Study objective: To determine the protective effect of
salbutamol, 100 μg, inhaled by different devices (pressurized
metered-dose inhaler [pMDI; Ventolin; GlaxoWellcome; Greenford, UK],
pMDI + spacer [Volumatic; GlaxoWellcome], or breath-activated pMDI[
Autohaler; 3M Pharmaceuticals; St. Paul, MN]) on bronchoconstriction
induced by methacholine.
double-blind, cross-over, placebo-controlled study.
Patients: Eighteen subjects with stable, moderate asthma,
asymptomatic, receiving regular treatment with salmeterol, 50 μg bid,
and inhaled beclomethasone dipropionate, 250 μg bid, in the last 6
months, with high hyperreactivity to methacholine (baseline provocative
dose of methacholine causing a 20% fall in FEV1[
PD20] geometric mean [GM], 0.071 mg). Subjects were
classified into two groups: subjects with incorrect (n = 5) pMDI
inhalation technique, and subjects with correct (n = 13) inhalation
Methods and measurements: After
cessation of therapy for 3 days, all subjects underwent four
methacholine challenge tests, each test 1 week apart, each time 15 min
after inhalation of salbutamol, 100 μg (via pMDI, pMDI + spacer, or
Autohaler), or placebo. The protective effect on methacholine challenge
test was evaluated as the change in the PD20,
and expressed in terms of doubling doses of methacholine in comparison
with placebo treatment.
Results: The PD20
was significantly higher after salbutamol inhalation than after placebo
inhalation, but no significant difference was observed among the three
different inhalation techniques. Only when salbutamol was inhaled via
pMDI + spacer, PD20 was slightly but not significantly
higher (pMDI GM, 0.454 mg; pMDI + spacer GM, 0.559 mg; and Autohaler
GM, 0.372 mg; not significant [NS]) than other inhalation techniques.
Similar results (mean ±SEM) were obtained with doubling doses of
methacholine (pMDI, 2 ± 0.47; pMDI + spacer, 3 ± 0.35; and
Autohaler, 2.4 ± 0.40; NS). No significant difference was found
among techniques when subjects with correct or incorrect inhalation
technique were separately considered.
data show that the protective effect of salbutamol, 100 μg, on
methacholine-induced bronchoconstriction is not affected by the
different inhalation techniques, although inhalation via
pMDI + spacer tends to improve the bronchoprotective ability of
salbutamol. These data confirm the clinical efficacy of salbutamol,
whatever the device, and the patient’s inhalation