Products
Ketotifen eye drops have been approved in many countries since 2000 (Zaditen Ophtha / -SDU, Zabak).
Structure and properties
Ketotifen (C19H19NOS, Mr = 309.43 g/mol) is a tricyclic benzocycloheptathiophene derivative structurally related to pizotifen (Mosegor, out of commerce). It is present in drugs as ketotifen hydrogen fumarate, a white to brownish yellow crystalline powder that is sparingly soluble in water.
Effects
Ketotifen (ATC S01GX08) has antihistamine, antiallergic, antiinflammatory, and mild anticholinergic properties. It is an antihistamine and also inhibits the release of inflammatory mediators such as histamine and the leukotrienes. The effects are rapid with topical application and last up to 12 hours.
Indications
For the treatment of seasonal allergic conjunctivitis.
Dosage
According to the professional information. Usually 1 drop is given twice daily in both eyes. See also under Administering eye drops. The duration of treatment should not exceed 6 weeks.
Contraindications
Ketotifen is contraindicated in cases of hypersensitivity. For complete precautions, see the drug label.
Interactions
Orally administered ketotifen may potentiate the effects of centrally depressant drugs and alcohol. When used topically, this interaction is unlikely.
Adverse effects
The most common potential adverse effects include local reactions to the eye such as causing burning and stinging. Systemic adverse reactions are observed only occasionally. Products without preservatives should be preferred because they may cause ocular side effects.
