Astemizole

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Astemizole
Clinical data
Pregnancy; category	C (USA);
Routes of; administration	Oral
ATC code	R06AX11 (WHO) ;
Legal status
Legal status	In general: unscheduled;
Pharmacokinetic data
Bioavailability	?
Metabolism	Hepatic
Elimination half-life	24 hours
Excretion	Fecal
Identifiers
	IUPAC name 1-[(4-fluorophenyl)methyl]- N-[1-[2-(4-methoxyphenyl)ethyl]- 4-piperidyl]benzoimidazol-2-amine;
CAS Number	68844-77-9;
PubChem CID	2247;
DrugBank	APRD00585;
E number	{{#property:P628}}
ECHA InfoCard	{{#property:P2566}}Lua error in Module:EditAtWikidata at line 36: attempt to index field 'wikibase' (a nil value).
Chemical and physical data
Formula	C28H31FN4O
Molar mass	458.571

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Astemizole (marketed under the brand name Hismanal) is a second generation antihistamine drug which has a long duration of action. Astemizole was discovered by Janssen Pharmaceutica in 1977. It has been withdrawn from the market in most countries because of rare but potentially fatal interactions with CYP3A4 enzyme inhibitors (e.g. erythromycin, grapefruit juice).

Pharmacology

Astemizole is an histamine H1-receptor antagonist. It is structurally similar to terfenadine and haloperidol (a butyrophenone antipsychotic). It has anticholinergic and antipruritic effects.

Astemizole competitively binds to histamine H1-receptor sites in the gastrointestinal tract, uterus, blood vessels, and bronchial muscle. This suppresses the formation of edema and pruritus (caused by histamine).

Astemizole does not cross the blood-brain barrier, and H1 receptor binding is mostly in the peripheral rather than central nervous system (CNS depression is thus minimal). Astemizole may also act on histamine H3 receptors, thereby producing adverse effects.

Astemizole is rapidly absorbed from the gastrointestinal tract; protein binding is around 96%.

Toxicity

Astemizole has an oral LD₅₀ of approximately 2052mg/kg (in mice).

Research

It has been reported that this drug might prevent 97% of the muscle wasting (atrophy) that occurs in immobile, bedridden patients.^[1] Testing upon mice showed that it blocked the activity of a protein present in the muscle that is involved in muscle atrophy.^[2] Recent studies have also suggested anti-malarial properties of astemizole. However the concerns for the drug's longterm effects on the heart preclude its routine use in humans for this indication.

Astemizole has recently been found to be a potent treatment for malaria. It has a mechanism of action similar to chloroquine but has activity even in chloroquine-resistant parasites.^[3]

External links

Footnotes

↑ "Drug 'could stop muscle wasting'". NetDoctor.co.uk. 25 May,2006. Retrieved 2006-05-27. Check date values in: |date= (help)
↑ Wang X, Hockerman GH, Green Iii HW, Babbs CF, Mohammad SI, Gerrard D, Latour MA, London B, Hannon KM, Pond AL (2006). "Merg1a K+ channel induces skeletal muscle atrophy by activating the ubiquitin proteasome pathway". FASEB J. PMID 16723379. Unknown parameter |month= ignored (help)
↑ Chong CR, Chen X, Shi L, Liu JO, Sullivan DJ (2006). "A clinical drug library screen identifies astemizole as an antimalarial agent". Nat Chem Biol. 2: 415&ndash, 16. doi:10.1038/nchembio806. PMID 16816845.

[1] "Drug 'could stop muscle wasting'". NetDoctor.co.uk. 25 May,2006. Retrieved 2006-05-27. Check date values in: |date= (help)

[FASEBJ2006-Wang-2] Wang X, Hockerman GH, Green Iii HW, Babbs CF, Mohammad SI, Gerrard D, Latour MA, London B, Hannon KM, Pond AL (2006). "Merg1a K+ channel induces skeletal muscle atrophy by activating the ubiquitin proteasome pathway". FASEB J. PMID 16723379. Unknown parameter |month= ignored (help)

[3] Chong CR, Chen X, Shi L, Liu JO, Sullivan DJ (2006). "A clinical drug library screen identifies astemizole as an antimalarial agent". Nat Chem Biol. 2: 415&ndash, 16. doi:10.1038/nchembio806. PMID 16816845.

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[2]

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v t e Antihistamines (R06)
Aminoalkyl ethers	Bromazine/Bromodiphenhydramine • Carbinoxamine • Clemastine • Chlorphenoxamine • Diphenylpyraline • Diphenhydramine • Doxylamine • Orphenadrine • Phenyltoloxamine
Substituted alkylamines	Brompheniramine • Chlorphenamine • Dexbrompheniramine • Dexchlorpheniramine • Dimetindene • Pheniramine • Talastine
Substituted ethylenediamines	Chloropyramine • Histapyrrodine • Mepyramine • Methapyrilene • Tripelennamine (Pyribenzamine)
Phenothiazine derivatives	Alimemazine • Hydroxyethylpromethazine • Isothipendyl • Mequitazine • Methdilazine • Oxomemazine • Promethazine
Piperazine derivatives	Buclizine • Cetirizine • Chlorcyclizine • Cinnarizine • Cyclizine • Hydroxyzine • Levocetirizine • Meclizine • Niaprazine • Oxatomide
Others for systemic use	Antazoline • Azatadine • Bamipine • Cyproheptadine • Deptropine • Dimebon • Ebastine • Epinastine • Ketotifen • Mebhydrolin • Mizolastine • Phenindamine • Pimethixene • Pyrrobutamine • Rupatadine • Triprolidine • selective (Acrivastine • Astemizole • Azelastine • Desloratadine • Fexofenadine • Loratadine • Terfenadine)
For topical use	Bamipine • Chloropyramine • Chlorphenoxamine • Clemastine • Dimetindene • Diphenhydramine • Isothipendyl • Mepyramine • Promethazine • Thenalidine
Antiallergic agents excluding corticosteroids	Antazoline • Azelastine
Other antiallergics	Emedastine • Epinastine • Ketotifen • Montelukast • Olopatadine

Clinical data
Pregnancy category	C (USA)
Routes of administration	Oral
ATC code	R06AX11 (WHO)
Legal status
Legal status	In general: unscheduled
Pharmacokinetic data
Bioavailability	?
Metabolism	Hepatic
Elimination half-life	24 hours
Excretion	Fecal
Identifiers
IUPAC name 1-[(4-fluorophenyl)methyl]- N-[1-[2-(4-methoxyphenyl)ethyl]- 4-piperidyl]benzoimidazol-2-amine
CAS Number	68844-77-9
PubChem CID	2247
DrugBank	APRD00585
E number	{{#property:P628}}
ECHA InfoCard	{{#property:P2566}}Lua error in Module:EditAtWikidata at line 36: attempt to index field 'wikibase' (a nil value).
Chemical and physical data
Formula	C₂₈H₃₁FN₄O
Molar mass	458.571