ABSTRACT
PURPOSE: The Respimat is a handheld, propellant-free, soft-mist inhaler. Observations by patients and physicians prompted development of an improved second-generation Respimat inhaler. Human-factor studies assessing the usability of the new inhaler and in vitro assessment of aerosol performance are important to demonstrate functionality of the updated inhaler. METHODS: Studies were performed to assess any possible impact of the reusable Respimat inhaler design on aerosol performance (delivered dose [DD] and fine-particle dose [FPD]) and iteratively assess and improve usability of the new design. The tiotropium-olodaterol inhalation solution for Respimat was used as a model. The DD and FPD of the reusable Respimat inhaler (across multiple cartridges) and the disposable Respimat inhaler were determined by laser diffraction and with an alternative Andersen cascade impactor. Usability was measured across three studies involving health care professionals and patients with diagnoses of COPD, asthma, or combined disease (with and without experience with the Respimat inhaler). These studies measured performance of handling tasks and collected subjective feedback directly related to the inhaler's new or altered features, which fed into optimization of the inhaler. RESULTS: DDs of tiotropium and olodaterol were stable up to 15 cartridges and consistently within the upper and lower limits of the disposable Respimat inhaler. The FPD was also found to be batch-consistent over the cartridges and comparable with the reference. The usability of the reusable Respimat inhaler compared with the disposable inhaler was improved in terms of assembly and daily use. Cartridge exchange was rated as intuitive and easy to very easy. CONCLUSION: The new reusable Respimat is a medical inhaler developed with enhanced features that meets health care professionals' and patients' needs. Drug delivery across multiple cartridges is not affected by the design. Compared with the original disposable inhaler, the usability of the reusable inhaler has been improved, and cartridge exchange was rated as easy to perform. The reusable Respimat provides greater convenience for patients vs the disposable inhaler, with reduced environmental impact.
