Betahistine

Pharmacological properties

The mechanism of action of betahistine is the effect on the histamine n1 and n3 receptors of the labyrinth and vestibular nuclei of the central nervous system. having a pronounced h1-agonistic effect on the receptors of the vessels of the inner ear, the drug promotes local vasodilation and significantly improves blood circulation in stria vascularis. The n3-antagonistic effect of the drug on the receptors of neurons of the vestibular nuclei helps to improve microcirculation, capillary permeability, increase histamine release and increase fluid exchange at the level of the microvasculature of the vascular strip, which leads to normalization of endolymph pressure in the labyrinth and cochlea. In addition, betahistine improves the processes of neuronal transmission by increasing the concentration of serotonin in synapses. the drug is also an inhibitor of the enzyme diamine oxidase, which inactivates histamine. Betahistine binding to voltage-dependent calcium channels of nerve cells, which are directly involved in the processes of ischemic damage, was also noted. the drug does not affect the H2 receptors of the stomach and does not increase the secretion and concentration of hydrochloric acid, both basal and stimulated. betahistine does not have a sedative effect, it also does not affect the performance of systemic hell. unlike other drugs of this group (cinnarizine, flunarizine), betahistine does not cause extrapyramidal disorders and can be used in elderly people with Parkinsons syndrome.

Pharmacokinetics When ingested, betahistine is completely absorbed in the digestive tract, slightly bound to blood plasma proteins. The drug does not accumulate in the tissues of the body and does not have a cumulative effect, is completely excreted in the urine as an inactive metabolite - 2-pyridylacetic acid for 24 hours. T_½ 3-4 hours

Indications

Menter disease and syndrome, characterized by three main symptoms:

• dizziness, which is sometimes accompanied by nausea and vomiting;
• hearing loss (hearing loss);
• tinnitus.

Application

Adult avertids are taken orally 2-3 times a day, preferably during or after meals. accurate dosing of the drug is carried out using a syringe embedded in the package. it is allowed to use undiluted solution, washing it down with a small amount of liquid, and also dilute the drug in a small amount of liquid. the course of treatment is from 2 weeks to 3 months, depending on the clinical effect. the best result is achieved with prolonged use of the drug avertid.

Typically, the drug is used at 8 mg (1 ml) 3 times a day. In case of severe symptoms of the disease or treatment failure, the dose can be increased to 16 mg (2 ml) 3 times a day or the drug can be used 24 mg (3 ml) 2 times a day. The maximum daily dose of the drug is 48 mg.

Contraindications

Hypersensitivity to the components of the drug, pheochromocytoma, treatment with disulfiram derivatives (avertide contains ethanol in an amount of 5% of the volume).

Side effects

Disorders from the immune system: hypersensitivity reactions, including the immediate type (anaphylaxis).

Disorders of the nervous system: headache.

Gastrointestinal disturbances: often - nausea and dyspepsia. In some cases, there were complaints of minor indigestion (vomiting, pain along the gastrointestinal tract, pain in the abdominal region due to bloating and flatulence). These side effects usually disappear when taking the drug with food or after a dose reduction.

Disorders from the skin and subcutaneous tissue: in isolated cases, hypersensitivity reactions from the skin and subcutaneous fat, in particular angioedema, rash, itching and urticaria.

The drug contains methylparaben (E218) and propylparaben (E216), which can cause allergic reactions (presumably, a delayed type).

special instructions

During treatment, it is necessary to carefully monitor the condition of patients with a history of BA and / or gastric and duodenal ulcers. in case of exacerbation of the course of BA, the drug must be canceled. with caution, avertid is used for peptic ulcer of the stomach or duodenum in the active phase, pheochromocytoma.

Use during pregnancy and lactation. There is not enough data regarding the use of betahistine in pregnant women. The potential risk to the fetus and newborn is unknown. Avertid should not be used during pregnancy, unless absolutely necessary. Breastfeeding must be stopped for the entire period of the use of the drug Avertid.

Children. The drug is not used.

The ability to influence the reaction rate when driving vehicles or other mechanisms. Betahistine is indicated for the treatment of Menieres syndrome, which is characterized by a triad of the main symptoms: dizziness, hearing loss, tinnitus, as well as for the symptomatic treatment of vestibular dizziness. Both conditions can adversely affect the ability to drive vehicles or other mechanisms. According to clinical studies studying the effect of this drug on the ability to drive vehicles or other mechanisms, betahistine did not affect or had a negligible effect on this ability.

Interactions

In vivo studies aimed at studying the interaction of betahistine with other drugs have not been conducted. based on in vitro data, in vivo inhibition of cytochrome p450 enzyme activity is not expected.

In vitro data indicate inhibition of betahistine metabolism by drugs inhibiting MAO activity, including a subtype of selective MAO-B inhibitors (e.g. Selegiline). Caution is advised while using betahistine and MAO inhibitors (including selective MAO-B inhibitors). When using the drug Avertid simultaneously with histamine H blockers₁-receptors, the effectiveness of betahistine is reduced, so before using it, antihistamines must be canceled. The finished preparation contains ethanol in an amount of 5% of the volume, which must be taken into account when treating with disulfiram derivatives or other drugs that block acetaldehyde decomposition enzymes (for example, metronidazole, nitrofuran derivatives).

Overdose

Several cases of drug overdose have been reported. in some patients, after taking doses up to 640 mg, mild or moderate symptoms (nausea, drowsiness, abdominal pain) occurred. more serious complications (convulsions, complications from the heart or lungs) were observed in cases of deliberate overdose of betahistine, especially in combination with an overdose of other drugs.

Treatment: symptomatic and supportive therapy.

Storage conditions

At a temperature not exceeding 25 ° C.