Comparison of albuterol and isoetharine for acute asthma

American Family Physician,  June, 1996  

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Isoetharine and albuterol are beta-adrenergic agonists used in nebulized form for the treatment of acute exacerbations of asthma. Albuterol is more selective for beta2 receptors and has a longer duration of action, although a slower onset, than isoetharine. Shrestha and colleagues conducted a randomized, double-blind study to compare the effects of these medications on adult patients with acute asthma attacks.

Patients were included in the study if they had an onset of asthma before age 45, had no more than a 10 pack-year history of smoking, showed no evidence of bronchitis, engaged in near-normal activity levels and had a forced expiratory volume in one second ([FEV.sub.1]) of less than 40 percent at presentation. Patients were randomized to receive either 0.5 mL of albuterol or 0.5 mL of isoetharine nebulized with 2.5 mL of saline. The nebulization treatment was repeated hourly, and the patients received other nonnebulized medications as needed. Patients were discharged if they had at least a 50 percent improvement in [FEV.sub.1] to at least 40 percent of their predicted value, an [FEV.sub.1] of at least 60 percent of their predicted value or an [FEV.sub.1] equal to their baseline [FEV.sub.1]. Patients were otherwise admitted for inpatient management. Patients were interviewed about side effects, and these responses were graded on a scale, of 1 to 4 (1 = just noticeable; 4 intolerable).

Of the 48 patients who completed the study, 21 were assigned to isoetharine treatment and 27 to albuterol treatment. Overall, the isoetharine group showed a greater improvement in [FEV.sub.1] after the first treatment than the albuterol group. While waiting for the second treatment, 19 (90 percent) of the 21 patients in the isoetharine group showed worsening [FEV.sub.1] values, compared with only 10 (36 percent) of the 28 patients in the albuterol group. Just before the second treatment, the [FEV.sub.1] of the two groups became identical. After three treatments, the average overall improvement in [FEV.sub.1] was essentially the same for the two groups; the isoetharine group showed greater improvements after each treatment but also showed more decline in [FEV.sub.1] between treatments than the albuterol group. The isoethamine group reported more adverse effects than the albuterol group (36 percent versus 4 percent). Major adverse effects were palpitations, nervousness and tremulousness. Most of these side effects were reported to be barely noticeable.

The authors conclude that albuterol use is probably the treatment of choice in most patients with asthma exacerbations, primarily because it has fewer side effects than isoetharine. However, the more rapid onset of isoetharine may make it preferred in the patient with severe bronchospasm. (Shrestha M, et al. Isoetharine versus albuterol for acute asthma: greater immediate effect, but more side effects. Am J Medicine 1996;100:323-7.)

COPYRIGHT 1996 American Academy of Family Physicians
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