| abstract |
A sustained release ophthalmic formulation comprising at least one hydrophobic drug and a micelle solution of a random block copolymer having a hydrophobic component and a hydrophilic component of general formula -(X+Y+Z-)<SB>m</SB> wherein m is an integer greater than 2, X is a monomer which will provide hydrogel formation properties to reduce the irritability to the eye and is a vinyl compound, Y is a monomer which will provide thermo-sensitivity properties and is of general formula R<SB>1</SB>R<SB>2</SB>N-(C=O)-CH=CH<SB>2</SB> wherein R<SB>1</SB> is a proton or C<SB>n</SB>H<SB>2n+1</SB>, n being from 3 to 6, and R<SB>2</SB> is a C3 to C6 alkyl group and Z is a monomer which will provide mucoadhesiveness and pH-sensitivity properties and is an acrylate-based monomer. In particular, the drug may be a non-steroidal anti-inflammatory drug (NSAID), m may lie in the range 10 to 4000, X may be vinyl pyrrolidone, vinyl alcohol, vinyl chloride or vinyl acetate, Y may be N-isopropyl acrylamide and Z may be acrylic acid or methyl methacrylate. A process of preparing such a formulation comprises the steps of preparing the micelle solution, mixing it with the hydrophobic drug, subjecting the mixture to stirring, heating, ultrasonic treatment, solvent evaporation or dialysis to physically incorporate the drug into the hydrophobic core of the micelle and purifying the mixture. |