Co-Crystallization: A Novel Technique to Improvise the Pharmaceutical Characteristics of API's

Background: The poor water solubility of an active pharmaceutical ingredient leads to a lower dissolution profile that in turn results in poor bioavailability of drugs. Various approaches like solid dispersion, nano-technology, complexation, and micronization techniques, etc. are frequently used by pharmaceutical researchers to overcome these issues. In this context, crystal engineering emerges as a viable technique. Objective: This review endeavors to cover the latest developments in the field of solubility enhancement using crystal engineering techniques. Methods: Extensive literature survey was conducted in order to gain information on the past and present developments in the field of crystal engineering. Results: In the co-crystallization process, the API and coformer interact with each other in a fixed stoichiometric ratio. The backbone of co-crystals is structurally repeating units called supramolecular synthons. These synthons provide the flexibility of transfer from one co-crystal system to another, making crystal engineering a viable approach for physicochemical property modification. Further, the availability of a large number of food and drug grade coformers with a diverse functional group and a range of preparation methods provide an excellent opportunity for tuning up desired physicochemical properties of an API. Conclusion: This review focuses on the latest developments in the field of crystal engineering in the context of screening, preparation methods, characterization, and their application in the pharmaceutical field. Also, the concern over scale-up and regulatory guidelines are covered.