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 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. Astemizole does also act as
FIASMA (functional inhibitor of
acid sphingomyelinase). Astemizole has been researched as a treatment for
Creutzfeldt-Jakob Disease (CJD). Like many
carbendazim-derived benzimidazoles, it has been reported to interact with
tubulin and inhibit its polymerization. ==Toxicity==