For the design and development of inhalation devices, it is critical that the device is safe, easy to use and delivers the right volume of drug during inhalation. Key design challenges for pMDI and DPI inhalers are the pharmaceutical performance criteria for aerodynamic particle size distribution (APSD), delivered dose uniformity (DDU) and plume geometry. Additionally, due to the market dynamics, including patent expiry, there can be significant pressure to meet an aggressive, pre-defined milestone. This paper examines the methodology of device design and techniques that can be employed to ensure an efficient and robust process. A fully integrated approach is presented, considering the device requirements from different sources such as i) usability for the patient, ii) device performance with respect to particle dispensing and iii) manufacturability to ensure the device can be produced at high volumes and for competitive costs. A systematic, defined process is required to minimise iterative loops and ensure a right first time design solution is achieved and realised. This approach can significantly reduce the overall timelines and cost for the development and industrialisation process.