A comparison of the onset of action of salbutamol and formoterol in reversing methacholine-induced bronchoconstriction
This single-centre, randomized, double-blind, double-dummy four-way cross-over study in 24 moderately severe asthmatic patients compared the speed of onset of recommended doses of salbutamol (200 μg) and formoterol (12 μg) delivered by metered-dose inhaler in reversing the bronchoconstriction induce...
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Veröffentlicht in: | Respiratory medicine 1998-12, Vol.92 (12), p.1346-1351 |
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Sprache: | eng |
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Zusammenfassung: | This single-centre, randomized, double-blind, double-dummy four-way cross-over study in 24 moderately severe asthmatic patients compared the speed of onset of recommended doses of salbutamol (200 μg) and formoterol (12 μg) delivered by metered-dose inhaler in reversing the bronchoconstriction induced by a cumulative dose of methacholine to produce a 20% decrease (PD
20) in forced expiratory volume in 1 s (FEV
1).
Specific airway conductance (
SG
aw) and airway resistance (
R
aw) were measured in baseline condition, immediately after challenge and 0·5, 1·5, 3, 5, 10, 15, 30, 60 min and every hour up to 4 h after inhalation of the trial drug. FEV
1 was measured in baseline condition, after challenge and 15, 30 and 60 min and then every 30 min up to 4 h after inhalation of the study drug. The primary efficacy parameter was the change in
SG
aw.
Salbutamol produced a two-fold increase in
SG
aw within 4 min and a maximum increase after 79·3 min. Formoterol produced a two-fold increase in
SG
aw after 5 min and a maximum increase after 119·6 min. Changes in
SG
aw were slightly, but consistently, higher during the first 2 h after inhalation of salbutamol, both in absolute values and as a percentage of the maximum response. Differences were significant at 10, 15 and 30 min time points. There was no significant difference between the maximum values of
SG
aw after the two drugs. Changes in
R
aw and FEV
1 reflected the differences in
SG
aw.
It was concluded that in methacholine-induced bronchoconstriction both formoterol and salbutamol have a very fast onset of action, achieving prechallenge values of
SG
aw within 3 min, salbutamol being slightly faster than formoterol. |
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ISSN: | 0954-6111 1532-3064 |
DOI: | 10.1016/S0954-6111(98)90140-8 |