pH-triggered drug release from biodegradable microwells for oral drug delivery

Line Hagner Nielsen, Johan Nagstrup, Sarah Gordon, Stephan Sylvest Keller, Jesper Østergaard, Thomas Rades, Anette Müllertz, Anja Boisen

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Microwells fabricated from poly-L-lactic acid (PLLA) were evaluated for their application as an oral drug delivery system using the amorphous sodium salt of furosemide (ASSF) as a model drug. Hot embossing of PLLA resulted in fabrication of microwells with an inner diameter of 240 μm and a height of 100 μm. The microwells were filled with ASSF using a modified screen printing technique, followed by coating of the microwell cavities with a gastroresistant lid of Eudragit® L100. The release behavior of ASSF from the coated microwells was investigated using a μ-Diss profiler and a UV imaging system, and under conditions simulating the changing environment of the gastrointestinal tract. Biorelevant gastric medium (pH 1.6) was employed, after which a change to biorelevant intestinal release medium (pH 6.5) was carried out. Both μ-Diss profiler and UV imaging release experiments showed that sealing of microwell cavities with an Eudragit® layer prevented drug release in biorelevant gastric medium. An immediate release of the ASSF from coated microwells was observed in the intestinal medium. This pH-triggered release behavior demonstrates the future potential of PLLA microwells as a site-specific oral drug delivery system.
Original languageEnglish
JournalBiomedical Microdevices
Issue number3
Number of pages7
Publication statusPublished - 2015


  • Biodegradable polymer
  • Oral drug delivery
  • Micro delivery systems
  • Furosemide
  • μ-Diss profiler
  • UV imaging


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