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.