Combining API in a dual-drug ternary cocrystal approach.

A new strategy is developed to design multi-drug solid forms. Using an inorganic salt as the glue sticking together two different APIs in a "drug-bridge-drug" approach, we successfully created and characterized three different ternary ionic cocrystals (TICCs). The link between binary and ternary ICCs and the importance of reaction stoichiometry was investigated using ternary solid-state phase diagrams. In addition, we highlighted the crucial role of water for the stability of these systems, as well as the impact on solubility compared to the respective parent compounds. We expect the strategy presented here to be applicable to a large series of drug combinations, opening up a promising new way of building multi-drug systems.