Vibratory mixing of pharmaceutical powders on a single-tablet-scale

A single-tablet-scale mixing process, being part of a setup for the production of individualized tablets, is developed and studied. The process relies on the principle of vibratory mixing to achieve a homogeneous powder blend in the order of seconds. To investigate the mixing performance under various frequencies and amplitudes, a contactless evaluation method was implemented based on high-speed video recordings, a colored tracer and image analysis. The high spatial and temporal resolution of the recordings proved a valuable tool to assess the quality of the mixing process. Depending on the vibration parameters, different intensities of diffusive and convective mixing were observed. It was found that for similar accelerations, lower frequencies lead to faster mixing. Applying vibrational frequencies of 100 and 150 Hz and accelerations of 112 g a homogeneous blend of Emcocel 90 M and dyed Avicel PH-102 was produced within 2 s. This indicates the suitability of this approach for the use in the design of a small-scale direct compression process.