Betahistine dihydrochloride.
Each uncoated tablet contains: Betahistine Dihydrochloride BP 16mg.
Betahist Forte tablet contains Betahistine Dihydrochloride BP 16mg as an antivertigo drug.
Excipients/Inactive Ingredients: Beta Cyclodextrin IHS, Maize Starch BP, Microcrystalline Cellulose BP, Colloidal Anhydrous Silica BP, Calcium Hydrogen Phosphate BP, Povidone BP, Sodium Lauryl Sulphate BP, Magnesium Stearate BP, Purified Talc BP, Sodium Starch Glycolate NF & Purified water.
Pharmacology: Pharmacodynamics: Mechanism of Action: Betahistine dihydrochloride is an analog of histamine which can be administered orally. It was developed as one of several beta-2-pyridyl alkylamine compounds with actions qualitatively similar to histamine but easier to administer than histamine itself; histamine is ineffective by the oral route. Betahistine is structurally similar to histamine.
The primary clinical indication for betahistine has been Meniere’s disease. Animal studies have demonstrated that betahistine induces histamine-like effects on inner ear microcirculation. Vasodilation of capillaries/arterioles of the spiral ligament and stria vascularis was reported with topical or intravenous use in guinea pigs, and electrical impedance plethysmograph studies suggested increases in cochlear blood flow by over 200% in the same animal model following intravenous betahistine.
Betahistine has also been evaluated in cerebrovascular disease. Cerebral vasodilation has been reported in animals and humans following oral or intravenous betahistine, including patients with arteriosclerotic dementia. Oral administration of betahistine 32 mg daily for one week was reported to significantly increase cerebral blood flow in patients with ischemic cerebrovascular disease; however, focal decreases in blood flow have also been observed, suggesting intracerebral "steal" may also be operative.
Betahistine appears to act predominantly as a histamine-1 (H1) receptor agonist.
However, agonist activity at H2 and H3 receptors has also been reported. In one study, cimetidine reversed betahistine-induced relaxation of the rat uterus contracted by acetylcholine; chronotropic effects of betahistine on guinea pig atria were blocked by the H2-receptor antagonist YM11170.
Similar to histamine, reduced blood pressure, headache, and flushing occur after intravenous betahistine administration. However, it is claimed overall to be less toxic than histamine itself. With oral betahistine, gastrointestinal intolerance is the most frequent adverse effect; blood pressure is not generally affected to a significant degree. In contrast to histamine, betahistine has not been reported to significantly increase gastric acid secretion in small studies.
Pharmacokinetics: Pharmacokinetic data for betahistine are limited; the drug is rapidly absorbed after oral doses, and converted to at least 2 metabolites. It is unclear if metabolites are pharmacologically active. Most of a dose is excreted via the urine as metabolites. An elimination half-life of 3.5 hours has been reported.
Betahistine Dihydrochloride is indicated in symptomatic treatment of the vertigo associated with Meniere's Syndrome.
Route of Administration: Oral.
Posology: Adult dosage: The initial dose is 1 tablet 3 times daily. To be taken with food.
Maintenance dose is 1 1/2 - 3 tablets daily. To be taken with food.
The symptoms of betahistine overdose are nausea, vomiting, dyspepsia, ataxia and seizures. More serious complications (convulsion, pulmonary or cardiac complications) were observed in cases of intentional overdose of betahistine especially in combination with other overdosed drugs. No specific antidote. Gastric lavage and symptomatic treatment are recommended.
Hypersensitivity to any of the ingredients. It is contraindicated in the patients with active peptic and phaeochromocytoma.
Caution should be exercised when Betahistine Dihydrochloride is given to patients with a history of peptic ulcer or asthmatic patients. Concomitant use with antihistamines should be avoided. There is insufficient data on the use of this medicine during pregnancy and lactation.
Effects on ability to drive and use of machines: Rare reports of drowsiness associated with betahistine have been made. Patients should be advised that if they are affected in this way they should avoid activities requiring concentration, such as driving and operating machinery.
There is a very limited amount of data from the use of betahistine in pregnant women. Animal studies, though insufficient do not indicate direct or indirect harmful effects with respect to reproductive toxicity. As a precautionary measure, it is preferable to avoid the use of Betahistine during pregnancy. There is insufficient information on the excretion of betahistine in human milk. Betahistine should not be used during breast-feeding.
Immune system disorders: skin rashes and pruritus.
Nervous system disorders: headaches, and occasional drowsiness.
Gastrointestinal disorders: gastro-intestinal upset, nausea and dyspepsia.
Cardiac disorders: palpitations.
Skin and subcutaneous tissue disorders: urticaria.
There are no proven cases of hazardous interactions.
There is a case report of an interaction with ethanol and a compound containing pyrimethamine with dapsone and another of potentiation of betahistine with salbutamol.
Betahistine is a histamine analogue, concurrent administration of H1 antagonists may cause a mutual attenuation of effect of the active agents.
Store at a temperature not exceeding 30°C. Protect from light & moisture.
Shelf Life: 30 months.
N07CA01 - betahistine ; Belongs to the class of antivertigo preparations.
Tab 16 mg (white, flat, circular, bevelled, uncoated, with a breakline on one side & plain on the other side) x 10 x 10's.
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