Three types of bronchodilators are commonly used for the treatment of COPD: beta adrenergic agonists, anticholinergics and methylxanthines. Bronchodilators are given on an as needed, or regular basis to prevent or reduce COPD symptoms.
Beta agonists can be either short-acting (effects lasting 4 to 6 hours) or long-acting (effects lasting 12 hours or more). Beta agonists can be given orally or by inhalation. The inhaled method is preferred, however, as it is quicker in onset and has less side effects.
When bronchodilators are administered by inhalation, proper use of a bronchodilator or metered dose inhaler (MDI) is an important aspect of effective treatment. The choice of an inhaler will depend upon your prescribing doctor and your ability to use them correctly, which can be determined during an office visit.
Long-acting or short-acting beta agonists have been shown to improve exercise tolerance in COPD.
Short-acting beta agonists include the following:
Some examples of long-acting beta agonists:
- Indacaterol (duration of action up to 24 hours)
Side effects of beta agonists are often dose related and more frequent in oral than inhaled methods of delivery. They include:
- Rapid heart rate (tachycardia)
- Premature ventricular contractions
- Sleep disturbances
- Decreased potassium levels (hypokalemia)
Anticholinergics are only available by the inhalation route. They have excellent bronchodilator effects and minimal side effects.
Anticholinergics may be of particular benefit to those patients who are not candidates for B-agonists or methylxanthines because of underlying heart disease.
The following lists some common antichlolinergics:
The most commonly reported side effects of anticholinergics are as follows:
- Dry mouth
- Metallic taste after inhalation
- Closed-angle glaucoma (extremely rare)
- Paradoxical bronchoconstriction (confirmed in asthmatics but not in COPD)
The mechanism underlying the beneficial effect of methylxanthines for the treatment of COPD is not well defined but may include improvement in respiratory muscle strength.
There are two types of methylxanthines that are commonly used in COPD, the first of which is taken by mouth and the second, intravenously (IV). They are:
- Theophylline (oral)
- Aminophylline (IV)
Because of the dangers of serious side effects, care must be taken when administering these medications, especially through the IV method, as a rapid heart rate or irregular heart rhythm can occur.
Serious side effects that indicate toxicity include:
- Heart dysrhythmias
Minor side effects may also be experienced in the way of headache, nausea, vomiting, diarrhea and heartburn.
Combination bronchodilator therapy - While the use of only one bronchodilator medication appears to be safe, combining them may actually increase the degree of bronchodilation, with the same or less side effects. For example, combining a short-acting beta agnonist and an anticholinergic appears to produce a greater improvement in FEV1, for a longer period of time, than either drug alone. Combining a beta agonist, an anticholinergic and/or theophylline may produce even greater improvements in lung function and overall health status. Combination therapy using formoterol and tiotropium (Spiriva) works better to improve FEV1 than the single components alone. Finally, combining a short-acting beta agonist and an anticholinergic is far superior in improving lung function and reducing symptoms than either drug alone.
Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2013. Available from: http://www.goldcopd.org.