Astemizole

Astemizole

Astemizole is a second-generation antihistamine drug that was once widely used for the treatment of allergic rhinitis. It was withdrawn from most markets in the late 1990s due to the risk of serious cardiac arrhythmias.

History

Astemizole was discovered by Janssen Pharmaceutica in 1977. It was widely marketed throughout the world by Janssen and other companies, including Hisamitsu Pharmaceutical in Japan, under various brand names including Hismanal, Astezen, and Astelong. However, it was withdrawn from most markets in the late 1990s due to the risk of serious cardiac arrhythmias.

Pharmacology

Astemizole is a second-generation antihistamine, which means it does not cross the blood-brain barrier and does not cause the sedation or drowsiness that are common side effects of first-generation antihistamines. It works by blocking the H1 receptor, which is the target of the histamine released during an allergic reaction.

Astemizole is also a potassium channel blocker, which is the reason for its risk of causing serious cardiac arrhythmias. This risk is increased when astemizole is taken in high doses, or when it is taken with certain other medications that inhibit its metabolism by the cytochrome P450 enzyme system.

Side effects and contraindications

The most common side effects of astemizole are headache, dizziness, and dry mouth. Rare but serious side effects include cardiac arrhythmias, especially torsades de pointes, a potentially fatal type of ventricular tachycardia.

Astemizole is contraindicated in people with a history of cardiac arrhythmias, and in those taking certain other medications, including macrolide antibiotics, azole antifungals, and certain antidepressants, which can inhibit its metabolism and increase the risk of cardiac arrhythmias.

See also

• Antihistamine
• Allergic rhinitis
• Cardiac arrhythmia

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