Characterising the surface adhesive behavior of tablet tooling components by atomic force microscopy.

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Surface Science

Background:

• Tablet sticking during compression is a common manufacturing issue.
• Understanding adhesive forces between tablet punches and formulation ingredients is crucial for process optimization.
• Existing methods for evaluating these interactions are limited.

Purpose of the Study:

• To develop an atomic force microscopy (AFM) based approach for studying adhesive forces between tabletting punches and model formulation ingredients.
• To understand and predict sticking issues during tabletting compression.
• To screen tablet punch materials and tabletting conditions.

Main Methods:

• Adhesive interactions were studied between single lactose particles and coated tablet punches using AFM.
• Adhesion was measured at varying relative humidities (RHs).
• Surface roughness was investigated using AFM imaging, and a modeling approach predicted its influence on adhesion.

Main Results:

• Surface roughness significantly influenced lactose-punch adhesion, with spatial mapping identifying high adhesion 'hot spots'.
• Adhesion was strongly affected by RH, with one punch showing a >3-fold increase between 30-60% RH.
• Punch hydrophilicity influenced RH-adhesion behavior, and a modeling approach predicted adhesion from roughness data.

Conclusions:

• A novel AFM method for screening tablet punch materials and tabletting conditions was introduced.
• Key factors influencing adhesive interactions in tablet compression were identified.
• AFM adhesion results correlated with manufacturing observations, providing a basis for predictive approaches to mitigate tabletting issues.