long-acting beta-agonist

A long-acting beta-agonist, or LABA, opens the airways the same way a rescue inhaler does, but the effect lasts many hours rather than a few — so it is used on a schedule to keep the airways comfortably open all day rather than to put out a sudden fire.

Like its short-acting cousin, it stimulates beta-2 receptors to relax airway muscle, but its chemistry anchors it near the receptor so it keeps working for around twelve to twenty-four hours, depending on the drug. Taken once or twice daily, it provides steady bronchodilation for maintenance therapy in COPD and as add-on therapy in asthma.

There is an important safety rule in asthma: a LABA should never be used alone. Used without an inhaled steroid, it can mask worsening inflammation and has been linked to worse outcomes, so in asthma it is always paired with an anti-inflammatory inhaler. In COPD the picture differs, and LABAs are often used with an antimuscarinic, with or without a steroid.