Two-piece, internal-channel osmotic delivery system flow modulator

1. A process of making a flow modulator for an osmotic delivery system, comprising:

forming an outer shell member and an inner core member from at least one non-metallic, nonreactive polymer material, the outer shell member comprising an inlet end, an outlet end, and an inner surface defining an internal volume for receiving the inner core member, the inner core member comprising an outer surface for engaging with the inner surface of the outer shell member when the inner core member is disposed in the internal volume, wherein at least one groove is formed in at least one of:

the inner surface of the outer shell member such that the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around an axis from the inlet end to the outlet end; and

the outer surface of the inner core member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end; and

disposing the inner core member in the internal volume such that the outer surface of the inner core member sealingly engages the inner surface of the outer shell member and the at least one groove defines at least one fluid channel between the inner surface of the outer shell member and the outer surface of the inner core member such that the at least one fluid channel extends from the inlet end to the outlet end and at least a portion of the at least one fluid channel has a helical shape around the axis from the inlet end to the outlet end.

2. The method of claim 1 , wherein at least one first groove is formed in the inner surface of the outer shell member and at least one second groove is formed in the outer surface of the inner core member such that when the inner core member is disposed in the internal volume, the at least one first groove complements the at least one second groove.

3. The method of claim 1 , at least one non-metallic, nonreactive polymer material is at least one of a polyaryletherketone, an ultra-high molecular weight polyethylene, a fluorinated ethylene-propylene, a polymethylpentene, and a liquid crystal polymer.

4. The method of claim 3 , wherein the polyaryletherketone is at least one of polyetheretherketone and polyaryletheretherketone.

5. The method of claim 1 , wherein:

the inner core member further comprises an outer shoulder;

the outer shell member further comprises an inner shoulder; and

disposing the inner core member in the internal volume comprises engaging the outer shoulder and the inner shoulder to prevent expulsion of the inner core member from the outer shell member.

6. The method of claim 1 , wherein the at least one groove is formed only in the inner surface of the outer shell member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end.

7. The method of claim 1 , wherein the at least one groove is formed only in the outer surface of the inner core member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end.

8. The method of claim 1 , wherein the at least one groove is formed only in the outer surface of the inner core member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end.

9. A method for mitigating back diffusion in an osmotic delivery system for an active agent formulation, the osmotic delivery system including a reservoir, a slidable piston defining within the reservoir a first chamber containing an osmotic engine and a second chamber containing the active agent formulation, and a semipermeable plug disposed at a first end of the reservoir adjacent the first chamber, the method comprising:

providing an outer shell member and an inner core member, the outer shell member comprising an inlet end, an outlet end, and an inner surface defining an internal volume for receiving the inner core member, the inner core member comprising an outer surface for engaging with the inner surface of the outer shell member when the inner core member is disposed in the internal volume, wherein at least one groove is formed in at least one of:

the inner surface of the outer shell member such that the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around an axis from the inlet end to the outlet end; and

the outer surface of the inner core member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end;

assembling a flow modulator by disposing the inner core member in the internal volume such that the outer surface of the inner core member sealingly engages the inner surface of the outer shell member and the at least one groove defines at least one fluid channel between the inner surface of the outer shell member and the outer surface of the inner core member such that the at least one fluid channel extends from the inlet end to the outlet end and at least a portion of the at least one fluid channel has a helical shape around the axis from the inlet end to the outlet end; and

positioning the flow modulator in an opening at a second end of the reservoir adjacent the active agent formulation in the osmotic delivery system such that by disposing the osmotic delivery system in a fluid environment, an amount of the active agent formulation is delivered to the fluid environment through the at least one fluid channel, the at least one fluid channel mitigating any back diffusion.

10. The method of claim 9 , wherein at least one first groove is formed in the inner surface of the outer shell member and at least one second groove is formed in the outer surface of the inner core member such that when the inner core member is disposed in the internal volume, the at least one first groove complements the at least one second groove.

11. The method of claim 9 , wherein the flow modulator is at least one of press-fitted into the opening at the second end of the reservoir and secured to the second end of the reservoir with one or more threads.

12. The method of claim 9 , wherein the at least one groove is formed only in the inner surface of the outer shell member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end.

13. A method for regulating a release rate of an active agent formulation from an osmotic delivery system, the osmotic delivery system including a reservoir, a slidable piston defining within the reservoir a first chamber containing an osmotic engine and a second chamber containing the active agent formulation, a semipermeable plug disposed at a first end of the reservoir adjacent the first chamber, and an outer shell member disposed at a second end of the reservoir adjacent the active agent formulation, the outer shell comprising an inlet end, an outlet end, and an inner surface defining an internal volume for receiving an inner core member, the method comprising:

providing one or more inner core members, each inner core member comprising an outer surface for engaging the inner surface of the outer shell member when the inner core member is disposed in the internal volume, wherein at least one groove is formed in the outer surface of each inner core member such that when the inner core member is disposed in the internal volume, the at least one groove extends from the inlet end to the outlet end and at least a portion of the at least one groove has a helical shape around the axis from the inlet end to the outlet end;

selecting one of the one or more inner core members based on a geometry of the at least one groove; and

assembling a flow modulator by disposing the selected inner core member in the internal volume such that the outer surface of the selected inner core member sealingly engages the inner surface of the outer shell member and the at least one groove defines at least one fluid channel between the inner surface of the outer shell member and the outer surface of the selected inner core member such that the at least one fluid channel extends from the inlet end to the outlet end and at least a portion of the at least one fluid channel has a helical shape around the axis from the inlet end to the outlet end, such that by disposing the osmotic delivery system in a fluid environment, the active agent formulation is delivered to the fluid environment through the at least one fluid channel at a release rate based at least in part on the geometry of the at least one groove.

14. The method of claim 13 , wherein the active agent comprises a protein or a peptide.

15. The method of claim 13 , wherein the geometry of the at least one groove includes a path length, an effective cross-sectional diameter of the at least one fluid channel defined by the at least one groove, and a cross-sectional shape of the at least one fluid channel defined by the at least one groove.

16. The method of claim 15 , wherein the path length ranges from about 10 mm to about 50 mm.

17. The method of claim 16 , wherein the path length is about 35 mm.

18. The method of claim 15 , wherein the effective cross-sectional diameter ranges from about 0.1 mm to about 0.5 mm.

19. The method of claim 18 , wherein the effective cross-sectional diameter is about 0.25 mm.

20. The method of claim 15 , wherein the cross-sectional shape is at least one of a circular shape and a D-shape.

21. The method of claim 13 , wherein the one or more inner core members comprise a plurality of inner core members, and the geometry of the at least one groove differs between each of the plurality of inner core members.

22. The method of claim 13 , further comprising:

disengaging the outer surface of a first inner core member from the inner surface of the outer shell member; and

removing the first inner core member from the internal volume of the outer shell member to replace the first inner core member with the selected inner core member.

23. The method of claim 22 , wherein the geometry of the at least one groove in the outer surface of the selected inner core member differs from the geometry of the at least one groove in the outer surface of the first inner core member.

24. The method of claim 13 , wherein:

the outer shell member further comprises an inner shoulder;

each inner core member further comprises an outer shoulder; and

disposing the selected inner core member in the internal volume comprises engaging the outer shoulder and the inner shoulder to prevent expulsion of the selected inner core member from the outer shell member.