| Summary: | Microneedle (MN) technology has been evaluated as a viable alternative to oral and parenteral drug delivery route. Polymeric MN patches are a type of MNs made from biocompatible materials. Polymeric MN are catalogued as soluble and hydrogel-forming MNs. Soluble MN patches are made from biodegradable components that encapsulates their cargo within the needle matrix, dissolving completely upon skin insertion, whereby the drug is released. Conversely, hydrogel-forming MN patches are fabricated from polymers which contain no drug themselves. In the dry state, hydrogel-forming MNs possess sufficient strength to pierce skin. Upon insertion, they rapidly take up skin interstitial to create continuous microconduits from patch-type drug reservoirs to the dermal microcirculation. The first project described a number of commercially-ready MN patches which were assessed using in-house mechanical tests. Such tests should be able to identify suitable MN patches that could be successfully used in the clinic within a margin of safety. Continuing with in vitro testing, the aim of the second project was to find an ideal synthetic skin mimic to perform in vitro MN permeation studies to avoid the variability associated with biological tissue. Complete assessment of the in vivo consequences of multiple applications of soluble and hydrogel-forming MN patches, as would occur in practical life, was carried out. This is an essential step to address potential regulatory issues. The aim of the fourth project was to compare, the difference between different applications strategies. MN patch self-applications using thumb pressure were assessed in a twenty volunteer study. The incorporation of a pressure-based feedback mechanism was evaluated as a component of a MN patch. The findings gathered in this thesis may encourage industrial and public sectors to further investment in MN technologies. The work presented here, therefore, supports the further development of MN technology considering industrial, clinical and end-user inputs.
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