Which skin allergy pills help best? The most effective antihistamines for children and adults - a list of medications with instructions and prices. Strong sedative effect of antihistamines.
Currently, in the specialized literature, opinions differ regarding which antiallergic drugs should be classified as second and third generation. In this regard, the list of 2nd generation antihistamines will have its own characteristics depending on what point of view modern pharmacists adhere to.
By what criteria are antihistamines classified into the second group?
According to the first point of view, second-generation drugs are all those antiallergic drugs that do not have a sedative effect because they do not penetrate the brain through the blood-brain barrier.
The second and most common point of view is that only those that, although they do not have an effect on nervous system, but can cause changes in the heart muscle. Medicines that do not affect the heart and nervous system are classified as the third generation of antihistamines.
According to the third point of view, only one drug that has antihistamine properties belongs to the second generation - ketotifen, because it has a membrane-stabilizing effect. And all those drugs that stabilize the mast cell membrane, but do not cause a sedative effect, constitute the third generation of antihistamines.
Why did antihistamines get this name?
Histamine is an essential substance that is predominantly found in mast cells connective tissue and blood basophils. Released under the influence various factors from these cells, it connects to the H 1 and H 2 receptors:
- H1 receptors, when interacting with histamine, cause bronchospasm, contraction smooth muscle, expand capillaries and increase their permeability.
- H 2 receptors stimulate an increase in acidity in the stomach and affect heart rate.
Indirectly, histamine can cause severe itching by stimulating the release of catecholamines from adrenal cells, increasing the secretion of the salivary and lacrimal glands, and also accelerating intestinal motility.
Antihistamines connect to H1 and H2 receptors and block the action of histamine.
List of drugs of the second group
According to the most common classification of antihistamines, the second generation includes:
- dimethindene,
- loratadine,
- ebastine,
- cyproheptadine,
- azelastine,
- acrivastine.
All these drugs do not penetrate the brain, so they do not cause a sedative effect. However, the possible development of cardiotoxicity limits the use of this group of drugs in older people and those who suffer from heart disease.
Increases myocardial damage during treatment with second-generation antihistamines when taken simultaneously with them antifungal agents and some antibiotics, such as clarithromycin, erythromycin, itraconazole and ketoconazole. You should also avoid using grapefruit juice and antidepressants.
Dimetindene (fenistil)
Available in the form of drops, gel and capsules for oral administration. It is one of the few drugs that can be used in children of the first year of life, with the exception of the neonatal period.
Fenistil is well absorbed orally and has a pronounced antiallergic effect, lasting after 1 dose for about 6–11 hours.
The drug is effective for skin itching, eczema, drug and food allergies, insect bites, itchy dermatoses and exudative-catarrhal diathesis in children. Its other purpose is to relieve mild household and sunburns.
Features of application. It is one of the few second-generation drugs that does cross the blood-brain barrier, so it may slow down your reaction time while driving. In this connection, it should be prescribed with extreme caution to drivers, and especially not during work that requires a quick reaction.
When applying the gel to the skin, it is necessary to protect this area from exposure to direct sunlight.
Dimetindene is contraindicated during the first trimester of pregnancy and in the neonatal period. It is used with caution in the second and third trimesters of pregnancy, with prostate adenoma, and angle-closure glaucoma.
Loratadine (claritin, lomilan, lotharen)
Like other drugs in this group, it effectively treats all kinds of allergic diseases, especially allergic rhinitis, conjunctivitis, nasopharyngitis, angioedema, urticaria, and endogenous itching. The drug is available in the form of tablets and syrup for oral administration, and is also part of multicomponent antiallergic gels and ointments for local treatment.
Effective for pseudoallergic reactions, hay fever, urticaria, itchy dermatoses. As an adjuvant it is prescribed for bronchial asthma.
Features of application. In older people it can cause sedative effect, not recommended during pregnancy and breastfeeding. Many drugs reduce the effectiveness of loratadine or increase its side effects, so be sure to consult your doctor before starting to take it.
Ebastine (kestin)
Also belongs to the group of second generation antihistamines. Its distinctive feature is the absence of interaction with ethanol, so it is not contraindicated when using medications containing alcohol. Concomitant use with ketoconazole increases toxic effect on the heart, which can lead to fatal consequences.
Ebastine is prescribed for allergic rhinitis, urticaria and other diseases accompanied by excessive release of histamine.
Cyproheptadine (peritol)
This drug for the treatment of allergic reactions can be prescribed to children from 6 months. Like other drugs in this group, cyproheptadine has a strong and long lasting effect, eliminating allergy symptoms. Distinctive feature peritol - relief of migraine headaches, calming effect, reduction of excess secretion of somatotropin in acromegaly. Cyproheptadine is prescribed for toxicoderma, neurodermatitis, complex therapy chronic pancreatitis, serum sickness.
Azelastine (allergodil)
This drug copes well with such types of allergies as allergic rhinitis and conjunctivitis. Available as a nasal spray and eye drops. In pediatrics it is prescribed to children from 4 years of age ( eye drops) and from 6 years (spray). The duration of treatment with azelastine, on the recommendation of a doctor, can last up to 6 months.
From the nasal mucosa, the drug is well absorbed into the general bloodstream and has systemic action on the body.
Acrivastine (Semprex)
The drug poorly penetrates the blood-brain barrier and therefore does not have a sedative effect, but drivers vehicles and those whose work requires quick and precise actions, you should refrain from taking it.
Acrivastine differs from other representatives of this group in that it begins to act within the first 30 minutes, and the maximum effect on the skin is observed within 1.5 hours after administration.
Drugs of the second group, about which there is controversy in scientific circles
Mebhydrolin (diazolin)
Most experts classify Diazolin as a first-generation antihistamine, while others, due to its minimally expressed sedative effect, classify this remedy to the second. Be that as it may, diazolin is widely used not only in adults, but also in pediatric practice, being considered one of the most inexpensive and accessible medicines.
