In vitro studies of drug-eluting films and coatings for intraocular lens
Tan, Dulcia Wei Ni
Date of Issue2015
School of Materials Science and Engineering
Topical ophthalmic eye drops are prescribed to patients as a post-operative care against infections and inflammations after a cataract surgery. However, this mode of administration exhibits a poor drug bioavailability of approximately 5%, resulting in high drug wastage. In addition, topical administrations also have an issue of poor patient compliance. The aim of this thesis is to investigate and develop a controlled release system for the administration of antibacterial agents over a sustained period of time. This delivery system can be used to deliver antibiotics such as Levofloxacin and Moxifloxacin to replace the eye drops and to improve the drawbacks faced by the current regimen. This research work is divided into 2 broad categories: drug-eluting films and drug-eluting coatings. First, in vitro studies were performed on Levofloxacin-loaded and Moxifloxacin-loaded PLC-based film formulations. Film characterization of formulation parameters, i.e. the effect of drug loadings and solvents were evaluated. The surface morphologies of the films fabricated with different drug loadings and solvents were investigated before and after the in vitro study. Surface morphology, drug loadings and solvent were found to affect the burst release and subsequent release from the systems. Both Levofloxacin and Moxifloxacin systems with THF solvent achieved the desired sustained release profile of 14 days. Next, studies were performed to characterize the drug-eluting coating delivery system and to evaluate its efficacy in achieving a sustained release for each drug. The coating mandrel designs for the coating attachment and various fabrication process parameters i.e. flow-rate, translational displacement (TD) and number of loops were investigated. Investigation of the coating morphologies as well as the drug loadings and their influence on the drug release profiles were also carried out. The results demonstrated that lower drug-loaded Levofloxacin coatings were able to lower the initial burst and achieve a sustained release for 14 days. Levofloxacin-loaded “sandwich” system managed to suppress the huge burst observed in single layer 25% coating and the thinner polymer-coated system was able to achieve release above targeted dosage for 9 days. However, due to the poor solubility of Moxifloxacin in DCM and THF, both coating systems suffered from low drug loadings and a sustained release above targeted dosage was unachievable.