children under one year old - 2.5 ml;
• from 5 to 10 years - 5 ml;
• 10+ years - 10 ml.

In case of any occurrence of side effects, it is necessary to consult a doctor.

We choose in advance means for pregnant women

During pregnancy, the drug affects not only the mother, but also the fetus. This is especially true of antihistamines of the first two generations, since they are able to penetrate the placenta, affecting the baby in the womb. In addition, histamines of the first groups have a large set of side effects. Therefore, they are prescribed only for health reasons.

Antiallergic drugs of the new generation are less embryotoxic due to their peripheral specific effect and they do not have a hypnotic effect. Particularly wary should be treated with antihistamines prescribed in the 1st trimester of pregnancy. This is due to the greatest impact on the fetus in this period. The last two trimesters are more favorable in relation to appointments. A few examples:

1. cetirizine. Belongs to the third group. Pregnancy is not a contraindication for prescribing the drug. Numerous tests have proven the absence of teratogenic effects on the fetus.
2. Telfast(second generation). The drug is prescribed by the attending physician under his supervision. It is highly undesirable to use in the 1st trimester of pregnancy due to side effects.
3. Suprastin(first group). It is prescribed only for health reasons when assessing the harm and benefit of the drug in the 2nd and 3rd trimesters.

Proper application is the key to successful treatment

Even the best antihistamine will not bring the expected effect if it is not used correctly. Antihistamines in most cases are dispensed in pharmacies without a prescription. It is important to note that self-treatment may lead to the development of undesirable effects. To prevent them, you must follow some rules:

1. Before starting use, you should consult your doctor. He will prescribe the most correct and successful treatment.
2. You should not take medications of the first groups for more than 7 days unless the doctor advises using them for longer, as they begin to accumulate in the body, which can lead to the development of side effects. Medicines of the last group should not be used for more than a year.
3. During the period of treatment, if side effects occur or they increase, it is necessary to consult a doctor.

Examples of Effective Antihistamines

The table lists the names of popular drugs for adults.

Name	Generation	Price, rub	Peculiarities
Suprastin	1	85-146	The rapid onset of benefits and its short duration
Diphenhydramine	1	1,8-9	Strong sedative effect. It dries out the skin and mucous membranes. Anesthetic action.
Claritin	2	170-200	High antihistamine activity. There is no drowsiness and potentiation effect. Can be combined with many drugs.
Desloratadine	3	130-160	High activity. Absence of sedative and cardiotoxic effects. Valid during the day. Benefit occurs within 30 minutes.
Tsetrin	3	150-200	High activity. Absence of sedative and cardiotoxic effects. Valid for 24 hours.

Compare popular products

For those who are interested in which is better - Erius or Kestin, it is important to remember that they belong to the 2nd group of antihistamines. Active substance Eriusa - loratadine, and Kestina - ebastine. The main difference is that the antihistamine effect of Erius is many times stronger. It can also be given to infants, and the effect occurs within 10 minutes after ingestion. Erius is available in the form of syrup and tablets, and Kestin only in tablets.

Now we will analyze which is better - Fencarol or Loratadine. Fenkarol belongs to the initial generation. Due to the lipophilic structure, it does not penetrate the BBB, like its brothers in the generation. Because of this, the sedative effect is not pronounced. A significant advantage over Loratadine and other drugs is its antiarrhythmic effect, while 2nd generation drugs can cause arrhythmic changes in the heart.

It's time to find out, Tavegil or Zirtek - which one is better for allergies. Tavegil has a pronounced sedative effect, so its use is sharply limited. After taking it, there may be a decrease in working capacity, lethargy, drowsiness. A plus is the possibility of parenteral administration in acute allergies. Zirtek is free from this drawback. It also has a longer duration of action and no weakening of the anti-inflammatory effect over time.

Regarding which of the drugs is better - Fenkarol or Suprastin, it is worth clarifying that they are from the same group - the first. However, due to the difference in chemical composition, their effects are different. Suprastin has the whole set of side effects, including a pronounced sedative effect. Fencarol is devoid of these shortcomings due to the inability to penetrate the BBB. Also, it does not have a cardiotoxic effect, there is an antiarrhythmic effect.

To find the most powerful allergy remedy for a particular patient, you need to consult a doctor. He will tell not only which drugs are antihistamines, which are better for eliminating the observed symptoms.

Antihistamines are a group of drugs whose principle of action is based on the fact that they block H1 and H2-histamine receptors. This blocking helps to reduce the reaction of the human body with a special mediator histamine. What are these medicines for? Doctors prescribe them during allergic reactions. Possessing good antipruritic, antispastic, antiserotonin and local anesthetic effects, antihistamines perfectly help with allergies, and also effectively prevent bronchospasm, which can be caused by histamine.

