Rodney J Wigent PhD
Rodney Wigent PhD
Research Professor of Pharmaceutics
Professor of Chemistry
BS (Michigan Technological University)
MS (Michigan Technological University)
PhD (Michigan Technological University)
Studying solution thermodynamics through activity and osmotic coefficients, density, and viscosity measurements. Investigating environmental factors that affect supercoiling of plasmid DNA in bacteria. Exploring how to optimize drug-carrageenan formations to improve drug release profiles. Thermodynamic properties of water and aqueous solutions Physical chemical properties and characterization of drug excipients Effect of drug binding on DNA topology
Solution thermodynamics: A large number of waters of hydration (20 _ 60) have been found for precipitates of tetra n_butylammonium 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 which 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 the TBAC 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
Expertise: Graduate Education, University Administration, Research Administration, Thermodynamics, Chemical Kinetics, Pharmaceutics (Drug Delivery), Electrolyte Solutions, Effect of Water on Drug Excipients and Biological Systems
Trained as a physical chemist, Dr. Wigent studied water and the effects on biological molecules using thermodynamics in graduate school. He also developed models to explain the thermodynamic properties of concentrated electrolyte solutions. Upon coming to PCPS, now USciences, as an Assistant Professor of Chemistry, he continued his studies on the effects of water on various physical systems such as the structure and stability of DNA, DNA supercoiling, and the physical properties of microcrystalline cellulose and carrageenans. These interests lead to his involvement with many projects with the faculty and graduate students in the Department of Pharmaceutics, where he received a secondary faculty appointment.
Dr. Wigent became very interest in the educational development of undergraduate and graduate students, especially in encouraging them to perform research. He began mentoring many of these students’ research endeavors. He served as the primary research advisor for many undergraduate and graduate students and served on many research advisory committees. He soon found himself as Director of the Graduate Programs in the Department of Chemistry and was heavily involved in the faculty governance of graduate education within the University.
Shortly after obtaining University status which required more scholarship/research and graduate education within the University, Dr. Wigent was given a second administrative appointment as Dean of the College of Graduate Studies in 1999 charged with the responsibility to make this happen. In 2003 he was appointed as Director of Research responsible for creating a viable research infrastructure within the University to increase research-based scholarship.
Dr. Wigent continues to teach a graduate-level chemical kinetics course and continues to mentor graduate students’ research endeavors while performing his administrative duties. He belongs to several professional organizations which support his academic interest, such as Sigma Xi, American Chemical Society and American Association of Pharmaceutical Scientist) as well as organizations which support his administrative interests, such as NAGAP, COGS and LES/AUTM).
Selected Scholarly Activity
Huang, J.; Wigent, R. J.; Schwartz, J. B. Drug-polymer interaction and its significance on the physical stability of nifedipine amorphous dispersion in microparticles of an ammonio methacrylate copolymer and ethylcellulose binary blend. J. Pharm. Sci. 2008, 97, 251-262.
Vaidya, A. P.; Wigent, R. J.; Moore, J. C.; Schwartz, J. B. Protective effect of carbopol on enzymatic degradation of a peptide-like substrate I: Effect of various concentrations and grades of carbopol and other reaction variables on trypsin activity. Pharm. Dev. Technol. 2007, 12, 89-96.
Huang, J.; Wigent, R. J.; Bentzley, C. M.; Schwartz, J. B. Nifedipine solid dispersion in microparticles of ammonio methacrylate copolymer and ethylcellulose binary blend for controlled drug delivery - Effect of drug loading on release kinetics. Int. J. Pharm. 2006, 319, 44-54.
Huang, J.; Wigent, R. J.; Schwartz, J. B. Nifedipine molecular dispersion in microparticles of ammonio methacrylate copolymer and ethylcellulose binary blends for controlled drug delivery: Effect of matrix composition. Drug Dev. Ind. Pharm. 2006, 32, 1185-1197.
Mayville, F. C.; Wigent, R. J.; Schwartz, J. B. Thermogravimetric analysis for the determination of water release rate from microcrystalline cellulose dry powder and wet bead systems. Pharm. Dev. Technol. 2006, 11, 359-370.
