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Diffuse reflectance near-infrared spectroscopy as a nondestructive analytical technique for polymer implants
R L Brashear1, D R Flanagan, P E Luner
1College of Pharmacy, Division of Pharmaceutics, The University of Iowa, Iowa City, Iowa 52242, USA.
Journal of Pharmaceutical Sciences
|December 10, 1999
Summary
A new near-infrared (NIR) spectroscopy method accurately quantifies drugs and excipients in polymer implants. This technique offers a reliable way to measure poly(ethylene glycol) (PEG) and lomefloxacin HCl content in poly(epsilon-caprolactone) (PCL) matrices.
Area of Science:
- Pharmaceutical Sciences
- Analytical Chemistry
- Materials Science
Background:
- Polymeric matrix implants are used for controlled drug delivery.
- Accurate quantification of drug and excipient content is crucial for implant performance and safety.
- Existing methods for quantifying components within implants can be destructive or labor-intensive.
Purpose of the Study:
- To develop and validate a non-destructive near-infrared (NIR) spectroscopic method for quantifying lomefloxacin HCl and poly(ethylene glycol) (PEG) within poly(epsilon-caprolactone) (PCL) matrices.
- To compare the accuracy of the NIR method with established analytical techniques.
Main Methods:
- Cylindrical implants were fabricated using a melt-mold technique with varying ratios of PCL and PEG, and different loadings of lomefloxacin HCl.
- Intact implant sections were analyzed using a Foss NIRSystems Model 5000 monochrometer.
- Spectral data underwent second derivative transformation, followed by linear regression and Partial Least Squares (PLS) analysis.
- Lomefloxacin HCl content was independently verified using UV analysis.
- Mid-infrared spectral data were used to interpret NIR findings.
Main Results:
- Second derivative spectral values at specific wavelength ratios showed linear correlations with PEG and lomefloxacin content.
- PEG content determined by NIR spectroscopy showed excellent agreement with theoretical values.
- Lomefloxacin HCl content determined by NIR spectroscopy demonstrated excellent agreement with UV analysis results.
- The developed NIR method proved to be accurate and reliable for quantifying both drug and excipient.
Conclusions:
- Near-infrared (NIR) spectroscopy provides a robust, non-destructive method for quantifying active pharmaceutical ingredients and excipients in polymeric implants.
- This technique can be effectively applied to quality control and formulation development of drug-eluting implants.
- The use of second derivative transformation and specific wavelength ratios enhances the accuracy of NIR quantification in complex matrices.