NCIt definition : The fumarate salt of ketotifen, a cycloheptathiophene derivative with anti-allergic
activity. Ketotifen selectively blocks histamine (H1) receptors and prevents the typical
symptoms caused by histamine release. This agent also interferes with the release
of inflammatory mediators from mast cells involved in hypersensitivity reactions,
thereby decreasing chemotaxis and activation of eosinophils.;