Pemirolast in Allergen Challenge (PEMAG)

Inclusion Criteria: * Age 18-65 years inclusive * Diagnosed asthma as defined by at least one of the following: * response to standard asthma treatment * episodic wheezing * change in lung function over short periods of time * Non-smoker for the past two years and a total of smoking less than 5 pack-years * Stable intermittent asthma, only using bronchodilator therapy as needed for the last 4 weeks * FEV1 ≥ 75 % of predicted * A positive skin prick test to pollen (grass, birch, mugwort) or animal dander (dog, cat) and a history of associated symptoms on exposure. Exclusion Criteria: * Any significant respiratory disease, other than asthma. * Subjects with seasonal asthma may not be included if they are in their season and subjects allergic to animal dander must not have a pet on their own or similar close exposure. * Use of: * Oral, injectable or inhaled glucocorticosteroid treatment for the last 4 weeks prior to inclusion or during the study * Inhaled long-acting β2-agonists, anticholinergic bronchodilators, antihistamines, theofyllines, nasal or inhaled cromones and antileukotrienes within 2 weeks of screening * Beta-blocking agents. * Immunomodulator drugs * NSAIDs. * Upper or lower respiratory tract infection within 4 weeks of screening * Females who are pregnant, intend to be or who are lactating. Female subjects of childbearing potential who are not willing to use adequate contraceptive methods (measures as required by local requirements or practice) during participation in the trial until at least three days after last intake of study treatments. Male subjects not surgically sterilized, who or whose partner is not using adequate contraceptive methods (measures as required by local requirements or practice) during participation in the trial until at least three days after last intake of study drug. * Subjects with BMI \>30. * Evidence (from clinical laboratory tests, physical examination or medical history) of hepatic disease (other than Gilbert´s Syndrome) * Evidence (from physical examination or medical history) of any diseases that affects gastrointestinal absorption. * A diagnosis of brittle asthma (rapid fluctuations in disease severity). * Participation in other study in the four weeks prior to screening. * Evidence of drug or alcohol abuse. * History of having taken barbiturates or other drugs affecting the liver drug-metabolising enzymes within one month of the start of the trial. * Blood donor during the last four months prior to study start and throughout the study.