Pharmaceutical syringe piston

Patent metadata

Field	Value
Publication number	US-11607498-B2
Application number	US-202217828055-A
Country	US
Kind code	B2
Filing date	May 31, 2022
Priority date	Apr 5, 2013
Publication date	Mar 21, 2023
Grant date	Mar 21, 2023

Abstract

A piston to be provided within an inner wall of a barrel of a pharmaceutical syringe for dispensing medicament retained in the barrel is described. The piston includes a body defining a central face, a cylindrical portion, and an annular curved portion between the cylindrical portion and the central face portion. The piston also includes an inert film enclosing the central face portion and at least a part of the annular curved portion. The cylindrical portion and the part of the annular curved portion are together configured to maintain a fluid-tight seal with the inner wall of the barrel. A pharmaceutical syringe is described for dispensing a medicament includes a barrel configured to retain the medicament and the piston.

First claim

What is claimed is:

1. A syringe for dispensing a medicament, the syringe comprising:
a barrel configured to retain the medicament, the barrel extending along a longitudinal axis of the syringe, the barrel defining an inner wall that is cylindrical and coaxial with respect to the longitudinal axis, the inner wall defining an inner diameter of the barrel;
a piston provided within the inner wall of the barrel, the piston comprising:
a body defining:
a central face portion oriented coaxially with the longitudinal axis and defining a first piston diameter measured perpendicularly to the longitudinal axis, wherein the first piston diameter is a maximum diameter of the central face portion and is less than the inner diameter of the barrel;
a cylindrical portion oriented coaxially with the longitudinal axis, the cylindrical portion defining a first axial end, a second axial end, and a wall extending essentially along the longitudinal axis between the first axial end and second axial end, the wall defining a second piston diameter measured perpendicularly to the longitudinal axis, the second piston diameter is larger than the inner diameter of the barrel; and
an annular curved portion between the first axial end of the cylindrical portion and the central face portion, the annular curved portion defining a curve, and

an inert film enclosing the central face portion and at least a part of the annular curved portion, the inert film defining an outer boundary, and the inert film is configured to maintain a contamination seal between the body of the piston and the medicament retained in the barrel,

wherein the cylindrical portion and the part of the annular curved portion together maintain a fluid-tight seal with the inner wall of the barrel and the outer boundary of the inert film is proximate to a leading-distal edge of the fluid-tight seal to minimize contact between the inert film and the inner wall of the barrel.

2. The syringe of claim 1 , wherein the fluid-tight seal defines a trailing-proximal edge at the second axial end of the cylindrical portion, and the fluid-tight seal is continuous between the leading-distal edge and the trailing-proximal edge.

3. The syringe of claim 2 , wherein the outer boundary of the inert film is disposed closer to the leading-distal edge of the fluid-tight seal than to the trailing-proximal edge of the fluid-tight seal.

4. The syringe of claim 1 , wherein the outer boundary of the inert film is adjacent to the leading-distal edge of the fluid-tight seal.

5. The syringe of claim 1 , further comprising a plunger shaft that extends longitudinally and that is coupled to the second axial end of the body of the piston.

6. The syringe of claim 5 , wherein the second axial end of the body of the piston defines a receiving cavity configured to receive an end of the plunger shaft.

7. The syringe of claim 5 , wherein the plunger shaft extends through an axial opening of the barrel.

8. The syringe of claim 1 , wherein the curve defines at least one of a concave shape with a radius of curvature that extends into the body or a convex shape with a radius of curvature that extends out away from the body.

9. A syringe for dispensing a medicament, the syringe comprising:
a barrel configured to retain the medicament, the barrel extending along a longitudinal axis of the syringe, the barrel defining an inner wall that is cylindrical and coaxial with respect to the longitudinal axis, the inner wall defining an inner diameter of the barrel;
a piston provided within the inner wall of the barrel, the piston comprising:
a body defining:
a central face portion oriented coaxially with the longitudinal axis and defining a first piston diameter measured perpendicularly to the longitudinal axis, wherein the first piston diameter is a maximum diameter of the central face portion and is less than the inner diameter of the barrel;
a cylindrical portion oriented coaxially with the longitudinal axis, the cylindrical portion defining a first axial end, a second axial end, and a wall extending essentially along the longitudinal axis between the first axial end and second axial end, the wall extends a distance along the longitudinal axis, the wall defining a second piston diameter measured perpendicularly to the longitudinal axis, the second piston diameter is larger than the inner diameter of the barrel, the wall contacts the inner wall of the barrel to maintain a fluid-tight seal with the inner wall of the barrel; and
an annular curved portion between the first axial end of the cylindrical portion and the central face portion, the annular curved portion defining:
a first portion defining a curve and a diameter that is less than the second piston diameter, and
a second portion with a diameter that is substantially equal to the second piston diameter, the second portion of the annular curved portion extends a distance along the longitudinal axis, and

an inert film enclosing the central face portion and at least a part of the annular curved portion, the inert film defining an outer boundary that does not extend axially beyond the first axial end of the cylindrical portion to minimize contact between the inert film and the inner wall of the barrel,

wherein the distance that the wall of the cylindrical portion extends along the longitudinal axis is greater than the distance that the second portion of the annular curved portion extends along the longitudinal axis.

10. The syringe of claim 9 , wherein the distance that the wall of the cylindrical portion extends along the longitudinal axis is at least twice as long as the distance that the second portion of the cylindrical portion extends along the longitudinal axis.

11. The syringe of claim 9 , further comprising a plunger shaft that extends longitudinally and that is coupled to the second axial end of the body of the piston.

12. The syringe of claim 11 , wherein the second axial end of the body of the piston defines a receiving cavity configured to receive an end of the plunger shaft.

13. The syringe of claim 11 , wherein the plunger shaft extends through an axial opening of the barrel.

14. The syringe of claim 9 , wherein the curve defines at least one of a concave shape with a radius of curvature that extends into the body or a convex shape with a radius of curvature that extends out away from the body.

15. A piston configured to be provided within an inner wall of a barrel of a syringe for dispensing medicament retained in the barrel, the piston comprising:
a body defining:
a central face portion oriented coaxially with respect to a longitudinal axis of the piston and defining a first piston diameter measured perpendicularly to the longitudinal axis, wherein the first piston diameter is a maximum diameter of the central face portion and is less than an inner diameter of the inner wall of the barrel;
a cylindrical portion oriented coaxially with the longitudinal axis, the cylindrical portion defining a first axial end, a second axial end, and a wall extending essentially along the longitudinal axis between the first axial end and second axial end, the wall defining a second piston diameter measured perpendicularly to the longitudinal axis, the second piston diameter is larger than the inner diameter of the barrel; and
an annular curved portion between the first axial end of the cylindrical portion and the central face portion, the annular curved portion defining a curve, and

an inert film enclosing the central face portion and at least a part of the annular curved portion, the inert film defining an outer boundary, and the inert film is configured to maintain a

Assignees

• West Pharmaceutical Services Inc

Inventors

• Laubach Jeffrey M
• Brinkhues Jurgen
• Gruen Heike
• Worman Joel
• Zhao Xia
• Mattia Jason

Classifications

• A61M5/31513 Primary

  Piston constructions to improve sealing or sliding · CPC title

• A61M2205/0222

  Materials for reducing friction · CPC title