A ballistic study of micro-particle penetration to the oral mucosa

This paper describes the results of an investigation into the impact of model micro-particles to ex vivo buccal mucosa (the cheek) of pigs and beagle dogs. The work is aimed at optimizing a unique form of pharmaceutical delivery. The pharmaceutical is formulated into particle form and accelerated toward the target of skin or mucosa by using a gas jet. In this study, research devices designed using analytical, computational (computational fluid dynamics) and experimental methodologies were used to deliver particles at uniform and predetermined velocities. These velocities were confirmed using light obscuration, pressure measurement and particle image velocimetry methods. Polystyrene, glass, stainless steel and gold micro-particles at a range of size distributions were used for the payloads for injection using these devices. Injection occurred with a wide range of impact conditions into fresh canine (dog) and porcine (pig) buccal mucosa. Final positions of the particles were determined from histological sections and the results analyzed in relation to the known particle impact parameters of size, density and velocity. The experimental results are collated using an empirical term, based on particle impact parameters. Comparison is then made to a semi-empirical penetration model. This is done by analysing the penetration results in terms of each particle impact parameter. Analysis shows that this model fits the experimental data well when reasonable estimates of the tissue mechanical properties are chosen.