Advanced engineering of contact lens coatings using electrohydrodynamic atomization

• Main Author: Mehta, Prina
• Published: De Montfort University 2018
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.768221

While the eye presents numerous opportunities for drug delivery (DD); there are many challenges met by conventional methods. Despite the exponential growth in research to overcome these downfalls and achieve sustained and controlled DD, the anatomical characteristics of the eye still pose formulation challenges. The research presented in this thesis utilises Electrohydrodynamic Atomization (EHDA) to engineer novel coatings for ocular contact lenses. EDHA was selected to develop coatings for the delivery of timolol maleate (TM); with the intention of achieving sustained drug release for treatment of glaucoma. The work presented here is a proof-of-concept; showing the versatility of a promising technique by applying it to a DD remit within which EHDA has not yet been fully exploited: Ocular Drug Delivery (ODD). The first step was to identify a suitable polymeric matrix to act as the vehicle/carrier and see the effects of different polymers on the in vitro release of TM and ex vivo TM permeation. Hereafter, based on the results of this work, 4 different PEs were incorporated to attempt to enhance TM release and permeation through the cornea. Further modification of the formulations saw the effect of integrating chitosan on the release of TM from the electrically atomised coatings. Characterisation of the atomised coatings at each stage demonstrated highly stable matrices, which possessed extremely advantageous morphologies and sizes (within the nanometre range). All coatings also demonstrated adequate to high encapsulation efficiencies (EEs) (>64%) with the highest EE being 99.7%. In vitro release (i.e. cumulative percentage release) steadily increased upon introduction of additives to the base polymeric formulations yielding different release profiles; ranging from biphasic profiles to triphasic profiles. Ex vivo analysis and biological compatibility testing also presented promising results. The use of EHDA has not yet been explored in depth within the ocular research remit. It has shown great potential in the work presented here; engineering on demand lens coatings capable of sustaining both TM release and TM permeation.