Efficacy of inhaled formoterol in reversing bronchoconstriction.
OBJECTIVE
To evaluate the effectiveness and onset of action of formoterol delivered by dry-powder inhaler in reversing methacholine-induced bronchoconstriction.


METHODS
Patients presenting a drop in forced expiratory volume in one second > 20% after methacholine inhalation were included. A total of 84 patients were evaluated. All of the participating patients presented respiratory symptoms of unknown origin, which were being investigated. The patients were randomized to receive 200 microg of spray fenoterol (n = 41) or 12 microg of dry-powder inhaler formoterol (n = 43), both administered in order to achieve immediate reversal of methacholine-induced bronchoconstriction. We evaluated the decrease in forced expiratory volume in one second (in relation to the baseline value) after methacholine challenge and the dose of methacholine required to provoke a drop of 20% in forced expiratory volume in one second, as well as the increase in forced expiratory volume in one second (in relation to the baseline value) at five and ten minutes after bronchodilator use.


RESULTS
There were no significant differences related to gender, age, weight, height or dose of methacholine required to provoke a drop of 20% in forced expiratory volume in one second. Nor were there any significant differences in terms of baseline or post-methacholine forced expiratory volume in one second. In the fenoterol group, the mean postbronchodilator increase in forced expiratory volume in one second increase was 34% (at five minutes) and 50.1% (at ten minutes), compared with 46.5% (at five minutes) and 53.2% (at ten minutes) in the formoterol group.


CONCLUSIONS
The bronchodilator effect of formoterol at five and ten minutes after methacholine-induced bronchoconstriction was similar to that of fenoterol. Despite being a long-acting bronchodilator, formoterol also has a rapid onset of action, which suggests that it could be employed as a relief medication in cases of bronchoconstriction occurring during asthma attacks.
Rubin
Adalberto Sperb
AS
Pavilhão Pereira Filho da Santa Casa de Misericórdia de Porto Alegre, Porto Alegre, Rio Grande do Sul, Brazil. arubin@terra.com.br
Perin
Christiano
C
Pelegrin
Liliana
L
Fernandes
Juliana Cardozo
JC
da Silva
Luiz Carlos Corrêa
LC
D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000627:therapeutic use*; D000328:Adult; D001249:Asthma / Q000188:drug therapy*; D001985:Bronchial Provocation Tests; D016084:Bronchoconstriction / Q000187:drug effects*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D004983:Ethanolamines / Q000008:administration & dosage*; D005260:Female; D005280:Fenoterol / Q000008:administration & dosage*; D005541:Forced Expiratory Volume / Q000187:drug effects; D000068759:Formoterol Fumarate; D006801:Humans; D008297:Male; D016210:Methacholine Chloride / Q000494:pharmacology; D008875:Middle Aged; D011446:Prospective Studies; D013147:Spirometry; D013997:Time Factors; D016896:Treatment Outcome
D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D004983:Ethanolamines; D016210:Methacholine Chloride; D005280:Fenoterol; D000068759:Formoterol Fumarate