Pharmaceutical co-crystals are novel class of pharmaceutical substances, which possess an apparent probability of advancement of polished physical properties offering stable and patentable solid forms. These multi-component crystalline forms influence pertinent physicochemical parameters like solubility, dissolution rate, chemical stability, physical stability, etc. which in turn result in the materials with superior properties to those of the free drug. Co-crystallization is a process by which the molecular interactions can be altered to optimize the drug properties. Co-crystals comprise a multicomponent system of active pharmaceutical ingredient (API) with a stoichiometric amount of a pharmaceutically acceptable coformer incorporated in the crystal lattice. By manufacturing pharmaceutical co-crystals, the physicochemical properties of a drug can be improved thus multicomponent crystalline materials have received renewed interest in the current scenario due to the easy administration in the pharmaceutical industry. There is an immense amount of literature available on co-crystals. However, there is a lack of an exhaustive review on a selection of coformers and regulations on co-crystals. The review has made an attempt to bridge this gap. The review also describes the methods used to prepare co-crystals with their characterization. Brief description on the pharmaceutical applications of co-crystals has also been incorporated here. Efforts are made to include reported works on co-crystals, which further help to understand the concept of co-crystals in depth.

One of the most crucial stages in the creation of a medicinal product is the characterization of an Active Pharmaceutical Ingredient (API). Unfortunately, not all APIs have the ideal characteristics for medicinal usage. Many freshly discovered active compounds, for example, have low solubility. However, various methods have been developed to change and improve an API's features to get desired physicochemical properties, which is an important tool in formulation development. The production of salt derivatives is a common technique for increasing the solubility of an active chemical. This method, however, has limits because not every API has the qualities to be transformed into a salt. In recent years, a novel engineering approach for creating new API forms with desirable features has been established. The development of pharmaceutical co-crystals is the result of these efforts which allow pharmaceutical companies to customise existing APIs or create new ones with specific properties. Aside from the scientific hurdles that come with developing a pharmaceutical, manufacturers are also faced with regulatory regulations that must be met in order to get approval and access the market. As pharmaceutical co-crystals are a relatively new API, little regulatory guidance for co-crystals has been developed for one of the world's largest pharmaceutical market the United States of America (USA). This article will look at what regulatory standards must be met in order to employ pharmaceutical co-crystals in generic medications intended for use in the United States. It will also go over which data should be included in the common technical document to justify its existence. In addition to, a brief information of various patents on co-crystals have also been included for better knowledge of the reader.

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