• They are long-acting bronchodilators for long-term regular use.
• Unlike short-acting bronchodilators, their effects usually last for 12 hours.
• The onset of bronchodilation for eformoterol occurs within 1 to 3 minutes and the time to peak effect is 1 to 2 hours.
• For salmeterol the onset of bronchodilation occurs within to to 30 minutes and peak effect occurs between 3 and 4 hours.

These differing response times are of no particular clinical significance when used appropriately on a long-term basis.

These agents are for patients who experience asthma symptoms despite treatment with conventionally prescribed doses of inhaled corticosteroids. They are particularly useful in the treatment of nocturnal asthma symptoms and in the management of exercise-induced asthma.

Long-acting beta2 agonists complement existing therapies:

• They do not replace inhaled or oral corticosteroid therapy. Patients must be warned not to stop or reduce their steroid therapy without medical advice, even if they feel better.
• They do not relieve acute asthma symptoms and are not indicated for an acute attack. Short-acting bronchodilators (e.g. salbutamol, terbutaline) remain the standard first-line treatment for acute relief of asthma symptoms. Patients must be cautioned to continue to have such rescue medication available at all times.

Short-acting bronchodilators are generally referred to as reliever medications. Long-acting bronchodilators will be known as 'symptom controllers'.

Content Updated August 1998