There are three (according to some authors - four) generation antihistamines.The first includes drugs that, in addition to the anti-allergic, and have a sedative / hypnotic effect.The second includes drugs with the least pronounced effect of sedation and a strong anti-allergic effect, but in some cases causing serious, life-threatening arrhythmias.Antihistamine drugs are new - third - generation are metabolic products (metabolites) of second generation, and their effectiveness is 2-4 times higher than that of their predecessors.They have a number of unique properties of positive and do not cause side effects such as sedation and adverse effects on the heart.It is about the third generation of drugs will be discussed in this article. Content
Medicines of this group act solely on the H1-histamine receptors, that is, have a selective effect.Antiallergic action they also ensured through the following mechanisms of action.Thus, these drugs are:
All the above mechanisms of action provide a powerful anti-allergic, and to some extent the anti-inflammatory effects: eliminate itching, reduce the permeability of the capillary walls, edema and hyperemia of tissues.It does not cause drowsiness, do not have a toxic effect on the heart.Do not bind to cholinergic receptors, therefore, does not cause side effects such as blurred vision and dry mouth.Have a high safety profile.Due to these properties, the new generation of antihistamines may be recommended for long-term treatment of a number of allergic diseases.
Typically, these drugs are well tolerated by patients.However, occasionally with their use may develop following undesirable effects:
indications for the use of drugs of this group are:
contraindicated new generation antihistamines only if the individual sensitivity of the patient to them.
This group of drugs includes:
consider each of them in detail.
Product: tablets, film-coated 120 mg and 180 mg.
pharmacologically active metabolite of the drug of the second generation of terfenadine.
After ingestion is rapidly absorbed in the digestive tract, reaching maximum concentration in blood after 1-3 hours. Almost does not bind to blood proteins, it does not penetrate the blood-brain barrier.The half-life of 11-15 hours. It is deduced mainly with bile.
drug develops antiallergic effect already 60 minutes after its single reception for 6 h effect increases and persists for days.
Adults and children older than 12 years are recommended to take 120-180 mg (1 tablet) once a day, before meals.Tablets should be swallowed without chewing, with 200 ml of water.The course of treatment is determined individually, depending on the characteristics of the disease.Even after regular use of fexofenadine for 28 days signs of intolerance did not arise.
For patients with severe renal or hepatic impairment, the drug should be used with caution.
during pregnancy should not be used as clinical studies in these patients have not been conducted.
drug passes into breast milk, so nursing mothers to take it, you should not.
Product: tablets, film-coated, and a drop of the solution for oral use syrup.
metabolite of hydroxyzine.Potent antagonist of H1-histamine receptors.
use of this drug in high therapeutic doses significantly improves the quality of life of patients suffering from seasonal allergic rhinitis and chronic.
Once inside the effect appears after 2 hours and lasts for a day or more.
Adults and children under the age of 12 years is recommended to take the drug in a daily dose of 10 mg (1 tablet is or 20 drops) in 1 reception.The dosage for children under 12 years: depending on age.
in patients with impaired renal function should be to adjust the dose of cetirizine as a function of creatinine clearance: in renal failure mild prescribed antihistamine 10 mg 1 time a day, which is a full dose;moderate - 5 1 mg once daily (half dose);if creatinine clearance rate corresponds to severe renal insufficiency, it is recommended to take 5 mg of cetirizine in a day, and patients on hemodialysis with renal disease, the drug does is contraindicated.
Contraindications to the use of cetirizine are also individual hypersensitivity to it, and congenital disorders of carbohydrate metabolism (malabsorption syndrome glucose-galactose and others).
cetirizine, taken in normal doses, may cause temporary adverse reactions such as fatigue, drowsiness, excitation of the central nervous system, dizziness and headache.In some cases, against the background of his admission marked dry mouth, accommodation disturbance eyes, difficulty urinating, and elevated liver enzymes.Typically, after the withdrawal of the drug, these symptoms disappear on their own.
During treatment should abandon admission alcohol.
Persons suffering from convulsive syndrome and epilepsy medication should be taken with extreme caution because of the increased risk of seizures.
In pregnancy to apply in case of emergency.The lactation is not taken, since it is excreted in breast milk.
Product: tablets, coated tablets, drops, oral syrup (dosage form for children).
derivative cetirizine.The affinity for histamine H1-receptors in this preparation several times higher than that of its predecessor.
When ingestion rapidly and completely absorbed, the extent of absorption is independent of food intake, but its rate in the presence of food in the stomach is reduced.In some patients the drug action begins within 12-15 minutes after ingestion, but the majority of developing still later, after 30-60 minutes.Maximum concentration in the blood is determined after 50 minutes and maintained for 48 hours. The half-life of from 6 to 10 hours.Excreted by the kidneys.
Individuals with severe renal insufficiency, the half-life of the drug is prolonged.
Provided with breast milk.
Adults and children over 6 years of age is recommended to use the tablet form of the drug.1 tablet (5 mg) taken by mouth without chewing, drinking plenty of water.Multiplicity of reception - 1 times a day.If levocetirizine assigned the drop, its dose for adults and children 6 years and older is 20 drops, 1 time per day.Children under 6 years of age are administered in form of syrup or drops, the dose depends on the age of the child.
Persons with severe impairment of renal function should be before the appointment of the drug to calculate creatinine clearance.If this value is indicative of the kidney function of the first degree, is recommended to receive a dose of the drug is an antihistamine 5 mg per day, that is complete.In the case of mild renal dysfunction, it is 5 mg 1 time in 48 hours, that is, every other day.In severe renal dysfunction drug should be taken at 5 mg 1 time in 3 days.
duration of treatment varies widely and is selected individually depending on the disease and the severity of its course.Thus, when pollinosis treatment usually is 3-6 months in chronic allergic diseases - up to 1 year, if a potentially possible contact with the allergen - 1 week.
Contraindications to the use of levocetirizine, in addition to individual intolerances or chronic severe renal insufficiency are inborn errors of metabolism of carbohydrates (galactose intolerance, lactase deficiency and others), as well as pregnancy and lactation.
side effects similar to those of other preparations of this group.
Taking levocetirizine, absolutely contraindicated drink alcoholic beverages.
Product: tablets, film-coated, 5 mg and oral solution containing 0.5 mg of active substance per ml (dosage form for children).Some drugs, in particular Allergomaks, also produced in the form of nasal spray.
primary active metabolite of loratadine.Inhibits the release of histamine and leukotriene C4 from mast cells, facilitates the flow and prevents the development of allergic reactions.
After ingestion well absorbed in the gastrointestinal tract, reaching peak blood concentrations of 2-6, an average - 3 hours. After the blood-brain barrier does not penetrate.Subject to changes in the liver.The half-life is 20 to 30 hours.
Adults and children 12 years and older is recommended to be taken orally, without regard to meals, 1 tablet (5 mg), 1 per day.Duration of treatment is determined individually.Dosages for children up to 12 years depending on the age of the child.
In severe renal insufficiency received with caution.
Some authors refer to the third-generation antihistamines are 3 ingredients: norastemizol (product sharing astemizole), descarboethoxyloratadine (metabolite of loratadine) and karebastin (product sharing ebastine).However, in broad medical practice they have not yet been introduced in the market and there are no Russian pharmaceuticals.
formulations described above, and are highly promising in the treatment of allergic diseases nature, but they are not completely safe.Therefore, in case of you have allergy symptoms, do not try to treat it yourself, but not immediately seek medical attention.