Astemizole

Mechanism :

Astemizole is a potent, long-acting, and selective histamine H1-antagonist. It produces a dose-related inhibition of skin reactions to intradermal histamine. Astemizole inhibits the nose reaction to nasal challenge with histamine and allergens. It inhibits the bronchial reaction to inhaled histamine and allergens in asthmatic patients. Astemizole has extremely weak serotonin antagonism, no anticholinergic properties, antagonism of dopamine and other catecholamines.

Indication :

• Seasonal allergic rhinitis
• Allergic conjunctivitis
• Chronic urticaria

Contraindications :

Concomitant administration of Astemizole with erythromycin is contraindicated because erythromycin is known to impair the cytochrome P450 enzyme system which also influences astemizole metabolism.

Concomitant administration of astemizole with ketoconazole tablets is contraindicated because oral ketoconazole significantly inhibits the metabolism of astemizole, resulting in elevated plasma levels of astemizole and desmethylastemizole, cardiovascular events are associated with elevation of astemizole and/or astemizole metabolite levels resulting in electrocardiographic QT prolongation.

Concomitant administration with itraconazole is also contraindicated.

Astemizole is contraindicated in patients with known hypersensitivity to astemizole or any of the inactive ingredients.

Dosing :

Adverse Effect :

Increase body weight due to an increase in appetite, hypersensitivity reactions (angioedema, bronchospasm, photosensitivity, pruritus, rash, anaphylactoid reactions, serious, life-threatening cardiovascular adverse events).

Interaction :

Ketoconazole/Itraconazole: Concomitant administration of ketoconazole tablets or itraconazole with astemizole is contraindicated.
Fluconazole, Metronidazole, and Miconazole IV: Due to the chemical similarity of ketoconazole, concomitant use of these products is not recommended.
Macrolides (Including Erythromycin): Concomitant administration of erythromycin with astemizole is contraindicated.
Macrolide Antibiotics: Concomitant administration of astemizole with other macrolide antibiotics, including troleandomycin, azithromycin, and clarithromycin, is not recommended.

Hepatic Dose :