Early Onset And Late Onset Asthma
Doctors have found that many asthma sufferers who inhaled an allergen did not begin to sneeze or wheeze immediately but only after several hours. Once they start wheezing they may continue to do so even for many hours and days. This interesting finding lead to laboratory and clinical studies which have shown that asthmatics react in two ways to inhalation challenges, both in real life and in the laboratory.
Normally on inhalation of the allergens airway narrows and the wheezing develops within ten minutes, peaks in thirty minutes, and resolves in one to three hours. This is called is called the early asthma response. But in almost 40% of the cases wheezing develops after three to four hours after the inhalation, peaks in four to eight hours, and may last for twenty-four hours. This is called the late asthma response. Late onset asthma produces heavy inflammation of bronchial tubes and is considered as the single most dominant cause of chronic asthma.
This interesting finding has produced very important changes in how doctors and specialists looks towards treating asthma. This has also prompted drug companies to focus their research on finding new molecules accordingly. The various asthma drugs have different actions in the early and late asthma responses. Bronchodilating drugs such as the beta agonists and theophylline work by opening up the bronchial tubes. While they prevent or relieve the symptoms of the early response, they have little or no effect on the late response. The non bronchodilating or anti-inflammatory drugs such as cromolyn and cortisone do not relieve symptoms once they occur but do prevent the late phase response. Cromolyn howewer is used to prevent both the early and late asthma responses. All patients with chronic asthma require an anti-inflammatory drug to control the inflammation of the late response. The broncho dilating medicines are useful only in mild asthma.