Crystal engineering of the composition of API's: Understanding polymorphs and designing pharmaceutical co-crystals

The emerging field of crystal engineering is poised to address two matters of topical relevance in the context of API's: intellectual property protection and improved formulation. In the context of the former, polymorphs can be rationalized and new compositions of matter can be designed from first principles. In the context of the latter, pharmaceutical co-crystals represent an attractive and broad ranging alternative to the traditional forms of API's: salts, solvates and polymorphs. General observations related to the functional groups commonly found in API's (e.g. alcohols, ethers, amides, acids) are presented along with a case study of Carbamazepine (Tegretol®), an API with well documented solubility, bioavailability and polymorphism problems.