Astemizole

Routes of
administrationOralATC codeLegal statusLegal status Pharmacokinetic dataProtein binding~96%MetabolismHepatic (CYP3A4)^[1]Elimination half-life24 hoursExcretionFecalIdentifiersCAS NumberPubChem CIDIUPHAR/BPSDrugBankChemSpiderUNIIKEGGChEBIChEMBLCompTox Dashboard (EPA)ECHA InfoCard100.065.837 Chemical and physical dataFormulaC₂₈H₃₁FN₄OMolar mass458.581 g·mol⁻¹3D model (JSmol)  (verify)

Astemizole (marketed under the brand name Hismanal, developmental code R43512) was a second-generation antihistamine drug that has a long duration of action. Astemizole was discovered by Janssen Pharmaceutica in 1977. It was withdrawn from the market globally in 1999 because of rare but potentially fatal side effects (QTc interval prolongation and related arrhythmias due to hERG channel blockade).^[2][3]

Pharmacology

Astemizole is a histamine H1-receptor antagonist. It has anticholinergic and antipruritic effects.

Astemizole is rapidly absorbed from the gastrointestinal tract and 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).

Despite some earlier reports that astemizole does not cross the blood–brain barrier, several studies^[4][5] have shown high permeability and high binding to protein folds associated with Alzheimer's.

Astemizole may also act on histamine H₃ receptors, thereby producing adverse effects.^{[citation needed]}

Astemizole does also act as FIASMA (functional inhibitor of acid sphingomyelinase).^[6]

Astemizole has been researched as a treatment for Creutzfeldt-Jakob Disease (CJD).^[7]

Toxicity

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

References

External links

• Statement on Astemizole from Health Canada