Christopher L. Burcham Senior Engineering Research Advisor Eli Lilly and Company Key Words: Particle Engineering, Crystallization, Solubility Enhancement Pharmaceutical products are held to high standards of quality, necessary to ensure that a patient receives medicines that are safe and effective. Regulatory bodies also expect and require that pharmaceutical manufacturers are able to produce medicines in a way that is reliable ensuring there is minimal risk to disrupting the supply of medicines to patients. The solid form of an active pharmaceutical ingredient can directly impact the performance of a solid oral dosage form. The physical properties of the drug substance can also negatively impact the ability to manufacture drug product. Control of and improvements to the physical properties of the drug substance can be achieved through crystallization process design, improving downstream manufacturing and ensuring optimal product performance. However, in some cases for poorly soluble drugs, improving the physical properties of a crystalline drug substance is not enough to ensure adequate product exposure. In these cases, alternative particle engineering techniques can be utilized to increase the solubility of the drug substance offering increased bioavailability. Examples of applications of particle engineering techniques to improve processability as well as product performance will be presented.