Page 360 - Basic _ Clinical Pharmacology ( PDFDrive )

20 Drugs Used in Asthma
C H A P T E R

Joshua M. Galanter, MD, &
Homer A. Boushey, MD

C ASE STUD Y

A 14-year-old girl with a history of asthma requiring daily and respirations are 32/min. Her mother states that she has
inhaled corticosteroid therapy and allergies to house dust used her albuterol inhaler several times a day for the past 3 days
mites, cats, grasses, and ragweed presents to the emergency and twice during the previous night. She took an additional
department in mid-September, reporting a recent “cold” com- two puffs on her way to the emergency department, but her
plicated by worsening shortness of breath and audible inspi- mother states that “the inhaler didn’t seem to be helping so I
ratory and expiratory wheezing. She appears frightened and told her not to take any more.” What emergency measures are
refuses to lie down but is not cyanotic. Her pulse is 120 bpm, indicated? How should her long-term management be altered?

A consistent increase in the prevalence of asthma over the past the bronchial vasculature, smooth muscle, secretory glands, and
60 years has made it an extraordinarily common disease. The goblet cells.
reasons for this increase—most striking in people under 18 years In mild asthma, symptoms occur only intermittently, as on
of age and shared across all modern, “Westernized” societies—are exposure to allergens or airway irritants such as air pollution
poorly understood. The global estimate of the number of affected or tobacco smoke, on exercise, or after viral upper respiratory
individuals is 300 million. In the United States alone, 17.7 million infection. More severe forms of asthma are associated with more
adults (7.4% of the population) and 6.3 million children (8.6% frequent and severe symptoms, especially at night. Chronic airway
of the population) have asthma. The condition accounts for constriction causes persistent respiratory impairment, punctuated
10.5 million outpatient visits, 1.8 million emergency department by periodic asthma exacerbations marked by acute worsening
visits, and 439,000 hospitalizations each year. Considering the of symptoms. These attacks are most often associated with viral
disease’s prevalence, the annual mortality in the USA is low— respiratory infections and are characterized by severe airflow
around 3500 deaths—but many of these deaths are considered obstruction from intense contraction of airway smooth muscle,
preventable, and the number has not changed much despite inspissation of mucus plugs in the airway lumen, and thickening
improvements in treatment. of the bronchial mucosa from edema and inflammatory cell infil-
The clinical features of asthma are recurrent episodes of tration. The spectrum of asthma’s severity is wide, and patients are
shortness of breath, chest tightness, and wheezing, often associ- classified based on two domains: impairment and risk. Measures
ated with coughing. Its hallmark pathophysiologic features are of impairment are based on the frequency and severity of symp-
widespread, reversible narrowing of the bronchial airways and a toms, the severity of airflow obstruction on pulmonary function
marked increase in bronchial responsiveness to inhaled stimuli. testing, and the intensity of therapy required for maintenance of
Its pathologic features are lymphocytic, eosinophilic inflamma- asthma control. Measures of risk are based on susceptibility to
tion of the bronchial mucosa. These changes are accompanied asthma exacerbations. Based on measures of impairment, patients
by “remodeling” of the bronchial wall, with thickening of the may be classified as having “mild intermittent,” “mild persistent,”
lamina reticularis beneath the epithelium and hyperplasia of “moderate persistent,” or “severe persistent” asthma, but will be

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