Astemizole was indicated for use in the relieving allergy symptoms, particularly rhinitis and conjunctivitis. It has been withdrawn from the market however due to concerns of arrhythmias.
Astemizole is a second generation H1-receptor antagonist. It does not significantly cross the blood brain barrier and therefore does not cause drowsiness or CNS depression at normal doses.
Mode of Action:
Astemizole competes with histamine for binding at H_-receptor sites in the GI tract, uterus, large blood vessels, and bronchial muscle. This reversible binding of astemizole to H_-receptors suppresses the formation of edema, flare, and pruritus resulting from histaminic activity. As the drug does not readily cross the blood-brain barrier and preferentially binds at H_ receptors in the peripehery rather than within the brain, CNS depression is minimal. Astemizole may also act on H_-receptors, producing adverse effects.
Almost completely metabolized in the liver and primarily excreted in the feces.
LD50=2052mg/kg in mice
Wang X, Hockerman GH, Green HW 3rd, Babbs CF, Mohammad SI, Gerrard D, Latour MA, London B, Hannon KM, Pond AL: Merg1a K+ channel induces skeletal muscle atrophy by activating the ubiquitin proteasome pathway. FASEB J. 2006 Jul;20(9):1531-3. Epub 2006 May 24. Pubmed Chong CR, Chen X, Shi L, Liu JO, Sullivan DJ Jr: A clinical drug library screen identifies astemizole as an antimalarial agent. Nat Chem Biol. 2006 Aug;2(8):415-6. Epub 2006 Jul 2. Pubmed
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