EFFECT OF DIFFERENT MODES OF INHALATION ON DRUG-DELIVERY FROM A DRY POWDER INHALER

Although the Spinhaler has been available for many years as a delivery device for sodium cromoglycate powder, the quantity of powder deliver ed to the lungs and the optimal mode of inhalation for this device hav e remained largely unknown. Lung deposition of 20 mg sodium cromoglyca te powder (labelled with the radionuclide Tc-99m) from the Spinhaler h as been measured in 10 healthy volunteers who inhaled by four carefull y controlled inhalation modes, involving fast (120 1 min(-1)) and slow (60 1 min(-1)) peak inhaled flow rates, holding the head in the norma l and tilted-back (60 degrees to the horizontal) positions, and breath -holding pauses of 0 and 10 s. Inhalation at 60 1 min(-1) significantl y (P < 0.001) reduced deposition in the lungs compared to inhalation a t 120 1 min(-1). Among the inhalation modes tested, delivery to the lu ngs was optimised (mean 17.1% of the dose) when powder was inhaled at 120 1 min(-1), with the head in the normal position, and with 10 s bre ath-holding.