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Research Abstracts Online
January 2009 - March 2010

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University of Minnesota Twin Cities
College of Pharmacy
Department of Pharmaceutics

PI: Ronald A. Siegel

Mathematical Modeling of Nonlinear Hydrogel Permeability and Mechanics Applied to Oscillatory Drug Release

Typically, a drug achieves its best results when delivered to the body at a constant rate. If the rate of delivery is too high, the drug is toxic; too low, and the drug is ineffective. For certain drugs, however, a dynamic pattern of release is critical to their efficacy. For example, this can be true of hormone drugs.

Hydrogels, polymers that absorb water, are often used to deliver drugs in a controlled fashion. When N-isopropyl acrylamide is copolymerized with an ionizable comonomer (e.g. methacrylic acid), it forms a hydrogel that demonstrates nonlinear properties that can be exploited to create a relaxation oscillator for rhythmic drug release.

The mechanism by which the hydrogel’s nonlinear membrane permeability results from a volume phase transition has not been demonstrated. These researchers have developed a model of the hydrogel consisting of coupled partial differential equations that describe spatiotemporal gel dynamics. The model successfully predicts a two-state permeability. This model is being used to explore ways of controlling this behavior, such as guiding the researchers’ efforts in modifying the system to oscillate under physiological conditions and scaling the device for practical implantation.

Group Members

David Barriet, Research Associate
Marie Gaumet, Research Associate
Daniel Jung, Graduate Student
Arun Kim, Graduate Student
Isha Koonar, Graduate Student
Jon Urban, Graduate Student