In accordance with the time of invention and release on sale, the whole variety of allergy remedies is classified into several levels. Antihistamines are classified into first, second, third and fourth generation drugs. The medicines included in each generation have their own specific features and properties. Their classification is based on the duration of the antihistamine effect, the existing contraindications and side effects. The medicine necessary for treatment must be selected based on the characteristics of each specific case of the disease.

Generations of antihistamines

First generation antihistamines

Preparations of the 1st (first) generation include sedatives. They work at the level of H-1 receptors. The duration of their action is four to five hours, after this period it will be necessary to take a new dose of the drug, and the dose should be large enough. Sedative antihistamines, despite their strong effect, have a number of disadvantages. For example, they can provoke dry mouth, dilated pupils, blurred vision.

Drowsiness and a decrease in tone may occur, which means it is impossible to take these drugs while driving a car and other activities that require a high concentration of attention. They also enhance the effect of taking other sedatives, sleeping pills and pain medications. The effect on the body of alcohol mixed with sedatives also intensifies. Most first generation antihistamines are interchangeable.
Their use is advisable in case of allergic problems with the respiratory system, for example, when coughing or nasal congestion. It is worth paying attention to the fact that first-generation antihistamines fight cough well. This makes it appropriate to use them in bronchitis.

They will also be useful to those people who suffer chronic diseases associated with difficulty breathing. Their use is quite effective in bronchial asthma. They can also have a fairly good effect in the treatment of acute allergic reactions. So, for example, their use will be appropriate for urticaria. The most common among them are:

• suprastin
• diphenhydramine
• diazolin
• tavegil

Also often on sale you can find peritol, pipolfen and fenkarol.

Second generation antihistamines

Preparations of the 2nd (second) generation are called non-sedative. They do not have such a large list of side effects as the drugs that make up the first generation of antihistamines. These are drugs, not causing drowsiness and do not reduce brain activity, and also do not have cholinergic effects. good effect gives their use for itching of the skin and allergic rashes.

However, their significant drawback is the cardiotoxic effect that these drugs can cause. Therefore, non-sedative drugs are prescribed only on an outpatient basis. In no case should they be taken by people suffering from diseases of the cardiovascular system. Names of the most common non-sedative drugs:

• trexil
• histalong
• zodak
• semprex
• fenistil
• claritin

Third generation antihistamines

Antihistamines of the 3rd (third) generation are also otherwise called active metabolites. They have strong antihistamine properties and have virtually no contraindications. The standard set of these drugs includes:

• cetrin
• zyrtec
• telfast

These drugs do not have a cardiotoxic effect, unlike second-generation drugs. Their use has a positive effect in asthma and acute allergic reactions. They are also effective in the treatment dermatological diseases. Quite often, third-generation antihistamines are prescribed by doctors for psoriasis.

New generation drugs are the most effective and harmless antihistamines. They are non-addictive, safe for the cardiovascular system, and also have a long period of action. They belong to the fourth generation of antihistamines.

Fourth generation antihistamines

Preparations of the 4th (fourth) generation have a small list of contraindications, which are mainly pregnancy and childhood, but, nevertheless, it is worth reading the instructions and consulting with a specialist before starting treatment. The list of these drugs includes:

• levocetirizine
• desloratadine
• fexofenadine

Based on them, a larger number of drugs are produced, which, if necessary, can be purchased at a pharmacy. These include erius, xizal, lordestin, and telfast.

Forms of release of antihistamines

There are several forms of release of drugs that block histamine receptors. In most cases, their most convenient type to use are tablets and capsules. However, on the shelves of pharmacies you can also find antihistamines in ampoules, suppositories, drops and even syrups. The action of each of them is unique, so only a doctor can help you choose the most appropriate form of taking the medicine.

Treatment of children with antihistamines

As you know, children are more susceptible than adults to allergic diseases. A qualified allergist should select and prescribe drugs for children. Many of them in the list of their contraindications are of children's age, therefore, if necessary, from the application to the preparation of a course of treatment, it is necessary to be especially careful. Children's organisms can react quite sharply to the effects of the drug, so the child's well-being during the period of their use must be monitored very carefully. In case of side effects, the drug should be stopped immediately and consult a doctor.

For the treatment of children, both somewhat outdated medicines and more modern ones are suitable. The drugs that are part of the first generation are mainly used for urgent removal acute symptoms allergies. During long-term use, more modern means are usually used.