Desloratadine (Eden, Erius)
It is most often classified as a third generation antihistamine because it is an active metabolite of loratadine.
Cetirizine (Zodak, Cetrin, Parlazine)
Most researchers classify this medicine as a second generation of antihistamines, although some confidently classify it as a third because it is an active metabolite of hydroxyzine.
Zodak is well tolerated and rarely causes side effects. Available in the form of drops, tablets and syrup for oral administration. With a single dose of the drug, it has therapeutic effect throughout the day, so it can be taken only once a day.
Cetirizine relieves allergy symptoms, does not cause sedation, and prevents the development of smooth muscle spasm and swelling of surrounding tissues. Effective for hay fever, allergic conjunctivitis, urticaria, eczema, and relieves itching well.
Features of application. If the drug is prescribed in large doses, then you should refrain from driving vehicles, as well as work that requires quick reactions. When used together with alcohol, cetirizine can enhance its negative effects.
The duration of treatment with this drug can be from 1 to 6 weeks.
Fexofenadine (Telfast)
Most researchers also consider it to be a third generation of antihistamines, because it is an active metabolite of terfenadine. It can be used by those whose activities involve driving, as well as those suffering from heart disease.
The article provides a list the best drugs 1st, 2nd and 3rd generation, which can make life easier for people prone to allergies. After reading the entire article, you will be able to understand why some antihistamines are better than others. Find out which of them and why pregnant and lactating women should not take them. You can watch an interesting video on the topic of what antiallergic medications you should take with you when going on vacation.
Antihistamines - which ones are better?
Drugs that suppress histamine (the hormone that triggers allergic reactions in the body) have different shape release. They can be purchased at the pharmacy in the form of capsules, tablets, nasal spray and even eye drops. Antihistamines can cause serious side effects in the body, so some are sold only with a doctor's prescription.
Pay attention! Only a doctor can answer the question of which antihistamines are best, and then on an individual basis, having familiarized himself with the characteristics of your body and identifying the allergen that worries you.
Currently, there are three generations of drugs that suppress histamine. They differ from each other in their constituent components, effect and duration of impact on the body:
- First generation: endowed with sedative properties (suppresses consciousness, calms, relieves irritability) and acts as a sleeping pill.
- Second generation: has a powerful anti-allergic effect. Such drugs do not suppress consciousness, but can seriously disrupt the normal rhythm of the heart, which, if a person is inattentive to his health and drug inactivity, leads to death.
- Third generation: active metabolites (product of bio-physical-chemical processing of 2nd generation drugs). The effectiveness of these drugs is more than 3 times higher than the effectiveness of 1st and 2nd generation antihistamines.
To choose the most best medicine, which is capable of blocking the activity of histamine without disrupting the functioning of the main systems of the body, you should have an idea of the main components of such drugs and the effectiveness of their effects. It is this topic that is addressed in the following sections of the article.
To treat allergies, you can use not only tablets, but also.
First generation drugs
The duration of exposure to antihistamines of this group is 4 - 6 hours, after which the patient must take new dose medicines. The list of main side effects includes dry mouth and temporary loss of blurred vision. Let's look at the popular types of drugs: different forms release.
The drug contains active ingredient chloropyramine. The product is effective for common types of allergies, including seasonal and those caused by insect bites. "Suprastin" is prescribed from 1 month of life. After administration, the medicine begins to act after 15 - 25 minutes. Maximum effect achieved within an hour and lasts up to 6 hours. The product helps stop gagging, is a moderate antispasmodic and has the ability to relieve inflammation.
"Suprastin" is sold in tablet form and as a solution in ampoules. It is recommended to take the tablets only with meals, which avoids irritation of the gastric mucosa. Injections are prescribed for prolonged allergies that cannot be cured with pills.
The approximate cost of the drug is 120 - 145 rubles. (available for free sale).
Another name for the soothing antihistamine is “Clemastine” (the active substance is clemastine hydrofumarate). The medicine is intended to alleviate allergies that may occur in response to pollen, pet dander, mosquito bites, skin contact with chemical. All these factors cause allergic symptoms(skin rash, sneezing, red eyes, nasal congestion). After taking Tavegil, the actions of histamine are blocked, as a result the mentioned symptoms disappear.
This type of antihistamine is a long-acting (long-acting) medicine. From gastrointestinal tract the drug penetrates the blood. After 2 hours, its maximum concentration in plasma is observed. After 5-6 hours, its antihistamine activity develops intensively, which can last 12-24 hours.
"Tavegil" can be purchased in the form of tablets, syrup and solution for injection. The price of the medicine starts from 120 rubles and depends on the form of release, as well as on the number of tablets or ampoules in the package. The product is dispensed without a doctor's prescription.
Typically, this drug is prescribed to children and adult patients whose bodies do not accept other antihistamines due to addiction. Compared to them, Fenkarol has a less pronounced sedative effect (does not suppress consciousness), which allows it to be taken in working hours. The antiallergic drug proves its effectiveness in the treatment of allergies to pollen, drugs and food.
45% of the active component of the drug (hifenadine) penetrates into the blood 30 minutes after administration. After 1 hour, the maximum content of the active substance in the blood plasma is reached. The duration of its effect lasts no more than 6 hours.
In pharmacies, the medicine is sold in tablet and powder form, as well as in the form of an injection solution. You can buy Fenkarol for 260 - 400 rubles (the cost depends on the form of release and the quantity in the package). The drug is sold without a prescription.
Second generation drugs
Compared to the drugs described above this group drugs that suppress histamine are much more effective, which is reflected in the following factors:
- Firstly, they do not cause drowsiness, do not cause stool problems, dry mucous membranes and difficulty urinating.
- Secondly, they do not affect mental and physical activity.
- Thirdly, they are not addictive, which allows them to be used for long-term treatment (over a year).
- Fourth, the duration of the corrective effect of the dose taken is 24 hours, which allows you to take the drug once a day.
