Compounding of low-dose pharmaceutical powders using a planetary centrifugal mixer

Abstract

The low-dose mixing efficiency of planetary centrifugal mixer (PCM) was evaluated by measuring content uniformity of processed mixtures (coefficient of variant; CV%). Atropine sulfate and crystalline lactose were mixed under various conditions, rotation speed (1000–2000 rpm), revolution speed (600–1200 rpm), filling rate (25, 50, 75 v/v%), and drug concentration (0.05–2 w/w%). As a result, a smaller CV% was obtained when higher speeds of both revolution and rotation and a moderate level of filling rate were used. Concentration of atropine sulfate slightly affected CV%, which was lower than 6.08% at a range of 0.25–2 w/w%. To confirm the reliability of this method, oxybutynin chloride and hydrocortisone were used as cohesive powders instead of atropine sulfate. The CV% was found to be below 6.08% at 1200 rpm at both speeds, indicating good uniformity. Particle size distribution analysis and scanning electron microscopy revealed that agglomerates of the drugs were broken down as primary particles, and dispersed on the surface of lactose particles, forming an interactive mixture. Finally, 0.1% atropine sulfate powder, a hospital formulation, was successfully prepared using PCM. Therefore, PCM is useful for compounding even small amounts of formulations.