Engineering a medical device for intranasal immunisation: ensuring targeted delivery and formulation stability

The efficacy of nasal vaccination critically depends on the delivery method, which must ensure precise and reproducible deposition of the vaccine within the nasal cavity to effectively stimulate mucosal immune structures such as the nasal\x{2011}associated lymphoid tissue (NALT). Transitioning from pre\x{2011}clinical models to human applications is challenging because of anatomical and physiological differences in nasal structure and airflow dynamics.

We developed a nasal\x{2011}spray device specifically designed for human nasal immunization. The device delivers a broad, homogeneous spray that is confined to the nasal cavity, thereby avoiding the lower respiratory tract and minimizing the risk of pulmonary exposure. It was engineered to be compatible with a wide range of vaccine formulations, preserving their physicochemical properties, stability, and delivery efficacy. To overcome the limitations of conventional rodent models, the device was validated using (i) in\x{2011}vitro human nasal cavity replicas (nasal casts) and (ii) an in\x{2011}vivo rabbit model, which is more appropriate for regulatory and translational studies.

The spray system achieved consistent, homogeneous deposition throughout the nasal cavity without spill\x{2011}over into the lower airways. Compatibility tests confirmed that the device does not alter the physicochemical characteristics or stability of a representative complex vaccine formulation. Validation in nasal casts and the rabbit model demonstrated reproducible delivery performance and supported the device\x{2019}s suitability for human use.

The presented transitory delivery platform offers a scalable, safe, and formulation\x{2011}compatible solution for intranasal vaccine administration. By ensuring targeted deposition and preserving vaccine integrity, the device reinforces the potential of mucosal immunization strategies across diverse indications and facilitates the translation of nasal vaccines from pre\x{2011}clinical research to clinical application.