|Stephen W. Hoag
Department of Pharmaceutical Sciences
20 North Pine Street
Baltimore, MD 21201
Phone: (410) 706-6865
Fax: (410) 706-0346
- B.S. (Biochemistry) 1982, University of Wisconsin Madison
- Ph.D. (Pharmaceutics) 1990, University of Minnesota, Twin Cities
Fields of Interest:
- Tablet Formulation, Process Development
- Capsule Filling
- Excipient Functionality Characterization
- Process Analytical Technology (PAT)
- Near Infrared (NIR) Analysis of Solid Oral Dosage Forms
- Raman Analysis
- Spectroscopic Characterization of Pharmaceutical Materials
- Controlled Release Formulation Development
- Fluid Bed and Pan Coating
- Controlled Release Polymer Characterization
- Polymer Film Coating
- Thermal Properties of Coating Polymers
- Colloidal Stability
- Pigments and Lakes Used in Coatings
- Film Formation
- Film Coat Curing
- Powder Flow
- Shear Cell Design
- Mass Transfer
- Controlled Release Gels
- Folic Acid (Neural Tube Defects) & Nutritional Supplements
Pharmaceutical Dosage Forms:
- Volume 1: Unit Operations and Mechanical Properties
- Volume 2: Rational Design and Formulation
- Volume 3: Manufacture and Process Control
I have two main areas of research; the first area involves developing systematic methods for formulating controlled and immediate release tablets:
- Tablet Press Instrumentation: By using computers and an instrumented tablet press to monitor tablet compaction, mathematical models can be derived that describe the tablet compaction process. These models serve as a basis for improving our understanding of tablet compaction and the mechanical stability of a tablet formulation. To conduct this research students who work in my laboratory become familiar with: tablet press operation, tablet press instrumentation and the design of instrumentation using finite element analysis (FEA), PC-based data acquisition systems and mathematical modeling.
- Formulation of Nutritional Supplements and Botanical Products: As an extension of this formulation research, we are also examining the formulation of folic acid containing multivitamin and mineral supplements. In a study conducted in our laboratory we found that 66% of the prenatal vitamins we tested failed to meet the USP dissolution specification for folic acid. Given the significant health implications of folic acid in the prevention of neural tub defects we are trying to determine why so many products failed and what can be done to improve their formulation. Students who conduct this research will become familiar with dissolution testing, determination of intrinsic dissolution rate for vitamins and the formulation of nutritional supplements and complex botanical products.
- Shear Cell Analysis and Formulation Scale-Up: With this area of research we are trying to correlate critical states in a powder bed with problems found during the scale-up of a formulation. Film coating polymers: we examine the interactions between common excipients and the film coating polymers and film coating dispersions.
- Process Analytical Technology (PAT): The goal of this research is to find the best practices for Near Infrared (NIR) spectroscopic monitoring of the different unit operations involved in tablet product, and determining the best practices for applying chemometric models to the spectroscopic datasets.
The second area of research involves the use of mathematical models to understand the mass transport processes in hydrogels. Typically hydrogels are used as diffusion barriers to either control the rate of release or to keep incompatible components of a system separated. Thus, the understanding of the diffusional properties of these gels is critical to their successful application. Studies to date have examined the factors that lead to heterogeneous Ca alginate gel formation and the release of bioactive molecules from these heterogeneous calcium alginate gels. Also, we have examined silk-elastinlike protein polymers and the effects of solute charge and hydrophobicity on the release from the protein polymers.