Blockade of H 1 receptors prevents bronchospasm caused by histamine and hyperemia, edema, skin itching. Therefore, indications for the use of H 1 -histamine blockers are primarily allergic diseases (especially those occurring with type I allergic reactions) and various conditions accompanied by the release of histamine in the tissues: hay, allergic, urticaria, reactions to insect bites, angioedema, skin dermatosis, reactions to blood transfusion, the introduction of radiopaque substances, medicines, etc. In addition, additional pharmacological effects are inherent in individual H 1 -histamine blockers, which are taken into account in the clinical use of B. g. Thus, dimebon, sequifenadine, cyproheptadine have an antiserotonin effect, which makes them preferable in case of dermatoses; phenothiazine derivatives have a-adrenergic blocking properties; many H 1 -histamine blockers, especially the first generation, exhibit the properties of anticholinergics, both peripheral (which helps to weaken allergic reactions) and central action (for penetrating the BBB); they potentiate the effect on the central nervous system. alcohol, hypnotics and a number of tranquilizers and themselves dose-dependently inhibit the central nervous system, which expanded the indications for their use as sedatives and even hypnotics (diphenhydramine), as well as antiemetics, in particular in Meniere's disease, vomiting of pregnant women, air and seasickness (dimenhydrinate). diphenhydramine, along with depressing central, also has a local anesthetic effect; like promethazine, it is part of the lytic mixtures used in anesthesiology.

With an overdose of H 1 -histamine blockers that affect the central nervous system, drowsiness, lethargy, muscular dystonia are noted, convulsions are possible, sometimes irritability (especially in children), sleep disorders; anticholinergic effects can be manifested by dry mouth, increased intraocular pressure, visual disturbances, impaired motility of the gastrointestinal tract, tachycardia. in acute poisoning with diphenhydramine or promethazine, anticholinergic effects are especially pronounced; often there are hallucinations, psychomotor agitation, convulsive seizures, a soporous state or coma develops (especially in case of poisoning against the background of alcohol intake), acute respiratory and cardiovascular.

Side effects of H 1 -histamine blockers and contraindications to their use are determined by the properties of specific drugs. Means that significantly affect the c.n.s. (diphenhydramine, phenothiazine derivatives, oxatomide, etc.) are not prescribed to persons who continue activities that require concentration of attention and maintaining the speed of reactions. For the period of treatment with drugs that depress the central nervous system, alcohol is excluded and the dosage of neuroleptics, hypnotics and tranquilizers used simultaneously is reviewed. A number of second-generation drugs (astemizol, terfenadine, etc.) are characterized by an arrhythmogenic effect on the heart, associated with a prolongation of the Q-T interval on the ECG; they are contraindicated in individuals with baseline QT prolongation due to the risk of developing ventricular tachyarrhythmias with possible sudden death. Drugs with a noticeable anticholinergic effect are contraindicated in angle-closure glaucoma. Almost all H1-histamine blockers are contraindicated in women during pregnancy and during breastfeeding.

Forms of release and a brief description of the main H 1 -histamine blockers are given below.

Azelastine(allergodil) - 0.05% solution (eye drops); nasal spray (1 mg/ml) by 10 ml in a vial. In addition to the main action, it blocks the release of inflammatory mediators from mast cells. It is applied topically for allergic e (1 drop in each eye 3-4 times a day) and e (1 inhalation in each nasal passage 1-2 times a day). Side effects: local dryness of the mucous membranes, bitterness in the mouth.

Astemizol(Asmoval, Astelong, Astemisan, Hismanal, Histalong, Stelert, Stemiz) - Tablets 5 and 10 mg; suspension (1 mg/ml) for oral administration at 50 and 100 ml in vials. Little penetrates through the BBB and almost does not show anticholinergic properties. After absorption, it is metabolized in the liver to form an active metabolite, desmethylastemizole; excreted mainly with bile; T 1/2 astemizole reaches 2 days, desmethylastemizole 9-13 days. some macrolides and antifungal drugs can reduce the intensity of astemizole metabolism. Assign to patients older than 12 years inside 10 mg 1 time / day (maximum dose - 30 mg/ day), children from 6 to 12 years old, 5 mg/ day, children from 2 to 6 years old - only in the form of a suspension at the rate of 0.2 mg/1 kg body weight 1 time / day; duration of treatment up to 7 days. Overdose and side effects: emotional disorders, paresthesia, convulsions, increased activity of hepatic transaminases, prolongation of the Q-T interval on the ECG, ventricular tachyarrhythmias; with prolonged use, an increase in body weight is possible. Contraindications: age up to 2 years; prolonged Q-T interval on ecg, hypokalemia; severe violations of the liver; pregnancy and lactation; simultaneous use of ketoconazole, itraconazole, olone, erythromycin, quinine, antiarrhythmic and other drugs that can prolong the QT interval.

Dimebon- tablets of 2.5 mg(for children) and 10 mg. The structure is close to mebhydrolin; additionally exhibits antiserotonin properties; has a sedative and local anesthetic effect. Assign adults 10-20 mg up to 3 times / day. within 7-12 days.

Dimenhydrinate(anauzin, dedalon, dramil, emedil, etc.) - 50 tablets mg- complex salt of diphenhydramine (diphenhydramine) with chlortheophylline. It has a pronounced central, in particular antiemetic effect. It is mainly used to prevent and stop the manifestations of air and sea sickness, Meniere's disease, bouts of vomiting of various origins. Assign adults inside before meals for 50-100 mg half an hour before boarding a plane or a ship, and for therapeutic purposes in the same dose 4 to 6 times a day. At the same time, anticholinergic effects (dry mouth, accommodation disorders, etc.) are possible, which can be eliminated by reducing the dose of the drug.

Dimetinden(fenistil) - 0.1% solution (drops for oral administration); retard tablets 2.5 mg; retard capsules 4 each mg; 0.1% gel in tubes for application to affected areas of the skin. In addition to H 1 -histamine blocking, antikinin action is expected; has a pronounced anti-edematous and antipruritic effects, exhibits weak sedative and anticholinergic properties (drowsiness and dry mouth are possible when used). Inside, patients over 12 years of age are prescribed 1 mg(20 drops) up to 3 times a day or retard tablets 2 times a day or retard capsules 1 time a day; daily dose for children under 1 G ode is 3-10 drops, from 1 to 3 years - 10-15 drops, from 3 to 12 years - 15-20 drops (in 3 divided doses). The gel is used 2-4 times a day.

Diphenhydramine(Alledril, Allergin, Amidril, Benadryl, Diphenhydramine, etc.) - tablets of 20, 25, 30 and 50 mg; 1% solution in ampoules and in syringe tubes 1 each ml; "sticks" (50 mg) on a polyethylene basis for laying in the nasal passages with allergic rhinitis; candles at 5, 10, 15 and 20 mg. Inhibits central nervous system, exhibits pronounced anticholinergic activity, incl. in the autonomic ganglia. In addition to allergic diseases, it is additionally used as a hypnotic and antiemetic (in particular, in Meniere's syndrome), as well as in chorea and as part of lytic mixtures for premedication in anesthesiology. As an anti-allergic agent, adults are prescribed inside 30-50 mg 1-3 times a day; maximum daily dose 250 mg; intravenously (drip) and intramuscularly administered 20-50 mg. Children: up to 1 G ode - 2-5 each mg; from 2 to 5 years - 5-15 mg; from 6 to 12 years - 15-30 mg appointment. As a sleeping pill, adults are prescribed 50 mg for the night. Contraindications: angle-closure, tic status, pyloroduodenal s, obstructive bladder emptying disorders, incl. with prostatic hypertrophy.

