A Study to Evaluate Efficacy and Safety of Methacholine Chloride Challenge Test in Diagnosis of Adult Asthma

Inclusion Criteria: * FEV1/forced vital capacity(FVC) must be 70% or more * \<10% decrease in FEV1 in response to inhalation of normal saline Exclusion Criteria: * Moderate airflow limitation (FEV1 \< 60% predicted or \< 1.5 L) * Heart attack or stroke in last 3 months * Uncontrolled hypertension, systolic BP\>200, or diastolic BP\>100