Ketotifen fumarate is a noncompetitive antagonist of histamine H1 receptors and functions additionally as a mast cell stabilizer It inhibits histamine-mediated allergic responses through preventing histamine receptor activation and limiting mast cell degranulation Its pharmacological activity involves suppression of calcium influx into mast cells thus inhibiting histamine release Ketotifen fumarate is extensively utilized in biomedical research focusing on allergy and asthma pathophysiology to assess mast-cell-mediated mechanisms and histamine signaling pathways In vitro studies report its IC50 values ranging approximately from 0 8 to 2 5 M depending on assay parameters and cell types This compound commonly serves as a pharmacological tool when investigating allergic inflammation asthma and histamine-dependent cellular events