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Tuesday 09 October 2007

Relative lung deposition of salbutamol following inhalation from a spacer and a Sidestream jet nebulizer following an acute exacerbation.

By: Mazhar SH, Ismail NE, Newton DA, Chrystyn H.

Br J Clin Pharmacol 2007 Oct;(): [Epub ahead of print]

What is already known about this subject * Studies have shown that a large volume spacer attached to a metered dose inhaler provides similar bronchodilator effects to nebulized dosing during the management of patients following an acute exacerbation. * Due to the high doses used, these effects could be measured at the top of the dose-response relationship and the response limited due to the patient's exacerbation. * Although clinical end-points are the gold standard to show comparability, some indication of similar lung deposition is useful to consolidate any claims. What this study adds * The urinary pharmacokinetic method we have used postinhalation provides an index of lung deposition for inhalation methods that can be incorporated into the routine management of patients with an acute exacerbation. * This is the first study to identify and compare lung deposition and systemic delivery for inhalation methods within the setting of the routine management of asthma and chronic obstructive pulmonary disease patients following hospitalization due to an acute exacerbation. * The study highlights the comparability of the doses for the two inhalation methods evaluated with respect to lung deposition, systemic delivery and bronchodilator response. Background Studies comparing inhalation methods in acute exacerbations have not assessed lung deposition. Methods Five 100-mug salbutamol doses were inhaled from a metered dose inhaler plus spacer (MDI + SP) and 5 mg was nebulized (NEB) following acute exacerbation hospitalization. Urinary salbutamol excretion was determined at 30 min (USAL0.5) and over 24 h (USAL24) postinhalation together with forced expiratory volume in 1 s (FEV(1)). Results The USAL0.5 mean ratio (90% confidence interval) post MDI + SP and NEB [n = 19 asthma, 11 chronic obstructive pulmonary disease (COPD)] was 1.01 (0.81, 1.26). USAL24 was less (P < 0.001) following MDI + SP, whereas FEV(1) was similar. Only a small difference between asthmatics and COPD patients was observed for the MDI + SP in that the USAL0.5 was higher in the asthmatics for the spacer method. Conclusion The relative lung deposition after inhaling 500 mug salbutamol from MDI + SP is similar to 5 mg from a Sidestream nebulizer following an acute exacerbation.

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