I. Definition and Diagnosis

Gastroesophageal reflux and asthma: are they related?

The relationship between asthma and gastroesophageal reflux (GER) is controversial. This paper reviews the evidence for an association between them, the effect of asthma on GER, and the effects of GER and antireflux therapy on asthma. The association between the two conditions seems firm but studies of the effects of GER on asthma and asthma on GER are contradictory. Critical review suggests that GER affects asthma symptoms but not pulmonary function. Antireflux therapy improves asthma symptoms and reduces medication requirements but does not improve pulmonary function. The paradox of GER causing asthma symptoms but not changing pulmonary function may be explained by its increasing minute ventilation rather than triggering bronchospasm.

Epidemiology of Asthma

Epidemiology of asthma is discussed in terms of the prevalence, risk factors associated with increasing morbidity and mortality, impact on life-style, long-term prognosis, and economic impact. Those most at risk for development of asthma are young children, African Americans, and those in lower economic status and inner-city communities. The primary contributing factor to increasing morbidity and mortality is undertreatment. Contributing factors may be restricted access to continuing medical care, unstable family situations, cultural and language barriers, failure to recognize severity of the disease, and inability to afford care.

A retrospective assessment of cost avoidance associated with the use of nedocromil sodium metered-dose inhaler in the treatment of patients with asthma

A retrospective analysis of patient charts was performed for a single, multioffice pulmonary practice in Toronto, Ontario. Canada, to assess hospital care utilization and associated cost reductions after asthma prophylaxis with nedocromil sodium inhalation aerosol. Data were obtained from 310 adult patients with mild, moderate, or severe asthma who were treated in the practice between January 1988 and June 1994 and who had been placed on nedocromil sodium for at least 1 year. The number of office visits increased with nedocromil sodium therapy due to initial surveillance of the new medication, but no other changes were made in the usual protocol for each visit. After initiation of nedocromil sodium therapy, patients showed better asthma control as measured by improvements in pulmonary function scores and by reduced hospital utilization (both emergency department visits and hospital admissions). It is likely that the improvements in asthma control could result in cost savings, and savings projections for the Canadian health care system were made using the retrospective data collected for asthma-related hospital services. Prospective data are needed to confirm our findings.

Salmeterol: a novel, long-acting beta 2-agonist

OBJECTIVE

The clinical pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of the long-acting beta 2-agonist salmeterol are reviewed.

DATA SOURCES

A MEDLINE search was performed to identify English-language publications pertaining to salmeterol.

STUDY SELECTION

Open and controlled trials were reviewed in assessing clinical efficacy. Only the results of controlled, randomized trials were considered in the effectiveness evaluation.

DATA EXTRACTION

The primary measures of effectiveness in the clinical trials were bronchodilator activity and reduction of hyperresponsiveness that may reflect antiinflammatory activity. Bronchodilator activity was measured as changes in pulmonary function; reduction of hyperresponsiveness was evaluated using respiratory challenge with methacholine, histamine, allergen, or cold air. Secondary measures included symptom scores, need for rescue doses, and patient preference.

DATA SYNTHESIS

Salmeterol is a selective, beta 2-agonist that has been studied in the treatment of exercise-induced, nocturnal, and allergen-induced asthma. Salmeterol interacts with the traditional beta-receptor in a similar manner as other beta-agonists, and it exhibits potent in vitro antiinflammatory effects as an inhibitor of inflammatory mediator release. Less evidence exists for its in vivo antiinflammatory activity. Salmeterol demonstrates prolonged receptor occupancy, which is thought to contribute to its long duration of action. The recommended dose is 50 micrograms via metered-dose inhaler or dry-powdered inhalation. In the published clinical trials, salmeterol was more effective than albuterol in treating asthma, including exercise and allergen-induced asthma. Salmeterol's major advantage over other inhaled beta-agonists is its long duration of action (12 hours), making it an excellent choice for treatment of nocturnal asthma. A potential disadvantage is delayed onset of action. Tachyphylaxis to salmeterol's bronchodilator effects has not been shown, but tolerance to its protective effects against methacholine-induced bronchoconstriction has occurred. Adverse effects reported have been mild and have included headache, tremor, and palpitations.

CONCLUSIONS

Salmeterol is an effective beta 2-agonist in the treatment of asthma. However, several issues require further investigation regarding its long-term effects on disease control, significance of antiinflammatory activity, and role as a rescue medication.