The protective effect of salbutamol inhaled using different devices on methacholine bronchoconstriction

Study objective: To determine the protective effect of salbutamol, 100 mu g , inhaled by different devices (pressurized Inetered-dose inhaler [pMDI; Ve ntolin; GlaxoWellcome; Greenford, UK], pMDI + spacer [Volumatic; GlaxoWellc ome], or breath-activated PMDI [Autohaler; 3M Pharmaceuticals; St. Paul, MN ]) on bronchoconstriction induced by methacholine. Design: Randomized, double-blind, cross-over, placebo-controlled study. Patients: Eighteen subjects with stable, moderate asthma, asymptomatic, rec eiving regular treatment with salmeterol, 50 mu g bid, and inhaled beclomet hasone dipropionate, 250 mu g bid, in the last 6 months, with high hyperrea ctivity to methacholine (baseline provocative dose of methacholine causing a 20% fall in FEV1 [PD20] geometric mean [GM], 0.071 mg). Subjects were cla ssified into two groups: subjects with incorrect (n = 5) pMDI inhalation te chnique, and subjects with correct (n = 13) inhalation technique. Methods and measurements: After cessation of therapy for 3 days, all subjec ts underwent four methacholine challenge tests, each test 1 week apart, eac h time 15 min after inhalation of salbutamol, 100 mu g (via pMDI, pMDI + sp acer, or Autohaler), or placebo. The protective effect on methacholine chal lenge 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 PO20 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 inhale d via pMDI + spacer, PD20 was slightly but not significantly higher (pMDI G M, 0.454 mg; pMDI + spacer GM, 0.559 mg; and Autohaler GM, 0.372 mg; not si gnificant [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 incorr ect inhalation technique were separately considered. Conclusions: Our data show that the protective effect of salbutamol, 100 mu g, on methacholine-induced bronchoconstriction is not affected by the diff erent inhalation techniques, although inhalation tia pMDI + spacer tends to improve the bronchoprotective ability of salbutamol. These data confirm th e clinical efficacy of salbutamol, whatever the device, and the patient's i nhalation technique.