Bronchoconstriction, inflammation, and loss of lung elasticity are the most common processes that result in respiratory compromise. Bronchoconstriction can be treated with adrenergic agonists, cholinergic antagonists, and some other compounds. Inflammation is treatable with corticosteroids. Obstruction of the airways can also occur with infection and increased secretions. The infection is treated with antibiotics. Because the antibiotics and steroids have been covered elsewhere, this chapter focuses on the bronchodilators. Most of this will be a review from autonomics.
Drugs used in the treatment of bronchoconstriction include inhaled corticosteroids, β-agonists, cholinergic antagonists, and methylxanthines.
If you add cromolyn and the leukotriene modifiers, which are prophylactic agents, and corticosteroids for chronic treatment, you are all set.
Most of these drugs are now administered by inhalation. This gets the drug to the site of action and limits the systemic effects.
β2-Agonists cause bronchodilation.
Inhaled corticosteroids used in the treatment of asthma include:
Inhaled corticosteroids reduce inflammation in the bronchial tree.
Interleukin-5 (IL-5) antibodies will also reduce inflammation by binding to IL-5 and blocking its binding to the IL-5 receptor on the surface of eosinophils. Since IL-5 is the major cytokine involved in growth, differentiation, and activation of eosinophils, it makes sense that inhibiting the action of IL-5 will reduce production of eosinophils and reduce airway inflammation. Two IL-5 antibodies are available at this time—reslizumab and mepolizumab (note ‘mab’ ending).
Inhaled short-acting β2-agonists are the most effective drugs available for treatment of acute bronchospasm and for prevention of exercise-induced asthma. β2-Selective agents are preferred, to avoid the cardiac effect of β1-activation. Use of long-acting β2-agonists has been associated with an increased risk of asthma-related death, intubation or hospitalization, and it is no longer recommended that long-acting β2-agonists be used as monotherapy for asthma.
There are a number of β-agonists that are used in the treatment of asthma and chronic obstructive pulmonary disease (COPD).
|β-Agonists Used as Bronchodilators |
|ALBUTEROL (SA) ||arformoterol (LA) |
|levalbuterol (SA) ||formoterol (LA) |
|pirbuterol (SA) ||indacaterol (LA) |
| ||olodaterol (LA) |
| ||salmeterol (LA) |
|SA, short-acting; LA, long acting || |
In an emergency, such as the bronchoconstriction associated with anaphylaxis, epinephrine can be used. Use of a short-acting β-agonist more than two to three times a week means that the asthma is not well controlled and adjustments to baseline medication need to be made. Long-acting β-agonists can be used in combination with inhaled corticosteroids to control asthma symptoms.
Leukotriene modifiers can be used as an alternative to inhaled corticosteroids, ...