Although pressurized metered dose inhalers (pMDIs) currently constitute a majority of the market share in the inhalation market, dry powder inhaler (DPI) products have become increasingly popular due to their reliability and product performance. One such DPI is the TAIFUN inhaler that is a reservoir-based DPI system with the ability to produce consistent and uniform doses in vitro. Originally developed for the pulmonary delivery of salbutamol, the TAIFUN inhaler platform has since been used to develop a product for breakthrough cancer pain management using fentanyl citrate as the active drug. In vivo results show the TAIFUN inhaler is able to deliver a rapid onset of action and increased relative bioavailability compared with other fentanyl products currently on the market.