SEALING ARRANGEMENT FOR SYRINGE

• US 20130102994A1
• Filed: 08/30/2012
• Published: 04/25/2013
• Est. Priority Date: 08/31/2011
• Status: Active Grant

• Current Assignee: Abbvie Incorporated
• Original Assignee: Abbvie Incorporated
• Inventors: Gibler, Martin J., Bennett, Mark A., Gillum, Christoph L., Parrott, David A., Hemingway, Jeremy L., Hogue, Kenneth E., Conjeevaram, Rajkumar V., Waeber, Kenneth R., Harrell, Patrick A., Mackey, Sean E., Wiesner, Bryan L., Zhou, Ji, Rebne, Thomas, Clark, Bradley A.
• Granted Patent: US 10,195,350 B2
• Time in Patent Office: Days
• US Class Current: 604/506
• CPC Class Codes: A61M 2005/3117 Means preventing contamination of the medicament compartment of a syringe
• CPC Class Codes: A61M 2205/0222 Materials for reducing friction
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: A61M 5/315 Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
• CPC Class Codes: A61M 5/31505 Integral with the syringe barrel, i.e. connected to the barrel so as to make up a single complete piece or unit
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding
• CPC Class Codes: B65B 1/04 Methods of, or means for, filling the material into the containers or receptacles

Abstract

A syringe containing a high water content product and for use in a drug infusion system is provided. The syringe includes a plunger carrying front and rear o-rings made of a diene rubber compound such as chlorobutyl rubber or bromobutyl rubber to impart very low gas permeability characteristics to the o-rings. The plunger may be molded as a single part or in two parts. If molded as one part with radially-engaging mold portions, the seal glands in the plunger may include parting lines from the mold. If molded as two parts with axially-engaging mold portions, the front seal gland may include a sealing surface and under cut that has no parting line. The o-rings may be surface treated with a lubricant to improve sealing where the molding process gives rise to parting lines in the seal glands.

Claims

1. A syringe for use in a drug infusion system, the syringe comprising:

a barrel having a front end, a rear end, and a cylindrical wall defining an outer surface and an inner surface, the rear end being open, and the front end including an orifice;

a plunger within the barrel, the plunger including a contact surface at a front end of the plunger, and a front seal gland extending circumferentially around the plunger;

a front o-ring made of a diene rubber compound, positioned in the front seal gland, and creating a gas-tight seal between the inner surface of the barrel and the plunger;

wherein a product chamber is defined between the inner surface of the barrel, the front o-ring, and contact surface;

wherein the product chamber is adapted to contain a product to be dispensed by the syringe;

wherein actuation of the plunger within the barrel decreases the volume of the product chamber to dispense the product through the orifice; and

wherein the front o-ring is sized to maintain the gas tight seal through a temperature range of −

25°

C. to 40°

C.

2. The syringe of claim 1 wherein the front o-ring is surface treated with a lubricant to ensure a gas-tight seal between the front o-ring and the front seal gland.

3. The syringe of claim 1, further comprising:

a rear seal gland axially spaced to the rear of the front seal gland and extending circumferentially around the plunger;

a rear o-ring made of a diene rubber compound;

wherein the rear o-ring is positioned in the rear seal gland; and

wherein the rear o-ring creates a gas-tight seal between the inner surface of the barrel and the plunger.

4. The syringe of claim 1, wherein a front end of the plunger defines a head that includes the contact surface;

wherein an outer diameter of the head is slightly smaller than an inner diameter of the barrel such that the head fits within the barrel with close tolerances;

wherein a rear end of the plunger includes an integrally-formed molded ring having a maximum outer diameter that is slightly less than an inner diameter of the barrel such that the integrally-formed molded ring fits within the barrel with close tolerances; and

wherein the head and integrally-formed molded ring resist tipping of the plunger within the barrel.

5. The syringe of claim 1, wherein the front o-ring is sized to maintain the gas tight seal through a temperature range of −

20°

C. to 40°

C.

6. The syringe of claim 1, wherein the plunger is molded as a single piece;

wherein the front seal gland includes a parting line arising from the molding process;

wherein the seal between the front o-ring and the front seal gland includes a leak path arising from the parting line; and

wherein the front o-ring is surface treated with a lubricant to gas-tightly seal the leak path.

7. The syringe of claim 1, wherein the plunger is molded as a front portion and a rear portion;

wherein the front portion is molded with axially-engaging mold portions to form a portion of the front seal gland with no parting lines; and

wherein the rear portion is molded with radially-engaging mold portions to form a portion of the front seal gland with parting lines; and

wherein the front o-ring is received within in the front seal gland with no leak paths between the o-ring and the portion of the front seal gland having no parting lines.

