Anyone who is looking for histamine drugs in pharmacies will definitely face a problem, since they are prescribed in extremely rare situations. In turn, antihistamines of different generations are presented today very widely. The fact is that histamine is a biological compound that is permanently present in the human body in an inactive state. Free histamine is so active that it blocks the work of vital organs. In order to suppress this active substance antihistamine medications are used.
How do antihistamines work?
Given the high rate of formation of the histamine-receptor complex, scientists have developed new-generation antihistamines that provide additional impact on the complex of inflammatory mechanisms:
- inactivate histamine;
- slow down the process of histamine synthesis and the formation of oxygen radicals;
- disrupt the process of cell activation by immobilizing calcium ions.
These medications affect the interaction of receptors and histamine, which is required for the biological effect on the mediator.
When histamine joins the H1 receptor, spasms appear in smooth muscle cells. If such a receptor acts on the end of nerve cells, the skin begins to itch, urticaria and hyperemia appear. When exposed to receptors on the chest mucus production increases.
In the situation of attaching the H2 receptor to histamine, the secretion of cells in the gastrointestinal tract is stimulated, followed by diarrhea, flatulence and rashes in the mouth.
H3 receptor is present in the cells of the nervous system, and therefore they react to histamine by fever, headache, nausea and migraine.
On the surface of mast cells is the H4 receptor, which is involved in the mobilization and movement of neutrophils.
Antihistamines are capable of combining with a certain type of receptor or lacking selectivity.
Generations of antihistamine drugs: list
Experts have determined the classification of allergy drugs by generations. It was formed from the time when histamine blockers were invented. The preparations entering into such generations differ in features. The classification was created on the basis of contraindications and undesirable consequences after administration.
For each patient medicine is selected individually, based on the symptoms. An important influence is exerted by individual features of the organism.
To the list of antihistamine drugs first generation include sedative medications active for H1 receptors. They are administered to the patient in large doses, and the effect of one lasts about 6 hours. After that, you have to enter another dose.
The effect of sedative drugs has some side effects: vision becomes blurred, mucous in the mouth dries out, pupils dilate. Using sedative medications, the patient notes drowsiness, decreased muscle tone. Such funds cannot be prescribed if the patient drives a car and is engaged in responsible work. When used with antihistamine drugs of the first generation of sleeping pills, painkillers and sedative medicines, the effect of taking the latter will be enhanced.
These allergy medications prescribed for certain problems:
- bronchial asthma;
- allergy, worsening the work of the respiratory system;
- acute contact allergies.
Due to the fact that such tools are excellent with cough, they are prescribed for bronchitis. Patients suffering from chronic illnesses who complicate breathing need such medicines. The most common among them are:
Antihistamines second generation – This is a drug without a sedative effect. The number of possible side effects is minimized. These medicines do not inhibit the reaction and do not cause drowsiness. Second-generation products have a good effect in the treatment of itching and skin rashes.
However, these drugs have a cardiotoxic effect. That is why they are prescribed in the hospital. Patients with pathologies of the heart and blood vessels are prohibited from using second generation antihistamines:
Third generation antihistamine drugs refers to the active metabolites. By blocking histamine synthesis, they have a strong effect on the body. These tools include: Cetrin, Zyrtec, Telfast. Unlike the medicines of the previous generation, these are used in the treatment of asthma, skin diseases and acute allergies. Often they are prescribed for the treatment of psoriasis.
Today, the latest generation of antihistamines are widely used. The new fourth generation is the means, practically not provoking by-effects (Erius, Telfast, Xizal).
The advantages of using the latest generation of antihistamines are:
- the rate of impact on the problem;
- duration of therapeutic effect up to 2 days;
- lack of tachyphylaxis effect;
- reduced need for corticosteroids;
- no side effects on the myocardium and central nervous system.
Despite advances in the development of pharmaceutical companies, it is not recommended to use these drugs during pregnancy. They are prescribed only under medical supervision.
5th generation antihistamines: list
To the latest new listing Allergy medications include:
All of the above funds can be found under other names, however, the main active ingredient remains the same.
A new drug that is currently under development is Norastemizol. This is a tool that is known only abroad.
Antihistamines for children and pregnant women
In the treatment of childhood allergic diseases used drugs of three generations. The first group is the means that quickly exhibit therapeutic properties and are easily eliminated from the body. Usually they are prescribed for the treatment of acute allergic reactions with short courses. The most effective among them are: Suprastin, Tavegil, Diazolin and Fenkarol.
Medicaments of the second group do not provoke sedation and their action lasts a long time, so they take them once a day. For the treatment of childhood allergies are usually prescribed Fenistil, Ketotifen and Cetrin.
The third group of allergy medications for children is used for the chronic form of the disease, because they have a long lasting effect.
Children can use antihistamines in the form of syrups, drops, ointments and tablets.
With regard to the appointment of antihistamines to pregnant women, it is necessary to understand here that this is prohibited during the first trimester. Starting from the second trimester, you can use the funds if absolutely necessary.
Pregnant women can prescribe natural antihistamines. in the form of vitamins B12 and C, nicotinic, oleic and pantothenic acid, fish oil and zinc.
The safest in pregnancy are Zyrtec, Claritin, Avil and Telfast. However, even their admission is necessarily consistent with your doctor.
Side Effects and Contraindications to Antihistamines
Antihistamines able to worsen the patient’s condition with diagnoses:
- urine stasis;
- enlarged prostate gland;
- intestinal obstruction.
In case of detection of these ailments, medicines for allergies prescribed carefully. The dosage will have to be reduced if the person suffers from kidney and liver failure. Basically, the dosage depends on the drug.
Up to six months of age, it is not advised to use Hydroxysin and Promethazine.
Sedative antihistamines are those that reduce concentration. This action is enhanced by the simultaneous use of drugs and alcohol.
When using antihistamines, especially first-generation drugs, following side effects:
- blurred vision;
- dry mucous membranes in the mouth;
- difficult urination;
- clouding of consciousness.
If some medicines are taken with antihistamines, they provoke drowsiness:
- Zopiclone and other medications that help you quickly fall asleep.
- Amitriptyline and similar antidepressants.
- Morphine and Codeine, as well as potent painkillers.
- Temazepam, Lorazepam, Diazepam.
In order to avoid side effects, antispasmodic, antipsychotic and anticholinergic drugs should not be taken with anti-allergic medicines.
Which doctor can help?
After the onset of allergic symptoms, you can contact the allergist or therapist. Additional advice is obtained from an ophthalmologist, ENT specialist and a dermatologist. In case of atopic rhinitis need to visit pulmonologist, to be screened to exclude bronchial asthma.
A competent recommendation by a nutritionist who excludes highly allergenic foods from the patient’s diet can also help.
Doctors note that allergy complications can be avoided if:
- follow a hypo-allergenic diet;
- take antihistamines in a timely manner;
- reduce the number of contacts with the allergen.
Selection of antihistamine drugs is carried out by a doctor taking into account the concomitant diagnoses, age, severity and general health of the person.