Teresa Carvajal is a faculty member of the Agricultural and Biological Engineering department at Purdue University. Dr. Carvajal’s research focuses on surface science to assess issues and behavior of powders as a result of the inherent solid state structural, physicochemical, particle surface (interactions e.g. adhesion/cohesion and electrostatics) and mechanical properties. The effects of these properties on powder agglomeration, dispersion and flow could be detrimental on the final pharmaceutical product. Her research interests are on probing surface and bulk properties at the microscopic level to be able to manipulate their characteristics at the macroscopic level and get involved in strategies for controlling behavior of powders. Her experimental approach is to use various techniques thermal, spectroscopic and surface characterization to interrogate materials. Her work on fundamental understanding of the systems extends to design, control and choose appropriate materials for formulation development of powders for inhalation and beverage.
Prior to joining Purdue University, Dr. Carvajal worked in the pharmaceutical industry for 13 years. She worked at Hoffmann-LaRoche (Nutley, NJ) in the area of oral dosage form development. Working on the behavior of powders and powder blends, her activities expanded to research and development of formulations for pulmonary delivery of small molecules and peptides. She later joined Bayer Pharmaceuticals (West Haven, CT) where she was responsible for pre-formulation activities as well as early formulation development for lead compounds of drug discovery. She has been an invited and keynote speaker at various national and international conferences. Dr. Carvajal gives short courses to industry on a various topics in Powder Technology to the USA, Europe and Latin America.
The physicochemical properties of drug particles from two polymorphs were studied in terms of their observable effects on the nature and strength of the interactive forces between drug particles from different polymorphs and lactose in dry powder mixes for inhalation. The type of systems was chosen to investigate the interactive properties of two different surfaces of the same chemical composition. The hypothesis was that the two polymorphs of the same drug would exhibit measurable differences in their inter-‐ particle cohesive/adhesive interactions. These manifest themselves macroscopically by having different ease of metering and in powder dispersion, that in turn at the molecular level are the result of surface energetics of the two polymorphs. The results of the surface energy properties of the two polymorphs revealed that polymorph A elongated crystal habit exhibited stronger cohesive and adhesive interactions that its counterpart polymorph B rounded. In addition, the results also suggest that the effects of surface geometry of the drug particles continues to play a significant, although not necessarily dominant role in the aerosol dispersion and deposition properties of the powder mixes.