Wednesday, 10 April 2019

Compound (β2-agonist–corticosteroid) inhalers

Key examples

  • Seretide ®
  • Symbicort ®

 

Common indications

  1. Asthma: control of symptoms and prevention of exacerbations, used at ‘steps 3–4’ in the management of chronic asthma.
  2. Chronic obstructive pulmonary disease (COPD): to control symptoms and prevent exacerbations in patients who have severe airflow obstruction on spirometry and/or recurrent exacerbations.

 

Mechanisms of action

  • Compound inhalers contain an inhaled corticosteroid to suppress airway inflammation, and a long-acting β2-agonist (LABA) to stimulate bronchodilation. 
  • The prescription of these drugs in combination reduces the number of different inhalers that need to be taken and increases adherence to treatment. 
  • In asthma, compound inhalers ensure that long-acting β2-agonists are not taken without an inhaled corticosteroid. This is important because, without a steroid, long-acting β2-agonists are associated with increased asthma deaths. 
  • In COPD, combined treatment is more effective in reducing exacerbations than either drug alone.
  • Seretide® contains fluticasone and salmeterol. Symbicort® contains budesonide and formoterol.

 

Important adverse effects

  • Inhaled corticosteroids most commonly cause local adverse effects, including oral thrush and a hoarse voice. 
  • There is some evidence that they increase the risk of pneumonia in people with COPD. 
  • Where used at very high doses for a long time, systemic adverse effects including adrenal suppression, growth retardation (children) and osteoporosis may occur. 
  • Long-acting β2-agonists can cause tremor, tachycardia, arrhythmias and muscle cramps.

 

Warnings

  • High-dose inhaled corticosteroids, particularly fluticasone, should be used with caution in COPD patients with a history of pneumonia and in children, where there is potential for growth suppression. 
  • Care should be taken when prescribing long-acting β2-agonists for patients with cardiovascular disease, in whom tachycardia may provoke angina or arrhythmias.

 

Important interactions

  • Interactions are not generally a problem due to low systemic absorption. 
  • However, β-blockers may reduce the effectiveness of β2-agonists.

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