Exceptional Powder Tabletability of Elastically Flexible Crystals

Reversible elastic deformation is deleterious to tablet formation by powder compaction. However, highly elastic caffeine and 4-chloro-3-nitrobenzoic acid cocrystal methanolate (CCM) exhibited surprisingly high tabletability, surpassing that of well-known plastically deformable crystals. We show that the exceptional tabletability of CCM powder is due to the activation of the (010) slip planes along the <001> direction during tableting. The same slip system is dormant when the needle-shaped CCM single crystals are bent on the side faces (11¯ 0) or (110). Thus, the successful prediction of tableting performance requires consideration of crystal anisotropy and stress conditions during powder compression instead of the qualitative single-crystal bending behavior.