Chronic obstructive pulmonary disease (COPD) is characterized by chronic progressive airflow limitation. COPD typically is thought of as chronic bronchitis and/or emphysema. However, chronic bronchitis, defined clinically as cough and sputum production for at least 3 months of the year in at least two consecutive years, occurs independently of COPD and may not be associated with fixed airflow limitation. Emphysema refers to alveolar destruction, one of several structural abnormalities in COPD. The current Global Obstructive Lung Disease (GOLD) guidelines do not include either term in the definition of COPD (GOLD, 2016).
In the United States, COPD affects 6.8 million noninstitutionalized adults (
Schiller et al., 2012) and 10.8% of institutionalized residents (NSRCF, 2010). COPD is the third leading cause of death in the United States accounting for 138,080 deaths in 2010 (
Schiller et al., 2012). In 2010, the cost of COPD in the United States was estimated to be nearly $50 billion, including nearly $30 billion in direct health care expenditures (
ALA, 2015).
Historically identified with older men, COPD demographics have shifted. In 2009, COPD prevalence was highest in women of all age groups, except for the oldest age groups (75 and older) in which the prevalence among men and women was the same (
Akinbami & Liu, 2011). COPD prevalence increases with age (
Akinbami & Liu, 2011). For women, the highest prevalence is among women aged 65 to 74. For men, the highest prevalence is among men aged 75 to 84. In men and women aged 45 to 64 and women aged 65 and older, the prevalence of COPD is higher in whites than in blacks (
NHLBI, 2012). One of the challenges identifying persons with COPD is that people are asymptomatic during the early stages of the disease; by the time symptoms appear, the disease has progressed significantly.
INITIATING DRUG THERAPY
The current GOLD guidelines recommend drug therapy based on the COPD group (
Table 26.2). Nondrug therapy includes tobacco cessation, avoidance of environmental and occupational irritants, and energy conservation. A variety of drug and
nondrug therapies are available for tobacco cessation. All health care professionals should ask every patient at every encounter about tobacco smoking and then advise, assess, assist, and arrange for smoking cessation interventions as appropriate. Outdoor exercise and exertion should be avoided when pollution levels are high or temperatures are extreme. Maintaining physical activity is recommended for all persons with COPD. Persons with group B or D COPD may benefit from pulmonary rehabilitation and energy conservation techniques.
Goals of Drug Therapy
COPD is an irreversible but treatable medical condition; the goals of therapy are to reduce symptoms and reduce risk (GOLD, 2016). Medications, improving exercise tolerance, and improving overall health status may reduce symptoms and improve quality of life. Risk may be reduced by delaying disease progression and preventing and treating exacerbations. Drugs used to treat COPD include beta
2-adrenergic agonists, anticholinergics, corticosteroids, methylxanthines, and phosphodiesterase 4 inhibitors (
Table 26.3).
Beta2-Adrenergic Agonists
Mechanism of Action
Beta2-adrenergic agonists stimulate beta2-adrenergic receptors, increasing the production of cyclic 3′5′ adenosine monophosphate (cAMP). Increased cAMP relaxes airway smooth muscle and increases bronchial ciliary activity. Adverse effects of beta2-adrenergic receptor stimulation include increased skeletal muscle activity, central nervous system stimulation, hyperglycemia, and hypokalemia. All beta2-adrenergic agonists have slight cardiovascular stimulatory effects including increased heart rate, increased force of cardiac contractility, and increased cardiac conductivity.
Dosage and Time Frame for Response
The short-acting inhaled beta2-adrenergic agonists (SABAs) (e.g., albuterol, levalbuterol) have a quick onset (peak effect 10 minutes) and a short duration of action (3 to 4 hours). Salmeterol, the first long-acting beta2-adrenergic agonist (LABA), has an onset of action of about 2 hours and a 12-hour duration of action. Formoterol and arformoterol have an onset of action of 3 minutes and 7 to 20 minutes, respectively, and a 12-hour duration of action. The newer LABAs indacaterol, vilanterol, and olodaterol, sometimes called ultra-long-acting beta2-adrenergic agonists (ULABAs), have an onset of action of several minutes and a 24-hour duration of action. Oral (e.g., albuterol syrup and tablets, terbutaline tablets) and parenteral (e.g., terbutaline) dosage forms are available but have limited clinical use due to the quick onset of action, ease of administration, beta2-adrenergic agonist specificity, and minimal systemic exposure with inhaled beta2-adrenergic agonists. SABAs are indicated for the relief of acute COPD symptoms. LABAs are indicated for chronic maintenance therapy.
