title: Comparative evaluation of olopatadine ophthalmic solution (0.1%) versus ketorolac ophthalmic solution (0.5%) using the provocative antigen challenge model.
abstract: OBJECTIVE
  This study was conducted to compare the efficacy and safety of olopatadine ophthalmic solution (0.1%) with ketorolac ophthalmic solution (0.5%) in a clinical model of acute allergic conjunctivitis. Olopatadine is a dual acting H1 histamine receptor antagonist and a mast cell stabilizer, shown to be effective in treating allergic conjunctivitis. Ketorolac is a non-steroidal anti-inflammatory drug approved in the United States for the relief of ocular itching associated with seasonal allergic conjunctivitis.
  
  
  METHODS
  The provocative antigen challenge model was used in this randomized, double-blind, single-center, crossover study. The allergen and concentration that consistently elicited a positive allergic reaction was used for challenge. After at least 14 days, subjects were randomized to receive either olopatadine in one eye and placebo in the contralateral eye, or ketorolac in one eye and placebo in the contralateral eye. Twenty-seven minutes after drug instillation subjects were challenged with allergen. At 3, 10, and 20 minutes following allergen challenge, subjects graded ocular itching and were assessed for hyperemia in conjunctival, ciliary, and episcleral vessel beds. Approximately 14 days later, subjects received the alternate treatment in one eye and placebo in the contralateral eye. They were again challenged with allergen and their responses were rated in the same manner.
  
  
  RESULTS
  Olopatadine significantly (p < 0.0001) reduced both ocular itching and hyperemia in all three vessel beds compared to placebo at all time points tested following allergen challenge. Ketorolac did not significantly reduce itching and showed a trend of increased hyperemia compared to placebo. Olopatadine was significantly (p < 0.001) more effective than ketorolac in reducing hyperemia and ocular itching at all time points and was also significantly (p < 0.05) more comfortable than ketorolac as reported by subjects immediately following drug instillation.
  
  
  CONCLUSIONS
  The study demonstrated that olopatadine is effective and safe in preventing and treating ocular itching and hyperemia associated with acute allergic conjunctivitis and is more effective and more comfortable than ketorolac.
authors.affiliation: Department of Ophthalmology, Royal Victoria Hospital, Montreal, Quebec.
authors.forename: J
authors.initials: J
authors.lastname: Deschenes
authors.forename: M
authors.initials: M
authors.lastname: Discepola
authors.forename: M
authors.initials: M
authors.lastname: Abelson
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000485:Allergens; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage*; D003233:Conjunctivitis, Allergic / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology; D018592:Cross-Over Studies; D003990:Dibenzoxepins / Q000008:administration & dosage*; D004311:Double-Blind Method; D005260:Female; D006634:Histamine H1 Antagonists / Q000008:administration & dosage*; D006801:Humans; D020910:Ketorolac / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D000069605:Olopatadine Hydrochloride; D009883:Ophthalmic Solutions; D012449:Safety; D012621:Seasons; D016896:Treatment Outcome
chemical_list: D000485:Allergens; D000894:Anti-Inflammatory Agents, Non-Steroidal; D003990:Dibenzoxepins; D006634:Histamine H1 Antagonists; D009883:Ophthalmic Solutions; D000069605:Olopatadine Hydrochloride; D020910:Ketorolac