Betagistin: instructions for using the medicine, structure, Contraindications
When ATH:
N07CA01
Betagistin: application
Disease and Meniere's syndrome (incl. tinnitus and hearing loss), vestibular vertigo of various origins (vertebrobasilar insufficiency, traumatic encephalopathy, cerebral atherosclerosis, vestibular neuritis, laʙirintit, benign positional vertigo after neurosurgical operations).
Betagistin: pharmachologic effect
Farmakodinamika.
The mechanism of action of betahistine is only partially understood.. Known, that there are several valid hypotheses, supported by animal and human studies.
Effect of betahistine on the histaminergic system.
Established, that betahistine partially exhibits agonistic activity relative to H1-receptors, as well as antagonistic activity against H3-histamine receptors in the nervous tissue and has little activity with respect to H2-histamine receptors.
Betahistine increases histamine metabolism and release by blocking presynaptic H3-receptors and induction of the process of reducing the amount of the corresponding H3-receptors.
Betahistine may increase cochlear blood flow, as well as throughout the brain.
There is information on improving blood circulation in the vessels vascular striae inner ear, perhaps, by relaxing the precapillary sphincters in the microcirculation system of the inner ear. Betahistine has also been shown to increase cerebral blood flow in humans..
Betahistine promotes vestibular compensation.
Betahistine accelerates recovery of vestibular function after unilateral neurectomy in animals, stimulating and facilitating the process of central vestibular compensation. This effect is characterized by increased regulation of histamine metabolism and release and is realized as a result of H antagonism.3-receptors. In humans, treatment with betahistine also reduced the recovery time of vestibular function after neurectomy..
Betahistine alters the activity of neurons in the vestibular nuclei.
It was also found, that betahistine has a dose-dependent inhibitory effect on the generation of peak potentials in neurons of the lateral and medial vestibular nuclei.
Known, that the pharmacodynamic properties of betahistine can provide a positive therapeutic effect of the drug in the vestibular system.
The effectiveness of betahistine has been shown in studies in patients with vestibular vertigo and Meniere's disease., which has been demonstrated by reducing the severity and frequency of vertigo attacks.
Pharmacokinetics.
Absorption. When administered orally, betahistine is rapidly and almost completely absorbed in all parts of the gastrointestinal tract.. After absorption, the drug is rapidly and almost completely metabolized to form the 2-pyridylacetic acid metabolite.. Plasma levels of betahistine are very low.
Therefore, all pharmacokinetic analyzes are performed by measuring the concentration of the 2-pyridylacetic acid metabolite in plasma and urine..
When taking the drug with food, the maximum concentration (Cmax) drug below, than in the fasting. At the same time, the complete absorption of betahistine is identical in both cases., which indicates, that food intake only slows down the absorption of the drug.
Distribution. Percentage of betahistine, which binds to plasma proteins, is less 5 %.
Biotransformation. After absorption, betahistine is rapidly and almost completely metabolized to 2-pyridylacetic acid. (which does not show pharmacological activity).
After taking betahistine orally, the concentration of 2-pyridylacetic acid in the blood plasma (and in urine) reaches its maximum through 1 hour after taking the drug and decreases with an elimination half-life of about 3,5 o'clock.
Deduction. 2-pyridylacetic acid is rapidly excreted in the urine. When taking the drug at a dosage 8-48 about mg 85 % initial dose found in urine. Renal or fecal excretion of betahistine is negligible.
Linearity. Recovery rate remains constant when taken orally 8-48 mg of drug, indicating the linearity of the pharmacokinetics of betahistine, and suggests, that the metabolic pathway involved is non-saturable.
Betagistin: Contraindications
Hypersensitivity, peptic ulcer in an active phase, bronchial asthma, pheochromocytoma, pregnancy (I trimester), childhood.
Betagistin: restrictions on use
Peptic ulcer of the digestive tract (history), pregnancy (II and III trimester), breast-feeding.
Betagistin: side effects
Gastrointestinal disorders (nausea, vomiting, a feeling of heaviness in the epigastric and others.), headache, allergic reactions (skin rash, itching and others.).
Betagistin: interaction
Research live, aimed at studying interactions with other drugs, not performed. In view of the study data in vitro not expected to inhibit cytochrome P450 enzyme activity live.
Data, obtained under the conditions in vitro, indicate inhibition of the metabolism of betahistine by drugs, that inhibit the activity of monoamine oxidase (MAO), including subtype B MAO (e.g. selegiline). It is recommended to be careful with the simultaneous use of betahistine and MAO inhibitors. (including selectively subtype B MAO).
Because betahistine is a histamine analogue, the interaction of betahistine with antihistamines could theoretically affect the effectiveness of one of these drugs.
Betagistin: overdose
Symptoms: headache, facial flushing, dizziness, tachycardia.
Treatment: symptomatic.
Betagistin: Dosing and Administration
Inside, 8-16 mg 3 once a day. The dose and duration of reception are selected individually.
Features of the use of Betahistine
During treatment with the drug, it is necessary to carefully monitor the condition of patients with bronchial asthma and / or a history of gastric ulcer and duodenal ulcer..
Use during pregnancy or lactation.
Pregnancy. There are no data on the use of betahistine in pregnant women..
Animal studies are not sufficient to assess the effect on pregnancy, development of the embryo / fetus, rodы and development postnatalynoe. The potential risk for humans is unknown. Betahistine should not be used during pregnancy, except in cases of undeniable necessity.
breastfeeding period. Unknown, Does betahistine pass into human breast milk?. Animal studies on the penetration of betahistine into milk have not been performed.. The benefit of the drug to the mother should be weighed against the benefits of breastfeeding and the potential risk to the baby..
The ability to influence the reaction rate when driving vehicles or operating other mechanisms.
Betahistine is indicated for the treatment of Meniere's syndrome, which is characterized by a triad of main symptoms: dizziness, hearing loss, tinnitus, – as well as for the symptomatic treatment of vestibular vertigo. Both conditions can adversely affect the ability to drive and use machines.. Known, that betahistine did not affect the ability to drive a car and work with mechanisms or had an insignificant effect on this ability.
Betagistin: precautions
Caution must be exercised in treating patients with gastrointestinal ulcer (incl. history).
