Graduate Faculty Directory
Rodney Wigent
Department of Pharmaceutical Sciences
Education
- BS, MS, PhD (Michigan Tech)
Title(s)
Dean, College of Graduate Studies
Director of Research
Faculty Appointments
Research Professor of Pharmaceutics
Professor of Chemistry
Research Interest
Thermodynamic properties of water and aqueous solutions
Physical chemical properties and characterization of drug excipients
Effect of drug binding on DNA topology
Synopsis
My research interests focus on three basic areas—solution thermodynamics, physical biochemistry, and, pharmaceutics.Solution Thermodynamics
A large number of waters of hydration (20–60) have been found for precipitates of tetra n-butylammonium (TBA) halides at temperatures ranging from 5 to 25ºC. It is believed that these clathrates may exist in solution. Studies of these solutions as a function of concentration and temperature may serve to model similar interactions that may occur in aqueous solutions of important biological molecules. We have studied these solutions through activity and osmotic coefficients, density, and viscosity measurements. It appears that as the concentration of a TBA halide increases, these molecules begin to share solvent cages, forcing ion-ion interactions to occur in solution at 25ºC. At 60ºC, our data suggest that the clathrate cage may not be thermally stable and the interactions are different than they are at 25ºC.
Physical Biochemistry
Also of interest are the environmental factors that effect the degree of supercoiling of plasmid DNA in bacteria. The degree of supercoiling may prove to be important in the translation and transcription processes and may also be important in the thermal stability of the DNA helix.
Pharmaceutics
The physical/chemical properties of the inert pharmaceutical excipient, microcrystalline cellulose (MCC), change upon forming dried pellets during the extrusion/marumerization process. We have proposed that if the surface tension of the granulating liquid is sufficiently high, then the evaporation of the granulating fluid from the interstitial spaces between the MCC fibrils causes these “pores” to collapse. This changes the rate in which water is sorbed and/or desorbed from these systems and changes the drug release profiles. Isothermal titration and differential scanning calorimetry have also been used to study the interaction of simple salts and drugs with lambda, kappa, and iota carrageenans. It is our hope that these results will lead to a better understanding of the mechanism by which these carrageenans “gel” and how to optimize the drug-carrageenan formulation to get improved drug release profiles.
Publications & Presentations
- “Differences in the Mechanical Strength of Dried Microcrystalline Cellulose Pellets Are Not Due to Changes in the Degree of Hydrogen Bonding,” G. P. Millili, R. J. Wigent, and J. Schwartz, Pharm. Devel. Tech., 1996, 1(3), 239.
- “Charge Transfer Complexes of Iodine and Nonionic Surfactants: Interpretation and Use in the Winkler Method,” F. J. Nowaczyk Jr., R. L. Schnaare, R. J. Wigent, and C. M. Ofner III, J. Pharm. Biomed. Anal., 1993, 11(9), 835.
- “Determination of the Contribution of Pair, Triplet and Higher Order Multiplet Interactions to the Excess Free Energy of Mixing in Mixed Electrolyte Solutions,” L. Leifer and R. J. Wigent, J. Phys. Chem., 1985, 89, 244.
Contact Information
Office:
Robert McNeil Graduate Study and Research Center
Room # 104
Box # 22
Phone: 215.596.7545
Email: r.wigent@usp.edu
