Products
Beta2-sympathomimetics are usually commercially available as inhalation preparations (powders, solutions) administered with an inhaler, for example, metered-dose inhaler, diskus, Respimat, Breezhaler, or Ellipta. There are few drugs on the market that can be given perorally.
Structure and properties
Beta2-sympathomimetics are structurally related to the natural ligands epinephrine and norepinephrine. They may exist as racemates or as pure enantiomers.
Effects
Beta2-sympathomimetics (ATC R03AC) have sympathomimetic, bronchodilator, and, in some cases, anti-inflammatory properties. Effects last from about 3 to over 24 hours depending on the active ingredient. The effects are due to selective binding to beta2-adrenoceptors. This stimulates adenylyl cyclases, increasing the formation of cyclic adenosine monophosphate (cAMP). cAMP relaxes smooth muscle cells in the airways, mediating bronchodilatation.
Indications
For the treatment of obstructive airway disease:
- Bronchial asthma
- Acute bronchospasm
- Chronic bronchitis, chronic obstructive pulmonary disease (COPD).
Other indications:
- Hyperkalemia (promote the absorption of potassium into cells).
- Inhibition of labor
Dosage
According to the professional information. Depending on the duration of action, the drugs are inhaled between once to four times a day. In asthma, with the exception of mild symptoms, a combination with inhaled glucocorticoids or anti-inflammatory treatment is required.
Abuse
Beta2-sympathomimetics can be abused as doping agents in sports because of their bronchodilator and anabolic properties. Overuse of beta2-sympathomimetics by patients can also be considered abuse. Especially in asthmatics without anti-inflammatory therapy.
Agents
SABA (short-acting beta-agonists, duration of action between 3 to 6 hours):
- Fenoterol (Berodual N, over-the-counter: Berotec N).
- Salbutamol (Ventolin, generic).
- Terbutaline (Bricanyl)
LABA (long-acting beta agonists, duration of action 12 hours):
- Formoterol (Foradil, Oxis).
- Salmeterol (Serevent)
ULABA (Ultra Long-Acting Beta-Agonists, duration of action over 24 hours):
- Indacaterol (Onbrez Breezhaler).
- Olodaterol (Striverdi Respimat)
- Vilanterol (e.g., Relvar Ellipta + fluticasone furoate).
Other active ingredients: Hexoprenaline (Gynipral) is approved as a labor inhibitor in many countries. The following agents are not commercially available in many countries:
- Bambuterol
- Clenbuterol
- Levosalbutamol
- Pirbuterol
- Rimiterol
Contraindications
Contraindications depend on the active ingredients. Contraindications include:
- Hypersensitivity
- Cardiac arrhythmia
- Prolongation of the QT interval
- Pregnancy and lactation
Full precautions can be found in the drug label.
Interactions
Drug interactions are possible with the following agents, among others:
- Drugs that prolong the QT interval.
- MAO inhibitors, antidepressants
- Levodopa, levothyroxine, oxytocin
- Sympathomimetics
- Beta blockers
Adverse effects
The most common possible adverse effects include palpitations, muscle cramps, a tremor (shaking), headache, dizziness, upper respiratory tract infections, and restlessness. Beta2-sympathomimetics may cause cardiovascular effects such as an increase in pulse, an increase in blood pressure, cardiac arrhythmias or ECG changes, and may prolong the QT interval. They may cause paradoxical bronchospasm and lead to hypokalemia and hyperglycemia.