Salbutamol pMDI gives less protection to methacholine induced airway obstruction than salbutamol via spacer or DPI.
BACKGROUND
Inhalation device and inhalation technique influence the deposition of drug in the lung. This study evaluated the efficacy of salbutamol as a bronchoprotective agent administered via Diskus, Turbuhaler, pMDI or pMDI + Volumatic against methacholine-induced bronchoconstriction.


METHODS
Twenty stable asthmatics participated in this open randomised comparison of the protective effects of 200 microg salbutamol, administered via the various inhalation devices on methacholine-induced airway obstruction, with respect to pulmonary function and dyspnoea sensation. The inhalation technique was controlled by measuring the peak inspiratory flow (and actuation time, in the case of pMDI and Volumatic) through the device, during inhalation.


RESULTS
Inhalation of salbutamol increased the provocative dose of methacholine by 1.2 doubling doses (dd) for pMDI, 1.9 dd for Diskus, 2.3 dd for Turbuhaler and 2.5 dd for Volumatic. Salbutamol via pMDI provided less protection from methacholine-induced airway obstruction than did salbutamol administered via Diskus, Turbuhaler or Volumatic (P<0.05). The inadequate pMDI use of 70% of our patients might contribute to a lower deposition of drug in the central airways, resulting in the lower protective effect. However, the PC20_FEV1 of the adequate- and inadequate pMDI users showed no significant difference.


CONCLUSIONS
Salbutamol administered via pMDI gave less protection from methacholine-induced bronchoconstriction than did salbutamol via Diskus, Turbuhaler or Volumatic. This study suggests that the pMDI may be less suitable for protecting a patient against bronchoconstriction due to airway hyperresponsiveness.
Broeders
Mariëlle E A C
ME
Department of Pulmonary Diseases Dekkerswald, University of Nijmegen, P.O. Box 9001, 6560, GB Groesbeek, The Netherlands. m.broeders@zonnet.nl
Molema
Johan
J
Hop
Wim C J
WC
Folgering
Hans Th M
HT
D000280:Administration, Inhalation; D000420:Albuterol / Q000008:administration & dosage* / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D001993:Bronchodilator Agents / Q000008:administration & dosage* / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D036501:Metered Dose Inhalers; D016210:Methacholine Chloride; D008875:Middle Aged; D009330:Nebulizers and Vaporizers
D016085:Bronchoconstrictor Agents; D001993:Bronchodilator Agents; D016210:Methacholine Chloride; D000420:Albuterol