Effect of different modes of inhalation on drug delivery from a dry powder inhaler

Abstract

Although the Spinhaler has been available for many years as a delivery device for sodium cromoglycate powder, the quantity of powder delivered to the lungs and the optimal mode of inhalation for this device have remained largely unknown. Lung deposition of 20 mg sodium cromoglycate powder (labelled with the radionuclide 99mTc) from the Spinhaler has been measured in 10 healthy volunteers who inhaled by four carefully controlled inhalation modes, involving fast (120 l min −1) and slow (60 l min −1) peak inhaled flow rates, holding the head in the normal and tilted-back (60° to the horizontal) positions, and breath-holding pauses of 0 and 10 s. Inhalation at 60 l min −1 significantly ( P < 0.001) reduced deposition in the lungs compared to inhalation at 120 I min −1. Among the inhalation modes tested, delivery to the lungs was optimised (mean 17.1% of the dose) when powder was inhaled at 120 l min −1, with the head in the normal position, and with 10 s breath-holding.