Ketotifen belongs to the group of cycloheptothiophenones and has a pronounced antihistamine effect. It is a non-bronchodilating anti-asthma . Its mechanism of action is associated with inhibition of the release of histamine and other mediators of mastatsitam, with blocking of histamine H1 receptors and inhibition of the phosphodiesterase enzyme, resulting in an increase in the level of cyclic adenosine monophosphate in mast cells. Suppresses the effects of TAF (platelet-activating factor). When used alone, it does not stop attacks of bronchial asthma, but prevents their occurrence and reduces their duration and intensity, while in some cases they completely disappear.