Important! Taking 2nd generation antiallergic drugs should be accompanied by medical supervision, because This group of drugs acts as blockers of potassium channels of the heart (responsible for the excitability and rest of the heart muscle). For this reason, self-medication is dangerous.
The product contains the active ingredient loratadine, which is able to cope with seasonal (caused by pollen, dampness) and year-round (caused by dust, animal dander, detergents) allergies. The drug is effective for allergies to mosquito bites and copes with the manifestations of pseudoallergic syndrome (the pathology is similar to allergies, but has other causes). It is also prescribed for the treatment of itchy dermatoses.
The medicine can be purchased in the form of syrup and tablets. The average cost in the pharmacy chain for Claridol is 90 rubles. (over the counter).
The active component of the drug is loratadine. This antiallergic drug is prescribed to patients to get rid of skin rashes, false allergies, inflammation of the mucous membranes of the nose and eyes. After 8 to 12 hours, after taking the tablets or syrup, the active substance enters the phase of maximum activity. The duration of its corrective effect in the body lasts 24 hours.
"Lomilan" is produced in tablets and in the form of a homogeneous (homogeneous) suspension. The average cost of Lomilan tablets is 120 rubles, the suspension is 95 rubles. Over-the-counter release.
The drug is made on the basis of the substance - rupatadine. The drug is prescribed for the treatment of runny nose and urticaria caused by allergies. Its active component quickly cleanses the skin of rashes, relieves itching, and makes breathing free. Rupatadine does not depress the central nervous system.
Peculiarity!“Rupafin” should not be taken with grapefruit juice, because the product increases the activity of rupatadine by 3.5 times, the human body will not be able to correctly perceive this factor, and this can result in serious consequences for him (the appearance of swelling, nausea and vomiting, disruption of the heart).
"Rupafine" is produced only in tablets (there are no other dosage forms), they are taken regardless of food intake (1 tablet, 1 time per day). The average cost of tablets in a pharmacy chain is 587 rubles. (available without a doctor's prescription).
III generation drugs
This group of antihistamines does not have a cardiotoxic (blocking potassium channels of the heart) or sedative (calming) effect, so the drugs can be prescribed to drivers, as well as people whose work requires increased concentration. The third generation of drugs is not addictive, which makes it possible to effectively treat both seasonal and year-round allergies.
The drug is prescribed to get rid of seasonal allergies and chronic urticaria. The active component of this antihistamine is fexofenadine hydrochloride, which, in turn, belongs to the active metabolites (bio-physical-chemical processing products) of terfenadine (2nd generation antihistamine).
The drug shows its effectiveness within 1 hour after administration. The maximum concentration of the drug in the blood plasma is observed after 6 hours. The duration of exposure to fexofenadine is 24 hours.
The active component of this antiallergic drug is desloratadine. The substance blocks histamine receptors for 27 hours, so the medicine needs to be taken only once a day (5 - 20 mg). Trexil does not have a negative effect on the human central nervous system. Does not suppress consciousness or induce sleep.
An antihistamine can be purchased at a pharmacy without a prescription for about 89 rubles.
The active ingredient of the drug is fexofenadine (the active metabolite of terfenadine - a 2nd generation histamine blocker). The medicine is available in tablet form, 30, 120 and 180 mg. The tablets are taken 1-2 times a day at the dose prescribed by the doctor. Fexofenadine quickly penetrates the blood plasma and blocks the production of histamine for 24 hours.
The cost of Telfast antihistamine depends on the quantity active substance in one tablet and can range from 128 to 835 rubles.
If you are going on vacation, then watch this video material. In it, the allergist names the medications that you should put in your suitcase. You should not take the recommendations of a specialist lightly, especially if you are going to an exotic country where there are many new plants and delicious fruits that you have never tried.
Question answer
What antiallergic drugs can pregnant women take?
Usually these are Levocetirizine and Fexofenadine. During pregnancy and breastfeeding, you should only take medications prescribed by your doctor.
What harm can they cause? antihistamines pregnant woman and fetus?
Particularly dangerous for women carrying a child are 1st generation antiallergic drugs, in particular Diphenhydramine and Diazolin, which can complicate the course of pregnancy (dizziness, increased fatigue, dry mucous membranes) and cause heart defects in the fetus.
What antiallergic drugs are prescribed to infants?
A child can be prescribed Zyrtec from birth (consultation with an allergist and pediatrician is required). The medicine is released in drops. The drug is contraindicated for premature babies and those whose mothers smoked during pregnancy.
Are antihistamines prescribed for chickenpox to relieve itching?
IN in this case the most common drugs are Suprastin, Diphenhydramine and Tavegil. Please note that they do not use lotions and creams that contain these components, but medications in the form of tablets.
What tablets can be given to children with allergies for mosquito bites?
You should definitely consult a pediatrician and allergist about this. Zirtec and Suprastin are usually prescribed. If allergies are hereditary, doctors do not recommend that parents give their children the same antiallergic drugs that they themselves take.
What to remember:
- There are 3 generations of histamine-suppressing medications.
- The best anti-allergy drugs are 3rd generation drugs, with correct use they do not carry serious side effects.
- Antihistamines are available in the form of tablets, syrup, injections and eye drops.
- During pregnancy and breastfeeding, women should not take 1st and 2nd generation medications; their active ingredients pose a danger to the baby.
- It is better to give anti-allergy medications to children as recommended by a doctor.
People who periodically suffer from allergies know this best. Sometimes only in a timely manner taken medicine can save them from painfully itchy rashes, severe attacks cough, swelling and redness. 4th generation antihistamines are modern means, which affect the body instantly. In addition, they are quite effective. The results are saved long time.
Impact on the body
To understand how 4th generation antihistamines differ, you need to understand the mechanism of action of antiallergic drugs.
These medications block H1 and H2 histamine receptors. This helps reduce the body's reaction to the mediator histamine. Thus, cupping occurs allergic reaction. In addition, these drugs serve as an excellent prevention of bronchospasms.
