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Drug release from thin films encapsulated by a temperature-responsive hydrogel
Oliver Werzer1, Stephan Tumphart, Roman Keimel
1Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria.
Soft Matter
|January 31, 2019
Summary
Temperature-responsive hydrogels control drug release. This study found that drug-polymer interactions, not just swelling, significantly impact release rates from N-isopropylacrylamide (NIPAAm) hydrogels.
Area of Science:
- Polymer Science
- Materials Science
- Drug Delivery Systems
Background:
- Temperature-responsive polymers offer tunable drug delivery.
- N-isopropylacrylamide (NIPAAm) hydrogels exhibit a lower critical solution temperature (LCST) around 29°C.
- Drug release from swollen hydrogels is often expected to be higher, but contradictory results exist.
Purpose of the Study:
- To investigate drug release mechanisms through NIPAAm hydrogels.
- To determine the influence of polymer swelling and drug-polymer interactions on release kinetics.
- To explore the role of pH in modulating drug release.
Main Methods:
- Synthesized p(NIPAAm-co-DEGDVE) hydrogel layers using initiated chemical vapor deposition (iCVD).
- Incorporated model drugs (phenytoin, clotrimazole, indomethacin) beneath hydrogel layers.
- Conducted dissolution experiments measuring drug release at various pH values.
Main Results:
- Drug release was observed through the p(NIPAAm-co-DEGDVE) hydrogel layers.
- Release kinetics were dependent on factors beyond simple hydrogel swelling.
- Drug-polymer interactions were identified as a critical factor influencing release.
Conclusions:
- Hydrogel swelling alone does not fully predict drug release rates.
- Drug-polymer interactions play a significant role in controlling drug permeation.
- This highlights the complexity of designing effective temperature-responsive drug delivery systems.
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