Astemizole

Astemizole
Astemizole
Systematic (IUPAC) name
1-[(4-fluorophenyl)methyl]- N-[1-[2-(4-methoxyphenyl)ethyl]- 4-piperidyl]benzoimidazol-2-amine
Clinical data
AHFS/Drugs.com Multum Consumer Information
MedlinePlus a600034
Pregnancy cat. C (USA)
Legal status Unscheduled
Routes Oral
Pharmacokinetic data
Bioavailability  ?
Metabolism Hepatic
Half-life 24 hours
Excretion Fecal
Identifiers
CAS number 68844-77-9 YesY
ATC code R06AX11
PubChem CID 2247
DrugBank APRD00585
ChemSpider 2160 YesY
UNII 7HU6337315 YesY
KEGG D00234 YesY
ChEBI CHEBI:2896 YesY
ChEMBL CHEMBL296419 YesY
Chemical data
Formula C28H31FN4O 
Mol. mass 458.571
SMILES eMolecules & PubChem
 N(what is this?)  (verify)

Astemizole (marketed under the brand name Hismanal) was 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 It has been withdrawn from the market in most countries because of rare but potentially fatal side effects (QTc interval prolongation and related arrhythmias).

Contents

Metabolism

It is metabolized by CYP3A4.[1]

It has been withdrawn from the market in most countries because of rare but potentially fatal interactions with CYP3A4 enzyme inhibitors (e.g. erythromycin, grapefruit juice).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%.

Astemizole may cause life threatening arrhythmia.

Toxicity

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

Research

It has been reported that this drug might prevent much of the muscle wasting (atrophy) that occurs in immobile, bedridden patients.[2] An experiment on a small number of mice showed that astemizole blocked the activity of a protein present in muscle that is involved in muscle atrophy.[3] However the concerns for the drug's long-term 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.[4]

External links

References

  1. ^ Matsumoto S, Yamazoe Y (February 2001). "Involvement of multiple human cytochromes P450 in the liver microsomal metabolism of astemizole and a comparison with terfenadine". British journal of clinical pharmacology 51 (2): 133–42. PMC 2014443. PMID 11259984. http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0306-5251&date=2001&volume=51&issue=2&spage=133. 
  2. ^ "Purdue researchers find 'switch' for skeletal-muscle atrophy". Purdue University. 2006-05-24. http://news.uns.purdue.edu/html4ever/2006/060524.Pond.atrophy.html. Retrieved 2009-06-22. 
  3. ^ Wang X, Hockerman GH, Green Iii HW, Babbs CF, Mohammad SI, Gerrard D, Latour MA, London B, Hannon KM, Pond AL (May24 2006). "Merg1a K+ channel induces skeletal muscle atrophy by activating the ubiquitin proteasome pathway". FASEB J 20 (9): 1531. doi:10.1096/fj.05-5350fje. PMID 16723379. 
  4. ^ 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 (8): 415–16. doi:10.1038/nchembio806. PMID 16816845.