title: Onset and duration of action of ketotifen 0.025% and emedastine 0.05% in seasonal allergic conjunctivitis : efficacy after repeated pollen challenges in the vienna challenge chamber.
abstract: OBJECTIVE
  To compare the efficacy, onset and duration of action, and the safety of ketotifen fumarate 0.025% ophthalmic solution and emedastine difumarate 0.05% ophthalmic solution in subjects with seasonal allergic conjunctivitis (SAC) induced by allergen exposure, using the Vienna Challenge Chamber model.
  
  
  METHODS
  This was a double-masked, randomised, comparative, crossover study conducted at an allergy outpatient clinic in Austria.
  
  
  METHODS
  Subjects with an allergy to grass pollen were exposed to the allergen in a pollen chamber for 4 hours, followed by a 3-hour break and then a second exposure for 3 hours.
  
  
  METHODS
  Study participants were randomised to a treatment sequence (ketotifen followed by emedastine or emedastine followed by ketotifen), receiving 1 drop per eye of ketotifen or emedastine 2 hours after the initial allergen exposure in the pollen chamber.
  
  
  RESULTS
  Individual and composite ocular, individual and composite nasal, and total (ocular + nasal) symptom complex scores were determined by repeated exposure to allergen 0-2 hours and 5-8 hours after dosing. Onset of action was defined as the time to the first observation of a 20% reduction from baseline in the composite ocular symptom score.
  
  
  RESULTS
  All 37 subjects enrolled completed the study. The median time to onset of action was 15 minutes for ketotifen and 30 minutes for emedastine. This difference was significant using the generalised linear model (p = 0.048), but not for the log-rank test analysis. In the initial 2 hours post dose, ketotifen provided significantly greater relief of both composite ocular symptoms (p = 0.026) and total symptom complex (p = 0.014). Both medications were effective in reducing symptoms 5 to 8 hours after dosing. No adverse events were reported for either treatment.
  
  
  CONCLUSIONS
  In the Vienna Challenge Chamber model, ketotifen and emedastine both effectively alleviated ocular symptoms of SAC after single-dose administration. Ketotifen had a faster onset of action and provided better symptom relief than emedastine during the first 2 hours after dosing. The rapid onset of action and symptom control make ketotifen a valuable treatment for SAC.
authors.affiliation: ENT Clinic, University of Vienna, Vienna, Austria.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Horak
authors.forename: Petra
authors.initials: P
authors.lastname: Stübner
authors.forename: René
authors.initials: R
authors.lastname: Zieglmayer
authors.forename: Alexander
authors.initials: A
authors.lastname: Kawina
authors.forename: Michael
authors.initials: M
authors.lastname: Moser
authors.forename: René
authors.initials: R
authors.lastname: Lanz