The Effect of HFA - Beclomethasone Dipropionate Qvar on Bronchial Hyperreactivity in Preschool Children

26 - 30 patients, between 3 -6 years old, mild asthmatics, with positive adenosine challenge test, will received in a randomized, double blind, cross over assignment Beclometasone dipropionate (100µg twice a day) or placebo, through an inhaler (autohaler) device, attached to a spacer device, during four consecutive weeks. Adenosine Challenge test will be performed another time at the end of this four weeks period. After 2 weeks with no medication (wash out period) the patients will receive the second intervention (beclometasone dipropionate or placebo) in a cross over manner and will be submitted to the last adenosine challenge test. Clinical evaluation, resting spirometry and subjective evaluation through an analogical symptoms scale will be recorded in each visit.