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.
- All β2 adrenergic agonists selectively stimulate β2 adrenergic receptors.
- Relax bronchial smooth muscle
|Pharmacodynamics of β2 adrenergic agonists |
|Characteristic||Agent||Onset of action||Duration of action|
|Short-acting beta agonists (SABA)|| || || |
|Long-acting beta agonists (LABA)|| || || |
| || |
- 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
- Hypokalemia (risk of life-threatening arrhythmias): β2-mediated stimulation of Na+/K+-ATPase → intracellular K+ shift
- Development of tolerance
Paradoxical bronchospasm may occur!
We list the most important adverse effects. The selection is not exhaustive.
Bronchial asthma: used to achieve spasmolysis of the bronchi.
- Acute exacerbation: use short-acting selective β2-agonists (e.g., albuterol)
- Prophylaxis (in chronic disease): use long-acting selective β2-agonists (e.g., salmeterol)
- COPD: used to achieve spasmolysis of the bronchi.
- Preterm/undesired contractions in obstetrics: used for tocolysis
- Hyperkalemia: Beta-2 adrenergic agonists drive K+ intracellularly.
Salmeterol should not be used as monotherapy during an acute asthma attack!
- Absolute contraindication: hypersensitivity to β2 adrenergic agonists
- Use with caution in patients with the following conditions:
- Cardiovascular disease (e.g., heart failure, hypertension, arrhythmias, coronary artery disease)
We list the most important contraindications. The selection is not exhaustive.
- A face mask is recommended for children < 4 years on inhalational therapy.