Impact of holding position during inhalation on drug release from a reservoir-, blister- and capsule-type dry powder inhaler.

OBJECTIVE: To determine whether drug release may be impaired by tilting some dry powder inhalers (DPIs).

METHODS: Using an inhalation simulator, we measured drug release from Turbuhaler® (TBH), Diskus® (DKS) and Breezhaler® (BZH) at several peak inhaled flow rates (PIFs) while the DPIs were held at level and tilted (80°). Drug release was then measured from all three DPIs at 0, 30, 60 and 90° of tilt, and capsule rotation was also recorded.

RESULTS: Drug release from TBH was flow-dependent while that from DKS and BZH was flow-independent. With TBH, the plot of drug release vs. PIF either at level or at tilted position scattered along approximately the same regression lines. With DKS and BZH, drug release at tilted position was significantly lower than that while at level. With DKS the decrease was almost 20%, while with BZH, drug release frequently failed. With BZH, significant reductions in drug release were observed while the device was tilted by 30-90°.

CONCLUSION: The position in which the DPI is held may affect drug delivery, especially when using BZH.