Gerard Klinzing

Department: Materials Science and Engineering

Advisor’s name: Dr. Antonios Zavaliangos

Research title: Understanding the effect of humidity on the structural integrity of bilayer pharmaceutical tablets

Lab Website: http://www.materials.drexel.edu/pmg/

E-mail address: grk34@drexel.edu

Undergraduate institution: University of Delaware, Chemical Engineering

Publications:

• Klinzing, G., et al. 2010. “Temperature and density evolution during compaction of a capsule shaped tablet.” Computers & Chemical Engineering (34), 1082-1091.
• Klinzing, G., Zavaliangos, A. “Modeling the Moisture Uptake of Microcrystalline Cellulose Talbets Exposed to Humidity,” In preparation.

Research: Tablets are the most prevalent form of drug delivery in the medical community, with over 80% of all therapeutic drugs administered through tablets. Tablets are popular due to the ease of delivery and convenience of dosage control. The development of bilayer tablets has presented a new technique for treating ailments with one tablet, whereas previously, several tablets would have been administered. For example, bilayer tablets present the opportunity to administer two therapeutic drugs which, until now, could not have been administered within the same tablet because of chemical incompatibilities. Moreover, bilayer tablets can be fabricated to contain one layer which dissolves away quickly for immediate therapeutic release where a second layer dissolves slowly to continue therapy throughout an extended period of time. Unknown to those outside the pharmaceutical industry is the effect humidity can have on pharmaceutical tablets. Many pharmaceutical materials are capable of absorbing variable quantities of ambient moisture from air, which can alter tablet integrity. Bilayer tablets composed of two different material layers can absorb moisture at different rates and quantities, causing tablets to split along the material interface. The cause of failure is the result of the differential expansion of each layer, resulting in a weak interface. Despite the fact that this current problem exists, moisture uptake is a well defined phenomenon in the pharmaceutical industry. However, very few studies contain information on the interaction between humidity and tablet properties. Most information available deals only with equilibrium conditions and no information exists on the transient effect of humidity on tablets. The goal of this research is to: a) establishing an understanding of the dominant mechanism controlling moisture diffusion through pharmaceutical tablets, b) characterizing the transient behavior of moisture uptake into pharmaceutical tablets, c) develop a physics based model to describe transient moisture uptake, and d) incorporate the model into finite elements in order to predict moisture uptake for more complex tablet geometries.

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