8. The syringe of claim 1, wherein the front seal gland includes a rear-facing undercut surface in front of the o-ring;

wherein a pocket is defined between the o-ring and the rear-facing undercut surface of the front seal gland; and

wherein the plunger includes a venting slot in the rear-facing undercut surface, the venting slot communicating between the pocket and the product chamber such that air in the pocket is evacuated through the venting slot when a vacuum is applied to the product chamber.

9. The syringe of claim 8, wherein the pocket is an annular pocket extending around the entire circumference of the front seal gland;

wherein the venting slot includes two diametrically opposed venting slots communicating with the annular pocket.

10. The syringe of claim 1, further comprising a deflectable tab in the plunger and an insert that deflects the deflectable tab radially outwardly;

wherein the deflectable tab, when deflected outwardly by the insert, bears against the inner surface of the barrel to prevent tipping of the plunger in the barrel.

11. The syringe of claim 10, wherein the deflectable tab includes a plurality of deflectable tabs;

and wherein the insert includes a ring-shaped insert the expands all deflectable tabs radially outwardly.

12. The syringe of claim 1, wherein the plunger further includes a flexible wiper that engages the inner surface of the barrel to prevent tipping of the plunger in the barrel.

13. The syringe of claim 12, wherein the flexible wiper is integrally formed with the plunger.

14. The syringe of claim 12, wherein the plunger further includes a circumferential slot;

and wherein the wiper is inserted into the circumferential slot and extends radially outwardly into contact with the barrel inner surface.

15. A method for storing and dispensing a product having a high content of water, the method comprising:

providing a syringe barrel having a front end, a rear end, and a cylindrical wall defining an outer surface and an inner surface, the rear end being open, and the front end including an orifice;

providing a plunger having a contact surface at a front end of the plunger, and a front seal gland extending circumferentially around the plunger;

forming a front o-ring of a diene rubber compound;

positioning the front o-ring in the front seal gland to define a plunger and front o-ring assembly;

inserting the plunger and front o-ring assembly into the barrel such that the front o-ring is deflected between the inner surface of the barrel and the plunger to create a sliding gas-tight seal between the inner surface of the barrel and the plunger;

defining a product chamber between the inner surface of the barrel, the front o-ring, and contact surface;

filling the product chamber with the product having high water content;

freezing the product-filled syringe at a temperature at least as low as −

20°

C.;

in response to freezing the product-filled syringe, changing the phase of the water content of the product to ice, resulting in expansion of the product within the syringe;

in response to expansion of the product within the syringe, displacing the plunger within the barrel to expand the volume of the product chamber to accommodate the product expansion, while maintaining the gas-tight seal between the front o-ring and the contact surface;

storing the frozen product-filled syringe until an approximate time of use;

at the approximate time of use, thawing the frozen product-filled syringe to a temperature of at least 2°

C. to 40°

C.;

in response to thawing of the frozen product-filed syringe, changing the phase of the water content of the water to liquid;

in response to changing the phase of the water content to liquid, contracting the product;

in response to contracting the product, developing vacuum bubbles within the product, thereby giving rise to a vacuum force on the plunger that is the product of the vacuum pressure and a surface area of the contact surface;

in response to the vacuum pressure, moving the plunger within the barrel to reduce the volume of the product chamber to accommodate a decreased volume occupied by the product while maintaining the gas-tight seal; and

actuating the plunger to decrease the volume of the product chamber and thereby dispense the thawed product from the syringe through the orifice.

16. The method of claim 15, further comprising the step of surface treating the front o-ring with a lubricant to ensure a gas-tight seal between the front o-ring and the front seal gland.

17. The method of claim 15, further comprising:

providing a rear seal gland in the plunger, axially spaced to the rear of the front seal gland and extending circumferentially around the plunger;

providing a rear o-ring made of a diene rubber compound;

positioning the rear o-ring in the rear seal gland; and

creating a sliding gas-tight seal between the inner surface of the barrel and the plunger.

18. The method of claim 15, further comprising:

defining a head with a front end of the plunger, the head including the contact surface, and an outer diameter of the head being slightly smaller than an inner diameter of the barrel such that the head fits within the barrel with close tolerances;

forming in a rear end of the plunger an integrally-formed molded ring having a maximum outer diameter that is slightly less than an inner diameter of the barrel such that the integrally-formed molded ring fits within the barrel with close tolerances; and

resisting tipping of the plunger within the barrel with the head and integrally-formed molded ring during movement of the plunger within the barrel.

