Relationship between amount of drug delivered to lungs and amount released from Diskhaler by inhalation with tapping.

It is well known that drug residue remains in a fluticasone propionate Diskhaler (FP-DH) following a single inhalation. Thus, the inspiratory ability of the patient has an influence on the effects of the drug. In a previous study, we reported that the amount of drug remaining in an FP-DH was decreased by tapping the device after the first inhalation. In the present study, we investigated the relationship between the amount of drug delivered to the lungs and amount of drug released from the FP-DH by inhalation along with tapping using an in vitro model. We measured the amounts delivered to the throat, stage 1, and stage 2 of a twin impinger device by HPLC-UV, following inhalation and tapping of 100 microg of FP-DH at various inspiratory flow rates, which ranged from 11.5 to 73.6 l/min for 2 s. A positive linear correlation between the amount of drug released from the FP-DH and that deposited in stage 2 was observed. Amounts deposited in stage 2 following tapping were estimated to be 6.0 microg at an inspiratory flow rate of 20 l/min and 10.6 microg at 60 l/min, while those without tapping were 2.0 microg and 10.2 microg, respectively. Notably, at an inspiratory flow rate of 20 l/min, the amount of drug deposited in stage 2 by tapping was increased about 3-fold in comparison to that without tapping. Our results indicate that the amount of drug deposited in stage 2, i.e., the lung in our model, is increased by tapping of the device, which would be particularly helpful for patients with a lower level of inspiratory ability.