Sustained Release Low Dose Formulations and Uses Thereof

1 . A drug delivery composition, comprising:

a microparticulate formulation, said microparticulate formulation further comprising:

a matrix, a solvent, and at least one low dose opioid receptor antagonist or a combination thereof, wherein said opioid receptor antagonist is incorporated into said matrix homogenously or substantially homogenously.

2 . The drug delivery composition of claim 1 , wherein the matrix controls release of said opioid receptor antagonist for initial release rate, daily release rate, duration, and completeness of release, allows release of exact amount of the opioid receptor antagonist, allows sustained release of the opioid receptor antagonist, or a combination thereof.

3 . The drug delivery composition of claim 1 , wherein the matrix comprises a solid hydrophobic component and a liquid hydrophobic component.

4 . The drug delivery composition of claim 1 , wherein the solvent is phosphate buffered saline or water.

5 . The drug delivery composition of claim 1 , wherein the low dose opioid receptor antagonist is selected from group consisting of naltrexone and naloxone.

6 . The drug delivery composition of claim 1 , wherein the microparticulate formulation is in a powder form or an injectable form.

7 . A method of manufacturing the drug delivery composition of claim 3 , comprising:

mixing the solid hydrophobic component and the liquid hydrophobic component of the matrix and the opioid receptor antagonist until a microparticulate formulation in a powder form is formed;

adding a small amount of water or phosphate buffered saline; and

mixing continuously to incorporate the opioid receptor antagonist homogenously or substantially homogenously into the matrix.

8 . A method of manufacturing the drug delivery composition of claim 3 , comprising:

adding the solid hydrophobic component and the liquid hydrophobic component of the matrix;

mixing said components by kneading, pressing, folding or combination thereof to obtain a kneadable macroscopic mass;

combining the macroscopic mass with the opioid receptor antagonist;

mixing the macroscopic mass with the opioid receptor antagonist by kneading, pressing, folding or a combination thereof to incorporate the opioid receptor antagonist homogenously into the matrix, thereby payloading the matrix;

micronizing the payloaded matrix by adding magnesium stearate to the payloaded matrix and mixing the payloaded matrix and magnesium stearate by kneading, pressing, folding or a combination thereof until a microparticulate formulation in a powder form is formed.

9 . The method of claim 8 , wherein said method further comprises:

fractionating the microparticulate formulation by sieving.

10 . A method to manufacture the drug delivery composition of claim 3 , comprising:

adding the solid hydrophobic component and liquid hydrophobic component of the matrix and the opioid receptor antagonist in a reaction vessel, wherein the solid hydrophobic component is added in a two-fold amount to the mixture; and

mixing the components and the opioid receptor antagonist by kneading, pressing, folding, grinding, milling, or a combination thereof so that the microparticulate formulation has a size and size distribution that allows it to be administered as an injectable.

11 . The method of claim 10 , further comprising:

fractioning the microparticulate formulation by sieving.

12 . The method of claim 10 , wherein said microparticulate formulation is resuspended in an aqueous or an oily suspension.

13 . The method of claim 10 , wherein the microparticulate formulation is prefilled in a syringe in powder form or dissolved in aqueous solution outside of the syringe and then used to fill the syringe.

14 . The method of claim 13 , wherein the prefilled syringe further comprises at least one of a biocompatible oil, saline, and saline with hyaluronic acid.

15 . A method of treating an individual with a chronic pain disorder, comprising:

administering the drug delivery composition of claim 1 to the individual.

16 . The method of claim 15 , wherein the drug delivery composition is administered intramuscularly, intravenously, intradermally, subcutaneously, or via another route.

17 . The method of claim 15 , wherein said administration allows sustained release of the opioid receptor antagonist in the individual's body.

18 . The method of claim 17 , wherein the individual is suffering from or has been diagnosed with fibromyalgia, Crohn's disease, multiple sclerosis, and pruritus associated with systemic sclerosis.