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Am Fam Physician. 2000;61(5):1494-1497

Some have suggested that regular use of long-acting bronchodilators, such as salmeterol, may cause the patient with asthma to be less responsive to a bronchodilator, such as albuterol, when needed in an emergency. Korosec and associates studied patients who were having an asthma attack and used salmeterol regularly to determine whether the patients were, in fact, less responsive to the short-acting bronchodilator used to abort an attack.

Patients who were at least 17 years of age and who took salmeterol regularly were included when they presented to an emergency department with an acute exacerbation of asthma. All patients reported periods of cough, dyspnea and wheeze, as well as symptom-free periods. Peak expiratory flow and pulse oximetry were measured. If the oxygen saturation was less than 90 percent, the patient was given supplemental oxygen.

A record was made of the patient's typical asthma attack presentation as well as medication usage. The best peak expiratory flow measurement (of three) was taken as the patient's baseline obstructive reading. In one group, subjects received 2.5 mg of nebulized albuterol for 20 minutes for three treatments. In another subgroup, patients received 5 mg of nebulized albuterol for 20 minutes for two treatments. Peak flow measurements were recorded after each treatment. After all treatments, patients were discharged if they were free of symptoms and signs (specifically, free of accessory muscle use and absent or diminished wheeze), and had a peak flow rate that was at least 60 percent of the predicted value. Length of hospital stay and number of return visits were also recorded.

There were 57 patients in each of the two groups: those who took salmeterol chronically and those who did not (control subjects). Thirty-three patients in each group received the lower-dose albuterol treatment; 24 patients received the higher dose. In those who had not taken salmeterol, the mean peak flow rate increased 39 percent. In those who had taken salmeterol, the figure was 50 percent.

These increases were not significantly different. Length of stay and number of admissions to the hospital were also not significantly different between the salmeterol and control groups.

The authors conclude that patients who take salmeterol chronically still respond to nebulized albuterol in cases of acute bronchoconstriction. Also, there is no need for patients taking salmeterol to increase the dosage of albuterol used in emergency situations.

In a related editorial, Peters and Fish call attention to the fact that salmeterol is known to be effective in the treatment of nocturnal asthma and may be useful in the treatment of aspirin-induced asthma. In addition, salmeterol is safer than theophylline. They find that the Korosec study answers the question of whether or not long-acting beta agonists reduce the effectiveness of albuterol with, as they say, “an unequivocal ‘no’.”

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