Affinity predictions computations and mechanosynthesis of carbamazepine based cocrystals
Affinity prediction computations based on the COSMO-RS approach of the Active Pharmaceutical Ingredient (API) carbamazepine have been performed with 75 coformers. A selection of coformers and cocrystallization trials by means of mechanosynthesis using liquid assisted grinding has been investigated. Two new cocrystals of carbamazepine with DL-mandelic acid and DL-tartaric acid and one new polymorph with indomethacin have been designed. The affinity predictions computations enabled to calculate the excess enthalpy ∆Hex of the API-coformer mixture relative to the pure components. The ability of ∆Hex to predict cocrystallization was assessed based on the new experimental results obtained in this study and data available in the literature. It is shown that affinity predictions computation might not be totally sufficient when it comes to the selection of all of the coformers that could cocrystallize with carbamazepine. A combination of the excess enthalpy ∆Hex with the fusion entropy of the pure coformer is suggested to be of interest for coformers screening in order to form a multicomponent system with a given API (co-crystal/co-amorphous).