Quifenadine(fenkarol) - tablets of 10 (for children's practice), 25 and 50 mg. In addition to the blockade of H 1 -histamine receptors, it reduces the content of free histamine in tissues by activating diamine oxidase. Little penetrates through the BBB and in therapeutic doses does not have a noticeable sedative and anticholinergic effect. Assign inside after eating (because of the irritating effect on the mucous membranes) for persons over 12 years of age, 25-50 mg 2-4 times a day; children under 3 years - 5 mg, from 3 to 7 years - 10 mg 1-2 times a day, from 7 to 12 years - 10-15 mg 2-3 times a day. Tolerability of the drug is good; sometimes dry mouth and dyspeptic disorders are observed, passing with a decrease in dose.

clemastine(angistan, rivtagil, tavegil, tavist),

mecloprodine fumarate, - tablets 1 each mg; syrup (0.1 mg/ml) for oral administration; 0.1% solution in ampoules of 2 ml for intramuscular or intravenous (slowly, for 2-3 min) introductions. Shows sedative and anticholinergic properties; decongestant and antipruritic effects of a single dose in allergy continues 12-24 h. Assign 2 times / day. inside patients older than 12 years, 1-2 mg(maximum daily dose for adults 6 mg), children from 6 to 12 years old - 0.5-1 mg; parenterally for adults - 2 each mg, children from 6 to 12 years old - at the rate of 25 mcg/kg.

Levocabastin(histimet) - 0.05% solution in vials of 4 ml(eye drops) and in vials of 10 ml in the form of an aerosol for intranasal use. It is used for allergic conjunctivitis (1 drop in each eye 2-4 times a day) and ah (2 injections in each nasal passage 2 times a day). Resorptive action is practically absent; possibly transient local irritation of the mucous membranes.

Loratadine(Claritin, Lomilan) - Tablets 10's mg; suspension and syrup (1 mg/ml) in vials. Assign inside 1 time per day: adults and children weighing more than 30 kg 10 each mg. Side effects: increased fatigue, dry mouth, nausea.

Mebhydrolin(diazolin, insidal, omeril) - dragee 50 and 100 mg, syrup 10 mg/ml Little penetrates through the BBB and therefore practically does not depress the central nervous system. (weak sedative effect); exhibits anticholinergic properties. Assign inside adults and children over 10 years old, 100-300 mg/ day (in 1-2 doses), children under 10 years old 50-200 mg/ day Contraindications are the same as for diphenhydramine (diphenhydramine).

Oksatomide(tinset) - tablets of 30 mg. In addition to the blockade of H 1 -histamine receptors, it inhibits the release of mediators of allergy and inflammation from mast cells. Oppresses ts.n.s. Assign inside adults for 30-60 mg(elderly - 30 mg) 2 times a day; children weighing 15-35 kg- 15 each mg once a day, with body weight over 35 kg- 30 each mg/ day (in 1 or 2 doses). Side effects: drowsiness, weakness, fatigue, dry mouth, dyskinesia (in children), increased activity of hepatic transaminases, increased appetite with weight gain (when used in high doses). Contraindications: age up to 6 years, pregnancy and breastfeeding of a child, active diseases and functional liver, simultaneous use of agents that depress the central nervous system.

Promethazine(allergan, diprazine, pipolfen, etc.) - dragee 25 mg; 2.5% solution in ampoules of 2 ml (50 mg) for intramuscular or intravenous administration. It has a pronounced effect on the central nervous system. (sedative and antiemetic effects, lowering body temperature), has a-adrenolytic, as well as anticholinergic (peripheral and central) effects. In addition to allergic diseases, it is used for Meniere's disease (syndrome), sea and air sickness, chorea, ah, ah and ah with agitation and sleep disorders, in anesthesiology as part of lytic mixtures - to potentiate anesthesia, as well as the action of analgesics and local anesthetics. Assign inside adults at 12.5-25 mg 2-4 times a day (maximum daily dose 500 mg); parenterally (according to emergency indications, before and after surgical interventions) is administered at 50 mg(maximum daily dose 250 mg). Children aged 2 to 12 months. inside appoint 5-7.5 mg 2-4 times a day, from 1 year to 6 years - 7.5-12.5 mg 2-4 times a day, from 6 to 14 years - 25 mg 2-4 times a day. Side effects: drowsiness, less often psychomotor anxiety, photophobia, extrapyramidal disorders; increased body temperature, orthostatic arterial (with intravenous administration); dry mouth, dyspeptic disorders; with prolonged use - deposits in the lens and in the cornea of ​​​​the eyes, menstrual disorders, glucose metabolism, sexual function. Contraindications: arterial hypotension; angle-closure, obstructive bladder emptying disorders, incl. with prostatic hypertrophy, pyloroduodenal s; pregnancy and the period of breastfeeding a child; simultaneous reception of MAO inhibitors.

Sequifenadine(bikarfen) - 50 tablets mg. Additionally, it blocks serotonin S 1 receptors, which, with severe dermatoses, is manifested by a pronounced antipruritic effect. Assign inside after eating for adults 50-100 mg 2-3 times a day for 3-4 days (when the maximum effect is achieved), then switch to a maintenance dose - 50 mg 2 times a day. Tolerability of the drug is the same as quifenadine.

Setastin(loderix, loridex) - tablets 1 each mg. In structure it is close to tavegil; additionally exhibits antiserotonin properties; penetrates through the BBB, has a sedative, hypnotic and anticholinergic effect.

Assign adults 1-2 mg 2-3 times a day (maximum daily dose 6 mg). Special contraindications: severe violations of the liver or kidneys.

Terfenadine(bronal, histadin, caradonel, tamagon, teridine, tofrin, trexil) - tablets 60 and 120 each mg, syrup or suspension (6 mg/ml) for oral administration. Metabolism of the drug in the liver can be inhibited by macrolides and some antifungal drugs. Virtually no effect on the central nervous system; able to lengthen the Q-T interval per ECG, cause ventricular tachyarrhythmias with the possibility of sudden death; with prolonged use, an increase in body weight is possible. Assign 2 times a day to patients over 12 years old for 60 mg, children from 6 to 12 years old - 30 mg appointment. Contraindications are the same as for astemizole.

Pheniramine(avil) - tablets of 25 mg; oral syrup (in pediatrics); solution for injection (22.75 mg/ml) in ampoules of 2 ml. It has a sedative and anticholinergic effect. Assign usually 2-3 times a day for adults, 25 mg, adolescents 12-15 years old - 12.5-25 mg, children - 7.5-15 mg. contraindications are the same as for diphenhydramine.

Chloropyramine(suprastin) - tablets of 25 mg; 2% solution for intramuscular or intravenous administration in ampoules of 1 ml. In terms of its effect on the central nervous system, peripheral, anticholinergic and side effects, it is close to diphenhydramine. Inside, adults are prescribed 25 mg 3-4 times a day. In severe allergic and anaphylactic reactions administered parenterally 1-2 ml 2% solution. contraindications are the same as for diphenhydramine.

cetirizine(Allercet, Zyrtec, Cetrin) - 10 tablets mg; 1% solution (drops for oral administration) in vials of 10 ml; 0.1% suspension for oral administration in vials of 30 ml. In addition to the blockade of H 1 -histamine receptors, it inhibits the migration of eosinophils and the release of mediators associated with the "late" (cellular) stage of an allergic reaction. In therapeutic doses, it practically does not affect the central nervous system. and has no anticholinergic effect. Adults and children over 12 years of age are prescribed inside 10 mg/ day (in 1-2 doses); children from 2 to 6 years - 5 mg(10 drops) 1 time per day or 2.5 mg 2 times a day; children from 6 to 12 years old - 10 mg/ day (in 2 doses).