Let's look at all the antihistamines and let us understand what the advantages of modern drugs are.
First generation drugs
This category includes: They block H1 receptors. The duration of action of these drugs is 4-5 hours. Medicines have an excellent antiallergic effect, but have a number of disadvantages, including:
- pupil dilation;
- dry mouth;
- blurred vision;
- drowsiness;
- decreased tone.
Common first generation medications are:
- "Diphenhydramine";
- "Diazolin";
- "Tavegil";
- "Suprastin";
- "Peritol";
- "Pipolfen";
- "Fenkarol".
These drugs are usually prescribed to people suffering from chronic diseases in which there is difficulty breathing (bronchial asthma). In addition, they will have a beneficial effect in case of acute allergic reaction.
2nd generation drugs
These medications are called non-sedatives. Such products no longer have an impressive list of side effects. They do not provoke drowsiness or decreased brain activity. Medicines in demand for allergic rashes and itchy skin.
The most popular drugs:
- "Claritin";
- "Trexyl";
- "Zodak";
- "Fenistil";
- "Gistalong";
- "Semprex".
However, the big disadvantage of these drugs is their cardiotoxic effects. That is why these drugs are prohibited for use by people suffering from cardiovascular pathologies.
3rd generation drugs
These are active metabolites. They have excellent antiallergic properties and have a minimal list of contraindications. If we talk about effective antiallergic drugs, then these drugs are precisely modern antihistamines.
Which drugs from this group are the most popular? These are the following medications:
- "Zyrtec";
- "Cetrin";
- Telfast.
They do not have a cardiotoxic effect. They are often prescribed for acute allergic reactions and asthma. They provide excellent results in the fight against many dermatological diseases.
4th generation drugs
Recently, specialists have invented new medicines. These are 4th generation antihistamines. They are distinguished by their rapid action and long-lasting effect. Such drugs perfectly block H1 receptors, eliminating all unwanted allergy symptoms.
The great advantage of such medications is that their use does not harm the functioning of the heart. This allows us to consider them quite safe means.
However, we should not forget that they have contraindications. This list is quite small, mainly childhood and pregnancy. But it is still recommended to consult a doctor before use. It would be useful to study the instructions in detail before using 4th generation antihistamines.
The list of such drugs is as follows:
- "Levocetirizine";
- "Erius";
- "Desloratadine";
- "Ebastine";
- "Fexofenadine";
- "Bamipin";
- "Fenspiride";
- "Cetirizine";
- "Xyzal."
The best drugs
It is quite difficult to identify the most effective drugs from the 4th generation. Since such drugs were developed not so long ago, there are few new antiallergic drugs available. In addition, all drugs are good in their own way. Therefore, it is not possible to identify the best 4th generation antihistamines.
Medicines containing fenoxofenadine are in great demand. Such drugs do not have a hypnotic or cardiotoxic effect on the body. These drugs today rightfully occupy the place of the most effective antiallergic medications.
Cetirizine derivatives are often used to treat skin manifestations. After taking 1 tablet, the result is noticeable after 2 hours. At the same time, it persists for quite a long time.
The active metabolite of the famous Loratadine is the drug Erius. This drug is 2.5 times more effective than its predecessor.
The medicine “Xyzal” has earned great popularity. It perfectly blocks the release process. As a result of this effect, this product reliably eliminates allergic reactions.
Medicine "Cetirizine"
That's enough effective remedy. Like all modern 4th generation antihistamines, the medicine is practically not metabolized in the body.
The drug has proven to be highly effective in skin rashes, since it is able to perfectly penetrate the epidermis. Long-term use of this medicine in children suffering from early atopic syndrome, significantly reduces the risk of progression of such conditions in the future.
2 hours after taking the tablet, the desired lasting effect occurs. Since it lasts for a long time, taking 1 pill per day is enough. Some patients can take 1 tablet every other day or twice a week to achieve the desired result.
The medicine differs minimally. However, patients suffering from kidney pathologies should use this remedy with extreme caution.
The drug in the form of a suspension or syrup is approved for use in children from two years of age.
Medicine "Fexofenadine"
This drug is a metabolite of terfenadine. This medication is also known as Telfast. Like other 4th generation antihistamines, it does not cause drowsiness, is not metabolized and does not affect psychomotor functions.
This product is one of the safest, but at the same time extremely effective medicines among all antiallergic medications. The drug is in demand for any manifestations of allergies. Therefore, doctors prescribe it for almost all diagnoses.
Antihistamine tablets "Fexofenadine" are prohibited for use by children under 6 years of age.
The drug "Desloratadine"
This medicine is also a popular antiallergic drug. It can be used for any age groups. Since medical pharmacologists have proven its high safety, this drug is sold in pharmacies without a prescription.
The drug has a slight sedative effect, does not have a detrimental effect on cardiac activity, and does not affect the psychomotor sphere. Often the medicine is well tolerated by patients. In addition, it does not interact with others.
One of the most effective medicines The drug “Erius” is considered from this group. This is a fairly powerful antiallergic medicine. However, it is contraindicated during pregnancy. In syrup form, the medicine is approved for use by children from 1 year of age.
The drug "Levocetirizine"
This remedy is better known as “Suprastinex”, “Cesera”. This is an excellent drug that is prescribed to patients suffering from pollen. The remedy is prescribed in case of seasonal manifestations or year-round. The drug is in demand in the treatment of conjunctivitis and allergic rhinitis.
Conclusion
New generation drugs are active metabolites of previously used drugs. Undoubtedly, this property makes 4th generation antihistamines extremely effective. Medicines in human body are not metabolized, but give a long-lasting and pronounced result. Unlike previous generations of drugs, such drugs do not have a detrimental effect on the liver.
Historically, the term “antihistamines” refers to drugs that block H1-histamine receptors, and drugs that act on H2-histamine receptors (cimetidine, ranitidine, famotidine, etc.) are called H2-histamine blockers. The former are used for treatment allergic diseases, the latter are used as antisecretory agents.
