Pharmaceutical dosage forms having immediate release and/or controlled release properties

1. A pharmaceutical dosage form of an absorption window active agent selected from the group consisting of baclofen, gabapentin, levodopa, α-methyldopa, valacyclovir, or a mixture of any thereof that exhibits prolonged absorption of the active agent in the small intestine comprising a plurality of controlled release particles, each particle comprising:

i. the absorption window active agent selected from the group consisting of baclofen, gabapentin, levodopa, α-methyldopa, valacyclovir, or a mixture of any thereof;

ii. an inner pH-sensitive polymer layer substantially enveloping the absorption window active agent; and

iii. an outer pH-sensitive polymer layer substantially enveloping the absorption window active agent and inner pH-sensitive layer;

wherein the dosage form provides prolonged absorption of the absorption window active agent in the small intestine, and wherein the outer pH-sensitive polymer layer dissolves at a lower pH than the inner pH-sensitive polymer layer.

2. The pharmaceutical dosage form of claim 1 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 5.5 or higher and the inner pH-sensitive polymer layer dissolves at a pH of about 6 or higher.

3. The pharmaceutical dosage form of claim 1 , further comprising an immediate release component.

4. The pharmaceutical dosage form of claim 3 , wherein the immediate release component comprises immediate release particles.

5. The pharmaceutical dosage form of claim 1 , further comprising a plasticizer.

6. The pharmaceutical dosage form of claim 5 , wherein the plasticizer is selected from the group consisting of: 1,2-propylene glycol, acetylated monoglycerides, castor oil, dibutyl sebacate, diethyl phthalate, phthalate esters, polyethylene glycol, propylene glycol, triacetin, tributyl citrate, triethyl citrate, or a mixture of any thereof.

7. The pharmaceutical dosage form of claim 1 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 3 or higher.

8. The pharmaceutical dosage form of claim 7 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 4 or higher.

9. The pharmaceutical dosage form of claim 8 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 4.5 or higher.

10. The pharmaceutical dosage form of claim 9 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 5 or higher.

11. The pharmaceutical dosage form of claim 10 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 5.5 or higher.

12. The pharmaceutical dosage form of claim 11 , wherein the outer pH-sensitive polymer layer dissolves at a pH of about 6 or higher.

13. The pharmaceutical dosage form of claim 1 , wherein the inner pH-sensitive polymer layer dissolves at a pH of about 5 or higher.

14. The pharmaceutical dosage form of claim 13 , wherein the inner pH-sensitive polymer layer dissolves at a pH of about 5.5 or higher.

15. The pharmaceutical dosage form of claim 14 , wherein the inner pH-sensitive polymer layer dissolves at a pH of about 6 or higher.

16. The pharmaceutical dosage form of claim 15 , wherein the inner pH-sensitive polymer layer dissolves at a pH of about 6.5 or higher.

17. The pharmaceutical dosage from of claim 1 , wherein the inner pH-sensitive polymer layer and/or the outer pH-sensitive polymer layer are comprised of pH-sensitive polymers selected from the group consisting of:

carboxymethylethylcellulose, cellulose acetate phthalate, cellulose acetate trimellitate, co-polymerized methacrylic acid, hydroxypropyl methylcellulose phthalate, methacrylic acid and methyl esters, polyvinyl acetate phthalate, or a mixture of any thereof.

18. The pharmaceutical dosage form of claim 17 , wherein the outer pH-sensitive polymer layer comprises co-polymerized methacrylic acid.

19. The pharmaceutical dosage form of claim 3 , wherein the ratio of the immediate release component to the controlled release component is from about 1:4 to about 4:1.

20. The pharmaceutical dosage form of claim 19 , wherein the ratio of the immediate release component to the controlled release component is from about 1:2 to about 2:1.

21. The pharmaceutical dosage form of claim 1 , wherein the absorption window active agent is in the amount of about 1 mg to about 1000 mg.

22. The pharmaceutical dosage form of claim 21 , wherein the absorption window active agent is in the amount of about 1.5 mg to about 500 mg.

23. The pharmaceutical dosage form of claim 22 , wherein the absorption window active agent is in the amount of about 2 mg to about 250 mg.

24. The pharmaceutical dosage form of claim 23 , wherein the absorption window active agent is in the amount of about 2.5 mg to about 200 mg.

25. The pharmaceutical dosage form of claim 24 , wherein the absorption window active agent is in the amount of about 10 mg to about 100 mg.

26. The pharmaceutical dosage form of claim 25 , wherein the absorption window active agent is in the amount of about 15 mg to about 50 mg.

27. The pharmaceutical dosage form of claim 21 , wherein the absorption window active agent is in the amount of about 300 mg to about 900 mg.

28. The pharmaceutical dosage form of claim 27 , wherein the absorption window active agent is in the amount of about 400 mg to about 800 mg.

29. The pharmaceutical dosage form of claim 28 , wherein the absorption window active agent is in the amount of about 450 mg to about 750 mg.

30. The pharmaceutical dosage form of claim 1 , wherein the pharmaceutical dosage form is a tablet.

31. The pharmaceutical dosage form of claim 1 , wherein the pharmaceutical dosage form is a capsule.

32. The pharmaceutical dosage form of claim 31 , wherein the capsule further comprises discrete units selected from the group consisting of beads, granules, particles, tablets, or a mixture thereof.

33. The pharmaceutical dosage form of claim 1 , wherein the absorption window active agent is baclofen.

34. The pharmaceutical dosage form of claim 33 , wherein the baclofen is in the form of a prodrug, metabolite or pharmaceutically acceptable salt thereof.

35. The pharmaceutical dosage form of claim 1 , wherein the absorption window active agent is a racemic mixture.

36. The pharmaceutical dosage form of claim 1 , wherein the absorption window active agent is an optically pure isomeric mixture.

37. The pharmaceutical dosage form of claim 1 , wherein the absorption window active agent is released in the stomach and small intestine.

38. The pharmaceutical dosage form of claim 1 , wherein the baclofen is released in the upper small intestine.

39. The pharmaceutical dosage form of claim 1 , wherein the baclofen is released in the duodenum.

40. The pharmaceutical dosage form of claim 1 , wherein the baclofen is released in the jejunum.

41. The pharmaceutical dosage form of claim 1 , wherein the outer polymer layer is present in an amount of about 5 weight percent to about 50 weight percent with respect to the particles.

42. The pharmaceutical dosage form of claim 41 , wherein the outer polymer layer is present in an amount of about 15 weight percent to about 35 weight percent with respect to the particles.

43. The pharmaceutical dosage form of claim 1 , wherein the inner polymer layer is present in an amount of about 5 weight percent to about 50 weight percent with respect to the particles.

44. The pharmaceutical dosage form of claim 43 , wherein the outer polymer layer is present in an amount of about 20 weight percent to about 30 weight percent with respect to the particles.

45. The pharmaceutical dosage form of claim 1 , wherein the inner pH-sensitive polymer layer envelops the particles and the outer pH-sensitive polymer layer envelops the particles and inner pH-sensitive layer.