• Clinical science

Beta-2 adrenergic agonists

Abstract

β2 adrenergic agonists are used in pulmonology as bronchodilators, in obstetrics as tocolytic agents, and to manage patients with hyperkalemia. There are both short-acting and long-acting β2 agonists, and their duration of action determines their clinical application. Their effects are achieved through β2 receptor stimulation. Side effects are partially mediated by the β1 receptor and include anxiety and tremor, as well as life-threatening conditions such as ventricular arrhythmias.

Effects

  • All β2 adrenergic agonists selectively stimulate β2 adrenergic receptors.
    • Relaxes bronchial smooth muscle
Characteristic Active ingredient Onset of action Duration of action
Short-acting beta agonists (SABA)
  • 1–5 min
  • 4–6 h
Long-acting beta agonists (LABA)
  • 1–5 min
  • ≥ 12 h
  • 30–45 min

References:[1][2]

Side effects

  • Cardiac: : ventricular arrhythmias; , vasoconstriction, angina pectoris, tachycardia, and palpitations; may aggravate cardiomyopathy in patients with cardiovascular disease
  • Central nervous system/muscular: tremor, headache, anxiety, and sleep disturbances
  • Electrolytes
    • Hyperglycemia
    • Hypokalemia (risk of life-threatening arrhythmias!)
      • β2-mediated stimulation of Na+/K+-ATPase → intracellular K+ shift
  • Development of tolerance

Paradoxical bronchospasm may occur!

References:[1][3][2][4]

We list the most important adverse effects. The selection is not exhaustive.

Indications

  • Bronchial asthma: mediates spasmolysis of the bronchi
  • COPD: mediates spasmolysis of the bronchi
  • Preterm/undesired contractions in obstetrics: mediates tocolysis
  • Hyperkalemia: drives K+ intracellularly

Salmeterol should not be used as monotherapy during an acute asthma attack!

Contraindications

References:[3]

We list the most important contraindications. The selection is not exhaustive.

Guidelines & therapy recommendations

  • A face mask is recommended for children < 4 years on inhalational therapy.
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  • Viera AJ, Wouk N. Potassium disorders: Hypokalemia and hyperkalemia. Am Fam Physician. 2015; 92(6): pp. 487–495. url: http://www.aafp.org/afp/2015/0915/p487.html.
  • Lam F, Gill P. β-Agonist Tocolytic Therapy. Obstet Gynecol Clin North Am. 2005; 32(3): pp. 457–484. doi: 10.1016/j.ogc.2005.05.001.
last updated 08/01/2018
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