Histamine, this most important mediator of various physiological and pathological processes in the body, was chemically synthesized in 1907. Subsequently, it was isolated from animal and human tissues (Windaus A., Vogt W.). Even later, its functions were determined: gastric secretion, neurotransmitter function in the central nervous system, allergic reactions, inflammation, etc. Almost 20 years later, in 1936, the first substances with antihistamine activity were created (Bovet D., Staub A.). And already in the 60s, the heterogeneity of histamine receptors in the body was proven and three of their subtypes were identified: H1, H2 and H3, differing in structure, localization and physiological effects that occurs during their activation and blockade. From this time on, an active period of synthesis and clinical testing of various antihistamines began.
Numerous studies have shown that histamine, acting on receptors in the respiratory system, eyes and skin, causes characteristic symptoms allergies, and antihistamines that selectively block H1-type receptors can prevent and relieve them.
Most of the antihistamines used have a number of specific pharmacological properties, characterizing them as separate group. This includes the following effects: antipruritic, decongestant, antispastic, anticholinergic, antiserotonin, sedative and local anesthetic, as well as prevention of histamine-induced bronchospasm. Some of them are caused not by histamine blockade, but by structural features.
Antihistamines block the effect of histamine on H1 receptors through the mechanism of competitive inhibition, and their affinity for these receptors is much lower than that of histamine. Therefore, these drugs are not able to displace the histamine bound to the receptor; they only block unoccupied or released receptors. Accordingly, H1 blockers are most effective in preventing immediate allergic reactions, and in the event of a developed reaction, they prevent the release of new portions of histamine.
In my own way chemical structure most of them are fat-soluble amines, which have a similar structure. The core (R1) is represented by an aromatic and/or heterocyclic group and is linked via a nitrogen, oxygen or carbon molecule (X) to the amino group. The core determines the severity of antihistamine activity and some of the properties of the substance. Knowing its composition can predict the strength of the drug and its effects, such as its ability to penetrate the blood-brain barrier.
There are several classifications of antihistamines, although none of them is generally accepted. According to one of the most popular classifications, antihistamines, based on the time of creation, are divided into first and second generation drugs. First generation drugs are also commonly called sedatives (based on the dominant side effect) in contrast to non-sedating second generation drugs. Currently, it is customary to distinguish the third generation: it includes fundamentally new drugs - active metabolites, which, in addition to the highest antihistamine activity, exhibit the absence of a sedative effect and the cardiotoxic effect characteristic of second-generation drugs (see).
In addition, according to their chemical structure (depending on the X-bond), antihistamines are divided into several groups (ethanolamines, ethylenediamines, alkylamines, derivatives of alphacarboline, quinuclidine, phenothiazine, piperazine and piperidine).
First generation antihistamines (sedatives). All of them are highly soluble in fats and, in addition to H1-histamine, also block cholinergic, muscarinic and serotonin receptors. Being competitive blockers, they reversibly bind to H1 receptors, which leads to the use of quite high doses. The following pharmacological properties are most characteristic of them.
- The sedative effect is determined by the fact that most first-generation antihistamines, easily soluble in lipids, penetrate well through the blood-brain barrier and bind to H1 receptors in the brain. Perhaps their sedative effect consists of blocking central serotonin and acetylcholine receptors. The degree of manifestation of the first generation sedative effect varies among different drugs and at different patients from moderate to pronounced and increases when combined with alcohol and psychotropic drugs. Some of them are used as sleeping pills (doxylamine). Rarely occurs instead of sedation psychomotor agitation(usually in moderate therapeutic doses in children and in high toxic doses in adults). Because of the sedative effect, most medications should not be used while performing tasks that require alertness. All first-generation drugs potentiate the effect of sedatives and hypnotics, narcotic and non-narcotic analgesics, monoamine oxidase inhibitors and alcohol.
- The anxiolytic effect characteristic of hydroxyzine may be due to suppression of activity in certain areas of the subcortical region of the central nervous system.
- Atropine-like reactions associated with the anticholinergic properties of drugs are most typical for ethanolamines and ethylenediamines. Manifested by dry mouth and nasopharynx, urinary retention, constipation, tachycardia and visual impairment. These properties ensure the effectiveness of the drugs under discussion for non-allergic rhinitis. At the same time, they can increase obstruction in bronchial asthma (due to an increase in sputum viscosity), cause exacerbation of glaucoma and lead to bladder outlet obstruction in prostate adenoma, etc.
- The antiemetic and anti-motion sickness effect is also likely associated with the central anticholinergic effect of the drugs. Some antihistamines (diphenhydramine, promethazine, cyclizine, meclizine) reduce the stimulation of vestibular receptors and inhibit the function of the labyrinth, and therefore can be used for movement disorders.
- A number of H1-histamine blockers reduce the symptoms of parkinsonism, which is due to the central inhibition of the effects of acetylcholine.
- The antitussive effect is most characteristic of diphenhydramine; it is realized through a direct effect on the cough center in the medulla oblongata.
- The antiserotonin effect, primarily characteristic of cyproheptadine, determines its use for migraine.
- α1-blocking effect with peripheral vasodilation, especially inherent in phenothiazine antihistamines, can lead to a transient decrease blood pressure in sensitive persons.
- A local anesthetic (cocaine-like) effect is characteristic of most antihistamines (occurs due to a decrease in membrane permeability to sodium ions). Diphenhydramine and promethazine are stronger local anesthetics than novocaine. At the same time, they have systemic quinidine-like effects, manifested by prolongation of the refractory phase and the development of ventricular tachycardia.
- Tachyphylaxis: decreased antihistamine activity with long-term use, confirming the need to alternate medications every 2-3 weeks.
- It should be noted that first generation antihistamines differ from the second generation in their short duration of action with a relatively rapid onset of clinical effect. Many of them are available in parenteral forms. All of the above, as well as low cost, determine the widespread use of antihistamines today.