Cyproheptadine(peritol) - tablets 4 mg; syrup (0.4 mg/ml). It has a sedative, anticholinergic and strong antiserotonin effect with a pronounced antipruritic effect; stimulates appetite; inhibits hypersecretion of somatotropin in acromegaly and ACTH in Itsenko-Cushing syndrome. It is used both for allergic diseases (especially for itching dermatoses), and for migraine, anorexia, as well as as part of a complex treatment for bronchial asthma, hron. e. Assign adults 2-4 mg 3 times a day or one-time (for migraine); maximum daily dose 32 mg. daily dose in children aged 2 to 12 years is approximately 1 mg for each year of a child's life. In case of an overdose in children, anxiety, hallucinations, ataxia, convulsions, facial flushing, mydriasis, collapse, coma are possible; in adults - lethargy, turning into a stupor, to whom; possible psychomotor agitation, convulsions, rarely - hyperthermia. Contraindications are mainly associated with anticholinergic effects (glaucoma, prostatic hypertrophy, etc.), which are enhanced by the simultaneous use of tricyclic antidepressants. The drug is not prescribed to patients who continue to perform work that requires concentration and quick reactions.

H 2 - histamine blockers are mainly used in gastroenterology as a means suppressing the secretory activity of the stomach, although histamine H 2 receptors are also found in the myocardium, blood vessels, in T-lymphocytes, in mast cells, in the central nervous system.

There are blockers of H 2 -histamine receptors of the 1st generation (cimetidine), the 2nd (nizatidine, ranitidine, etc.) and the 3rd generation (famotidine). By blocking H 2 -histamine receptors of the parietal (parietal) cells of the stomach, they significantly reduce their basal secretion and secretion stimulated by food, histamine, pentagastrin and caffeine. Secretion stimulated by acetylcholine (carbocholine) decreases under their influence to a lesser extent, and cimetidine practically does not change it, because. does not have an anticholinergic effect. Increasing the pH in the stomach, H 2 -histamine blockers reduce the activity of pepsin and generally reduce the value of the peptic factor in the formation of ulcers and erosions of the stomach and duodenum, contributing to their healing.

indications for the use of H 2 -histamine blockers: peptic ulcer of the stomach and duodenum (in the acute phase, with a complicated course, as well as for the prevention of exacerbations), Zollinger-Ellison syndrome, reflux esophagitis, acute and chronic (in the acute phase) cholestasis a) . There are also headache, dizziness, transient mental disorders, leukocyte and. Cimetidine inhibits the activity of cytochrome P-450 and a number of other microsomal liver enzymes involved in the metabolism and inactivation of various substances, incl. some drugs (for example, indirect anticoagulants, diphenine, theophylline, diazepam), which can cause manifestations of their "overdose" when used in normal doses. This drug stimulates the secretion of prolactin, inhibits the absorption of vitamin B 12, leading to its deficiency, has an antiandrogenic effect; with prolonged use, it is possible (nizatidine also has this effect), impotence in men. When using ranitidine and famotidine, disorientation, aggressiveness, hallucinations are possible. In addition, ranitidine can increase intraocular pressure in patients with glaucoma, slows down atrioventricular conduction and suppresses the automatism of pacemakers, causing bradycardia, sometimes asystole; when using famotidine, cases of alopecia were noted.

Contraindications: age up to 7 years, pregnancy and breastfeeding, significant violations of the liver and kidneys, heart failure, simultaneous use of cytostatics.

Forms of release and dosing of the main H 2 -histamine blockers are given below.

Nizatidine(axide) - capsules of 150 and 300 mg; concentrate for intravenous infusions 100 mg in vials of 4 ml. For the treatment of exacerbation of peptic ulcer inside appoint 150 mg 2 times a day or 300 mg 1 time per night; with a preventive purpose - 150 mg 1 time per night. For intravenous infusion 100 mg drug (4 ml) bred at 50 ml 0.9% sodium chloride solution or 5% glucose solution and administered within 15 min 3 times a day; for continuous infusion (at a rate of 10 mg/h) at 150 ml these solutions are diluted 300 mg drug (12 ml).

Ranitidine(acidex, acilok-E, bezacid, gistak, zantak, raniberl, ranitin, ranisan, ulcosan, etc.) - tablets of 150 and 300 mg; 1% and 2.5% solutions for intramuscular or intravenous administration in ampoules, respectively, 5 and 2 ml(by 50 mg). The use and dose of the drug inside in adults with peptic ulcer are the same as for nizatidine; with Zolinger-Ellison syndrome, the initial dose inside is 150 mg 3 times a day and can be increased to 600-900 mg/ day For the prevention of Mendelssohn's syndrome, 150 mg the night before and 150 mg for 2 h before the introduction into anesthesia; with the onset of labor - 150 mg every 6 h. In acute gastrointestinal bleeding, the drug is administered intravenously or intramuscularly, 50 mg every 6-8 h. If necessary, use for peptic ulcers in children, the daily dose inside (for 2 doses) is determined at the rate of 2 mg/kg body weight (but not more than 300 mg/day).

Roxatidine(roxan) - tablets of 75 and 150 mg. With peptic ulcer and reflux esophagitis, adults are prescribed inside 75 mg 2 times a day or 150 mg 1 time per night. With prolonged use, a decrease in libido is possible. The drug is not recommended for children.

famotidine(antodin, blockacid, gastrosidin, kvamatel, lecedil, topcid, ulfamide, ulceran, famonit, famosan, famocid) - tablets of 20 and 40 mg; lyophilized dry matter for infusions 20 mg in vials with the supplied solvent. For the treatment of peptic ulcer and reflux esophagitis, it is prescribed orally for 20 mg 2 times a day or 40 mg 1 time per night; with Zolinger-Ellison syndrome - 20-40 each mg every 6 h(maximum daily dose 480 mg). For jet intravenous administration, the contents of the vial are diluted in 5-10 ml, for drip - in 100 ml and 0.9% solution of sodium chloride. The drug is not recommended for children.

Cimetidine(belomet, gistodil, neutronorm, primamet, simesan, tagamet, etc.) - tablets of 200, 400 and 800 mg

Histamine H2 receptor blockers are among the most common antiulcer drugs currently available. In clinical practice, several generations of these drugs have been used. After cimetidine, which for a number of years was the only representative of histamine H2 receptor blockers, ranitidine, famotidine, and a little later, nizatidine and roxatidine were synthesized sequentially. The high antiulcer activity of histamine H2 receptor blockers is primarily due to their ability to reduce the production of hydrochloric acid.

Cimetidine preparations

Histamine H2 receptor blocker for the treatment of stomach ulcers: Histodil

The active ingredient is cimetidine. Suppresses the production of hydrochloric acid, both basal and stimulated by histamine, gastrin and acetylcholine. Reduces the activity of pepsin. Indicated for the treatment of stomach ulcers in the acute phase. Available in the form of tablets of 200 mg and in the form of a solution for injection of 200 mg in an ampoule (2 ml).

