Products
Astemizole was commercially available in tablet and suspension form (Hismanal). It has been withdrawn from the market in many countries because of potential adverse effects and is no longer available (see below). It may well be replaced by other, better-tolerated antihistamines, such as cetirizine, loratadine, and fexofenadine.
Structure and properties
Astemizole (C28H31FN4O, Mr = 458.6 g/mol) exists as a white powder that is practically insoluble in water. It is a benzimidazole and piperidine derivative.
Effects
Astemizole (ATC R06AX11) has antihistamine and antiallergic properties. The effects are due to competitive antagonism at histamine H1 receptors.
Indications
For the treatment of hay fever, allergic rhinitis, urticaria, and allergic conjunctivitis.
Dosage
According to the SmPC. Medicines can be taken once daily because of the long half-life.
Contraindications
Full details of precautions and interactions can be found in the drug label.
Adverse effects
Astemizole may prolong the QT interval and cause cardiac arrhythmias. It is a substrate of CYP3A4 and susceptible to drug-drug interactions with CYP inhibitors.
