Ocular implant made by a double extrusion process
The invention provides biodegradable implants sized for implantation in an ocular region and methods for treating medical conditions of the eye. The implants are formed from a mixture of hydrophilic end and hydrophobic end PLGA, and deliver active agents into an ocular region without a high burst release.
1. A method for making a bioerodible implant for treating a medical condition of the eye, the method comprising:
a) milling a hydrophilic ended poly(D,L-lactide-co-glycolide) (PLGA) copolymer;
b) milling a hydrophobic ended poly(D,L-lactide-co-glycolide) (PLGA) copolymer;
c) blending the milled polymers together with particles of a steroidal anti-inflammatory agent to form a blended mixture comprising hydrophilic ended PLGA, hydrophobic ended PLGA, and a steroidal anti-inflammatory agent, wherein at least about 75% of the particles of the steroidal anti-inflammatory agent have a diameter of less than about 20 μm;
d) carrying out a first extrusion of the blended mixture to thereby obtain a first extrusion product;
e) pelletizing the first extrusion product; and
f) carrying out a second extrusion of the pelletized first extrusion product, thereby obtaining a bioerodible implant for treating a medical condition of the eye;
wherein the implant has a total weight ranging from about 100-5000 μg.
2. The method of claim 1 , wherein the steroidal anti-inflammatory agent is dexamethasone, fluocinolone, hydrocortisone, methylprednisolone, prednisolone, prednisone, or triamcinolone.
3. The method of claim 2 , wherein the hydrophilic ended PLGA and hydrophobic ended PLGA together constitute about 20 to about 90 weight percent of the bioerodible implant.
4. The method of claim 3 , wherein the ratio of lactic to glycolic acid monomers in the hydrophilic ended PLGA and in the hydrophobic ended PLGA is about 50/50 weight percentage.
5. The method of claim 4 , wherein the ratio of hydrophilic end PLGA to hydrophobic end PLGA in the blended mixture is 3:1 by weight.