Polymeric microneedle systems for enhanced transdermal drug delivery

  • Ahlam Zaid Alkilani

Student thesis: Doctoral ThesisDoctor of Philosophy


Conventional drug delivery methods, such as oral and parenteral have many problems that may be potentially overcome by advanced drug delivery methods like enhanced transdermal drug delivery. Delivery across skin offers many advantages compared to oral or parenteral routes e.g. non-invasive, avoiding first-past metabolism, improved bioavailability and reduction of systemic side effects. Microneedle (MN) are minimally-invasive devices that painlessly by-pass the skin's stratum corneum, which is the principal barrier to topically-applied drugs.

Polymeric MN delivery systems were designed and evaluated to transdermally deliver two model drugs, the small water soluble drug ibuprofen sodium and the large protein ovalbumin (OVA). A range of hydrogel forming materials for MN production was evaluated to identify the most suitable super swelling hydrogel MN array that are hard in the dry state but, upon insertion into skin, rapidly take up interstitial fluid. The MN themselves contain no drug, but instead drug are loaded into lyophilized patches. Novel super swelling hydrogel forming MN arrays were fabricated from aqueous blends containing 20% w/w poly(methyl vinyl ether co maleic acid) (Gantrez® S97), 7.5% w/w poly(ethylene glycol) (PEG) and 3% sodium carbonate (Na2C03). In addition, dissolving MN arrays loaded with a high dose of non-potent therapeutic drug were fabricated from aqueous blends of 70% w/w Gantrez® AN 139 (pH 7) and 30% ibuprofen sodium. Successful drug delivery was achieved in this research work using novel polymeric MN, super swelling hydrogel MN and dissolving MN. The in vitro studies has been shown first ever example of polymeric MN being loaded with a NSAIDs, in which MN arrays of 0.5 cm 2 delivered 33 mg ibuprofen sodium in 24 hours. The novel concept of super swelling hydrogel MN integrated with lyophilized patches loaded with ovalbumin was evaluated. They enabled the sustained delivery of the ibuprofen sodium and ovalbumin both in vitro and in vivo. Furthermore, gamma sterilization is not required to reduce microorganism loading but to satisfy the regulators. Gamma sterilization can be done without compromising polymeric MN properties. Finally, hydrogel forming MN arrays can be successfully and reproducibly applied by human volunteers given appropriate instruction so the use of MN applicator devices may not be necessary, thus possibly enhancing patient compliance.
Date of AwardDec 2013
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SupervisorRyan Donnelly (Supervisor) & Thakur Raghu Raj Singh (Supervisor)

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