Histamine H2 receptor blocker for the treatment of stomach ulcers: Primamet

The original drug of the company, the active ingredient of which is cimetidine. Primamet tablets are intended for those who suffer from increased acidity of gastric juice. The use of conventional hydrochloric acid neutralizers in most cases brings only temporary relief. Primamet acts more effectively - it does not neutralize excess hydrochloric acid, but affects the secretory cells of the stomach, preventing its excessive formation. Thus, the acidity of gastric juice decreases for a long period of time, stomach pains and disorders associated with indigestion disappear. Within an hour after taking one tablet of Primamet, discomfort and pain associated with increased acidity of gastric juice are completely eliminated. Available in tablets of 200 mg.

Histamine H2 receptor blocker for stomach ulcers: Cimetidine

It belongs to the group of antiulcer drugs that reduce the activity of the acid-peptic factor. The drug inhibits the production of hydrochloric acid and pepsin. It is used both in the phase of exacerbation of peptic ulcer, and for the prevention of recurrence of gastric ulcers. Cimetidine is available in the form of film-coated tablets of 200 mg.

Ranitidine preparations

Histamine H2 receptor blocker for the treatment of stomach ulcers: Gistak

The gold standard in the treatment of gastric ulcers and other acid-peptic disorders. It has a number of advantages: a high percentage of cure for peptic ulcer, fast and lasting relief from pain, the ability to combine with other drugs for the treatment of stomach ulcers, the possibility of long-term prevention of recurrence, no side effects even with long-term use, does not affect the liver, does not cause impotence and gynecomastia. The action of a single dose lasts for 12 hours. After taking Gistak in the form of effervescent tablets, the effect is more pronounced and occurs earlier. The drug prevents the reflux of gastric contents into the esophagus. Eating does not affect the absorption of the drug. The maximum concentration is reached when taken orally after 1-2 hours. Gistak is a drug with high safety. Gistak is the only ranitidine available in a simple and effervescent form. Available in the form of coated tablets, 75, 150 and 300 mg; effervescent tablets of 150 mg and in ampoules for injections of 50 mg - 2 ml.

Histamine H2 receptor blocker for stomach ulcers: Zantac

Specific fast-acting blocker of histamine H2 receptors. Zantac is the number one drug in the treatment of stomach ulcers. It has high efficiency in treatment, guaranteed rapid analgesic action, complete safety in long-term use, significantly improves the patient's quality of life. Zantac suppresses the production of gastric juice, reducing both the volume and content of hydrochloric acid and pepsin (aggressive factors) in it. The duration of action with a single oral administration is 12 hours. The maximum concentration in blood plasma when administered intramuscularly is achieved in the first 15 minutes after administration. Available in the form of tablets of 150 and 300 mg; coated tablets, 75 mg; effervescent tablets of 150 and 300 mg; solution for injections of 25 mg in 1 ml in ampoules of 2 ml.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Ranitidine-Acri

The main drug in the treatment of peptic disorders. Belongs to the group of H2-receptor blockers of histamine II generation, is the most used and reliable drug in the treatment and prevention of peptic disorders associated with peptic ulcer. The drug significantly reduces the production of hydrochloric acid and reduces the activity of pepsin. Ranitidine has a long-lasting effect (12 hours) after a single dose. Easy to use and well tolerated by patients. Available in the form of tablets of 0.15 g.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Kvamatel

Blocker of H2-histamine receptors of the III generation. Kvamatel is an antiulcer drug, the active substance of which is famotidine. Suppresses the production of hydrochloric acid and reduces the activity of pepsin. Easy to use - after ingestion, the effect of the drug begins after 1 hour and lasts 10-12 hours. The drug has been widely used in the treatment of stomach ulcers. Produced in the form of film tablets of 20 and 40 mg, lyophilized powder for injection in vials complete with a solvent of 20 mg.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Lecedil

Blocker of H2-histamine receptors of the III generation. Lecedil is an original development of a pharmaceutical company, the active ingredient of the drug is famotidine. Lecedil is a powerful blocker of hydrochloric acid production, and also reduces the activity of pepsin. After oral administration, the drug is rapidly absorbed from the gastrointestinal tract. The maximum concentration of the drug in the blood plasma is reached 1-3 hours after ingestion. The duration of action of the drug in a single dose depends on the dose and ranges from 12 to 24 hours. Lecedil can be used both for the treatment and for the prevention of exacerbations of peptic ulcer. It is produced in the form of tablets containing 20 and 40 mg of famotidine.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Ulfamide

The original product of the company. Ulfamid provides a rapid improvement in the symptoms of stomach ulcers, cures and prevents recurrence of ulcers. The active substance of the drug is famotidine. Famotidine was the first H2 receptor blocker whose dosage regimen allowed most patients to take it only once a day. The effectiveness of Ulfamid is much higher than the effectiveness of H2-receptor blockers of the I and II generation. Ulfamid blocks gastric secretion at night, has a maximum effect on secretion during the day. Available in tablets of 40 and 20 mg.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Ulceran

A drug famotidine. Selective blocker of H2-histamine receptors of the III generation. Causes a pronounced suppression of all phases of gastric secretion (hydrochloric acid and pepsin), including basal and stimulated (in response to gastric distention, exposure to food, histamine, gastrin, pentagastrin, caffeine and, to a lesser extent, acetylcholine), suppresses nocturnal gastric secretion juice. It has a long-term effect (12-24 hours), which allows you to prescribe it 1-2 times a day. Unlike cimetidine and ranitidine, it does not inhibit microsomal oxidation associated with cytochrome P450, therefore it is safer in relation to drug interactions, as well as in patients with concomitant diastolic hypertension, heart failure with hyperaldosteronism and diabetes mellitus with excessive secretion of growth hormone. Ulceran does not have serious central side effects, and therefore is more preferable in patients with diseases of the nervous system and in elderly patients. Due to the lack of antiandrogenic activity, it is considered as a first-line drug for adolescents and young men. Ulceran has been successfully used as monotherapy for the treatment of gastric ulcers. Effective for Zollinger-Ellison syndrome, reflux esophagitis, symptomatic ulcers. The drug has a broad index of therapeutic action. Due to its high safety, it is allowed in a number of countries for over-the-counter dispensing in order to eliminate the symptoms of indigestion in adults. Perhaps the appointment of the drug in pediatric practice. Available in tablets containing 20 and 40 mg of the active substance.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Famosan

Blocker of H2-histamine receptors of the III generation. Famosan is the best choice in the treatment of stomach ulcers. The active substance of the drug is famotidine. The drug has a powerful antisecretory effect, reduces the aggressiveness of gastric juice, causes dose-dependent suppression of hydrochloric acid production and a decrease in pepsin activity, which creates optimal conditions for ulcer scarring. Famosan does not cause side effects characteristic of H2-histamine receptor blockers of the first generation. In addition, the drug does not interact with androgens and does not cause sexual disorders. May be prescribed to patients with concomitant liver disease. Famosan can be used for both treatment and prevention of exacerbations. Available in the form of coated tablets of 20 and 40 mg.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Famotidine

Blocker of H2-histamine receptors of the III generation. famotidine- a highly selective antiulcer drug that effectively reduces the volume and acidity of gastric juice and the production of pepsin. It has a more pronounced therapeutic effect compared to other drugs. Famotidine has a wide therapeutic dose range. It is the drug of choice in the treatment of gastric ulcers in alcoholics. Perhaps the combination of Famotidine with other drugs. Taking the drug does not affect the exchange of androgens (male sex hormones). Available in the form of film-coated tablets of 20 and 40 mg.

Histamine H2 receptor blocker for the treatment of stomach ulcers: Famotidine-Acri

Antiulcer drug, blocker of H2-histamine receptors of the III generation. The drug effectively reduces the production of hydrochloric acid. Easy to use - for stomach ulcers, it is used once a day, the duration of the drug's action at a single dose depends on the dose and ranges from 12 to 24 hours. Famotidine-Acri has the fewest side effects. Available in the form of coated tablets, 20 mg.