Moreover, many of the qualities discussed allowed the “old” antihistamines to occupy their niche in the treatment of certain pathologies (migraine, sleep disorders, extrapyramidal disorders, anxiety, motion sickness, etc.) not related to allergies. Many first generation antihistamines are included in combination drugs, used for colds as sedatives, sleeping pills and other components.
The most commonly used are chloropyramine, diphenhydramine, clemastine, cyproheptadine, promethazine, fenkarol and hydroxyzine.
Chloropyramine(suprastin) is one of the most widely used sedative antihistamines. It has significant antihistamine activity, peripheral anticholinergic and moderate antispasmodic effects. Effective in most cases for the treatment of seasonal and year-round allergic rhinoconjunctivitis, Quincke's edema, urticaria, atopic dermatitis, eczema, itching of various etiologies; in parenteral form - for the treatment of acute allergic conditions requiring emergency care. Provides a wide range of therapeutic doses used. Does not accumulate in blood serum, therefore does not cause overdose when long-term use. Suprastin is characterized by a rapid onset of effect and short duration (including side effects). In this case, chloropyramine can be combined with non-sedating H1-blockers in order to increase the duration of the antiallergic effect. Suprastin is currently one of the best-selling antihistamines in Russia. This is objectively related to proven high efficiency, the controllability of its clinical effect, the availability of various dosage forms, including injections, and low cost.
Diphenhydramine, best known in our country under the name diphenhydramine, is one of the first synthesized H1 blockers. It has fairly high antihistamine activity and reduces the severity of allergic and pseudo-allergic reactions. Due to its significant anticholinergic effect, it has an antitussive, antiemetic effect and at the same time causes dryness of the mucous membranes and urinary retention. Due to its lipophilicity, diphenhydramine produces pronounced sedation and can be used as a hypnotic. It has a significant local anesthetic effect, as a result of which it is sometimes used as an alternative in cases of intolerance to novocaine and lidocaine. Diphenhydramine is available in various dosage forms, including for parenteral use, which determined its widespread use in emergency therapy. However, a significant range of side effects, unpredictability of consequences and effects on the central nervous system require increased attention when using it and, if possible, the use of alternative means.
Clemastine(tavegil) is a highly effective antihistamine, similar in action to diphenhydramine. It has high anticholinergic activity, but penetrates the blood-brain barrier to a lesser extent. Also exists in injection form, which can be used as an additional remedy for anaphylactic shock and angioedema, for the prevention and treatment of allergic and pseudoallergic reactions. However, hypersensitivity to clemastine and other antihistamines with a similar chemical structure is known.
Cyproheptadine(peritol), along with an antihistamine, has a significant antiserotonin effect. In this regard, it is mainly used for some forms of migraine, dumping syndrome, as an appetite enhancer, and for anorexia. of various origins. It is the drug of choice for cold urticaria.
Promethazine(pipolfen) - a pronounced effect on the central nervous system determined its use in Meniere's syndrome, chorea, encephalitis, sea and air sickness, as antiemetic. In anesthesiology, promethazine is used as a component lytic mixtures to potentiate anesthesia.
Quifenadine(fenkarol) - has less antihistamine activity than diphenhydramine, but is also characterized by less penetration through the blood-brain barrier, which determines the lower severity of its sedative properties. In addition, fenkarol not only blocks histamine H1 receptors, but also reduces the content of histamine in tissues. May be used in cases of developing tolerance to other sedating antihistamines.
Hydroxyzine(atarax) - despite the existing antihistamine activity, it is not used as an antiallergic agent. It is used as an anxiolytic, sedative, muscle relaxant and antipruritic agent.
Thus, antihistamines first generation, affecting both H1- and other receptors (serotonin, central and peripheral cholinergic receptors, a-adrenergic receptors), have various effects, which determined their use in many conditions. But the severity of side effects does not allow them to be considered as the first choice drugs in the treatment of allergic diseases. The experience gained from their use made it possible to develop unidirectional drugs - the second generation of antihistamines.
Second generation antihistamines (non-sedating). Unlike the previous generation, they have almost no sedative and anticholinergic effects, but are distinguished by their selectivity of action on H1 receptors. However, they exhibit a cardiotoxic effect to varying degrees.
The most common properties for them are the following.
- High specificity and high affinity for H1 receptors with no effect on choline and serotonin receptors.
- Rapid onset of clinical effect and duration of action. Prolongation can be achieved due to high protein binding, accumulation of the drug and its metabolites in the body and slow elimination.
- Minimal sedative effect when using drugs in therapeutic doses. It is explained by weak passage of the blood-brain barrier due to the structural features of these drugs. Some particularly sensitive individuals may experience moderate drowsiness, which is rarely a reason to discontinue the drug.
- Absence of tachyphylaxis with long-term use.
- The ability to block potassium channels in the heart muscle, which is associated with prolongation of the QT interval and cardiac arrhythmias. The risk of this side effect increases when antihistamines are combined with antifungals (ketoconazole and intraconazole), macrolides (erythromycin and clarithromycin), antidepressants (fluoxetine, sertraline and paroxetine), when drinking grapefruit juice, as well as in patients with pronounced violations liver functions.
- There are no parenteral forms, but some of them (azelastine, levocabastine, bamipin) are available in forms for topical use.
Below are second generation antihistamines with their most characteristic properties.
Terfenadine- the first antihistamine without an inhibitory effect on the central nervous system. Its creation in 1977 was the result of a study of both the types of histamine receptors and the features of the structure and action of existing H1 blockers, and marked the beginning of the development of a new generation of antihistamines. Currently, terfenadine is used less and less, which is associated with an increased ability to cause fatal arrhythmias associated with prolongation of the QT interval (torsade de pointes).
Astemizole- one of the longest-acting drugs in the group (the half-life of its active metabolite is up to 20 days). It is characterized by irreversible binding to H1 receptors. It has virtually no sedative effect and does not interact with alcohol. Since astemizole has a delayed effect on the course of the disease, when acute process its use is inappropriate, but may be justified in chronic allergic diseases. Since the drug has the ability to accumulate in the body, the risk of developing serious violations heart rhythm, sometimes fatal. Due to these dangerous side effects Sales of astemizole in the US and some other countries have been suspended.
