Dr. Jian Wang SVP J-Star Research – a Porton Company Between API or drug substance (DS) processing and drug product (DP) processing, there is a conventional gap (or wall) that adds additional time and efforts to new drug development programs and limits special formulation development. It is common for desired DP performance(s) to request the DS meeting specs of particle size distribution, morphology, bulk density, flow property, hygroscopicity control, and others aside from meeting specs of purity, residual solvent content, polymorph ID/content, etc.. Even for a DS delivered with required quality attributes, after significant developmental efforts, challenges still remain in DP processing. Such as, the needs for further milling (either de-lumping or micronization) of DS, accurate subdivision into vials or capsules, even blending with excipients, instability during compression, and more and more often, the needs for solubility or dissolution enhancement, controlled release (slow or fast or in combination), etc.. Many of such technical hurdles in DS and DP developments and processing can be addressed with much greater efficiency through DS-DP co-processing. In solid dosage processes, DS is generally blended with excipients via wet or dry granulation, which can be better or more effectively handled by co-processing. Co-processing is a relatively new area of particle engineering in which commonly used excipients can be combined with the API in a more deliberate and controlled manner to design a pharmaceutical composite material (PCM)1,2. This approach combines two or more materials in a specific way in order to produce a composite material with improved physical or chemical properties. A PCM can be designed to resolve some of the common issues related to solid dosage production such as material flow, stability, compactibility, release profile, bioavailability, solubility and dissolution3, food effect, content uniformity, taste, and even containment issues related to potent or toxic compounds. Cases and on-going efforts in DS-DP co-processing at the Center for Pharma Crystallization (CfPC) will be discussed, highlighting the benefits of bridging the gap between DS and DP via co-processing. 1. M. Saffari, A. Ebrahimi, T. Langrish, A novel formulation for solubility and content uniformity enhancement of poorly water soluble drugs using highly porous mannitol. Eur. J. Pharm. Sci., 83(2016), pp 52-61 2. Nima Yazdanpanah, Christopher J. Testa, Siva R. K. Perala, Keith D. Jensen, Richard D. Braatz, Allan S. Myerson, and Bernhardt L. Trout “Continuous Heterogeneous Crystallization on Excipient Surfaces” Crystal Growth and Design, 2017, 17, 3321-3330 3. Qian, et al. J Pharm Sci. 2010, 99(7), 2941-2947.