Roxatidine preparations

Histamine H2 receptor blocker for the treatment of stomach ulcers: Roxane

The active substance is roxatidine. The drug significantly inhibits the production of hydrochloric acid by the cells of the gastric mucosa. After oral administration, it is absorbed from the gastrointestinal tract. Concomitant food intake, as well as antacids, does not affect the absorption of Roxan. It is produced in the form of 75 mg retard coated tablets and 150 mg retard forte coated tablets.

In 1966, scientists proved the heterogeneity of histamine receptors, and found that the effect of the action of histamine depends on which receptor it binds to.

Three types of histamine receptors have been identified:

• H1 - histamine receptors;
• H2- histamine receptors;
• H3 - histamine receptors.

H1 - histamine receptors located mainly on the cells of smooth (non-striated) muscles and large vessels. The binding of histamine to H1 - histamine receptors leads to spasm of the muscle tissue of the bronchi and trachea, increases vascular permeability, and also increases itching and slows down atrioventricular conduction. Through H1 - histamine receptors, pro-inflammatory effects are realized.

H1 receptor antagonists are first and second generation antihistamines.

H2 receptors present in many tissues. The binding of histamine to H2-histamine receptors stimulates the synthesis of catecholamines, gastric secretion, relaxes the muscles of the uterus and bronchial smooth muscles, and increases myocardial contractility. Through H2 - histamine receptors, the pro-inflammatory effects of histamine are realized. In addition, through H2 - receptors, histamine enhances the function of T-suppressors, and T-suppressors maintain tolerance.

Histamine H2 receptor antagonists are burinamide, cimetidine, methylamide, ranitidine, etc.

H3 - histamine receptors are responsible for the suppression of histamine synthesis and its release in the central nervous system.

Histamine receptors

• All information on the site is for informational purposes and is NOT a guide to action!
• Give you an ACCURATE DIAGNOSIS only DOCTOR!
• We kindly ask you DO NOT self-medicate, but book an appointment with a specialist!
• Health to you and your loved ones!

Histamine is a biologically active component that takes part in the regulation of various body functions.

The formation of histamine in the human body occurs due to the synthesis of histidine - an amino acid, one of the components of the protein.

Inactive histamine is found in some organs (intestines, lungs, skin) and tissues.

Its release occurs in histiocytes (special cells).

Activation and release of histamine occurs due to:

In addition to the synthesized (one's own) substance, histamine can be obtained in nutritious foods:

Excess histamine can be obtained from long-term stored foods.

Especially a lot of them at insufficiently low temperatures.

Strawberries and eggs are able to stimulate the production of internal (endogenous) histamine.

Active histamine, which has penetrated into the human bloodstream, has a powerful and rapid effect on some systems and organs.

Histamine has the following (primary) effects:

• a large amount of histamine in the blood causes anaphylactic shock with specific symptoms (a sharp drop in pressure, vomiting, loss of consciousness, convulsive phenomena);
• increased permeability of small and large blood vessels, resulting in headache, pressure drop, nodular (papular) rash, skin flushing, swelling of the respiratory system; increased secretion of mucus and digestive juices in the nasal passages and bronchi;
• the stress hormone adrenaline, secreted from the adrenal glands, contributes to an increase in heart rate and an increase in blood pressure;
• involuntary spasm of smooth muscles in the intestines and bronchi, accompanied by respiratory disorders, diarrhea, stomach pain.

Allergic reactions assign histamine a special role in all sorts of external manifestations.

Any such reaction occurs when antibodies and antigens interact.

An antigen, as you know, is a substance that at least once was inside the body and caused an increase in its sensitivity.

Antibodies (immunoglobulins) can only react with a specific antigen.

The following antigens that have arrived in the body are attacked by antibodies, with the sole purpose of completely neutralizing them.

As a result of this attack, we receive immune complexes of antigens and antibodies.

These complexes are deposited on mast cells.

Then, histamine becomes active, leaving the granules in the blood (degranulation of mast cells).

Histamine can be involved in processes that are similar to allergies, but are not (the “antigen-antibody” process does not participate in them).

Histamine affects special receptors located on the cell surface.

Simplistically, histamine molecules can be compared with keys that unlock certain locks - receptors.

In total, there are three subgroups of histamine receptors that cause a specific physiological response:

In allergy sufferers, in the tissues of the body, there is an increased content of histamine, which indicates the genetic (hereditary) causes of hypersensitivity.

Histamine blockers, histamine antagonists, histamine receptor blockers, histamine blockers are medicinal substances that help eliminate the physiological effects of histamine by blocking receptor cells that are sensitive to them.

Indications for the use of histamine:

• experimental studies and diagnostic methods;
• allergic reactions;
• pain of the peripheral nervous system;
• rheumatism;
• polyarthritis.

However, most therapeutic measures are directed against the undesirable effects caused by histamine itself.

Chickenpox (chickenpox) haunts people of all ages, but most often children succumb to this disease.

Facial hair causes women a lot of worries and problems, one of which sounds something like this: how to permanently remove facial hair?

Some parents have to deal with the problem of their long-awaited babies from the very moment of their birth.

Alcoholic hepatitis is an inflammatory process in the liver that occurs as a result of excessive consumption of alcoholic beverages.

Histamine receptors

Histamine is a biologically active substance involved in the regulation of many body functions and is one of the main factors in the development of certain pathological conditions, in particular, allergic reactions.

Where does histamine come from?

Histamine in the body is synthesized from histidine - one of the amino acids, which is an integral component of the protein. In an inactive state, it is part of many tissues and organs (skin, lungs, intestines), where it is contained in special mast cells (histiocytes).

Under the influence of certain factors, histamine passes into an active form and is released from the cells into the general circulation, where it exerts its physiological effect. Factors leading to the activation and release of histamine can be trauma, burns, stress, the action of certain drugs, immune complexes, radiation, etc.

In addition to the "own" (synthesized) substance, it is possible to obtain histamine in food. These are cheeses and sausages, some types of fish, alcoholic beverages, etc. The production of histamine often occurs under the action of bacteria, so there is a lot of it in long-term stored products, especially at insufficiently low temperatures.

Certain foods can stimulate the production of endogenous (internal) histamine - eggs, strawberries.

The biological action of histamine

Active histamine, which enters the bloodstream under the influence of any of the factors, has a quick and powerful effect on many organs and systems.

Main effects of histamine:

• Spasm of smooth (involuntary) muscles in the bronchi and intestines (this is manifested, respectively, by abdominal pain, diarrhea, respiratory failure).
• The secretion of the “stress” hormone adrenaline from the adrenal glands, which increases blood pressure and increases the heart rate.
• Increased production of digestive juices and secretion of mucus in the bronchi and nasal cavity.
• The impact on the vessels is manifested by the narrowing of large and the expansion of small blood paths, increasing the permeability of the capillary network. The consequence is swelling of the respiratory mucosa, skin hyperemia, the appearance of a papular (nodular) rash on it, a drop in pressure, and a headache.
• Histamine in the blood in large quantities can cause anaphylactic shock, in which convulsions, loss of consciousness, vomiting develop against the background of a sharp drop in pressure. This condition is life-threatening and requires emergency care.

Histamine and Allergy

A special role is given to histamine in the external manifestations of allergic reactions.

