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Catanionic drug-surfactant mixtures: phase behavior and sustained release from gels
Tobias Bramer1, Mattias Paulsson, Katarina Edwards
1Department of Pharmacy, Uppsala University, SE-751 23 Uppsala, Sweden.
Pharmaceutical Research
|November 19, 2003
Summary
Mixtures of sodium dodecyl sulfate (SDS) and drugs form novel phases for sustained drug release. These phases, like vesicles and branched micelles, significantly slow drug release from gels, enhancing drug delivery systems.
Area of Science:
- Physical Chemistry
- Materials Science
- Pharmaceutical Sciences
Background:
- Surfactant-drug interactions are crucial for developing advanced drug delivery systems.
- Understanding phase behavior in mixtures of anionic surfactants and cationic drugs can lead to novel formulations.
Purpose of the Study:
- To investigate phase diagrams of sodium dodecyl sulfate (SDS) with diphenhydramine, tetracaine, and amitriptyline.
- To explore the potential of specific phases for sustained drug release from gel matrices.
Main Methods:
- Phase diagrams were constructed using visual, rheological, and cryotransmission electron microscopy analyses.
- In vitro drug release studies were conducted using the USP paddle method from Carbopol 940 and agar gels.
Main Results:
- Vesicle and branched micelle phases were observed in SDS-rich regions for all drug systems.
- The tetracaine system uniquely exhibited a vesicle phase on the drug-rich side.
- Drug release was significantly retarded (over 10-fold) when drugs were incorporated into vesicle or branched micelle phases within gels.
Conclusions:
- SDS and positively charged drugs form unique phases analogous to catanionic mixtures.
- These identified phases offer potential for creating effective controlled-release drug delivery systems utilizing gel carriers.