LACK OF EFFECT ON CARDIAC RHYTHM FROM REPEATED DOSES OF ALBUTEROL AEROSOL (AA) ADMINISTERED FROM A METERED DOSE INHALER (MDI)

Abstract

Beta agonists administered by aerosol are effective treatment for asthma. They produce prompt, significant bronchodilation. Side effects are few but cardiac arrhythmias may occur when the patient exceeds the prescribed dose. Our previous study (J. Peds 103:655, 1983) showed that 2 puffs of AA did not disturb cardiac rhythm. We have now studied the potential effect of frequently repeated inhalation of AA to simulate the pattern of use by some patients at home. 15 stable outpatient asthmatic children (9 to 14 years old) were treated with 2 puffs of AA (180mcg) followed either by hourly placebo or hourly AA for 5 hours (10 puffs=900mcgs) in a randomized, double blind cross over study. Cardiac rhythm was Holter monitored and pulmonary function was tested hourly for 5 hours. Heart rate (HR) was analyzed at hourly intervals. Pretreatment HR of 95bpm declined by 1-2bpm after single dose and similarly 2-5bpm from 99bpm during multiple doses. No one developed arrhythmia, and side effects were infrequent on either day. FEV1 increased 35, 38, 42, 41, 44 and 44% above the baseline period at 30, 60, 120, 180, 240 and 300 minutes after multiple doses and 36, 40, 38, 33, 27 and 19% at the same intervals after single dose. The difference was significant (P< 0.05) at 240 and 300 minutes. No cardiac toxicity occurred with hourly administration (for 5hrs) of AA using MDI. Hence there is apparently a substantial margin of safety in administration of this agent to asthmatic children.