Drug delivery systems and applications

1. A medical material comprising

a biodegradable hydrophilic hydrogel comprising dispersed lipophilic microparticles that have a diameter from 1-500 microns and consist essentially of a low water soluble lipophilic compound that has a solubility in 20° C. distilled water that is from 0.001 to 0.5 mg/ml and a therapeutic protein having a secondary and/or a tertiary structure disposed as a solid particle of less than 20 microns diameter in the microparticles, with the microparticles having no more than 4 parts of the lipophilic compound for every one part of the therapeutic protein on a w/w basis, with the particle releasing 100% the protein in less than 24 hours in the absence of the hydrogel upon exposure to physiological solution.

2. The medical material of claim 1 wherein the low water soluble lipophilic compound has a molecular mass of no more than about 2000 Daltons.

3. The medical material of claim 1 wherein the microparticles have a melting point of between about 25° C. and about 60° C.

4. The medical material of claim 1 wherein the low water soluble lipophilic compound has a logP of at least about 2.

5. The medical material of claim 3 wherein the lipophilic microparticles are a solid at physiological temperature.

6. The medical material of claim 1 wherein the hydrogel comprises covalently crosslinked hydrophilic polymers.

7. The medical material of claim 6 wherein the polymers comprise a member chosen from the group consisting of polyethylene oxide, polyvinyl pyrrolidinone, hyaluronic acid, and polyhydroxyethlymethacrylate.

8. The medical material of claim 1 wherein the hydrogel biodegrades by spontaneous hydrolysis of hydrolytically degradable linkages chosen from the group consisting of esters, carbonates, anhydrides and orthocarbonates.

9. The medical material of claim 1 wherein the hydrogel comprises ionically crosslinked polymers.

10. The medical material of claim 9 wherein the polymers comprise a member chosen from the group consisting of alginate, gellan, collagen, and polysaccharide.

11. The medical material of claim 1 wherein a cumulative amount of release of the agent reaches 90% of the agent at a time between about 1 month and about 6 months after placement of the hydrogel and particles in a physiological solution.

12. The medical material of claim 1 wherein the lipophilic microparticles comprise at least one member chosen from the group consisting of lauric acid, methyl stearate, and methyl palmitate.

13. A process of making a medical material comprising

coating a protein powder with a low water soluble lipophilic compound that, has a solubility in 20° C. distilled water that is from 0.001 to 0.5 mg/ml to make microparticles that have a diameter from 1-500 microns and that consist essentially of the protein disposed as a solid particle of less than 20 microns diameter in the microparticles and the low water soluble lipophilic compound, with the microparticles having no more than 4 parts of the lipophilic compound for every one part of the therapeutic protein on a w/w basis, with the particle releasing 100% the protein in less than 24 hours upon exposure to physiological solution and

dispersing the particles in a medical hydrogel implant, and

with the protein having a secondary and/or a tertiary structure.

14. The process of claim 13 wherein the lipophilic compound comprises a fatty acid with a melting point between about 25° C. and about 60° C.

15. The process of claim 13 wherein the low water soluble lipophilic compound has a molecular mass of no more than about 2000 Daltons.

16. The process of claim 13 wherein the lipophilic compound is provided as a melt, and wherein coating a protein powder with a lipophilic compound to make microparticles comprises mixing the powder with the melt to coat the powder with the compound, cooling the mixture to a solid, and breaking up the solid to form the microparticles.

17. The process of claim 13 wherein the hydrogel is formed in a shape chosen from the group consisting of a rod and a disc.

18. The process of claim 13 further comprising dehydrating the hydrogel for storage.

19. The process of claim 13 wherein the hydrogel is formed in situ in a patient.

20. The process of claim 19 wherein the microparticles are mixed r with a precursor that is reacted to form the hydrogel in situ.

21. The process of claim 20 wherein the precursor is reacted by a technique chosen from the group consisting of free radical polymerization and thermally sensitive gelation in response to a body temperature of the patient.

22. The process of claim 20 wherein the precursor is a first precursor comprising nucleophilic groups, and further comprising reacting the first precursor with the second precursor comprising electrophilic groups, with the electrophilic groups and nucleophilic groups reacting with each other to form covalent bonds to thereby form the hydrogel.

23. The process of claim 13 wherein coating, a protein powder with the lipophilic compound to make microparticles comprises

mixing the protein powder with the lipophilic compound to form a mixture of the powder and the compound,

dispersing the mixture into a solution to form droplets of the mixture, and

cooling the droplets to a solid phase and thereby forming the microparticles.

24. The process of claim 23 wherein cooling the droplets comprises providing the solution as a non-solvent for the lipophilic compound at a temperature below the melting point of the lipophilic compound.

25. The process of claim 13 further comprising providing the hydrogel as a plurality of hydrogel microparticles.

26. The process of claim 13 wherein the particles are dehydrated for storage and, at the time of use, mixed with a carrier to form a slurry that is injectable into a patient.

27. The process of claim 13 wherein the microparticles have a melting point between about 25° C. and about 60° C.

28. The process of claim 13 wherein the micro articles are solid at physiological temperatures in vivo and have a melting point of less than about 60° C.

29. The process of claim 13 wherein the peptide in the particle is substantially free of denaturation as measurable by comparison of the protein in the microparticle to the protein before mixing with the hydrophobic coating, with the comparison being made by enzyme-linked immunosorbent assay and isoelectric focusing.

30. The process of claim 13 wherein, after placement of the medical material in an excess of physiological solution at, physiological temperature, a cumulative amount of release of the agent reaches 90% of the agent at a time between about 1 and about 6 months after placement of the hydrogel and particles in a saline solution.

31. A method of delivering a therapeutic agent to a patient comprising placing the medical material of claim 1 in a patient, with the therapeutic agent being released into the patient.

32. The method of claim 31 wherein the hydrogel is molded into a unitary implant that is subsequently implanted in the patient.

33. The method of claim 31 wherein the implant is implanted in a substantially dehydrated state.

34. The method of claim 31 wherein the hydrogel is an injectable suspension or slurry that is injected into the patient.

35. The method of claim 31 wherein the hydrogel is placed into the patient at or near an eye at a location chosen from the group consisting of intravitreal, cornea, retinal, subconjunctival, scleral, and punctal.

36. The method of claim 31 wherein the hydrogel is placed through a 25 gauge or finer needle into the target tissue.

37. The method of claim 31 wherein the hydrogel is placed in a tissue, in an organ, subcutaneously, or intramuscularly.

38. The medical material of claim 1 wherein the lipophilic microparticles are solid at 20° C., with the protein being released from the microparticles and the medical material in a conformation that is substantially free of denaturation as measurable by enzyme-linked immunosorbent assay, and isoelectric focusing.

39. The method of claim 13 with the protein being released from the microparticles and the medical material in a conformation that is substantially free of denaturation as measurable by enzyme-linked immunosorbent assay and isoelectric focusing.

40. The method of claim 31 with the protein being released from the microparticles and the medical material in a conformation that is substantially free of denaturation as measurable by enzyme-linked immunosorbent assay and isoelectric focusing.