Identification of critical process variables for coating actives onto tablets via statistically designed experiments

The objective of this work was to identify, using a statistical experimental design, the critical processing variables that affect content uniformity and loading of active agent coated on tablets in a 24" Accela-Cota. United States Pharmacopeia (USP) specifies that the % relative standard deviation (RSD) of drug content within a batch should be less than 6%. A Plackett-Burman experimental design was used to identify the process variables that influence the content uniformity and loading efficiency of the drug in the aqueous-based film coat of the tablets. The process variables investigated were inlet airflow, pan speed, inlet air temperature, coating time, atomization pressure, and fan pressure. Atomization pressure was identified as a major variable with respect to content uniformity (P<0.01). Pan speed and coating duration were also identified as variables significantly affecting content uniformity (P<0.05). Fan pressure was identified as a critical variable affecting recovery (P<<0.01). Temperature also significantly affected recovery (P<0.05). A good correlation was obtained between observed and predicted values for content uniformity (r(2)=0.85) and recovery (r(2)=0.95). It was possible to achieve % RSD less than 6% while maintaining the recovery at 80% or higher.