Understanding differences in residual forces and color gradients in tablets composed of microcrystalline cellulose and lactose

This study aims to determine whether the atypical residual force profile, referred to as the “high residual force profile,” previously identified in microcrystalline cellulose (MCC)-based mixtures, is specific to this material type or can also be observed in materials of a different nature, such as lactose. A colored pigment was incorporated into the mixtures to visualize densification gradients, facilitating the analysis of stress and density distribution. The results clearly highlight differences in compression behavior between the two materials, consistent with well-established findings in the literature. Additionally, high residual force profiles were observed exclusively in MCC-based mixtures. This suggests that these atypical profiles may be specific to viscoplastic materials like MCC and are not exhibited by materials such as lactose. Furthermore, a comparison of color gradients on the tablet bands of the two materials reveals additional complexity. In MCC-based tablets, color intensity variations cannot be solely attributed to differences in densification, suggesting the involvement of additional mechanisms influencing color gradients. This study confirms the uniqueness of high residual force profiles in MCC-type materials while providing new insights into the factors affecting density and color gradients. These findings highlight the importance of understanding material-specific behaviors during compression and open avenues for further investigation into the mechanisms driving these phenomena.