Mark T. DeCrosta, Joesph B. Schwartz, Rodney J. Wigent and Keith Marshall, “Thermodynamic Analysis of Compact Fromation; Compaction, Unloading and Ejection. II. Mechanical Energy (Work) and Thermal Energy (Heat) Determinations of Compact Unloading and Ejection”, Int. J. Pharm., 213, 45-62 (2001).
Lijuan Tang, Joseph B. Schwartz, Stuart C. Porter, Roger L. Schnaare, and Rodney J. Wigent, “Drug Release from Film Coated Chlorpheniramine Maleate Nonpareil Beads: Effect of Water-Soluble Polymer, Coating Level, and Soluble Core Material”, Pharm. Devel. Tech., 5(3), 383-390 (2000).
Kosasih, Bill J. Bowman, Rodney J. Wigent, and Clyde M. Ofner III, “Characterization and In Vitro Release of Gelatin/Methotrexate Conjugates Formed using Different Preparation Variables”, Intern. J. Pharmaceutics, 204, 81-89 (2000).
Mark T. DeCrosta, Joesph B. Schwartz, Rodney J. Wigent and Keith Marshall, “Thermodynamic Analysis of Compact Formation; Compaction, Unloading, and Ejection. I. Design and Development of a Compaction Calorimeter AND Thermal Energy Determinations of Powder Compaction”, Inter. J. Pharm. Rev., 198, 113-134 (2000).
Li-Juan Tang, Rodney J. Wigent, and Joesph B. Schwartz, “Drug Release from Film Coated CPM Non-pareil Beads: Water Influx and Development of a New Drug Release Model”, Pharm. Devel. Tech., 4, 481-490 (1999).
Francis C. Mayville, Faraj Atassi, Rodney J. Wigent and Joseph B. Schwartz, “Humidity Studies for Samples of Microcrystalline Cellulose taken from the Extrusion/Maurumerization Process”, Pharm. Devel. Tech., 4(4), 467 (1999).
G.P. Millili, R.J. Wigent, and J. Schwartz, “Differences in the Mechanical Strength of Dried Microcrystalline Cellulose Pellets Are Not Due to Changes in the Degree of Hydrogen Bonding.”, Pharm. Devel. Tech., 1(3), 239 (1996).
F.J. Nowaczyk, R.L. Schnaare, C.M. Ofner, and R.J. Wigent, "A Spectrophotometric Modification of the Winkler Method for Measurement of Dissolved Oxygen", Pharmaceutical Research, 10(2) 305 (1993).
F.J. Nowaczyk Jr., R.L. Schnaare, R.J. Wigent, and C.M. Ofner III, "Charge Transfer Complexes of Iodine and Nonionic Surfactants: Interpretation and Use in the Winkler Method", J. Pharm. Biomed. Anal., 11(9) 835 (1993).
G. Zhang, J. Schwartz, R. Schnaare, R. Wigent, and E. Sugita, "Bead Coating: II. Effect of Spheronization Technique on Drug Release From Coated Spheres", Drug Development and Industrial Pharmacy, 17(6), 817 (1991).
G. Zhang, J.B. Schwartz, R.L. Schnaare, E.T. Sugita, and R.J. Wigent, "Kinetics of Sphere Growth in Marumerization", J. China Pharm, Univ, 21(2), 73 (1990).
G.P. Millili, R.J. Wigent, and J.B. Schwartz, "Autohesion in Pharmaceutical Solids", Drug Development and Industrial Pharmacy, 16(16), 2383 (1990).
L. Leifer and R.J. Wigent, "Determination of the Contribution of Pair, Triplet and Higher Order Multiplet Interactions to the Excess Free Energy of Mixing in Mixed Electrolyte Solutions." J. Phys. Chem., 89, 244, (1985).
R.J. Wigent and L. Leifer, "Determination of Osmotic and Activity Coefficients in Mixed Electrolyte Systems. Systems Containing Clathrate_Forming Salts." J. Phys. Chem., 88, 4420 (1984).
|Office location:||McNeil Room 124|
|Mailing address:||Box 48|
University of Sciences
600 South 43rd Street
Philadelphia, PA 19104-4495
r [dot] wigent [at] usciences [dot] edu