According to the National Asthma Education Prevention Program, beta agonists are the recommended first-line treatment for asthma. For acute exacerbations, this medication is usually given with aerosolized saline in a dosage of 2.5 to 5 mg every 20 minutes for the first hour. The optimal dosage of albuterol has not been determined by controlled studies, although pediatric data indicate that higher cumulative dosages lead to greater improvement in pulmonary function. In Europe, dosages of 5 to 10 mg are commonly used for treatment of acute asthma. Emerman and colleagues compared the efficacy of 2.5 mg of albuterol with that of 7.5 mg in adults with acute asthma.

Patients enrolled in the study were 18 to 50 years of age and had presented to the emergency department with an acute exacerbation of asthma. Patients with a previous diagnosis of chronic obstructive pulmonary disease, lung surgery or lung cancer were excluded. Also excluded were patients with clinical evidence of pneumonia, congestive heart failure or pneumothorax. Oxygen was given to maintain a saturation of more than 91 percent, and three measurements of the forced expiratory volume in one minute (FEV₁) were obtained, with the highest value used as the baseline value. The patients were then randomized in a double-blind fashion to receive either 2.5 or 7.5 mg of nebulized albuterol every 20 minutes for one hour. The patients were also given 60 mg of oral prednisone. Spirometry was obtained after each of the first two treatments and 40 minutes after the third dose of albuterol. The patients were discharged or admitted to the hospital based on spirometry values and the clinical decision of the emergency department physician.

A total of 160 patients were randomized into the study; most of them were women. All of the study subjects had been receiving out-patient therapy for asthma. Most of the study subjects were using beta agonists (84 percent), and significantly smaller percentages of patients were using inhaled steroids, theophylline or oral steroids. Thirty percent of the study subjects were smokers.

The mean pretreatment FEV₁ was 36.9 percent of predicted in the low-dose albuterol group and 41.5 percent of predicted in the high-dose group. After three treatments, the final FEV₁ was 50.6 percent of predicted in the 2.5-mg group and 56.3 percent of predicted in the 7.5-mg group. These values were not statistically significant, nor were the overall improvements in FEV₁ in both groups of patients. Forty-three percent of the patients in the low-dose group and 39 percent in the high-dose group were admitted to the hospital. Almost 50 percent of the patients in the low-dose group complained of nausea, tremor, chest pain, palpitations or headache, compared with 44.2 percent in the high-dose group.

The authors conclude that a 7.5-mg dosage of albuterol offers no apparent clinical advantage to the standard 2.5-mg dosage in the acute treatment of asthma. As shown in previous studies, patients with an inadequate response to the first dosage of albuterol do not respond to an increased dosage and usually require hospital admission.