COLL 447 |
| Derya Gulsen and Anuj Chauhan. Chemical Engineering Department, University of Florida, Room 237 CHE PO Box 116005, Gainesville, FL 32611 |
| Approximately 90% of all ophthalmic drug formulations are now applied as eye-drops. While eye-drops are convenient and well accepted by patients, a majority of the drug contained in the drops is lost due to absorption through conjunctiva or through tear drainage. A major fraction of the drug eventually enters the blood stream and causes side effects. Furthermore, topical ophthalmic drug delivery results in a relatively high drug concentration in the tear film followed by a rapid decline. This results in sharp variations in the drug delivery rates to the cornea, reducing the efficacy of ophthalmic drugs. To reduce drug loss, eliminate systemic side effects, and improve drug efficacy, we propose to develop disposable soft contact lenses as a new vehicle for ophthalmic drug delivery. The essential idea is to encapsulate the ophthalmic drug formulations in nanoparticles, and to disperse these drug-laden particles in the lens material. These devices can also be used as skin patches, and ocular inserts for drug delivery to various parts of the body. We focus on dispersing small unilamellar small vesicles (SUV) of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) in poly-2-hydroxyethyl methacrylate (p-HEMA) hydrogels. The mean particle size of the liposome nanoparticles is about 80 nm. The drug laden p-HEMA hydrogels are synthesized by free radical solution polymerization of the monomers in presence of nanoparticles. We characterize the microstructure of the gels by SEM studies and by measuring transmittance in the visible range. We also measure the release rates of a model drug Lidocaine. SEM studies provide direct evidence of liposome entrapment in the gel. The transparency of the hydrogels depends on the liposome particle size; liposomes that have a particle size smaller than 200 nm produce transparent hydrogels. We obtain a liposome loading of 0.4% and a drug loading of 0.16% in the hydrogels. We show that the drug delivery rates can be controlled by tailoring the microstructure of the hydrogel and by manipulating the size, concentration and structure of the nanoparticles. We also report the effect of gel thickness, liposome size and liposome concentration and drug loading on the drug release rates from the drug-laden hydrogels. These systems can be used for therapeutic drug delivery to eyes and also possibly for providing anti-bacterial agents and lubricants such as mucin or viscous fluids to the eye to alleviate infection and dry eye problems that are prevalent in extended-lens wear.
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Nanoscience and Nanotechnology
2:00 PM-5:15 PM, Wednesday, March 31, 2004 Marriott -- Orange County 5, Oral
Division of Colloid and Surface Chemistry |