Short-acting ?2-adrenergic agonists
The most generally used ‘relieving’ medication of asthma is short-acting ?2-adrenergic agonists. The short-acting ?2-adrenergic agonists relax smooth bronchial muscle and provide prompt relief of symptoms, usually within 30 minutes after administered by inhalation (i.e., metered-dose inhaler MDI or nebulizer). Common examples of such agonists include albuterol, bitolterol, pirbuterol and terbutaline. Its recommended use is in ameliorating acute attacks, because an increase in the use of short-acting ?2-adrenergic agonists or use of more than one canisters in a month indicates exacerbation of the disease. For example, Ventolin (Salbutamol) nebulized with oxygen can cause side effect including tachycardia, arrhythmias, tremor.
2. Systemic corticosteroids
A short course of systemic corticosteroids is also used as relieving medication by alleviating the inflammatory reaction in an acute episode. Although their onset of action is slow, more than 4 hours after administering orally or parenterally, systemic corticosteroids may be used to treat moderate to severe conditions because of their action in preventing exacerbation, early relapses, and speeding recovery.
3. Anticholinergic agents
It is one of quick asthma-relieving medications. By blocking effects of postganglionic efferent vagal pathways, it prevents bronchoconstriction.
Inhaling these medications produces bronchodilation by direct action on the large airways and does not change the composition or viscosity of the bronchial mucus. The commonly used examples include ipratropium. It is thought that they may provide some additive benefit for treatment of asthma exacerbations when administered with inhaled ?2-adrenergic agonists.