A Closer Look at Bronchodilators in Treatment of COPD

Patients who have COPD are often prescribed medications called bronchodilators. Bronchodilators work by relaxing and expanding the smooth muscle of the airways making it easier to breath. Three types of bronchodilators are commonly used for the treatment of emphysema: beta adrenergic agonists, anticholinergics and methylxanthines.

1. Beta Agonists

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:

• Albuterol
• Metaproterenol
• Terbutaline

Some examples of long-acting beta agonists:

• Salmeterol
• Formoterol
• Bambuterol

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)
• Palpitations
• Premature ventricular contractions
• Tremors
• Sleep disturbances
• Decreased potassium levels (hypokalemia)

2. Anticholinergics

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:

• Atrovent
• Spiriva
• Combivent

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)

3. Methylxanthines

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
• Convulsions

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 more information about bronchodilator inhalers, ask your healthcare provider. Not getting the answers you need? Let's talk in the COPD Forum.

_Source:

Global Strategy for the Diagnosis, Management and Prevention of COPD, Global Initiative for Chronic Obstructive Lung Disease (GOLD) 2006. Available from: http://www.goldcopd.org.