Akrivastine(Semprex) is a drug with high antihistamine activity with minimally expressed sedative and anticholinergic effects. A feature of its pharmacokinetics is low level metabolism and lack of accumulation. Acrivastine is preferable in cases where there is no need for constant antiallergic treatment due to the rapid achievement of effect and short-term action, which allows the use of a flexible dosing regimen.
Dimetenden(fenistil) - is closest to first-generation antihistamines, but differs from them by a significantly less pronounced sedative and muscarinic effect, higher antiallergic activity and duration of action.
Loratadine(claritin) is one of the most widely purchased second-generation drugs, which is understandable and logical. Its antihistamine activity is higher than that of astemizole and terfenadine, due to greater binding strength to peripheral H1 receptors. The drug has no sedative effect and does not potentiate the effect of alcohol. In addition, loratadine practically does not interact with other medicines and does not have a cardiotoxic effect.
The following antihistamines are classified as drugs local action and are intended to relieve local manifestations of allergies.
Levocabastine(histimet) is used in the form of eye drops to treat histamine-dependent allergic conjunctivitis or as a spray for allergic rhinitis. At local application enters the systemic circulation in small quantities and does not have undesirable effects on the central nervous and cardiovascular systems.
Azelastine(allergodil) is a highly effective treatment allergic rhinitis and conjunctivitis. Used as a nasal spray and eye drops, azelastine has virtually no systemic effects.
Another topical antihistamine, bamipin (Soventol) in the form of a gel, is intended for use in allergic skin lesions accompanied by itching, insect bites, jellyfish burns, frostbite, sunburn, and also thermal burns mild degree.
Third generation antihistamines (metabolites). Their fundamental difference is that they are active metabolites of previous generation antihistamines. Their main feature is the inability to influence the QT interval. Currently there are two drugs available: cetirizine and fexofenadine.
Cetirizine(Zyrtec) is a highly selective antagonist of peripheral H1 receptors. It is an active metabolite of hydroxyzine, which has a much less pronounced sedative effect. Cetirizine is almost not metabolized in the body, and the rate of its elimination depends on renal function. Its characteristic feature is high ability penetration into the skin and, accordingly, effectiveness in skin manifestations allergies. Cetirizine, neither experimentally nor in the clinic, showed any arrhythmogenic effect on the heart, which predetermined the area practical use metabolite drugs and determined the creation of a new drug - fexofenadine.
Fexofenadine(Telfast) is an active metabolite of terfenadine. Fexofenadine does not undergo transformations in the body and its kinetics does not change with impaired liver and kidney function. It does not enter into any drug interactions, does not have a sedative effect and does not affect psychomotor activity. In this regard, the drug is approved for use by persons whose activities require increased attention. A study of the effect of fexofenadine on the QT value showed both in experiment and in the clinic complete absence cardiotropic effect when using high doses and long-term use. Along with maximum safety, this drug demonstrates the ability to relieve symptoms in the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria. Thus, the pharmacokinetic features, safety profile and high clinical efficacy make fexofenadine the most promising of the antihistamines at present.
So, in the doctor’s arsenal there is sufficient quantity antihistamines with various properties. It must be remembered that they provide only symptomatic relief for allergies. In addition, depending on the specific situation, you can use both various drugs, and their diverse forms. It is also important for the doctor to remember the safety of antihistamines.
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Today we will talk about new antihistamines, latest generation, their list, how effective they are, pharmacological action, how to take, side effects and much more.
Groups of antihistamines
The prevalence of allergic diseases among the population is steadily increasing every year.
In order to relieve the symptoms of allergies, improve well-being and completely eliminate the likelihood of severe and sometimes fatal complications, the use of antiallergic medications is required.
For second generation antihistamines
There is no pronounced sedative effect and most of these drugs have a prolonged effect, that is, they can be taken once a day.
The prescription of such drugs should be carried out with caution, as they have a cardiotoxic effect. That is, their use is completely contraindicated for those who have a history of cardiovascular pathologies.
An example is the drug.
Pharmacological action of drugs
Antihistamines from last group have selectivity of their action - they act only on H1 - histamine receptors.
The antiallergic effect on the body occurs due to several changes.
These medications:
- They inhibit the production of mediators (including cytokines and chemokines) that affect systemic allergic inflammation;
- Reduce the total number and change the functioning of adhesion molecules;
- Reduce chemotaxis. This term refers to the release of leukocytes from the vascular bed and their penetration into damaged tissue;
- Inhibits the activation of eosinophils;
- Prevents the production of superoxide radical;
- Reduces bronchial hypersensitivity.
All changes that occur under the influence of the latest generation of antihistamines lead to a decrease in the permeability of the vascular walls. As a result of this, swelling, hyperemia, and itching disappear skin and mucous membranes.
The lack of influence on histamine receptors types 2 and 3 determines the absence of pronounced side changes in the form of drowsiness and toxic influence on the heart muscle.
The newest antiallergic medications do not interact with choline receptors, and therefore patients are not bothered by dry mouth and blurred vision.
Due to their high anti-inflammatory and antiallergic effects, antihistamines of the third group can be prescribed when necessary.
Possible side effects
Patients taking the latest generation antihistamines rarely notice adverse reactions. But it cannot be said that they are completely absent.
When treated with these drugs, the occurrence of:
- Headaches;
- Increased fatigue;
- Periodic dizziness;
- Severe drowsiness or, conversely, insomnia;
- Hallucinations;
- Tachycardia;
- Dry mouth;
- Dyspeptic disorders in the form of nausea, colic and abdominal pain, vomiting;
- Pain in different groups muscles;
- Rash on the skin.
Very rarely when long-term treatment hepatitis developed. If you are predisposed to allergies, there is an increased likelihood of body itching, anaphylactic reactions, including Quincke's edema.
