Methacholine challenge

Hello,
People that have bronchitis or asthma usually have to do a methacholine challenge test. Methacholine challenge is a test, used to determine if the patient's airways, called bronchial tubes are overly sensitive or hyper reactive. This is determined while the patient is breathing a drug called methacholine, which causes the airways to narrow. Duration of test is approximately 1.5 hours and before taking methacholine challenge you should eat normaly and drink plenty of fluids. Important is not take any antihistamines or bronchodilators for 12 hours prior to the test (I guess a doctor impacts these things).
I hope this has satisfied your question.