OPHTHALMIC NANOPARTICLES DRUG DELIVERY SYSTEMS (Ezine Ready)
In cosmetic surgery, tiny PMMA microspheres suspended in some biological fluid are injected under the skin to reduce wrinkles or scars permanently. ADVANTAGES AND LIMITATIONS Advantages 1. Material is very hard. 2. Material is clear and can be coloured in any colour from opaque to translucent. 3. Good weathering resistance 4. Good optical properties. 5. High gloss. 6. Scratch resistant (but not as good as glass because it does scratch - this is why car wind screens are not made from PMMA). Limitations 1. Brittle under impact conditions and failure is by shattering. 2. Difficult to mould thin walled products because of poor flow properties. 3. Poor hot-melt strength limits processing methods. 4. Flow properties make processing slow compared to other materials. 5. Does not have significant elastic deformation before failure i.e. goes straight to brittle fracture. REFERENCES Alonso MJ, Snchez A. Biodegradable nanoparticles as new transmucosal drug carriers. Snke Svenson eds. Carrier-Based Drug Delivery. 2004; 283–295. ACS Symposium Series Washington DC. Calvo P, Snchez A, Martnez J, et al. Polyester nanocapsules as new topical ocular delivery systems for cyclosporine A. Pharmacol Res. 1996;13:311–315. Calvo P, Thomas C, Alonso MJ, Vila-Jato JL, Robinson JR. Study of the mechanism of interaction of poly-e-caprolactone nanocapsules with the cornea by confocal laser scanning microscopy. Int J Pharmacol. 1994; 103:283–291. Harmia T, Speiser P, Kreuter J. A solid colloidal drug delivery system for the eye: encapsulation of pilocarpin in nanoparticles. J Microencapsulation.Pages: 1 2 3 4 5 6 7 8 9 10 11 12 [13] 14
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01.02.2010
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