The objective was to study the relationship between crystal structure, particle deformation properties and tablet-forming ability for the monoclinic form of paracetamol (PRA), two cocrystals and a salt crystal of PRA in addition to two coformers (oxalic acid and 4,4’-bipyridine). Thus, the structure – property – performance relationship was investigated. Analytical powder compression was used for determination of effective plasticity, as inferred from the Heckel yield pressure and the Frenning parameter, and the elastic deformation was determined from in-die tablet elastic recovery.

plasticity could not be linked to the crystal lattice structure as crystals containing zig-zag layers displayed similar plasticity as cThe rystals containing slip planes. In addition, crystals containing slip-planes displayed both high and low plasticity.

The mechanical properties could neither be linked to the tablet-forming ability as the tablet tensile strength, unexpectedly, displayed a tendency to reduce with increased plasticity stiffness. Furthermore, the elastic deformation could not explain the tablet forming ability.

It was concluded that no relationship between structure – property – performance for paracetamol and its cocrystals and salt could be established. Thus, it was indicated that to establish such a relationship an improved knowledge of crystallographic structure and inter-particle bonding during compaction is needed.