In any of these reactions, the interaction of the antigen and antibodies occurs. An antigen is a substance that has already entered the body at least once and caused hypersensitivity. Special memory cells store data about the antigen, other cells (plasma cells) synthesize special protein molecules - antibodies (immunoglobulins). Antibodies have a strict correspondence - they are able to react only with a given antigen.

The subsequent intake of the antigen into the body causes an attack of antibodies that “attack” the antigen molecules in order to neutralize them. Immune complexes are formed - an antigen and antibodies fixed on it. Such complexes have the ability to settle on mast cells, which contain histamine in an inactive form inside special granules.

The next stage of the allergic reaction is the transition of histamine to its active form and the release from the granules into the blood (the process is called mast cell degranulation). When the concentration in the blood reaches a certain threshold, the biological effect of histamine, which was mentioned above, is manifested.

Reactions involving histamine are possible, similar to allergic reactions, but they are not really allergic (they lack antigen-antibody interaction). This may be in the case of a large amount of histamine intake with food. Another option is the direct effect of certain products (more precisely, the substances that make up them) on mast cells with the release of histamine.

Histamine receptors

Histamine exerts its effect by influencing special receptors located on the surface of cells. Simplified, you can compare its molecules with keys, and receptors with the locks that they unlock.

There are three subgroups of receptors, the impact on each of which causes its own physiological effects.

Histamine receptor groups:

1. H 1 receptors are found in the cells of smooth (involuntary) muscles, the inner lining of blood vessels and in the nervous system. Their irritation causes external manifestations of allergies (bronchospasm, swelling, skin rashes, abdominal pain, etc.). The action of antiallergic drugs - antihistamines (diphenhydramine, diazolin, suprastin, etc.) - consists in blocking H 1 receptors and eliminating the effect of histamine on them.
2. H 2 -receptors contained in the membranes of the parietal cells of the stomach (those that produce hydrochloric acid). Drugs from the group of H 2 -blockers are used in the treatment of stomach ulcers, because they suppress the production of hydrochloric acid. There are several generations of such drugs (cimetidine, famotidine, roxatidine, etc.).
3. H 3 -receptors located in the nervous system, where they take part in the conduction of a nerve impulse. The effect on the H 3 receptors of the brain explains the calming effect of diphenhydramine (sometimes this side effect is used as the main one). Often this action is undesirable - for example, when driving a vehicle, it is necessary to take into account possible drowsiness and a decrease in the reaction after taking antiallergic drugs. Currently, antihistamines have been developed with a reduced sedative (calming) effect or its complete absence (astemizole, loratadine, etc.).

Histamine in medicine

The natural production of histamine in the body and its intake with food play an important role in the manifestation of many diseases, especially allergic ones. Allergy sufferers have been noted to have elevated histamine content in many tissues: this can be considered one of the genetic causes of hypersensitivity.

Histamine is used as a therapeutic agent in the treatment of certain neurological diseases, rheumatism, in diagnostics, etc.

However, in most cases, therapeutic measures are aimed at combating the undesirable effects that histamine causes.

• Allergy 325
  • Allergic stomatitis 1
  • Anaphylactic shock 5
  • Urticaria 24
  • Quincke's edema 2
  • Pollinosis 13
• Asthma 39
• Dermatitis 245
  • Atopic dermatitis 25
  • Neurodermatitis 20
  • Psoriasis 63
  • Seborrheic dermatitis 15
  • Lyell's syndrome 1
  • Toxidermia 2
  • Eczema 68
• General symptoms 33
  • Runny nose 33

Full or partial reproduction of site materials is possible only if there is an active indexed link to the source. All materials presented on the site are for informational purposes only. Do not self-medicate, recommendations should be given by the attending physician during an internal consultation.

Post Views: 823

This group is among the leading pharmacological preparations, belongs to the means of choice in the treatment of peptic ulcers. The discovery of H2 histamine receptor blockers over the past two decades is considered the largest in medicine, helping to solve economic (affordable cost) and social problems. Thanks to H2-blockers, the results of therapy for peptic ulcers have improved significantly, surgical interventions have been used as rarely as possible, and the quality of life of patients has improved. "Cimetidine" was called the "gold standard" in the treatment of ulcers, "Ranitidine" in 1998 became the sales record holder in pharmacology. A big plus is the low cost and at the same time the effectiveness of drugs.

Usage

Histamine H2 receptor blockers are used to treat acid-dependent gastrointestinal diseases. The mechanism of action is the blocking of H2 receptors (otherwise they are called histamine) cells of the gastric mucosa. For this reason, the production and entry into the lumen of the stomach of hydrochloric acid is reduced. This group of drugs belongs to antisecretory

Most often, H2 histamine receptor blockers are used in cases of manifestations of peptic ulcer. H2 blockers not only reduce the production of hydrochloric acid, but also suppress pepsin, while gastric mucus increases, the synthesis of prostaglandins increases here, and the secretion of bicarbonates increases. The motor function of the stomach is normalized, microcirculation improves.

Indications for the use of H2-blockers:

• gastroesophageal reflux;
• chronic and acute pancreatitis;
• dyspepsia;
• Zollinger-Ellison syndrome;
• respiratory reflux-induced diseases;
• chronic gastritis and duodenitis;
• Barrett's esophagus;
• ulcers of the esophageal mucosa;
• stomach ulcer;
• ulcers medicinal and symptomatic;
• chronic dyspepsia with retrosternal and epigastric pain;
• systemic mastocytosis;
• for the prevention of stress ulcers;
• Mendelssohn's syndrome;
• prevention of aspiration pneumonia;
• bleeding of the upper gastrointestinal tract.

Histamine H2 receptor blockers: classification of drugs

There is a classification of this group of drugs. They are divided by generation:

• The first generation includes Cimetidine.
• "Ranitidine" is a blocker of H2 histamine receptors of the II generation.
• The III generation includes "Famotidine".
• Nizatidine belongs to the IV generation.
• The V generation includes "Roxatidin".

"Cimetidine" is the least hydrophilic, due to this, the half-life is very short, while liver metabolism is significant. The blocker interacts with cytochromes P-450 (a microsomal enzyme), while the rate of hepatic metabolism of the xenobiotic changes. "Cimetidine" is a universal inhibitor of hepatic metabolism among most drugs. In this regard, it is able to enter into pharmacokinetic interaction, therefore, cumulation and increased risks of side effects are possible.

Among all H2 blockers, Cimetidine penetrates tissues better, which also leads to increased side effects. It displaces endogenous testosterone from its connection with peripheral receptors, thereby causing sexual dysfunction, leads to a decrease in potency, develops impotence and gynecomastia. "Cimetidine" can cause headaches, diarrhea, transient myalgia and arthralgia, increased blood creatinine, hematological changes, CNS lesions, immunosuppressive effects, cardiotoxic effects. Blocker H2 histamine receptors III generation - "Famotidine" - less penetrates into tissues and organs, thereby reducing the number of side effects. Do not cause sexual disorders and drugs of subsequent generations - "Ranitidine", "Nizatidin", "Roxatidin". All of them do not interact with androgens.

Comparative characteristics of drugs

There were descriptions of H2 histamine receptor blockers (preparations of the extra-class generation), the name is "Ebrotidine", "Ranitidine bismuth citrate" is singled out, this is not a simple mixture, but a complex compound. Here, the base - ranitidine - binds to trivalent bismus citrate.

