Spray Pattern (SP) and Plume Geometry (PG) testing have long been part of U.S. regulatory expectations. They are now explicitly addressed in the 2026 revision of the European Medicines Agency guideline on inhalation and nasal medicinal products. The revision includes SP and PG as characterisation tests where appropriate. It also notes their use to ensure consistency during development. They serve as a baseline for comparability assessments and lifecycle changes. This change reflects a broader international move toward more data-driven, development-stage in vitro performance assessment of orally inhaled and nasal drug products (OINDPs).
Concurrently, advances in high-speed digital imaging and automated image analysis have transformed SP and PG. They are no longer just static geometric descriptors. They now provide dynamic, data-rich measurements that capture transient plume behaviour. Modern platforms, including the SprayVIEW® measurement system with Viota® software, enable extraction of both conventional metrics and time-resolved parameters, including plume front velocity. This supports a deeper mechanistic understanding of aerosol momentum and product performance.
Together, regulatory alignment and technological innovation have elevated SP and PG testing. They are no longer just supportive visualisation tools. They are now central to quality assessment, comparability evaluation, and lifecycle management strategies. As OINDP development increasingly emphasises data-driven and mechanistically informed approaches, advanced spray characterisation plays a critical role during product development. It supports formulation optimisation, device selection, and demonstration of performance consistency.
OINDPs are complex drug combination products in which therapeutic performance depends on tightly coupled interdevice actions between formulation properties, device design, and patient use. Unlike conventional oral dosage forms, aerosolised drug delivery involves highly dynamic processes, including atomisation, plume formation, droplet evaporation, and particle transport. Consequently, regulatory authorities require a multifaceted in vitro characterisation strategy, incorporating tests such as delivered dose uniformity, aerodynamic particle size distribution (APSD), and spray characterisation to ensure consistent performance and product quality.