Antihistamines are not usually available in special "children's" forms. For the treatment of children, the same drugs are used as for adults, but in smaller doses. Drugs such as zyrtec and ketotifen are usually prescribed from the moment the child reaches the age of six months, all others - from two years. Do not forget that taking medicines by a child should be under the supervision of an adult.

In the case of an illness of a small child, the selection of antihistamines is much more complicated. For newborns, medications that have a slight sedative effect, that is, first-generation drugs, may be suitable. The most commonly used in the treatment of very young children is suprastin. It is safe for both toddlers and older children, as well as for nursing mothers and pregnant women. Depending on the disease and the condition of the child's body, the doctor may prescribe tavigil or phencarol, and in the case of an allergic skin reaction, an antihistamine cream. For infants, the same drugs are suitable as for newborns.

Antihistamines during pregnancy and lactation

Due to the increased production of cortisol in a woman's body, allergies during the childbearing period are quite rare, but, nevertheless, some women still face this problem. During pregnancy, the intake of absolutely all medications must be agreed with the doctor. This also applies to allergy remedies, which have a fairly wide range of side effects and can harm the child. The use of antihistamines is strictly prohibited in the first trimester of pregnancy; in the second and third trimesters they can be used, observing, however, necessary measures precautions.

Unintentional ingestion of the drug into the child's body is possible not only during pregnancy, but also during breastfeeding. During lactation, the use of antihistamines is highly undesirable and is prescribed only in the most urgent cases. The question of which remedy a nursing woman will use can only be decided by a doctor. Even the newest and most modern medicines can cause irreparable harm, so in any case, do not self-medicate by feeding your baby with your milk.

Side effects of antihistamines

As mentioned earlier, the body of each person is individual, and only a specialist can choose the right remedy for treatment. Taking the wrong medicine for a person and violating the dosage can seriously harm health. The harm of antihistamines can manifest itself in addition to their usual side effects such as drowsiness, runny nose and cough in violation of the timing of ovulation in women, the occurrence of allergic edema and asthma. Therefore, be sure to consult your doctor before you start drinking the medicine, and strictly follow the recommendations for taking it.

People who experience allergies regularly buy antihistamines and know what it is.

Timely taken pills save from a debilitating cough, swelling, rash, itching and redness of the skin. The pharmaceutical industry has been releasing similar drugs for many years, and each new batch is formulated as a separate generation.

Today we will talk about the latest generation of antihistamines and consider the most effective of them.

General concept of antihistamines

To everyone who wants to understand in depth the question of what it is - antihistamines, doctors explain that these drugs are designed to counter histamine - an allergic mediator.

When the human body comes into contact with an irritant, specific substances are produced, among which histamine exhibits increased activity. In a healthy person, it is located in mast cells and remains inactive. Under the influence of an allergen, histamine enters the active phase and provokes allergy symptoms.

To stop negative reactions at different times, medicines were invented that could lower the amount of histamine and neutralize its harmful effects on humans. Thus, antihistamines is a general definition of all drugs that have the indicated effectiveness. To date, their classification has 4 generations.

The advantages of the drugs in question are a gentle effect on the body, in particular, on cardiovascular system, rapid relief of symptoms and prolonged effect.

Review of new generation antihistamines

Antihistamines are also called H1 receptor blockers. They are quite safe for the body, but still have some contraindications. For example, during pregnancy and in childhood, the doctor has the right not to prescribe allergy pills if these conditions are listed among the contraindications in their instructions.

All new generation antihistamines - list of new drugs:

• Erius.
• Ksizal.
• Bamipin.
• Cetirizine.
• Ebastine.
• Fenspiride.
• Levocetirizine.
• Fexofenadine.
• Desloratadine.

It is difficult to single out the most effective 4th generation antihistamines from this list, because some of them have appeared relatively recently and have not yet managed to prove themselves 100%. Fenoxofenadine is a popular allergy treatment option. Taking tablets containing this substance does not have a hypnotic and cardiotoxic effect on the patient.

Medications with cetirizine well remove skin manifestations of allergies. One tablet brings significant relief after 2 hours from the moment of use. The result is stored for a long time.

The drug Erius is an improved analogue of Loratadine. But its efficiency is about 2.5 times higher. Erius is suitable for children over the age of 1 who are prone to allergies. They are given the drug in liquid form with a dosage of 2.5 ml 1 time per day. From the age of 5, the dosage of Erius is increased to 5 ml. From the age of 12, the child is given 10 ml of medication per day.

The drug Ksizal is also in high demand today. It prevents the release of inflammatory mediators. Effectiveness is determined by the reliable elimination of allergic reactions.

