Hydrogel-forming microneedles (MN) were fabricated and evaluated for transdermal therapeutic monitoring of glucose as an endogenous biomarker model and two drugs, sodium valproate, as an anion model drug, and lithium as a cation model drug. A range of hydrogel-forming materials were characterized and evaluated to identify the most suitable formulation for fabrication of MN suitable for transdermal TM. MN contain no drugs themselves, upon insertion into skin they can rapidly imbibe ISF and undergo a transition to form discrete in situ hydrogel bulbs while maintaining their structural integrity and removed intact from the skin. Drug can thus diffuse through the swollen MN, which act as a continuous unblockable conduit between ISF and MN matrix. Hydrogel-forming MN were prepared from an optimised aqueous blend containing 11.1% w/w poly (methyl vinyl ether maleic anhydride) (Gantrez AN139), 5.6% w/w poly (ethylene glycol) (PEG 10,000). Successful transdermal extraction and detection of glucose was achieved in vitro through neonatal porcine skin and in vivo from healthy human volunteers. In vitro glucose was detected following application for 5 minutes but in vivo glucose was detected from MN applied for 1 hr. Results showed good correlation to blood glucose concentration with a lag time of 1 hr. Sodium valproate extraction was unsuccessful in vitro and was limited by the chemical nature of the drug, the MN fabrication material and the negative charge of the skin, in addition to the sensitivity of the analytical method. Finally, lithium was successfully extracted in vitro and in vivo from Sprague Dawley rats and gave a good reflection of picture of lithium serum level. In the view of these promising findings, with current work focusing on further optimisation of this technology, the future seems bright for a hydrogel-forming microneedle-based diagnostic and monitoring tool.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:705914 |
| Date | January 2016 |
| Creators | Eltayib, Eyman Mohamed |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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