Low-Energy Mechanochemical Dry Coating for Improving the Flowability of Sodium Naproxen

Sodium naproxen is a widely used nonsteroidal anti-inflammatory drug (NSAID) known for its therapeutic efficacy but also for its poor flowability, which complicates manufacturing processes. This study aimed to improve the flow properties of sodium naproxen through a patented mechanochemical dry coating method using nanostructured silica (Aerosil^® R972) as a flow modifier. The process was conducted in a modified V-type tumbler mixer under selected conditions, including a 7:1 ball-to-powder mass ratio, a 10-min mixing time, and a 10 rpm rotational speed. Flowability was evaluated using Carr's indices, while mechanical properties were assessed via shear testing with a Jenike cell. Surface morphology was characterized by SEM. Results showed that the modified sodium naproxen samples demonstrated a substantial improvement in flow indices, a shift to an "easy-flowing" classification at higher consolidation stresses, and a marked reduction in cohesion compared to the unmodified material. SEM confirmed partial silica deposition on particle surfaces. These findings indicate that the applied method effectively improves the handling characteristics of sodium naproxen powders. The process is relatively simple, requires low energy, is potentially applicable at a larger scale, and shows potential for pharmaceutical powder processing requiring flow enhancement of cohesive active ingredients.