Blocker H2 histamine receptors III generation "Famotidine" and II - "Ranitidine" - have greater selectivity than "Cimetidine". Selectivity is a dose-dependent and relative phenomenon. "Famotidine" and "Ranitidine" more selectively than "Cinitidine", affect H2 receptors. For comparison: "Famotidine" is eight times more powerful than "Ranitidine", "Cinitidine" - forty times. Differences in potency are determined by dose equivalence data of different H2 blockers that affect hydrochloric acid suppression. The strength of connections with receptors also determines the duration of exposure. If the drug is strongly bound to the receptor, dissociates slowly, the duration of the effect is determined. On the basal secretion "Famotidine" affects the longest. Studies show that "Cimetidine" provides a decrease in basal secretion for 5 hours, "Ranitidine" - 7-8 hours, 12 hours - "Famotidine".

H2 blockers belong to the group of hydrophilic drugs. Among all generations, Cimetidine is less hydrophilic than others, while moderately lipophilic. This gives it the ability to easily penetrate into various organs, affect H2 receptors, which leads to many side effects. "Famotidine" and "Ranitidine" are considered highly hydrophilic, they penetrate poorly through tissues, their predominant effect on the H2 receptors of parietal cells.

The maximum number of side effects in "Cimetidine". "Famotidine" and "Ranitidine", due to changes in the chemical structure, do not affect metabolizing liver enzymes and give fewer side effects.

Story

The history of this group of H2-blockers began in 1972. An English company in the laboratory under the leadership of James Black investigated and synthesized a huge number of compounds that were similar in structure to the histamine molecule. Once safe compounds were identified, they were transferred to clinical trials. The very first buriamid blocker was not entirely effective. Its structure was changed, methiamide turned out. Clinical studies have shown greater efficacy, but greater toxicity has manifested itself in the form of granulocytopenia. Further work led to the discovery of "Cimetidine" (I generation of drugs). The drug passed successful clinical trials, in 1974 it was approved. It was then that histamine H2 receptor blockers began to be used in clinical practice, it was a revolution in gastroenterology. James Black received the Nobel Prize in 1988 for this discovery.

Science does not stand still. Due to the multiple side effects of Cimetidine, pharmacologists began to focus on finding more effective compounds. So other new H2 blockers of histamine receptors were discovered. Drugs reduce secretion, but do not affect its stimulants (acetylcholine, gastrin). Side effects, "acid rebound" orient scientists to search for new means to reduce acidity.

outdated medicine

There is a more modern class of drugs called proton pump inhibitors. They are superior in acid suppression, in the minimum of side effects, in the time of exposure to histamine H2 receptor blockers. The drugs whose names are listed above are still used quite often in clinical practice due to genetics, for economic reasons (more often it is Famotidine or Ranitidine).

Modern antisecretory agents used to reduce the amount of hydrochloric acid are divided into two large classes: proton pump inhibitors (PPIs), as well as histamine H2 receptor blockers. The latter drugs are characterized by the effect of tachyphylaxis, when repeated administration causes a decrease in the therapeutic effect. PPIs do not have this disadvantage and therefore, unlike H2 blockers, they are recommended for long-term therapy.

The phenomenon of the development of tachyphylaxis when taking H2-blockers is observed from the beginning of therapy within 42 hours. In the treatment of ulcers, it is not recommended to use H2-blockers, preference is given to proton pump inhibitors.

resistance

In some cases, histamine H2 blockers are listed above), as well as PPI preparations sometimes cause resistance. When monitoring the pH of the gastric environment in such patients, no changes in the level of intragastric acidity are detected. Sometimes cases of resistance to any group of H2 blockers of the 2nd or 3rd generation or to proton pump inhibitors are detected. Moreover, increasing the dose in such cases does not give a result, it is necessary to choose a different type of drug. The study of some H2-blockers, as well as omeprazole (PPI) shows that from 1 to 5% of cases have no changes in daily pH-metry. With dynamic monitoring of the process of treatment of acid dependence, the most rational scheme is considered, where daily pH-metry is studied on the first, and then on the fifth and seventh day of therapy. The presence of patients with complete resistance indicates that in medical practice there is no drug that would have absolute effectiveness.

Side effects

Histamine H2 receptor blockers cause side effects with varying frequency. The use of "Cimetidine" causes them in 3.2% of cases. Famotidine - 1.3%, Ranitidine - 2.7%. Side effects include:

• Dizziness, headaches, anxiety, fatigue, drowsiness, confusion, depression, agitation, hallucinations, involuntary movements, visual disturbances.
• Arrhythmia, including bradycardia, tachycardia, extrasystole, asystole.
• Diarrhea or constipation, abdominal pain, vomiting, nausea.
• Acute pancreatitis.
• Hypersensitivity (fever, rash, myalgia, anaphylactic shock, arthralgia, erythema multiforme, angioedema).
• Changes in liver function tests, mixed or holistic hepatitis with or without jaundice.
• Elevated creatinine.
• Hematopoietic disorders (leukopenia, pancytopenia, granulocytopenia, agranulocytosis, thrombocytopenia, aplastic anemia and cerebral hypoplasia, hemolytic immune anemia.
• Impotence.
• Gynecomastia.
• Alopecia.
• Decreased libido.

Famotidine has the most side effects on the gastrointestinal tract, with diarrhea often developing, in rare cases, on the contrary, constipation occurs. Diarrhea occurs due to antisecretory effects. Due to the fact that the amount of hydrochloric acid in the stomach decreases, the pH level rises. In this case, pepsinogen is more slowly converted to pepsin, which helps break down proteins. Digestion is disturbed, and diarrhea most often develops.

Contraindications

Histamine H2 receptor blockers include a number of drugs that have the following contraindications for use:

• Disorders in the work of the kidneys and liver.
• Cirrhosis of the liver (portosystemic encephalopathy in history).
• Lactation.
• Hypersensitivity to any drug of this group.
• Pregnancy.
• Children under 14 years of age.

Interaction with other tools

H2 blockers of histamine receptors, the mechanism of action of which is now understood, have certain pharmacokinetic drug interactions.

absorption in the stomach. Due to the antisecretory effects of H2 blockers, they are able to influence the absorption of those electrolyte drugs where there is a dependence on pH, since the degree of diffusion and ionization may decrease in drugs. "Cimetidine" is able to reduce the absorption of drugs such as "Antipyrin", "Ketoconazole", "Aminazin" and various iron preparations. To avoid such malabsorption, drugs should be taken 1-2 hours before the use of H2 blockers.

hepatic metabolism. Blockers of H2 histamine receptors (preparations of the first generation especially) actively interact with cytochrome P-450, which is the main oxidizer of the liver. At the same time, the half-life increases, the effect may be prolonged and an overdose of the drug, which is metabolized by more than 74%, may occur. Cimetidine reacts most strongly with cytochrome P-450, 10 times more than Ranitidine. Interaction with "Famotidine" does not occur at all. For this reason, when using Ranitidine and Famotidine, there is no violation of the hepatic metabolism of drugs, or it manifests itself to a small extent. When using Cimetidine, the clearance of drugs is reduced by about 40%, and this is clinically significant.

Hepatic blood flow rate. It is possible to reduce the rate of hepatic blood flow up to 40% when using Cimetidine, as well as Ranitidine, it is possible to reduce the systemic metabolism of high-clearance drugs. "Famotidine" in these cases does not change the rate of portal blood flow.

tubular excretion of the kidneys. H2-blockers are excreted with active secretion of the tubules of the kidneys. In these cases, interactions with concurrent drugs are possible if they are excreted by the same mechanisms. "Imetidine" and "Ranitidine" are able to reduce renal excretion to 35% of novocainamide, quinidine, acetylnovocainamide. "Famotidine" does not affect the excretion of these drugs. In addition, its therapeutic dose is able to provide a low plasma concentration, which will not significantly compete with other agents at the levels of calcium secretion.

