Formulation of spray dried enzymes for dry powder inhalers: An integrated methodology.

One of the main challenges when developing a spray dried formulation of an inhalable enzyme is the generation of a safe and effective aerosol, able to reach the lungs, while preserving protein function and structural levels of the biologic. Hence, an appropriate excipient selection based on enzyme stabilization, inhalation precedence and spray drying (SD) process development is required to meet this balance. Herein, an integrated methodology is presented to expedite the selection of the best dry powder inhaler excipient system to formulate three model enzymes of increasing molecular mass and structural complexity belonging to the oxidoreductase class and often implicated in oxidative stress: superoxide dismutase, glucose oxidase and catalase.