Inclusion criteria:

• Age 5 to 12 years at time of screening
• Chronic asthma as evidenced by one or more of the following historical findings for at least 6 months during the past year:
• Asthma symptoms at least 2 times per week
• 2 or more usages per week of an inhaled bronchodilator
• Daily asthma medication
• Current asthma symptoms either by diary symptom code of 1 or greater or am or pm PEFR less than 80% of personal best post-bronchodilator value by diary, on 8 or more days during the prn screening period
• Methacholine sensitivity: estimated PC20 FEV1 less than or equal to 12.5 mg/ml
• Consent of guardian and assent of child
• Ability to comply with trial for 5 - 6.5 years

Exclusion criteria:

• Presence of one or more of the following confounding or complicating problems:
• Any other active pulmonary disease
• Any chronic condition presumed to interfere with the successful completion of the project or confound its interpretation
• Pulmonary function testing findings suggesting a ventilatory defect other than asthma, or evidence of existing irreversible lung damage
• Severe chronic sinusitis or nasal polyposis
• Introduction of or a change in allergen immunotherapy within the past month
• Use of more than 4 sprays of nasal steroids daily (only beclomethasone allowed)
• Pregnancy
• Current use of metoclopramide, ranitidine, or cimetidine
• Treatment for gastroesophageal reflux
• Participation in another drug study
• Evidence of severe asthma as indicated by one or more of the following:
• Two or more hospitalizations for asthma in the past year
• Six or more steroid bursts in the past year
• Demonstrated need for continuous use of glucocorticoids, either oral or inhaled
• When off inhaled O2-agonist for more than 4 hrs and theophylline for more than 24 hrs, FEV1 less than 65% predicted
• Intubation for asthma at any time in the past
• Need for 9 or more puffs/day of albuterol for each of 3 consecutive days (excluding preventive use prior to exercise), or nocturnal asthma awakenings more than 1.5 times per week on average, or average diary card symptom code greater than 2, or requirement for other medications to control asthma, during prn screening period
• Inability to perform 3 acceptable FVC maneuvers of which at least 2 reproducible FEV1s are within 10% of the largest FEV1
• Inability to complete the methacholine challenge or methacholine PC20 FEV1 greater than 12.5 mg/ml
• Evidence that patient or family may be unreliable or non-compliant or may move from the metropolitan area before trial completion