Approaches in Topical Ocular Drug Delivery and Developments in the Use of Contact Lenses As drug-delivery Devices

Mehta, Prina; Haj‐Ahmad, Rita; Al-Kinani, Ali A.; Arshad, Muhammad Sohail; Chang, Ming Wei; Alany, Raid G.; Ahmad, Zeeshan

doi:10.4155/tde-2017-0018

Cited by 21 publications

(16 citation statements)

References 132 publications

(178 reference statements)

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“…Despite being an accessible organ, it is the structure of the eye (more specifically the corneal structure) that poses great challenges with respect to ocular drug delivery (Mehta, et al 2017a;Taskar, et al 2017). The cornea is a transparent tissue located in anterior of the iris; with a primary function of providing protection to the front of the eye and to focus light entering the eye.…”

Section: Introductionmentioning

confidence: 99%

Development and characterisation of electrospun timolol maleate-loaded polymeric contact lens coatings containing various permeation enhancers

Mehta

Al-Kinani

Arshad

et al. 2017

International Journal of Pharmaceutics

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Despite exponential growth in research relating to sustained and controlled ocular drug delivery, anatomical and chemical barriers of the eye still pose formulation challenges. Nanotechnology integration into the pharmaceutical industry has aided efforts in potential ocular drug device development. Here, the integration and in vitro effect of four different permeation enhancers (PEs) on the release of anti-glaucoma drug timolol maleate (TM) from polymeric nanofiber formulations is explored. Electrohydrodynamic (EHD) engineering, more specifically electrospinning, was used to engineer nanofibers (NFs) which coated the exterior of contact lenses. Parameters used for engineering included flow rates ranging from 8 to 15μL/min and a novel EHD deposition system was used; capable of hosting four lenses, masked template and a ground electrode to direct charged atomised structures. SEM analysis of the electrospun structures confirmed the presence of smooth nano-fibers; whilst thermal analysis confirmed the stability of all formulations. In vitro release studies demonstrated a triphasic release; initial burst release with two subsequent sustained release phases with most of the drug being released after 24h (86.7%) Biological evaluation studies confirmed the tolerability of all formulations tested with release kinetics modelling results showing drug release was via quasi-Fickian or Fickian diffusion. There were evident differences (p<0.05) in TM release dependant on permeation enhancer.

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Section: Introductionmentioning

confidence: 99%

Development and characterisation of electrospun timolol maleate-loaded polymeric contact lens coatings containing various permeation enhancers

Mehta

Al-Kinani

Arshad

et al. 2017

International Journal of Pharmaceutics

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“…Topically administered drugs often display limited bioavailability (< 5%) due to many physical and biochemical barriers including the pre‐corneal tear film, the structure and biophysiological properties of the cornea, the limited volume that can be accommodated by the cul‐de‐sac, the lacrimal drainage system, reflex tearing and the aqueous outflow within the eye (Peyman and Ganiban, ; Ranta and Urtti, ; Rodríguez Villanueva et al, ). Newer methods of drug delivery include sustained release preparations that allow reduced frequency of drug administration (Rodríguez Villanueva et al, ; Mehta et al, ). Preservative‐free eye drops can be achieved with a new multidose bottle with an Airless Antibacterial Dispensing System (Pfizer Inc, USA) containing a valve system and an airless pump with a silver antibacterial coil (Ghate and Edelhauser, ).…”

Section: Introductionmentioning

confidence: 99%

Principles of pharmacology in the eye

Awwad

Mohamed-Ahmed

Sharma

et al. 2017

British J Pharmacology

162

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*These authors contributed equally to this work.The eye is a highly specialized organ that is subject to a huge range of pathology. Both local and systemic disease may affect different anatomical regions of the eye. The least invasive routes for ocular drug administration are topical (e.g. eye drops) and systemic (e.g. tablets) formulations. Barriers that subserve as protection against pathogen entry also restrict drug permeation. Topically administered drugs often display limited bioavailability due to many physical and biochemical barriers including the precorneal tear film, the structure and biophysiological properties of the cornea, the limited volume that can be accommodated by the cul-de-sac, the lacrimal drainage system and reflex tearing. The tissue layers of the cornea and conjunctiva are further key factors that act to restrict drug delivery. Using carriers that enhance viscosity or bind to the ocular surface increases bioavailability. Matching the pH and polarity of drug molecules to the tissue layers allows greater penetration. Drug delivery to the posterior segment is a greater challenge and, currently, the standard route is via intravitreal injection, notwithstanding the risks of endophthalmitis and retinal detachment with frequent injections. Intraocular implants that allow sustained drug release are at different stages of development. Novel exciting therapeutic approaches include methods for promoting transscleral delivery, sustained release devices, nanotechnology and gene therapy.

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“…The ability to achieve controlled and/or sustained ocular drug delivery is a constant challenge faced by research scientists [1,2]. Whilst more conventional dosage forms such as eye drops boast ease of formulation, there is the issue of eye micro-structure serving as a barrier.…”

Section: Introductionmentioning

confidence: 99%

“…increasing viscosity [3], forming complexes with cyclodextrins [4,5]), the issue of sustaining drug delivery is still prominent. As a result, novel approaches have been introduced which include the use of ocular devices as drug reservoirs [2]. The most common concept to emerge from this are contact lenses.…”

Section: Introductionmentioning

confidence: 99%

Assessing the ex vivo permeation behaviour of functionalised contact lens coatings engineered using an electrohydrodynamic technique

et al. 2018

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In vitro testing alone is no longer considered sufficient evidence presented solely with respect to drug release and permeation testing. These studies are thought to be more reliable and representative when using tissue or animal models; as opposed to synthetic membranes. The release of anti-glaucoma drug timolol maleate from electrically atomised coatings was assessed here using freshly excised bovine corneal tissue. Electrohydrodynamic processing was utilised to engineer functionalised fibrous polyvinylpyrrolidone-Poly (N-isopropylacrylamide) coatings on the outer side of commercial silicone contact lenses. Benzalkonium chloride, ethylenediaminetetraacetic acid, Brij ® 78 and borneol were employed as permeation enhancers to see their effect on ex vivo permeation of timolol maleate through the cornea. Formulations containing permeation enhancers showed a vast improvement with respect to cumulative amount of drug permeating through the cornea as shown by a six fold decrease in lag time compared to enhancer-free formulations. Most drug delivery systems require the drug to pass or permeate through a tissue or biological membrane. This study has shown that to fully appreciate and understand how a novel drug delivery system will behave not only within the device but with the external environment or tissue, it is imperative to have in vitro and ex vivo data in conjunction.

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Approaches in Topical Ocular Drug Delivery and Developments in the Use of Contact Lenses As drug-delivery Devices

Cited by 21 publications

References 132 publications

Development and characterisation of electrospun timolol maleate-loaded polymeric contact lens coatings containing various permeation enhancers

Development and characterisation of electrospun timolol maleate-loaded polymeric contact lens coatings containing various permeation enhancers

Principles of pharmacology in the eye

Assessing the ex vivo permeation behaviour of functionalised contact lens coatings engineered using an electrohydrodynamic technique

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