β-agonist effect in the lung
β-agonist effects in the lung
Stimulation of β2-receptors relaxes constricted airway smooth muscle (ASM). These agents can be administered by either inhalation or oral therapy. Although the inhaled route is preferred in order to minimize systemic side effects that occur from non-β2-receptor specific binding.
In addition to direct effects on constriction, the intracellular signal trafficking leads to a higher level of PKA that also can modulate (decrease) inflammation. However, clinically this is not very significant. To see this mechanism, see also theophylline.
β-agonists act for about 4 hours.
β-agonists begin to act after about 30 minutes.
Extra info: When inhaled, these agents act almost immediately to reduce bronchial constriction.
β2-agonists are effective agents useful in combination with anticholinergic agents.
Extra info: This is true since both agents work by different mechanisms to inhibit bronchial smooth muscle cells.