List of drugs
To antihistamines newest generation include:
- Fexofenadine;
- Levocetirizine;
- Cetirizine;
- Desloratadine;
- Hifenadine;
It must be remembered that the listed products are also available under other names, but their main active ingredient does not change.
Norastemizole and a number of other drugs that are still better known abroad are in the development stage.
Indications for use
The effectiveness of allergy treatment is largely determined by correct selection drug, which must be entrusted to a doctor.
Third generation antiallergic medications are used to treat patients with:
- Seasonal and year-round;
- Conjunctivitis that occurs under the influence of allergens;
- Contact dermatitis;
- Urticaria of acute and chronic course;
The latest generation of drugs can be used as a course and after elimination acute symptoms anaphylactic shock, drug allergies, Quincke's edema.
General contraindications to their use are considered only intolerance by the patient to the main or additional components of the drug.
Fexofenadine
The drug is available in two dosage forms. Tablets have dosages of 30, 60, 120 and 180 mg.
The suspension contains 6 mg of the main antiallergic substance in one ml.
Allergy symptoms begin to subside about an hour after oral use.
The maximum effect begins to appear after 6 hours and then remains at the same level throughout the day.
You should take the medicine following the following rules:
- Patients over 12 years of age need to take the drug daily at a dose of 120 and 180 mg. The tablet is taken once a day, preferably at the same time.
- From 6 to 11 years old daily dose is 60 mg, but it is recommended to divide it into two doses.
- The tablet does not need to be chewed. You should drink it with one glass of clean water.
- The duration of therapy depends on the type of allergic reaction and its severity.
Fexofenadine was successfully taken by a group of patients for a month or more without developing symptoms of intolerance.
The drug is best used to cope with allergic rhinitis; it is recommended to prescribe it for hay fever, rashes on the body and urticaria.
Fexofenadine is not prescribed if the child is under 6 years old. Caution when treating with this drug should be exercised by those who have a history of renal or hepatic pathologies.
The components of the drug penetrate into breast milk, and therefore cannot be used during lactation.
It is not clear how Fexofenadine acts during pregnancy, so this drug is prescribed to expectant mothers only in exceptional cases.
It is distinguished by the fastest development of antiallergic effects on the body - some patients note a decrease in allergy symptoms within 15 minutes after administration.
Most people taking the drug feel better within 30-60 minutes.
The maximum concentration of the main active ingredient is determined over two days. The drug passes into breast milk.
Levocetirizine is prescribed for the treatment of various forms of allergic rhinitis; the drug helps with urticaria, etc.
It is accepted based on the following rules:
- The tablet form is prescribed to children over 6 years of age and adults.
- You need 5 mg of the drug per day, which is contained in one tablet. It is drunk regardless of when a meal is planned, but the drug must be washed down with a glass of water.
- The drug in drops from 6 years of age is prescribed 20 drops per day. If the child is younger, the dosage is selected depending on his weight.
- The duration of the course of treatment depends on the type and severity of the allergic reaction. For patients with hay fever, Levocetirizine can be prescribed for up to 6 months. For chronic allergies, taking the drug sometimes continues for a year. If possible contact with an allergen is suspected, the medicine can be taken within a week.
Levocetirizine is not prescribed in pediatric practice for children under two years of age. Contraindications to its use also include pregnancy, severe renal failure, congenital pathologies carbohydrate metabolism.
For patients with impaired renal function, the dose of the drug is selected after testing. In cases of mild and moderate degree pathology, a dose of 5 mg can be taken once every two or three days.
Analogues of Levocetirizine are: Alerzin, Aleron Neo, L-cet, Glencet, Zilola.
Cetirizine
Available in the form of tablets, drops, syrup. The drug is a metabolite of hydroxyzine.
Cetirizine relieves skin itching well, so its effect is optimal in the treatment of urticaria and itchy dermatoses.
The product is highly effective in eliminating the symptoms of acute and chronic rhinitis caused by the influence of allergens, in particular ragweed.
The medicine eliminates the symptoms of allergic conjunctivitis - lacrimation, itching, hyperemia of the sclera.
The antiallergic effect occurs after two hours and lasts for at least one day.
The drug is prescribed depending on the patient’s age:
It is necessary to adjust the dose of the drug in patients with impaired renal function.
Treatment with Cetirizine is contraindicated during breastfeeding, congenital disorders in carbohydrate metabolism, with individual hypersensitivity.
This medicine should be used with caution by those who have a history of epilepsy and seizures.
During pregnancy, the drug is prescribed only in extreme cases.
The most famous analogues of Cetirizine include Rolinoz, Allertek, Amertil, Cetrinal, skin rashes and urticaria, hay fever.
The active substance of the drug retains its antiallergic activity in the body throughout the day.
The tablet form is prohibited for use under 12 years of age. Children over one year of age should receive the drug in the form of syrup.
Hifenadine (trade name Fenkarol)
Available in tablet form and as a solution for intramuscular injection.
Oral administration ensures the onset of antiallergic action within an hour, injection administration leads to a decrease in allergy symptoms within half an hour.
Hifenadine and its analogues are prescribed for:
- Dermatoses accompanied by itching and skin irritation;
- Chronic and acute urticaria;
- Food and;
- Hay fever, allergies to ragweed;
- Allergic conjunctivitis and rhinitis;
- Angioedema.
The daily dose of the drug for adults is up to 200 mg, divided into three doses.
The dosage for children is prescribed depending on their age and the type of allergic reaction. Treatment should last from 10 to 20 days.
Hifenadine is contraindicated throughout pregnancy, children under three years of age, lactation period. Trade names medicines Fenkarol-Olaine, Fenkarol.
An allergist should prescribe any antihistamine medication. A qualified doctor takes into account not only the severity of the allergic reaction, but also the patient’s age and the presence of other diseases, including chronic diseases.
Self-treatment often causes the development of severe forms of allergies and this should always be remembered.
