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Plasticisation of amylodextrin by moisture: consequences for drug release from tablets
R Steendam1, A C Eissens, H W Frijlink
1Deparment of Pharmaceutical Technology and Biopharmacy, Groningen University Institute for Drug Exploration, The Netherlands. rob.steendam@akzonobel.com
International Journal of Pharmaceutics
|September 30, 2000
Summary
Controlling moisture in amylodextrin tablets is key for predictable drug release. Optimal moisture levels (10-17%) and compaction pressure ensure consistent tablet performance and sustained theophylline monohydrate release.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
Background:
- Moisture significantly impacts amylodextrin powder consolidation, affecting tablet porosity and mechanical strength.
- Understanding these effects is crucial for controlling drug release from amylodextrin-based tablets.
Purpose of the Study:
- To correlate moisture content and compact properties with theophylline monohydrate release from amylodextrin tablets.
- To investigate the influence of moisture and porosity on drug release mechanisms and kinetics.
Main Methods:
- Preparation of amylodextrin tablets containing theophylline monohydrate.
- Systematic variation of moisture content and compaction pressure during tablet manufacturing.
- Characterization of tablet porosity and mechanical properties.
- In vitro drug release studies under varying conditions.
Main Results:
- Drug release follows a leaching mechanism, with crack formation in the hydrated matrix leading to near-constant release rates.
- A unique, moisture-independent relationship exists between tablet porosity and release rate.
- A critical porosity of 0.075 dictates tablet behavior: above it, disintegration and rapid release occur; below it, sustained release is observed.
- Small moisture variations cause significant changes in release rates.
Conclusions:
- Precise control of moisture content (10-17%) is essential for reproducible drug release from amylodextrin tablets.
- Sufficient compaction pressure (>300 MPa) combined with optimal moisture ensures constant release behavior.
- Lubrication enhances tablet robustness and improves amylodextrin's reliability as a release-controlling excipient.