Pharmaceutical co‐crystal: An alternative strategy for enhanced physicochemical properties and drug synergy

Abstract A growing number of co‐crystals in the literature are proof of how significant the co‐crystallization concept has become. Co‐crystallization enhances physicochemical properties through the formation of intermolecular interactions between a drug and a co‐former. A co‐crystal is a single crystalline material consisting of at least two molecular components solid at room temperature and present in a definite stoichiometric ratio. Pharmaceutical co‐crystals consist of the active pharmaceutical ingredient and the co‐former selected from generally regarded as safe (GRAS) list of the United State Food and Drug Administration. Co‐crystal formation requires an understanding of a drug target, a proper choice of a co‐former and is only achieved experimentally after several trials. Other beneficial co‐crystallization outcomes include binary eutectics, solid dispersions, amorphous forms, etc. Several key issues including design strategies, co‐former selection, and co‐crystallization methods; tradition and newly synthetic methods that are more efficient and suitable for large scale have been briefly described. The co‐crystal preference is demonstrated with a particular emphasis on multidrug co‐crystals and their contribution to the drug combination strategies used for the treatment and management of drug resistance and adverse side effects in serious medical conditions that require the administration of high doses such as HIV/AIDS, tuberculosis, and others.