Pharmacodynamic interactions. The interaction of H2-blockers with groups of other antisecretory drugs can increase therapeutic efficacy (for example, with anticholinergics). The combination with drugs that act on Helicobacter (preparations of metronidazole, bismuth, tetracycline, clarithromycin, amoxicillin) accelerates the tightening of peptic ulcers.

Pharmacodynamic adverse interactions have been established when combined with drugs containing testosterone. "Cimetidine" hormone is displaced from its connection with receptors by 20%, while the concentration in the blood plasma increases. "Famotidine" and "Ranitidine" do not have a similar effect.

Trade names

In our country, the following preparations of H2-blockers are registered and acceptable for sale:

"Cimetidine"

Trade names: Altramet, Belomet, Apo-cimetidine, Yenametidine, Histodil, Novo-cimetine, Neutronorm, Tagamet, Simesan, Primamet, Cemidin , "Ulcometin", "Ulkuzal", "Cymet", "Cimehexal", "Cygamet", "Cimetidine-Rivofarm", "Cimetidine Lannacher".

"Ranitidine"

Trade names: "Acilok", "Ranitidine Vramed", "Atsideks", "Asitek", "Histak", "Vero-ranitidin", "Zoran", "Zantin", "Ranitidine Sediko", "Zantak", "Ranigast" , "Raniberl 150", "Ranitidine", "Ranison", "Ranisan", "Ranitidine Akos", "Ranitidine BMS", "Ranitin", "Rantak", "Ranx", "Rantag", "Yazitin", "Ulran ", "Ulkodin".

"Famotidine"

Trade names: "Gasterogen", "Blokatsid", "Antodin", "Kvamatel", "Gastrosidin", "Lecedil", "Ulfamid", "Pepsidin", "Famonit", "Famotel", "Famosan", "Famopsin" , Famotidine Akos, Famocid, Famotidine Apo, Famotidine Akri.

"Nizatidin". Trade name "Axid".

"Roxatidin". Trade name "Roxan".

"Ranitidine bismuth citrate". Trade name "Pylorid".

5239 views

Histamine is one of the hormones vital for a person. It performs the functions of a kind of “watchman” and comes into play under certain circumstances: heavy physical exertion, injuries, illnesses, allergens entering the body, etc. The hormone redistributes blood flow in such a way as to minimize possible damage. At first glance, the work of histamine should not harm a person, but there are situations when a large amount of this hormone brings more evil than good. In such cases, doctors prescribe special drugs (blockers) in order to prevent the histamine receptors of one of the groups (H1, H2, H3) from starting to work.

Why do you need histamine?

Histamine is a biologically active compound involved in all major metabolic processes in the body. It is formed from the breakdown of an amino acid called histidine and is responsible for the transmission of nerve impulses between cells.

Normally, histamine is in an inactive state, but at dangerous times associated with illness, injury, burns, the intake of toxins or allergens, the level of free hormone increases sharply. In the unbound state, histamine causes:

• spasms of smooth muscles;
• lowering blood pressure;
• expansion of capillaries;
• increased heart rate;
• increased production of gastric juice.

Under the action of the hormone, the secretion of gastric juice and adrenaline increases, tissue edema occurs. Gastric juice is a rather aggressive medium with high acidity. Acid and enzymes not only help digest food, they are able to act as an antiseptic - to kill bacteria that enter the body at the same time as eating.

The "management" of the process occurs with the help of the central nervous system and humoral regulation (control through hormones). One of the mechanisms of this regulation is triggered through special receptors - specialized cells that are responsible, among other things, for the concentration of hydrochloric acid in gastric juice.

Histamine receptors

Certain receptors called histamine (H) respond to the production of histamine. Doctors divide these receptors into three groups: H1, H2, H3. As a result of excitation of H2 receptors:

• the functioning of the gastric glands is enhanced;
• the tone of the muscles of the intestine and blood vessels increases;
• allergies and immune reactions appear;

Blockers of H2 histamine receptors act only partially on the mechanism of release of hydrochloric acid. They reduce the production caused by the hormone, but do not stop it completely.

Important! High acid content in gastric juice is a threatening factor in some diseases of the gastrointestinal tract.

What are blocker drugs?

These drugs are designed to treat diseases of the gastrointestinal tract, in which a high concentration of hydrochloric acid in the stomach is dangerous. They are anti-ulcer drugs that reduce secretion, that is, they are designed to reduce the flow of acid into the stomach.

Blockers of the H2 group have various active ingredients:

• cimetidine (Histodil, Altamet, Cimetidine);
• nizatidine (Axid);
• roxatidine (Roxane);
• famotidine (Gastrosidin, Kvamatel, Ulfamid, Famotidine);
• ranitidine (Gistak, Zantak, Rinisan, Ranitiddin);
• ranitidine bismuth citrate (Pyloride).

Funds are issued in the form of:

• ready-made solutions for intravenous or intramuscular administration;
• powder for solution preparation;
• tablets.

To date, cimetidine is not recommended for use due to a large number of side effects, including a decrease in potency and an increase in the mammary glands in men, the development of pain in the joints and muscles, an increase in creatinine levels, changes in the composition of the blood, damage to the central nervous system, etc.

Ranitidine has far fewer side effects, but it is less and less used in medical practice, as next-generation drugs (Famotidine) are coming to replace, whose effectiveness is much higher, and the duration of action is several hours longer (from 12 to 24 hours).

Important! In 1–1.5% of cases, patients experience resistance to blocker drugs.

When are blockers prescribed?

An increase in the level of acid in the gastric juice is dangerous when:

• stomach or duodenal ulcer;
• inflammation of the esophagus when the contents of the stomach are thrown into the esophagus;
• benign tumor of the pancreas in combination with a stomach ulcer;
• reception for the prevention of the development of peptic ulcer during long-term therapy of other diseases.

The specific drug, doses and duration of the course are selected individually. Cancellation of the drug should be gradual, as with a sharp end of the reception, side effects are possible.

Disadvantages of histamine blockers

H2 blockers affect the production of free histamine, thereby reducing the acidity of the stomach. But these drugs do not act on other stimulants of acid synthesis - gastrin and acetylcholine, that is, these drugs do not give complete control over the level of hydrochloric acid. This is one of the reasons why doctors consider them relatively outdated remedies. Nevertheless, there are situations when the appointment of blockers is justified.

There is a rather serious side effect of therapy using H2 histamine receptor blockers - the so-called "acid rebound". It lies in the fact that after the withdrawal of the drug or the end of its action, the stomach seeks to "catch up", and its cells increase the production of hydrochloric acid. As a result, after a certain period of time after taking the medicine, the acidity of the stomach begins to rise, causing an exacerbation of the disease.

Another side effect is diarrhea caused by the pathogen Clostridium. If, together with the blocker, the patient takes antibiotics, then the risk of diarrhea increases tenfold.

Modern analogues of blockers

New drugs are coming to replace blockers - but they cannot always be used in treatment due to the genetic or other characteristics of the patient or for economic reasons. One of the obstacles to the use of inhibitors is the fairly common resistance (resistance to the drug).

H2-blockers differ from proton pump inhibitors for the worse in that their effectiveness decreases with a repeated course of treatment. Therefore, long-term therapy involves the use of inhibitors, and H-2 blockers are sufficient for short-term treatment.

Only a doctor has the right to make a decision on the choice of drugs based on the patient's history and research results. Patients with gastric or duodenal ulcers, especially in the chronic course of the disease or at the first appearance of symptoms, need to individually select acid-suppressing agents.