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Dip-coating as a strategy to modify drug release from silicone elastomer drug delivery devices

School of Pharmacy | PHD
Funding
Unfunded
Reference Number
PMY/2251/KM3
Application Deadline
None specified
Start Date
None specified

Overview

Within the field of drug delivery, two types of drug delivery device are commonly considered: matrix-type devices (also known as monolithic systems) contain the drug homogeneously dispersed throughout the entire volume of the device; reservoir-type devices contain the drug within a central core which is covered by drug-free rate-controlling membrane. The kinetics of drug release are very different for these systems – matrix-type devices show steadily declining daily drug release rates, while reservoir-type devices show constant daily release rate following an initial lag or burst. Silicone elastomers are widely used in the manufacture of matrix-type and reservoir-type drug delivery devices for sustained or controlled release. Reservoir-type devices (such as Estring®, Femring®, Annovera®, Jadelle®) are usually manufactured by injection molding methods, involving fabrication of the drug-loaded cores and subsequent overmolding with a drug-free silicone elastomer membrane. However, the membrane thickness is often relatively large, due to limitations in producing thin membranes using existing injection molding strategies. If it were possible to form very thin membranes, drug release rates could be significantly enhanced. A silicone elastomer matrix-type vaginal ring releasing the antiretroviral drug dapivirine over 28 days – developed in part here at Queen's University Belfast – has recently been approved for preventing sexual transmission of HIV. As expected, the device provides steadily declining drug release with time. For release over longer durations, it may be beneficial to develop a reservoir-type controlled release device, with relatively large daily release rates (and therefore a relatively thin rate-controlling membrane).

In this project, for the first time, we will assess the potential to dip-coat silicone elastomer drug-loaded matrices (such as the matrix-type dapivirine ring) using solvent-based silicone dispersions to apply a very thin rate-controlling membrane to the device. We anticipate that the drug release rate can be easily modulated by applying membranes of different thickness or multiple layers. We will also evaluate the dip-coating strategy for application of drug-containing membranes to the devices.

The project will provide extensive training and skills development for the student in the following topics:
· drug formulation methods
· preparation and and characterisation of matrix-type and reservoir type drug delivery devices
· drug quantification using high performance liquid chromatography (HPLC) and other analytical methods
· in vitro drug release testing
· use of thermal analysis methods
· rheological and mechanical testing methods
· planning and organising skills: designing and planning of experiments
· numeracy and statistical skills
· teamwork skills: working confidently as part of a large research team

The project is well positioned to impact next generation drug delivery devices offering controlled release of drugs over months/years. The successful applicant will have opportunities to present their research at national and international conferences. The work will be of interest to silicone elastomer supply companies and pharmaceutical companies.

Project Summary
Supervisor

Professor Karl Malcolm

More Information

k.malcolm@qub.ac.uk

Research Profile


Mode of Study

Full-time: 3 Years


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