Sustained release formulations of nalbuphine

1. An oral sustained release formulation of nalbuphine comprising nalbuphine compound or a pharmaceutically acceptable salt thereof homogeneously dispersed within a hydrophilic gel matrix, wherein the hydrophilic gel matrix comprises xanthan gum, a hydrophilic cellulose ether or both, wherein the formulation provides an analgesic effect for at least about 8 hours.

2. The sustained release formulation of claim 1 , wherein the nalbuphine or pharmaceutically acceptable salt thereof is present in an amount of about 1 mg to about 200 mg in the formulation.

3. The sustained release formulation of claim 1 , wherein the nalbuphine or pharmaceutically acceptable salt thereof is present in an amount of about 60 mg in the formulation.

4. The sustained release formulation of claim 1 , wherein the formulation provides an analgesic effect for at least about 12 hours.

5. The sustained release formulation of claim 1 , wherein the hydrophilic gel matrix comprises xanthan gum and a hydrophilic cellulose ether.

6. The sustained release formulation of claim 1 , wherein the hydrophilic cellulose ether is hydroxypropylcellulose.

7. The sustained release formulation of claim 1 , wherein the hydrophilic cellulose ether is hydroxypropylmethylcellulose.

8. The sustained release formulation of claim 1 , wherein the hydrophilic gel matrix further comprises a cross-linking agent.

9. The sustained release formulation of claim 1 , wherein the hydrophilic gel matrix further comprises a pharmaceutical diluent.

10. The sustained release formulation of claim 1 , wherein the hydrophilic gel matrix further comprises a cationic cross-linking agent.

11. The sustained release formulation of claim 1 , wherein the hydrophilic gel matrix further comprises a lubricant.

12. The sustained release formulation of claim 5 , wherein the hydrophilic gel matrix further comprises a cross-linking agent, a cationic cross-linking agent, a pharmaceutical diluent, and a lubricant.

13. The sustained release formulation of claim 12 , wherein the hydrophilic cellulose ether is hydroxypropylcellulose, the cross-linking agent is locust bean gum, the pharmaceutical diluent is mannitol, the cationic cross-linking agent is calcium sulfate dihydrate, and the lubricant is magnesium stearate.

14. The sustained release formulation of claim 5 , wherein the hydrophilic gel matrix further comprises a pharmaceutical diluent and a lubricant.

15. The sustained release formulation of claim 14 , wherein the pharmaceutical diluent comprises lactose, microcrystalline cellulose or both.

16. The sustained release formulation of claim 11 , wherein the hydrophilic cellulose ether is hydroxypropylmethylcellulose.

17. A solid dosage form comprising the formulation of any one of claims 1 - 2 , 4 and 5 - 16 .

18. The solid dosage form of claim 17 , wherein the formulation is a tablet.

19. The solid dosage form of claim 17 , wherein the formulation is a powder.

20. The solid dosage form of claim 17 , wherein the formulation is a capsule.

21. The solid dosage form of claim 17 , wherein the oral dosage form provides a blood serum level of nalbuphine or a pharmaceutically acceptable salt thereof characterized by one or more peaks followed by plateau region.

22. The solid dosage form of claim 21 , wherein the plateau region has a duration of at least about 1 hour.

23. The solid dosage form of claim 21 , wherein the blood serum level of nalbuphine or a pharmaceutically acceptable salt thereof at each time point in the plateau region ranges from about 75% to about 125% of the mean blood serum level in the plateau region.

24. The solid dosage form of claim 21 , wherein 75%-100% of the nalbuphine or a pharmaceutically acceptable salt thereof is released after about 12 hours as determined using USP Apparatus III at 15 dpm in a pH 6.8 buffer at 37° C.