Research progress in soft mist inhalers and challenges

Given the unique physiological structure of lungs, pulmonary drug delivery has distinct advantages over oral or injectable administration routes for treating both pulmonary and systemic diseases, hence increasing interest in related research. Despite the ability to achieve pulmonary drug delivery, conventional inhalable formulations have such limitations as low rates of pulmonary deposition, a lack of user-friendliness, relatively high carbon emissions, and poor patient compliance. As a novel inhalation device, soft mist inhalers (SMIs) promise good potential and advantages. This article outlines the aerosol characteristics and principles of SMIs, summarizes their origins, leading advantages, and clinical value, and analyzes its applications in shear-sensitive formulations based on related literature and patents. Recent representative patents related to SMIs are listed. Furthermore, the challenges facing the development of SMIs are discussed, involving the optimization of drug solution formulations, enhancement of nozzle design precision, and reduction of production costs. Future developments are also predicted.