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Solid-state NMR studies of pharmaceutical solids in polymer matrices
Joseph W Lubach1, Brian E Padden, Stephanie L Winslow
1Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Ave, Lawrence, KS 66047, USA.
Analytical and Bioanalytical Chemistry
|June 25, 2004
Summary
Solid-state NMR spectroscopy effectively analyzes drug stability in biodegradable drug-delivery systems. This technique identifies drug forms and interactions within matrices, crucial for controlled release applications.
Area of Science:
- Materials Science
- Analytical Chemistry
- Pharmaceutical Science
Background:
- Biodegradable drug-delivery systems offer controlled medication release over extended periods.
- Assessing the long-term stability of drugs and matrices is critical for effective formulation.
- Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful tool for analyzing solid-state materials.
Purpose of the Study:
- To demonstrate the utility of solid-state NMR spectroscopy in characterizing drug forms within biodegradable matrices.
- To investigate the solid-state forms of bupivacaine in tristearin/protein microspheres.
- To evaluate the application of solid-state NMR for studying biomolecule-polymer interactions in lyophilized formulations.
Main Methods:
- Solid-state 13C NMR spectroscopy was employed to analyze drug-loaded microspheres and lyophilized biomolecule-polymer mixtures.
- Characterization of bupivacaine free base and bupivacaine-HCl in bulk and within a tristearin/protein matrix.
- Study of uniformly 13C-labeled asparagine (Asn) in poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) matrices.
Main Results:
- Solid-state 13C NMR spectra clearly distinguished between different crystalline forms of bupivacaine.
- The drug form within the tristearin matrix was identifiable at low concentrations (1:100 w/w).
- Solid-state NMR successfully characterized interactions between asparagine and polymer matrices (PVP, PVA).
Conclusions:
- Solid-state NMR spectroscopy is effective for determining drug solid forms and stability in biodegradable delivery systems.
- The technique can identify drug forms at low loadings and elucidate drug-matrix interactions.
- Solid-state NMR is valuable for characterizing lyophilized biomolecules within polymer matrices, aiding in the development of advanced drug delivery.