Poster: Applications Of Traditional Lubricants Using A Dry Particle Coating Technique

By: Qi Tony Zhou, Li Qu, Ian Larson, Peter J Stewart (Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Australia)

Powder bulk functionalities such as flow, fluidization and aerosolization are fundamental to the handling and performance of many pharmaceutical products. It is generally a major challenge to achieve satisfactory flow, fluidization and aerosolization performance with fine cohesive powders. In this study, we investigated the effect of surface engineering via mechanical dry coating with a traditional lubricant on the bulk functionalities of either a milled cohesive excipient powder or micronized drug powders.

A fine milled lactose powder (Pharmatose® 450M, VMD 20 µm) and two micronized drug powders (salbutamol sulphate, SS and salmeterol xinafoate, SX) (VMD 3 µm) were coated with 1%, 5% and 5%, respectively, of magnesium stearate (MgSt) using a AMS Mini "mechanofusion" system. All samples were also blended using a conventional tumbling mixer as a comparison.

Powder flow properties were characterized using both traditional methods of Carr index and angle of repose as well as a FT4 powder rheometer (Freeman Technology, UK). Specific energy (SE) is defined and determined as the energy required for the powder to flow. Powder cohesion and flow function was measured by shear testing. Fluidization behaviors were represented as flow energy during aeration measured by the FT4. Coating quality was characterized using ToF-SIMS. The aerosolization performance of the drug powders was evaluated using a Twin Stage Impinger (TSI).

All flow indicators demonstrated that the flow of lactose powders was substantially improved, from poor flow to free-flowing characteristics after coating with MgSt. The coated powder was denser as it packed more efficiently. These aspects are attributed to the reduction in powder cohesion.