Betagistin - instructions for use, dose, side effects, contraindications

The drug is a synthetic analog of histamine. The mechanism of action of betagistin is known in part. There are several possible hypotheses, confirmed by preclinical and clinical data:

1. Effect on the histaminergic system

Partial agonist histamine H₁receptor antagonist and histamine H antagonist₃receptors of the vestibular nuclei of the central nervous system, has little activity in relation to H₂receptors. Betagistin increases histamine metabolism and its release by blocking presynaptic H₃-receptors and reduce the amount of H₃receptors.

2. Increased blood flow of the cochlear region, as well as the entire brain

According to pre-clinical studies, betagistin improves blood circulation in the vascular stria of the inner ear by relaxing precapillary sphincters of the vessels of the inner ear. It is also shown that betagistin increases the blood flow of the brain in humans.

3. Facilitating the process of central vestibular compensation

Betagistin accelerates the recovery of vestibular function in animals after unilateral vestibular neurectomy, speeding up and facilitating central vestibular compensation due to antagonism with histamine H₃receptors.

The recovery time after vestibular neurectomy in humans in the treatment with betahistine is also reduced.

4. Excitation of neurons in the vestibular nuclei

It dose-dependently reduces the generation of action potentials in the neurons of the lateral and medial vestibular nuclei.

Pharmacodynamic properties found on animals provide a positive therapeutic effect of betahistine in the vestibular system.

The efficacy of betahistine was demonstrated in patients with vestibular dizziness and Menier's syndrome, which was manifested by a decrease in the severity and frequency of dizziness.

Pharmacokinetics:

Suction

When taken orally betagistin quickly and almost completely absorbed from the digestive tract. After absorption, the drug is rapidly and almost completely metabolized to form a metabolite of 2-pyridylacetic acid. The concentration of betagistin in the blood plasma is very low. Thus, pharmacokinetic analyzes are based on measuring the concentration of the metabolite of 2-pyridylacetic acid in plasma and urine. When taking the drug with food C_max betahistine in the blood is lower than when taken on an empty stomach. However, the total absorption of betahistin is the same in both cases, indicating that eating only slows the absorption of betahistine.

Distribution

Binding of betahistine to plasma proteins is less than 5%.

Metabolism

After suction betagistin quickly and almost completely metabolized to form a metabolite of 2-pyridylacetic acid (which does not have pharmacological activity). C_max 2-pyridylacetic acid in blood plasma (or urine) is achieved 1 h after administration. The half-life is approximately 3.5 hours.

Excretion

2-pyridylacetic acid is rapidly excreted in the urine. When taking the drug at a dose of 8-48 mg, about 85% of the initial dose is found in the urine.The excretion of betagistin by the kidneys or through the intestine is negligible.

Linearity

The elimination rate remains constant with 8-48 mg of oral ingestion, indicating the linearity of the pharmacokinetics of betahistin, and suggests that the involved metabolic pathway remains unsaturated.

Indications:

Meniere's syndrome, characterized by the following main symptoms: dizziness (accompanied by nausea, vomiting); hearing loss (hearing loss); noise in ears.

Symptomatic treatment of vestibular vertigo.

ICD-10

VIII.H80-H83.H81 Violations of the vestibular function

VIII.H80-H83.H81.0 Ménière's disease

VIII.H80-H83.H81.3 Other peripheral dizziness

VIII.H90-H95.H93.0 Degenerative and vascular diseases of the ear

VIII.H90-H95.H93.1 Noise in the ears (subjective)

Contraindications:

Pheochromocytoma; hypersensitivity to the components of the drug.

Betagistin is not recommended for use in children and adolescents under the age of 18 due to insufficient data on efficacy and safety.

Carefully:

FROM caution and under close supervision of the doctor should be appointed patients with bronchial asthma, peptic ulcer of the stomach and / or duodenum.

Pregnancy and lactation:

The available data on the use of betagistin in pregnant women is not enough. The potential risk to humans is unknown. Betagistin should not be used during pregnancy, except in cases of absolute necessity.

It is not known whether betagistin with breast milk. Do not prescribe the drug during breastfeeding. The question of prescribing the mother should be taken only after comparing the benefits of breastfeeding with the potential risk for an infant.

Dosing and Administration:

The drug is prescribed inside while eating. The dose should be selected individually depending on the response to treatment.

For of adults the dose is 24-48 mg per day.

Improvement is sometimes observed only after several weeks of treatment, and a stable therapeutic effect - after several months of treatment. There is evidence that the administration of the drug at the onset of the disease prevents its progression and / or hearing loss at later stages.

Despite the limited data from clinical trials, extensive post-marketing experience suggests that dose adjustment in elderly patients not required.

Special clinical trials in patients with renal and / or liver failure were not conducted, however, post-registration experience gives grounds to assume that dose adjustment in this group of patients is not required.

Side effects:

From the digestive system: often (from ≥ 1/100 to <1/10) - nausea and indigestion.

From the nervous system: often a headache.

From the digestive system: moderately expressed - vomiting, gastrointestinal pain, bloating. As a rule, these effects usually disappear after taking the drug simultaneously with food or after lowering the dose.

Allergic reactions: hypersensitivity reactions, including angioedema, urticaria, pruritus, rash, anaphylactic reaction.

Overdose:

There are several cases of drug overdose.

Symptoms: mild and moderate nausea, drowsiness, abdominal pain were observed in some patients after taking the drug at doses up to 640 mg. More serious complications (convulsions, cardiopulmonary complications) were observed with the deliberate use of beta-histidine in elevated doses, especially in combination with an overdose of other drugs.

Treatment: symptomatic therapy.

Interaction:

Research in vivo, aimed at studying the interaction with other medicinal products, were not conducted.

Based on the data in vitro, it can be assumed that there is no inhibition of the activity of cytochrome P450 isoenzymes in vivo.

Data in vitro showed inhibition of beta-histidine metabolism by drugs that inhibit MAO, including MAO of subtype B (eg, selegiline). Caution should be exercised while concomitant administration of betagistin and MAO inhibitors (including MAO-B).

Betagistin is an analog of histamine, the interaction of betahistine with H blockers₁-gistaminovyh receptors can theoretically affect the effectiveness of one of these drugs.

The patient should inform the doctor about taking any medications now or in the recent past.

Special instructions:

Impact on the ability to drive vehicles and manage mechanisms

Betagystine does not influence or slightly affect the ability to drive vehicles and work with machinery.In clinical trials, undesirable reactions that could affect this ability have not been identified.

Instructions

Betagistin (Betahistinum)