Pulmonary drug delivery from the Taifun dry powder inhaler is relatively independent of the patient's inspiratory effort

The Taifun(R) dry powder inhaler (Leiras OY, Turku, Finland) is a breath-ac tuated, multidose device, each metered dose containing 200 mu g of budesoni de. A two-way randomized crossover gamma scintigraphic study was performed in 10 asthmatic patients to determine the in vivo deposition pattern of bud esonide inhaled from the Taifun(R). In vituo radiolabelling validation stud ies demonstrated that the radiolabel could be used as an accurate marker to assess in vivo drug deposition. Patients used either maximal inspiratory e ffort (targeted peak inhalation flow 30 L/min) or submaximal inspiratory ef fort (targeted peak inhalation flow 15 L/min) on each study day. Mean (S.D. ) whole lung deposition (% of metered dose) was 34.3 (5.8)% and 29.6 (5.9)% for the two inhalation flows. The intersubject coefficient of variation in lung deposition was less than 20% on both study days. Drug was deposited u niformly across the central, intermediate, and peripheral lung regions for maximal and submaximal inspiratory efforts. The study suggests that the Tai fun(R) is a superior drug delivery device compared with many other inhalers , in terms of the amount of drug deposited in the lungs, the reproducibilit y of the lung dose, and the relative flow-independence of lung deposition.