19. The method of claim 15, wherein the step of freezing the product-filled syringe includes freezing the product-filled syringe at a temperature of about −

25°

C. while maintaining the gas-tight seal; and

wherein the step of thawing the frozen product-filled syringe includes thawing the product-filled syringe to temperatures of about 40°

C. while maintaining the gas-tight seal.

20. The method of claim 15, wherein providing a plunger includes molding the plunger as a single piece with a parting line in the front seal gland arising from the molding process;

the method further comprising the step of surface treating the front o-ring with a lubricant to gas-tightly seal the front o-ring with respect to the parting line in the front seal gland.

21. The method of claim 15, wherein providing a plunger includes separately molding a front portion of the plunger and a rear portion of the plunger;

wherein molding the front portion includes using axially-engaging mold portions to form a portion of the front seal gland with no parting lines;

wherein molding the rear portion includes using radially-engaging mold portions to form a portion of the front seal gland with parting lines;

the step of providing a plunger further comprising snap-fitting the front portion of the plunger and rear portion of the plunger together to define the front seal gland;

wherein the front seal gland includes no leak paths between the o-ring and the portion of the front seal gland provided by the front portion of the plunger.

22. A syringe for use in a drug infusion system, the syringe comprising:

a barrel having a front end, a rear end, and a cylindrical wall defining an outer surface and an inner surface, the rear end being open, and the front end including an orifice;

a plunger within the barrel, the plunger including a front end and defining an external seal surface;

an overmolded seal constructed of one of a thermoplastic rubber and a thermoplastic elastomer covering the front end of the plunger and the external seal surface, the overmolded seal covering the front end of the plunger to define a contact surface over the front end of the plunger, and a radially-extending wiper that creates a gas-tight seal between the inner surface of the barrel and the plunger;

wherein a product chamber is defined between the inner surface of the barrel, the radial wiper of the overmolded seal, and the contact surface;

wherein the product chamber is adapted to contain a product to be dispensed by the syringe;

wherein actuation of the plunger within the barrel decreases the volume of the product chamber to dispense the product through the orifice; and

wherein the radial wiper is sized to maintain the gas tight seal through a temperature range of −

25°

C. to 40°

C.

23. The syringe of claim 22, the overmolded seal is molded over the front end of the plunger to ensure a gas-tight seal between the overmolded seal and the external seal surface of the plunger.

24. The syringe of claim 22, wherein the plunger includes a rear circumferential seal gland axially spaced to the rear of the overmolded seal, the syringe further comprising:

a rear o-ring made of a diene rubber compound;

wherein the rear o-ring is positioned in the rear seal gland; and

wherein the rear o-ring creates a gas-tight seal between the inner surface of the barrel and the plunger.

25. The syringe of claim 22, wherein a rear end of the plunger includes an integrally-formed molded ring having a maximum outer diameter that is slightly less than an inner diameter of the barrel such that the integrally-formed molded ring fits within the barrel with close tolerances;

and wherein the radially-extending wiper and the integrally-formed molded ring resist tipping of the plunger within the barrel.

26. The syringe of claim 22, wherein the radial wiper is sized to maintain the gas tight seal through a temperature range of −

20°

C. to 40°

C.

27. The syringe of claim 22, wherein the radial wiper is a front radial wiper, the overmolded seal further including a rear radial wiper spaced axially from the front radial wiper;

wherein the rear radially-extending wiper creates a gas-tight seal between the inner surface of the barrel and the plunger.

28. The syringe of claim 22, further comprising a deflectable tab in the plunger and an insert that deflects the deflectable tab radially outwardly;

wherein the deflectable tab, when deflected outwardly by the insert, bears against the inner surface of the barrel to prevent tipping of the plunger in the barrel.

29. The syringe of claim 28, wherein the deflectable tab includes a plurality of deflectable tabs;

and wherein the insert includes a ring-shaped insert the expands all deflectable tabs radially outwardly.

30. The syringe of claim 22, wherein the plunger further includes a second flexible wiper that is not part of the overmolded seal, the second flexible wiper engaging the inner surface of the barrel to prevent tipping of the plunger in the barrel.

31. The syringe of claim 30, wherein the flexible wiper is integrally formed with the plunger.

32. The syringe of claim 31, wherein the plunger further includes a circumferential slot;

and wherein the wiper is inserted into the circumferential slot and extends radially outwardly into contact with the barrel inner surface.