Formoterol induces tolerance to the bronchodilating effect of Salbutamol following methacholine-provocation test in asthmatic children.
OBJECTIVE
To study whether Formoterol treatment affect the bronchodilator response to salbutamol after methacholine-provocation test (MPT) in asthmatic children.


METHODS
A prospective, double-blind, randomized, placebo-controlled study. Children aged 7-16 years with mild-persistent to moderate asthma treated with inhaled corticosteroids, were enrolled. After 2-weeks of run-in period, subjects were randomized to inhaled Formoterol 9 microg bid (n=19) or placebo (n=19) for 2 weeks. MPT with salbutamol-recovery curve was performed at the beginning and at the end of the trial period. Measurements of peak expiratory flow rate (PEFR), symptoms score, rescue bronchodilator usage and side effects were recorded daily. The primary end-points were the change in FEV1 0-10 min after salbutamol inhalation and the recovery time from 80 to 100% of pretest FEV1. Statistical analyses were performed by ANOVA with repeated measures.


RESULTS
There was a decrease in the bronchodilator response to salbutamol and an improved PEFR in the Formoterol group. There was no difference in all other parameters.


CONCLUSIONS
Formoterol decreases the bronchodilator response to salbutamol following MPT. Whether this phenomenon has clinical implication during acute asthma needs further studies.
Adler
Amos
A
Department of Pediatrics, Sapir Medical Center, Tsharnichovsky Street, Kfar-Saba, Israel. netaadle@post.tau.ac.il
Uziel
Yosef
Y
Mei-Zahav
Meir
M
Horowitz
Israel
I
D000293:Adolescent; D000420:Albuterol / Q000494:pharmacology*; D001249:Asthma / Q000188:drug therapy*; D001772:Blood Cell Count; D001985:Bronchial Provocation Tests; D001993:Bronchodilator Agents / Q000009:adverse effects / Q000494:pharmacology / Q000627:therapeutic use; D002648:Child; D004311:Double-Blind Method; D004347:Drug Interactions; D004361:Drug Tolerance; D004804:Eosinophils / Q000166:cytology; D004983:Ethanolamines / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D000068759:Formoterol Fumarate; D006801:Humans; D008297:Male; D008448:Maximal Expiratory Flow Rate / Q000187:drug effects; D016210:Methacholine Chloride; D011446:Prospective Studies
D001993:Bronchodilator Agents; D004983:Ethanolamines; D016210:Methacholine Chloride; D000420:Albuterol; D000068759:Formoterol Fumarate