Evaluate the Effects on Asthma Control of Rabeprazole Given Twice Daily in Subjects With Asthma.

Inclusion Criteria:

• Subjects must demonstrate their willingness to participate in the study and comply with its procedures by signing a written informed consent.
• Subjects must be 18 years of age or older.
• Subjects baseline FEV1 must be greater than or equal to 50% of predicted at both Visit 1 and visit 2, when all bronchodilators medications have been withheld for the specified intervals.
• Subjects must have physician-diagnosed asthma at visit 1 and report ongoing chronic or intermittent symptoms that include at least one of the following: wheezing, chest tightness, dyspnea, or cough.
• All subjects with a baseline FEV1 greater than or equal to 70% predicted must have a positive methacholine challenge (provocative dose required to reduce FEV1 20% is less than or equal to 10 mg inhaled methacholine) at either visit 1 or visit 2.
• All subjects with a baseline FEV1 greater than 50% but less than 70% must demonstrate at least 12% improvement in FEV1 after a bronchodilator is administered at visit 1 or visit 2.
• Subjects must report using rescue inhaled beta adrenergic agonist treatment at least twice weekly for asthma symptoms (e.g. 2 or more nebulized treatments or 4 or more puffs of inhaled albuterol per week).
• Subjects must experience asthma symptoms (wheezing, shortness of breath, cough, chest tightness, or nocturnal awakening) of at least mild severity on at least 2 days out of each week of run-in (1 week equals 7 days). In addition, the asthma symptom diary card score (over a two week period) must total at least 10 as recorded by the study subject in the run-in diary card. The run-in period may vary in length from 7 days to 28 days, as long as the 10 point score is achieved in a 10 day period.
• Subjects must be free of any clinically significant disease other than asthma.
• Women of childbearing potential must have a negative urine (hCG) pregnancy test at visit 1 or visit 2 and agree, if sexually active, to use medically accepted contraception as defined in ICH guidelines throughout the study.
• Subjects must agree to have the investigator inform their usual treating physician (if other than the study investigator) of their participation in the study.

Exclusion Criteria:

• Female subjects who are pregnant or lactating.
• Subjects who have required daily or alternate day oral corticosteroid treatment for more than a total of 21 days during the 6 months immediately prior to Visit 1.
• Subjects who require daily treatment with proton pump inhibitors, H2-receptor antagonists, or OTC anti-reflux medications).
• Subjects on immunotherapy, unless they are on a stable maintenance schedule for at least 6 months.
• Subjects who have used any investigational drug in the 30 days prior to visit 1.
• Subjects who have experienced allergic or idiosyncratic reactions to PPI, corticosteroid, or inhaled beta adrenergic agonist agents.
• Subjects demonstrating a change in FEV1 of 20% or more between visit 1 and 2.
• Subjects who have required ventilatory support for respiratory failure due to asthma within 5 years of Visit 1.
• Subjects who smoke, have smoked within the past 6 months, or have more than a 15 pack-year history of smoking.
• Subjects who have required hospitalization for asthma in the previous 3 months.