A REVIEW ON TOPICAL OPHTHALMIC DRUG DELIVERY SYSTEMS
Formulations including creams, gels and ointments were used as ophthalmic products6. Polycarbophil is water insoluble cross linked polyacrylic acid helps in the retention of the drug delivery system in the eye7 due to the formation of hydrogel bonds and mucoadhesive strength. Hyaluronic acid offers a biocompatible and biodegradable matrix for fabrication of ocular sustained release dosage form - Dosage forms based on the benzyl esters of hyaluronic acid were used for ophthalmic sustained release of methyl prednisolone. Films and microspheres were also prepared from hyaluronic acid. Polysaccharide such as xanthan gum was found to increase the viscosity8. Today, hydrophilic polymers continue to be used in formulation of ophthatmic products Outs the" lunotions are mere for patient comfort and for bioadhesion rather than viscosity enhancement. Viscosity vehicles increases the contact time and no marked sustaining effect is seen. 2. Gels : Gel formation is an extreme case of viscosity enhancement through the use of viscosity enhancers. So the dosing frequency can be decreased to once a day9. Cellulose acetate phthalate dispersion constituted a micro-reservoir system of high viscosity. Poloxamer 407 is used as an ophthalmic vehicle for pilocarpine delivery and found that the gel formation enhances the activity of pilocarpine10. Timolol maleate form thermogelling drug delivery system composed of cellulose ether ethylhydroxylethylcellulose11. The effect of flurbiprofen a non steroidal anti inflammatory, formulated in carbopol 940 and pluronic F 127 hydrogels were compared in ocular hypertension.Pages: 1 2 [3] 4 5 6 7 8 9 10 11 12 13 14
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