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

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.

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.