Mary Skowronski

Effect of long-term salmeterol treatment on exercise-induced asthma.

BACKGROUND With long-term administration of salmeterol, the extent of protection afforded by the drug against experimental precipitants of asthma such as methacholine and adenosine may decrease. Whether this effect extends to a clinically relevant stimulus such as exercise is unknown. METHODS We performed a random-order, double-blind, crossover trial in 20 patients with exercise-induced asthma. Each patient received inhaled salmeterol or placebo twice daily for a month, with a one-week washout period between treatments. The patients performed cycle ergometry while breathing frigid air 30 minutes after the morning dose and 9 hours later on the 1st, 14th, and 29th study days. The primary end point was the extent of the decrease in forced expiratory volume in 1 second (FEV1) 10 minutes after exertion. RESULTS With placebo, significant airway narrowing developed at all times (mean [+/-SE] decrease from base line in FEV1, 19+/-2 percent in the morning and 18+/-2 percent in the evening). The morning dose of salmeterol attenuated the degree of bronchoconstriction at all times (decrease in FEV1 on day 1, 5+/-2 percent; on day 14, 10+/-3 percent; and on day 29, 9+/-3 percent; P=0.10). Its ability to act throughout the day, however, decreased with long-term administration (decrease in FEV1 from morning to evening on day 1, 6+/-2 percent; on day 14, 15+/-3 percent; and on day 29, 14+/-3 percent; P=0.003). CONCLUSIONS Protection against exercise-induced asthma is maintained with long-term administration of salmeterol, but the length of time that the drug remains active after a single dose decreases.

Observations on the physiological interactions between obesity and asthma

To explore whether asthma and obesity share overlapping pathogenic features, we examined the impact of each alone, and in combination, on multiple aspects of lung function. We reasoned that if they influenced the lungs through similar mechanisms, the individual physiological manifestations in the comorbid state should interact in a complex fashion. If not, then the abnormalities should simply add. We measured specific conductance, spirometry, lung volumes, and airway responsiveness to adrenergic and cholinergic agonists in 52 normal, 53 asthmatic, 52 obese, and 53 asthmatic and obese patients using standard techniques. Six-minute walks were performed in subsets from each group. Asthma significantly lowered specific conductance and the spirometric variables while increasing airway reactivity and residual volume. Obesity also reduced the spirometric variables as well as total lung capacity and functional residual capacity. Residual volume, specific conductance, and airway responsivity were unaltered. With comorbidity, the disease-specific derangements added algebraically. Features that existed in isolation appeared unchanged in the combination, whereas shared ones either added or subtracted depending on the individual directional changes. Synergistic interactions were not observed. Body mass index weakly correlated with spirometry and lung volumes in asthma, but not with specific conductance or bronchial reactivity. Exercise performance did not aid in differentiation. Our findings indicate asthma and obesity appear to influence the respiratory system through different processes.

Salmeterol does not compromise the bronchodilator response to albuterol during acute episodes of asthma

PURPOSE The present study was undertaken to determine whether regular use of salmeterol reduces the emergency effectiveness of albuterol. PATIENTS AND METHODS Acutely ill asthmatic patients chronically taking salmeterol, and similar patients who were not taking salmeterol, were treated with albuterol, either as three aerosols of 2.5 mg every 20 minutes for 1 hour or two doses of 5.0 mg every 20 minutes. Peak expiratory flow measurements were monitored before and after each treatment. The time to disposition and the number of return visits were also recorded. RESULTS One hundred fourteen patients, 57 who took salmeterol and 57 who served as control patients, completed the study. Thirty-three patients in each group received the lower dose of albuterol, and 24 were given the larger amount. There were no significant pretreatment differences between the salmeterol and control groups in the severity of symptoms or the degree of airway obstruction. Both albuterol regimens improved peak flow. Responses in the control group and in the salmeterol group were similar (low-dose albuterol increase in peak flow = 49%, control = 35%, P = 0.37; high-dose albuterol increment in peak flow = 43%, control = 41%, P = 0.81). There were no significant differences between the control group and the salmeterol group in the mean length of stay, the proportion of subjects admitted to the hospital, or the number of return visits. CONCLUSIONS In patients with asthma, chronic use of salmeterol doses not interfere with the effects of standard doses of albuterol for the treatment of acute decompensations.