3. Vomiting and antiemetic. Classification. Mechanism of action. Indications for use. Side effects. Contraindications Comparative evaluation of drugs.

Vomiting is a complex reflex act that is controlled by the corresponding center of the medulla oblongata.

Classification of emetics:

1) central action (on dopamine receptors trigger zone) - apomorphine hydrochloride,

2) reflex action - thermopsis and ipecacuanha,

3) peripheral action - copper sulfate and zinc sulfate.

Apomorphine is mainly used.

Apomorphine - stimulates dopamine trigger-zone receptors. Used for acute poisoning, treatment of alcoholism. Side effects - collapse, visual hallucinations, neurological disorders. Contraindications: burns of the stomach with acids and alkalis, peptic ulcer, lung disease with possible bleeding, heart disease.

Antiemetic classification:

1) dopamine receptor blockers (inhibit the trigger zone) - a derivative

benzamide (metoclopramide), Phenothiazine derivatives (thiethylperazine, ethaperazine, chlorpromazine, triftazine) Butyrophenone derivatives (haloperidol)

2) blockers of M-cholinergic receptors - "Aeron", scopolamine,

3) blockers of histamine H1 receptors - diprazine, diphenhydramine,

4) blockers of serotonin receptors in the central nervous system and in the periphery - ondansetron, tropisetron.

1) phenothiazine derivatives: chlorpromazine, triftazine, ethaperazine, fluorophenazine, thiethylperazine (torecan). Thiethylperazine (torecan) is considered the best due to its strong selective effect. There is evidence that in addition to the block of dopamine receptors of the trigger zone, thiethylperazine has a depressing effect directly on the vomiting center. The drug is well tolerated.

2) butyrophenone derivatives (haloperidol).

1) and 2) groups are effective in vomiting caused by substances whose action is directed to the trigger zone (digitalis glycosides, apomorphine, etc.). They also eliminate vomiting that occurs in the postoperative period, with radiation sickness, toxicosis of pregnant women.

When motion sickness drugs of these groups are ineffective.

Side effects are possible: dry mouth, drowsiness, tachycardia, hypotension, with prolonged use - parkinsonism.

3) benzamide derivative - metoclopramide (raglan, cerucal), the central effects of which, including antiemetic, are associated with the fact that it blocks dopamine D2 receptors, and in high doses, serotonin 5-HT4 receptors.

The drug has an antiemetic and antiemetic effect. In addition, it regulates the function of the gastrointestinal tract, normalizes tone and motility, and is effective for vomiting of any genesis, with the exception of motion sickness and diseases of the inner ear. Unlike manuf. phenothiazine, which have an M-anticholinergic effect, metoclopramide is a strong parasympathomimetic and therefore it helps to accelerate the evacuation of stomach contents.

As an antiemetic, metoclopramide is indicated for vomiting and nausea:

- associated with irritation of the gastrointestinal mucosa;

- with radiation sickness;

- uremia;

- intoxication with cardiac glycosides;

- for the prevention of side effects of cytostatics and antiblastoma antibiotics;

- diet disorders;

- complex therapy of peptic ulcer disease, patients with gastritis;

- dyskinesia of the abdominal organs, flatulence;

- vomiting of pregnant women;

Side effects: in rare cases, parkinsonism may occur (caffeine must be administered), as well as drowsiness, tinnitus, dry mouth.

An antagonist of dopamine D2 receptors is also an antiemetic agent, domperidone (motilium), which is structurally similar to the group of butyrophenone preparations (droperidol), and is similar in action to metoclopramide. The drug does not cross the blood-brain barrier (unlike metoclopramide) and does not cause extrapyramidal disorders. It is used as an antiemetic and prokinetic agent.

Domperidone is indicated for functional disorders of the gastrointestinal tract, gastric hypotension, reflux esophagitis. The drug softens biliary dyskinesia.

Side effects: increased prolactin levels, headache, dry mouth, dizziness.

4. Blockers of serotonin 5-HT3-receptors - tropisetron (novoban), ondansetron (emetron).

They block the serotonin 5-HT3 receptor in the chemoreceptor trigger zone and in the gastrointestinal tract and are indicated for the prevention or elimination of vomiting during chemotherapy of tumors and radiation sickness.

Side effects: dyspepsia, dizziness, constipation, increased blood pressure.

4. Means used in the treatment of protozoal infections (amebiosis, leishmaniasis, giardiasis, trichomonadosis, balantidiasis). Classification. Mechanism of action. Indications for use. Side effects. Contraindications Comparative evaluation of drugs.

Amoebiasis: at any localization (metronidazole); in the intestinal lumen (quiniofon); in the lumen and wall of the intestine (tetracycline); in the wall of the intestine and liver (emetine); in the liver (hingamin).

Mechanism:amoebicidal, tetracycline inhibits intestinal flora and this inhibits the growth and reproduction of amoebas (indirect division). A side effect is diarrhea, emetine accumulates (damage to the CVS, gastrointestinal tract, nervous system, kidneys and liver). It is impossible for diseases of the heart and kidneys. Combinations of drugs are used: metronidazole + quiniofon.

Leishmaniasis: for visceral and skin (solusurmin), for skin (monomycin, metronidazole), topically (akrikhin).

Mechanism:bactericidal. Side effects - nausea, headache, rash, inhibition of hematopoiesis, ↓ blood pressure. In case of an overdose of solusurmin - unitiol. Contraindications: acute infectious diseases, intoxication, organ damage to internal organs. Monomycin oto- and nephrotoxicity. Akrikhin is not allowed for mental illness.

Giardiasis:metronidazole, aminoquinol, furazolidone. Mechanism: ↓ activity of enzyme systems, disruption of protein and nucleic acid synthesis. Side effects - dyspepsia, headache, allergies, inhibition of hematopoiesis. Contraindications: violation of hematopoiesis, diseases of the central nervous system.

Trichomoniasis: metronidazole, tinidazole, trichomonacid, nitazole. Mechanism: bactericidal action. Side effects - dyspepsia, tremors. Contraindications: pregnancy in the 1st trimester, lactation, hematopoiesis disorder, central nervous system diseases. Tinidazole is more active than metronidazole.

Toxoplasmosis:chloridine, sulfonamides, pentamidine. Mechanism: bacteriostatic (chloridine inhibits the transition of dihydrofolic acid to tetrahydrofolic acid). Side effects - teratogenic effects, anemia, leukopenia. Contraindications: pregnancy, blood and kidney diseases.

Balantidiasis: monomycin, tetracycline, quiniophone.