Nebulized isoetharine and fenoterol in acute attacks of asthma

Isoetharine versus albuterol for acute asthma: greater immediate effect, but more side effects

PURPOSE

To compare the magnitudes of the immediate effects of the nebulized beta-agonists isoetharine and albuterol in the treatment of acute severe asthma.

PATIENTS AND METHODS

Fifty-one adults presenting with severe asthma exacerbations (forced expiratory volumes in the first second of exhalation [FEV1] <40% of predicted) to the emergency department were randomized (double-blind) to receive hourly inhaled nebulization treatment with either isoetharine (5 mg) or albuterol (2.5 mg). The FEV1 was measured immediately before and after each nebulized treatment. Any side effects were recorded.

RESULTS

Immediately after the first nebulized treatment, the isoetharine group improved its mean FEV1 (+/-SEM) by a significantly greater amount than did the albuterol group: 60% +/- 11% versus 39% +/- 5%, respectively (P <0.05). One hour later the mean FEV1 were equivalent. This pattern repeated itself after the second hourly treatment. The two groups did not differ in any outcome parameters (FEV1 at discharge, number of nebulized treatments required, the number of inpatient admissions, number of clinical relapses after discharge). More patients treated with isoetharine had side effects (36% versus 4% for albuterol, P <0.01), 1 of whom required discontinuation from the study.

CONCLUSIONS

Both medications were equally effective in alleviating bronchospasm. The immediate effect of isoetharine was significantly greater, but equalized that of albuterol within an hour after treatment. There were more side effects with isoetharine.

A randomized, controlled comparison of isoetharine and albuterol in the treatment of acute asthma

STUDY OBJECTIVE

To determine whether treatment of acute asthma with repeated doses of nebulized albuterol leads to greater bronchodilation and lower hospital admission rate than treatment with nebulized isoetharine.

DESIGN

Randomized, double-blinded, controlled trial of albuterol and isoetharine.

TYPE OF PARTICIPANTS

Patients between 18 and 50 years old presenting with acute asthma. Patients were excluded if they had a history of sensitivity to the study drugs, had congestive heart failure or chronic-obstructive pulmonary disease, or were unable to perform spirometry. One hundred three patients were entered into the study.

INTERVENTIONS

All patients received oxygen and methylprednisolone in addition to administration of either isoetharine or albuterol. The nebulized aerosol was given at hourly intervals for a total of three doses.

MEASUREMENTS AND MAIN RESULTS

Spirometry was performed before treatment and again at 90 and 180 minutes. Initial forced expiratory volume at one minute (FEV1) was 38.1% of predicted normal for the albuterol group and 36.0% of predicted normal for the isoetharine group. At 180 minutes, FEV1 was 55.6% of predicted normal for the albuterol group and 57.1% of predicted for the isoetharine group (NS). Twenty-eight percent of the albuterol group required admission compared with 26% of the isoetharine group (NS). There was no difference in occurrence of side effects between the two groups.

CONCLUSION

Repeated doses of albuterol do not lead to a greater improvement in pulmonary function or a lower hospital admission rate than treatment with isoetharine.

Randomized clinical trials: problems and values

Problems with randomization can be grouped as ethical or methodological. Those who consider randomization unethical believe it deprives patients of their best chance for a good result or actually does them harm. Methodological criticisms are based on the selectivity of randomized studies in terms of time and money. Finally, although no one suggests that randomization produces any statistical disadvantage, some critics think that its statistical advantages have been exaggerated.

Fenoterol: a beta2-adrenergic agonist for use in asthma. Pharmacology, pharmacokinetics, clinical efficacy and adverse effects

Fenoterol (hydroxyphenylorciprenaline) is chemically closely related to metaproterenol (orciprenaline). It has a higher bronchodilating potency than metaproterenol, albuterol (salbutamol in Europe) or terbutaline. The beta 2 selectivity of fenoterol at normal oral and inhaled doses is the same as for albuterol and terbutaline. Its pharmacodynamic effects are similar to those of other selective beta 2-adrenoceptor agonists. It has a high first-pass metabolism. The long half-life previously reported in the literature (7 hours) is mainly the half-life of inactive fenoterol metabolites. The duration of action at equipotent bronchodilating doses seems to be the same as for albuterol and terbutaline, and not longer, as previously reported. Inhalation of beta-adrenoceptor agonists is the superior route of administration. Side effects do not usually occur at normal therapeutic doses. One puff of fenoterol (200 micrograms) is about equipotent to 2 puffs of albuterol (2 X 100 micrograms) or 2 puffs of terbutaline (2 X 250 micrograms) with the same duration of effect. In patients who overdose with the metered-dose inhaler (MDI), side effects occur at half the number of puffs with fenoterol. Dosage for an acute attack in children is 1 puff (200 micrograms), repeated within 5 minutes if necessary; in adults 1-3 puffs can be given. For maintenance therapy, the dose in adults is 1-2 puffs 2-4 times daily, while in children 1 puff at night and 1 in the morning may be sufficient. The usual oral dosage has been 5-10 mg 3 times daily.

Comparison of nebulized terbutaline and subcutaneous epinephrine in the treatment of acute asthma

Nineteen children who presented for treatment of acute asthma symptoms were studied. They were randomized to receive either subcutaneous epinephrine 0.01 mg/kg (0.3 mg maximum) or nebulized terbutaline 1 mg in 2 mL normal saline. The drugs were administered using the double-blind method. Each patient received either subcutaneous epinephrine with concurrent nebulized normal saline or nebulized terbutaline with a concurrent subcutaneous injection of normal saline. Depending on the patient's clinical status, up to three doses of the same drug and placebo were administered. Pulmonary functions (FEV1, FVC, FEF25-75), heart rate, respiratory rate, and pulmonary index were obtained before treatment, at 20 minutes, and at one hour after the final treatment. Except for the baseline respiratory rate, the mean number of treatments, pulmonary index, heart rate, and respiratory rate (at 20 minutes and one hour) were not statistically different. Pulmonary functions were not significantly different at any time. The one-hour post-treatment pulmonary functions (percentage of predicted normal) for terbutaline and epinephrine were FEV1, 49.2 +/- 18.4% and 49.4 +/- 16.9%; FVC, 72.7 +/- 23.4% and 62.7 +/- 21.6%; and FEF25-75, 31.8 +/- 18.6% and 39.0 +/- 12.2%, respectively. The data presented support our hypothesis that terbutaline by nebulization is at least as effective as epinephrine in the management of children with similar degrees of pulmonary obstruction.