Relationships between the particle velocity and introduction of drug-loaded microparticles into the skin in a microparticulate bombardment system.

Recently, it has been suggested that a microparticulate bombardment system would be a very useful tool for the delivery of a variety of powdered drugs as an alternative to parenteral injection via a needle. However the relationship between the particle dynamics and introduction into the skin has not been researched using this system. In the present study, we analyzed the velocity of microparticles bombarded by the Helios(TM) gun system under various conditions using particle image velocimetry (PIV). The particle kinetic energy, which depended on the particle velocity and particle mass, was increased with increasing helium pressure and particle size, decreasing bombardment dose, resulting in the increased percentage introduction and relative bioavailability (F(0-24 h)). The particle velocity had a greater influence than the particle mass. Therefore, in order to be the most effective system for introduction into the skin, it is necessary to use a high helium pressure and microparticles of high density. However, it is also necessary to consider the skin damage after bombardment.