Hydrophobic polyamine copolymer hydrogels, loaded with caffeine, release the drug at rates that vary sharply with pH. At neutral pH virtually no caffeine is released, while at pH 3 and 5 the drug is released with near-zero order kinetics, the release rate being greater at pH 3. Water sorption was measured concurrently, and the release of caffeine closely follows water uptake at pH 3 and 5, providing strong evidence for a moving front mechanism for sorption and release.
Bibliographical noteFunding Information:
This work was funded by grants from NIH (DK 38035) and the Diabetes Research and Education Foundation.