Lung Deposition of Salbutamol from the Leiras Metered Dose Powder Inhaler

ABSTRACT The deposition patterns of salbutamol inhaled from a new metered dose dry powder inhaler (Leiras Oy, Finland) were assessed using gamma scintigraphy. The drug formulation was labelled with the radionuclide 99Tm, and in vitro validation experiments performed with an Andersen Cascade Impactor demonstrated that the radiolabel would act as a marker of in vivo drug distribution. Eleven healthy volunteers took part in the study, inhaling through the device at a mean (SEM) flow rate of 31.2 (3.6) L-mhv1. The mean (SEM) whole lung deposition was 41.6 (1.7) % of the delivered dose, and 23.9 (1.4) % of the metered dose. The drug was distributed fairly evenly throughout the lungs with a mean ratio of peripheral/central deposition of 1.2. It was concluded that drug delivery from the Leiras dry powder inhaler was comparable or superior to that observed for other metered dose powder inhalers.