Solid Form Screening and Selection
In the pharmaceutical industry, regulations require that polymorph screening be carried out during active pharmaceutical ingredient (API) development to determine if the API can exist in polymorphic forms and, if so, whether the choice of polymorph will affect the drug's efficacy or safety. Beyond that, a search for solid forms of an API is often conducted to overcome production, formulation, or drug product problems caused by the form produced initially.
Target forms can be polymorphs, hydrates, solvates, salts, cocrystals, and non-crystalline forms. Our current inability to predict crystallization outcomes means that solid form screening is an empirical exercise, and experience has proven that the crystallization technique used can be critical.
Chemfocus has a vast amount of experience in solid form screening (finding them) and selection (property evaluation). We are familiar with state-of-the-art crystallization techniques (solvent-based, thermal, sonication, grinding, high-throughput, etc.) and the analytical techniques necessary to initially sort, then fully characterize, forms found.
Chemfocus can provide screening procedures to meet various needs, identify laboratories to carry out the work, analyze data, and recommend additional work needed for form selection or patent applications. Dr. Stahly has helped many clients understand seemingly confusing data sets to identify the best form for development.
Cocrystals
A word about cocrystals is in order. Cocrystals, which are unique crystalline structures containing multiple components, have been known since 1893. However, the concept of using cocrystals as APIs is new to the pharmaceutical industry.
There is every reason to consider them viable API candidates, so suddenly the experimental space to be covered when searching for solid forms has greatly expanded.
Pharmaceutical companies are developing cocrystal forms of new APIs, and some companies are searching for patentable cocrystals of generic or soon-to-be-off-patent APIs in order to establish intellectual property positions. Chemfocus is uniquely qualified to establish cocrystal screening protocols and aid in the patenting and development of those found.
For a discussion of cocrystals, as well as polymorph and cocrystal screening, see Dr. Stahly's article in Crystal Growth & Design 2007, 7, 1007-1026, which may be downloaded at no cost here.