Feksadin (Allegra, Telfast)

The drug with fexofenadine reduces the production of histamine and completely blocks histamine receptors. Suitable for the treatment of seasonal allergies and chronic urticaria. The tool is not addictive. The body is affected for 24 hours.

Feksadin should not be taken during pregnancy, breastfeeding and children under 12 years of age.

Zodak (Cetrin, Zyrtec, Cetirizine)

The effectiveness of the taken pill is felt after 20 minutes, and after the drug is discontinued, it remains for another 72 hours. Zodak and its synonyms are used for the treatment and prevention of allergies. Long-term use is allowed. The release form is not only tablets, but also syrup and drops.

In pediatrics, Zodak drops have been used since 6 months. After 1 year, syrup is prescribed. Children can take tablets from the age of 6. Dosages for each type of medication are selected individually.

Cetirizine should not be taken by pregnant women. If there is a need to treat allergies during lactation, the baby is temporarily weaned.

Xyzal (Suprastinex, Levocetirizine)

Drops and tablets Ksizal work 40 minutes after ingestion.

The drug is indicated for the treatment of urticaria, allergies, pruritus. For children, fourth-generation antihistamines for allergies called Ksizal are prescribed from the age of 2 and 6 (drops and tablets, respectively). The pediatrician calculates the dosage according to the age and weight of the child.

Xyzal is prohibited during pregnancy. But it can be taken while breastfeeding.

Suprastinex helps well with seasonal allergies, when the body reacts to pollen flowering plants. As the main medicine it is used in the treatment of conjunctivitis and allergic rhinitis. Take Suprastinex with food.

Desloratadine (Erius, Lordestin, Desal)

Desloratadine and its synonyms have antihistamine and anti-inflammatory properties.

They quickly treat seasonal allergies and recurrent hives, but occasionally cause side effects such as headaches and dry mouth. Desloratadine is sold in the form of tablets and syrup.

For children 2 to 6 years old, doctors prescribe syrup. Tablets are allowed to be used only from 6 years. Pregnant and lactating women Desloratadine is completely contraindicated. But with Quincke's edema and bronchospasm, a specialist can choose a gentle option for using this medication.

Antihistamines for toddlers

Newborns are not recommended to take antihistamines. But sometimes there are situations when it is impossible to do without drugs, for example, if the baby was stung by an insect. From 1 month of life, a child can be given Fenistil in drops.

Diphenhydramine, which was previously given to children in different occasions, pediatricians today prescribe only from the 7th month of life.

The most gentle option for the smallest is Suprastin. He quickly shows medicinal properties without causing the slightest harm to the body. Also, children are prescribed Fenkarol and Tavegil. With urticaria, drug dermatosis and food allergies, it is better for a child to give Tavegil. Tablets relieve puffiness, restore skin color and work as an antipruritic agent.

Analogues of Tavegil are Donormil, Dimedrol, Bravegil and Clemastin. Their child takes in the presence of contraindications to the use of Tavegil.

From 2 to 5 years, the child's body gradually strengthens and can normally tolerate more strong medicines. When the skin is itchy, the names of antihistamines for this age group The patient specialist will consider the following:

Erius was mentioned above, now we will focus on Tsetrin. These tablets can be used to prevent allergies in children prone to negative reactions. With individual intolerance to the constituent components, Cetrin is replaced by analogues - Letizen, Cetirinax, Zodak, Zetrinal. After 2 years, the child can take Astemizol.

From the age of 6, the list of antihistamines is expanded, since drugs are suitable for such children. different generations- from 1 to 4. junior schoolchildren can drink tablets Zyrtec, Terfenadin, Clemastine, Glenset, Suprastinex, Caesera.

What Komarovsky says

The famous pediatrician E.O. Komarovsky does not advise parents to give antihistamines to young children without emergency and medical prescriptions. If a pediatrician or an allergist has deemed it necessary to prescribe an antiallergic agent to a child, it can be taken for no more than 7 days.

Evgeny Olegovich also forbids combining antihistamines with antibiotics and says that it is not at all necessary to give a child antihistamine pill before vaccination or after vaccination.

Some parents, based on their own considerations, try to give their child Suprastin to drink before DTP, but Komarovsky does not see any point in this. The children's doctor explains that the reaction of the body to the vaccine has nothing to do with the manifestations of allergies.

Allergic women planning to have offspring are always interested in what antihistamines can be taken during pregnancy and preferably during lactation, or is it worth enduring the inconvenience associated with hay fever, rash and swelling. Doctors say that during the gestation period, it is better for women not to take any medications, because they are potentially dangerous for the mother and fetus.