Betahistine Chemical Properties

Boiling point:

113-114 °C30 mm Hg(lit.)

Density 

0.984 g/mL at 25 °C(lit.)

vapor pressure 

17.7Pa at 25℃

refractive index 

n20/D 1.518(lit.)

Flash point:

206 °F

storage temp. 

Keep in dark place,Inert atmosphere,Room temperature

solubility 

Chloroform (Slightly), DMSO (Sparingly), Ethyl Acetate (Slightly), Methanol (Slightly)

pka

pKa 3.46 (Uncertain)

form 

Oil

color 

Light Yellow to Yellow

Water Solubility 

1000g/L at 25℃

Merck 

13,1181

LogP

0.68

CAS DataBase Reference

5638-76-6(CAS DataBase Reference)

EPA Substance Registry System

2-Pyridineethanamine, N-methyl- (5638-76-6)

Safety Information

Hazard Codes 

Xi,C

Risk Statements 

36/37/38

Safety Statements 

26-37/39

WGK Germany 

2

RTECS 

UT5552000

Hazard Note 

Corrosive

HS Code 

2933399990

MSDS

• Language:English Provider:SigmaAldrich

Betahistine Usage And Synthesis

Description

Betahistine is an analogue of histamine with weak agonist properties at histamine H1 receptors and more potent antagonistic effects at histamine H3 receptors.
This drug is broadly used worldwide, except for the USA, since it has not been approved by the US Food and Drug Administration. Betahistine is a structural analog of histamine that acts as a weak partial postsynaptic histamine H1 receptor agonist and presynaptic H3 receptor antagonist, with no effect on postsynaptic H2 receptors (Gbahou et al, 2010). The mechanism of action of the drug appears to depend mainly on its action on H3 receptors mediated by two metabolites, aminoethylpyridine and hydroxyethylpyridine (Bertich et al, 2014).

Uses

Betahistine is a vasodilator, a mild H1 histamine agonist, and a potent H3 histamine antagonist. The mechanism of action in Meniere's disease is unknown, but theories include reducing the endolymphatic pressure through improved circulation in the stria vascularis or inhibiting activity in the vestibular nuclei. It has been found to be a safe drug with a very low side effect profile. Betahistine was FDA approved for Meniere's disease in the US market for a short period of time in the 1970s, but approval was then rescinded due to lack of evidence supporting its efficacy. However, based on clinical experience and several observational studies, it is still widely used elsewhere in the world.

Uses

Anti - Vertigo/Anti-Nauseants/Antiemetics

Indications

Betahistine is indicated in treatment of Meniere's disease (vertigo, hearing loss and tinnitus); it is not effective in preventing vertigo attacks.

Definition

ChEBI: Betahistine is an aminoalkylpyridine that is pyridine substituted by a 2-(methylamino)ethyl group at position 2. It acts as a histamine agonist and a vasodilator, and is thought to improve the microcirculation of the labyrinth, resulting in reduced endolymphatic pressure. It is used (generally as the hydrochloride or mesylate salt) to reduce the symptoms of vertigo, tinnitus, and hearing loss associated with Meniere's disease. It has a role as a vasodilator agent and a H1-receptor agonist. It is an aminoalkylpyridine and a secondary amino compound.

brand name

Serc (Unimed).

Mechanism of action

The precise mechanism of betahistine's actions is unclear; it has antagonistic actions on histamine H3 receptors, and is a weak agonist at H receptors. In animal studies, it inhibits generation of spikes in vestibular nuclei. Its vasodilator activity (similar to histamine's) presumably improves blood flow in the inner ear and brainstem.

Pharmacokinetics

After oral administration, betahistine is rapidly and completely absorbed, rapidly metabolised (to one major metabolite, 2-pyridylacetic acid) and 90% excreted within 24 hours. Plasma and urinary half-lives are about 3.5 hours.

Side effects

Common adverse reactions include headache, nausea and dyspepsia. More rarely, hypersensitivity reactions (rash, pruritis, bronchospasm) and hypotension may occur.

Drug interactions

Co-administration of betahistine and monoamine oxidase inhibitors type B reduces metabolism of betahistine. Theoretically, interactions might occur with concurrent antihistamines; however, no significant problems have been reported.

Dosage forms

Betahistine is provided as scored tablets, 16 mg. Dose is 8-16 mg taken three times daily. It should be taken with food to minimise risk of GIT upsets. Patients are warned that it may take several weeks for beneficial effects to be noticed.

Precautions

Betahistine should be used with caution in individuals with asthma, urticaria, phaeochromocytoma or hypersensitivity to any components of tablets. Betahistine is contraindicated in people with active or history of peptic ulcer. Betahistine is classified in Pregnancy Safety Category B2: insufficient data available; it is contraindicated in pregnancy and lactation, and in children under 18.

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