Asthma is a reversible airway inflammation characterized by excessive mucus production, thicking of airways, hypertrophy of submucosal glands, hyperplasia of mucus secreting cells and remodeling of airway. This inflammtory condition is caused by exposure to certain triggers e.g. pollen, fur, leather, latex, cold, dust, mites etc. Short-acting beta blockers e.g. albuterol, terbutaline and metaproterenol reverse asthma attack.