Structure-mechanics and improved tableting performance of the drug-drug cocrystal metformin:salicylic acid

Here at Gamlen we are highlighting some of the fascinating and ground-breaking research that has been carried out by our customers in our Paper of the Month posts.

The aim of this study was to examine the structure-function relationship of a drug-drug cocrystal, metformin:salicylic acid. Drug-drug cocrystals offer a range of potential advantages to the patient and the manufacturer but to fully realise these advantages the structure-function relationship must be well understood.

  • Metformin:salicylic acid (MET:SAL) cocrystals were prepared
  • A range of characterization techniques were used to confirm the crystal structure of the cocrystal and its components, metformin HCl (MET) and salicylic acid (SAL).
  • A Gamlen Powder Compaction Analyser was used to evaluate the compression performance of the MET, SAL and MET:SAL using a “a material sparing, fast, simple, and accurate ‘in-die’ Heckel method”.
  • The compressibility, compactibility and tabletability of MET, SAL and MET:SAL was assessed. It was found that the cocrystal displayed significantly improved tableting performance relative to its components. The cocrystal could be directly compressed, without binders, and produce a tablet of acceptable hardness.


From the data gathered, the authors successfully linked the intermolecular level changes caused by cocrystallisation to the material’s tableting behaviour and the final properties of the tablet. This is an excellent example of the central principle of materials science, that a materials structure, properties, processing history and performance are all interconnected.