Astemizole Chemical Properties

Melting point:

172.9°C

Boiling point:

627.3±65.0 °C(Predicted)

Density 

1.1587 (estimate)

storage temp. 

2-8°C

solubility 

DMSO: >20mg/mL

pka

pKa 4.85(H2O t=25.0 I=0.025) (Uncertain);8.69(H2O t=25.0 I=0.025) (Uncertain)

form 

powder

color 

Crystals

Water Solubility 

It is soluble in DMSO (25 mg/ml ), ethanol (25 mg/ml), chloroform, methanol, and water (partly miscible).

Stability:

Stable for 1 year from date of purchase as supplied. Solutions in DMSO or ethanol may be stored at -20°C for up to 3 months.

Safety Information

Hazard Codes 

Xn

Risk Statements 

22-36/37/38

Safety Statements 

26-36

RIDADR 

UN 2811 6.1 / PGII

WGK Germany 

3

RTECS 

DD8968000

HS Code 

2933992600

Hazardous Substances Data

68844-77-9(Hazardous Substances Data)

Toxicity

LD50 orl-rat: >2560 mg/kg AIPTAK 251,39,81

MSDS

• Language:English Provider:Astemizole
• Language:English Provider:SigmaAldrich

Astemizole Usage And Synthesis

Uses

Astemizole is a histamine H1-receptor antagonist with IC50 of 4.7 nM. Astemizole is also a potent inhibitor of ether à-go-go 1 (Eag1) and Eag-related gene (Erg) potassium channels. Astemizole has antineoplastic and antipruritic effects.

Description

Astemizole belongs to the second-generation class of non-sedating, non-anticholinergic antihistamines. Its non-sedating properties appear to result from its poor penetration of the blood brain barrier. As a result it shows no potentiation of CNS depressants, including alcohol. Its long half-life allows once-daily dosing.

Chemical Properties

Crystalline Solid

Originator

Janssen (Belgium)

Uses

Nonsedating-type histamine H1-receptor antagonist. Potential for combination therapy with antivancer drugs such as doxorubicin in resistant leukemia. Antihistaminic

Uses

scabicide

Uses

Astemizole is used for preventing and treating severe seasonal and chronic allergic rhinitis, allergic conjunctivitis, hives, Quinke’s edema, other allergic conditions and dermatitis. Synonyms of this drug are hismanal, histazol, and others.

Definition

ChEBI: A piperidine compound having a 2-(4-methoxyphenyl)ethyl group at the 1-position and an N-[(4-fluorobenzyl)benzimidazol-2-yl]amino group at the 4-position.

Manufacturing Process

A mixture of 2.3 parts of 2-(4-methoxyphenyl)ethyl methanesulfonate, 4.9 parts of 1-[(4-fluorophenyl)methyl]-N-(4-piperidinyl)-1H-benzimidazol-2- amine dihydrobromide, 3.2 parts of sodium carbonate, 0.1 part of potassium iodide and 90 parts of N,N-dimethylformamide is stirred overnight at 70°C. The reaction mixture is poured onto water. The product is extracted with methylbenzene. The extract is washed with water, dried, filtered and evaporated. The residue is purified by column-chromatography over silica gel using a mixture of trichloromethane and methanol (98:2 by volume) as eluent. The pure fractions are collected and the eluent is evaporated. The residue is crystallized from 2,2'-oxybispropane, yielding 2.2 parts (48%) of 1- (4-fluorophenylmethyl)-N-[1-[2-(4-methoxyphenyl)ethyl]-4-piperidinyl]-1Hbenzimidazol- 2-amine, MP 149.1°C.

brand name

Hismanal (Janssen);Alermizol;Astezol;Astol;Histamanal;Novo-nastizol;EISMANAL.

Therapeutic Function

Antiallergic, Antihistaminic

World Health Organization (WHO)

The first clinically interesting histamine ti-antagonists were introduced in the late forties and early fifties. Several histamine ti-antagonists have a similar cardiac effect to that seen with astemizole and terfenadine. Serious cardiovascular adverse reactions have been reported when used concomitantly with imidazole antifungals and macrolide antibiotics.

Biological Activity

Orally active, potent histamine H 1 antagonist (IC 50 = 4 nM) that displays 20-fold, > 250-fold and > 250-fold selectivity over 5-HT, dopamine and muscarinic acetylcholine receptors respectively. Exhibits antimalarial activity in multidrug resistant strains in vitro (IC 50 = 227 - 734 nM). Also potent hERG K + channel blocker (IC 50 = 0.9 nM) that displays cardiotoxicity in vivo .

Biochem/physiol Actions

Astermizole is a potent hERG potassium channel blocker (IC50 of 0.9 nM) and may used as a pharmacological chaperone to correct folding defects and restore protein function for some mutated forms of hERG channels. It has also been studied for treatment of malaria, hERG and hEAG channel function in cancer and as a second generation antihistamine H-1 antagonist.

Safety Profile

Poison by subcutaneous andintravenous routes. Moderately toxic by ingestion. Humansystemic effects by ingestion: arrhythmias, coma, nauseaor vomiting, somnolence. When heated to decompositionit emits toxic fumes of F?? and NOx.

Synthesis

Astemizole, 1-[(4-fluorophenyl)methyl]-N-[1-[2-(4-methoxyphenyl) ethyl]-4- piperidinyl]-benzimidazol-2-amine (16.1.31), is synthesized in a multi-stage synthesis from 1-carbethoxy-4-aminopiperidine and 2-nitroisothiocyanobenzol, from which a derivative of thiourea (16.1.26) is synthesized upon their reaction. The nitro group of the product is reduced and the further S-methoxided. In reaction conditions intermolecular cyclization into a derivative of benimidazol, N-[1-[2-(4-carethoxy)]-4-piperidinyl]benzimidazol-2-amine (16.1.28) occurs. The obtained aminobenzimidazole derivative is alkylated with 4-fluorobenzylchoride into 1-[(flurophenyl)methyl]-N-[1-[2-(4-carethoxy)]-4-piperidinyl] benzimidazol- 2-amine (16.1.29). The carbethoxyl group of the resulting compound (16.1.29) is hydrolyzed by hydrobromic acid, forming a non-substituted on the nitrogen atom derivative of piperidine (16.1.30), the alkylation of which with 2-(4-methoxyphenyl)ethylmetanesulfonate leads to the formation of astemizole (16.1.31).

storage

Store at +4°C

References

1) Richards et al. (1984), Astemizole. A review of its pharmacodynamic properties and therapeutic efficacy; Drugs, 28 38 2) Laduron et al. (1982), In vitro and in vivo binding characteristics of a new long-acting histamine H1 antagonist, astemizole; Mol. Pharmacol., 21 294

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