Ketotifen Fumarate

About Ketotifen Fumarate

Ketotifen is a histamine H1 receptor blocker and mast cell stabilizer used to treat mild atopic asthma and allergic conjunctivitis.

Ketotifen is a benzocycloheptathiophene derivative with potent antihistaminic and mast cell stabilizing properties. It has a similar structure to some other first-generation antihistamines such as cyproheptadine and azatadine.

Ketotifen was first developed in Switzerland in 1970 by Sandoz Pharmaceuticals and was initially marketed for the treatment of anaphylaxis. In the US, it is now used in an over-the-counter ophthalmic formulation for the treatment of itchy eyes associated with allergies, and in Canada a prescription-only oral formulation is available and indicated as an add-on therapy for children with atopic asthma. In addition, oral ketotifen is used in Mexico and across Europe for the treatment of various allergic symptoms and disorders, including urticaria, mastocytosis, and food allergy.

Administered orally, ketotifen is indicated as an add-on medication in the chronic treatment of mild atopic asthma in children. It is also available as an over-the-counter ophthalmic solution which is indicated for the temporary prevention of itching of the eye due to allergic conjunctivitis.

Ketotifen is a non-competitive histamine antagonist and mast cell stabilizer. Administered orally, it functions as a non-bronchodilator antiasthmatic drug by inhibiting the effects of endogenous substances known to be inflammatory mediators. While effects can take 6 to 12 weeks to become apparent, the use of ketotifen has been demonstrated to reduce the frequency, severity, and duration of asthma symptoms, and may allow for a reduction in the use of other asthma therapies.

The precise mechanism(s) through which ketotifen exerts its therapeutic effects are unclear. Ketotifen is a potent and non-competitive antagonist of H1 histamine receptors, which is likely to be a significant contributor to its anti-allergic activity. In addition, ketotifen stabilizes mast cells and has demonstrated in vitro the ability to inhibit the release of allergic and inflammatory mediators such as histamine, leukotrienes C4 and D4 (i.e. SRS-A), and platelet-activating factor (PAF).

Other in vivo observations thought to contribute to ketotifen\'s efficacy in asthma include the inhibition of various PAF-mediated processes (e.g. airway hyperreactivity, eosinophil and platelet accumulation in the airways), prevention of leukotriene-induced bronchoconstriction, and suppression of eosinophil priming.