A Study Of The Effects Of OC000459 In Subjects Known To Suffer From Grass Pollen Induced Allergic Rhinitis

The study will assess the efficacy of OC000459 200 mg twice daily orally in comparison to placebo when subjects are challenged in the Vienna Challenge Chamber for 6 hours. This is a randomised, double blind, placebo controlled, two way crossover evaluation. There will be a screening period of up to three weeks and a washout period of at least one week between the two treatment periods. There will be a follow up one to three weeks after the last dose of study drug.