US 12,420,019 B2
Plunger rod for an auto-injector
Simon Francis Brereton, Cambridge (GB); Thomas Kemp, Ashwell (GB); Rosie Burnell, Cambridge (GB); and Matthew Ekman, Cheshire (GB)
Assigned to Sanofi-Aventis Deutschland GMBH, Frankfurt am Main (DE)
Filed by Sanofi-Aventis Deutschland GMBH, Frankfurt am Main (DE)
Filed on Jan. 13, 2025, as Appl. No. 19/018,045.
Application 19/018,045 is a division of application No. 18/755,814, filed on Jun. 27, 2024, granted, now 12,214,171.
Application 18/755,814 is a continuation of application No. 18/487,215, filed on Oct. 16, 2023.
Application 18/487,215 is a continuation of application No. 17/126,962, filed on Dec. 18, 2020, granted, now 11,819,670, issued on Nov. 21, 2023.
Application 17/126,962 is a continuation of application No. 15/897,872, filed on Feb. 15, 2018, granted, now 10,894,132, issued on Jan. 19, 2021.
Application 15/897,872 is a continuation of application No. 13/983,809, granted, now 9,925,344, issued on Mar. 27, 2018, previously published as PCT/EP2012/052647, filed on Feb. 16, 2012.
Claims priority of application No. 11155040 (EP), filed on Feb. 18, 2011.
Prior Publication US 2025/0144308 A1, May 8, 2025
This patent is subject to a terminal disclaimer.
Int. Cl. A61M 5/315 (2006.01); A61M 5/20 (2006.01); A61M 5/32 (2006.01); A61M 5/46 (2006.01)
CPC A61M 5/31501 (2013.01) [A61M 5/20 (2013.01); A61M 5/2033 (2013.01); A61M 5/3157 (2013.01); A61M 5/3158 (2013.01); A61M 5/322 (2013.01); A61M 5/326 (2013.01); A61M 5/46 (2013.01); A61M 2005/206 (2013.01); A61M 2005/208 (2013.01); A61M 2205/581 (2013.01); A61M 2205/582 (2013.01); A61M 2205/583 (2013.01)] 30 Claims
OG exemplary drawing
 
1. A plunger rod for an auto-injector, the plunger rod comprising:
a transverse portion extending in a direction perpendicular to a longitudinal axis of the plunger rod, the transverse portion configured to engage a compression spring of the auto-injector for proximally biasing the plunger rod within the auto-injector;
a proximally-extending portion extending proximally from the transverse portion, the proximally-extending portion being sized to fit within a barrel of a syringe for the auto-injector; and
a distally-extending portion extending distally from the transverse portion, wherein a distal portion of the distally-extending portion of the plunger rod comprises a first opening that extends radially inward from an outer surface of the distally-extending portion, the first opening configured to releasably engage a sleeve of the auto-injector to limit proximal movement of the plunger rod relative to the sleeve prior to a radially inward deflection which releases the first opening of the plunger rod from the sleeve,
wherein the plunger rod is configured to allow the compression spring to be disposed around the distally-extending portion such that a distance between an inner surface of the compression spring and the outer surface of the distally-extending portion of the plunger rod is substantially constant along a central portion of the distally-extending portion of the plunger rod, the distance being measured in the direction perpendicular to the longitudinal axis of the plunger rod.
 
10. A plunger rod for an auto-injector, the plunger rod comprising:
a transverse portion configured to engage a compression spring for proximally biasing the plunger rod within the auto-injector;
a proximal portion extending proximally from a proximal surface of the transverse portion and having a proximal end configured to engage a stopper of a syringe disposed within the auto-injector;
a first distally-extending portion extending distally from a distal surface of the transverse portion and having a first outer surface, a first transverse opening being formed on the first outer surface and extending radially inward; and
a second distally-extending portion extending distally from the distal surface of the transverse portion and having a second outer surface, a second transverse opening being formed on the second outer surface and extending radially inward,
wherein the plunger rod is configured such that when the compression spring is disposed around the first and second distally-extending portions, a first distance between an inner surface of the compression spring and the first outer surface of the first distally-extending portion of the plunger rod is substantially constant along a first central portion of the first distally-extending portion, the first distance being measured in a first direction that is perpendicular to a longitudinal axis of the plunger rod, and
wherein sidewalls of the first and second transverse openings of the plunger rod are configured to releasably engage a sleeve of the auto-injector such that a radially inward deflection releases the plunger rod from the sleeve to allow proximal movement of the plunger rod relative to the sleeve.
 
19. A plunger rod for an auto-injector, the plunger rod comprising:
a transverse portion extending in a direction perpendicular to a longitudinal axis of the plunger rod, the transverse portion configured to engage a compression spring of the auto-injector for proximally biasing the plunger rod within the auto-injector;
a proximally-extending portion extending proximally from the transverse portion, the proximally-extending portion being sized to fit within a barrel of a syringe for the auto-injector; and
a distally-extending portion having a sidewall that extends distally from the transverse portion to a distal end of the plunger rod, the sidewall having
a first region spanning at least one third of an overall axial length the distally-extending portion, a thickness of the sidewall in the first region being substantially constant throughout the first region, the first region being sized to allow the compression spring to surround the first region such that a substantially constant radial gap exists between the compression spring and the plunger rod along the first region; and
a second region that is distal to the first region, the second region defining one or more openings configured to releasably limit proximal movement of the plunger rod relative to a sleeve of the auto-injector prior to one or more flexible arms deflecting radially inward relative to the sleeve to release the plunger rod from the sleeve,
wherein the distally-extending portion is configured to allow an inner portion of a distal side of the transverse portion to be viewable from the distal end of the plunger rod when viewed along the longitudinal axis of the plunger rod, the inner portion being radially inward of the distally-extending portion.
 
25. A plunger rod comprising:
a transverse portion extending in a direction perpendicular to a longitudinal axis of the plunger rod, the transverse portion for receiving a proximally-directed biasing force from a compression spring;
a proximally-extending portion extending proximally from the transverse portion, the proximally-extending portion for displacing a stopper of a syringe; and
a distally-extending portion extending distally from the transverse portion, the distally-extending portion defining
one or more first openings having walls configured to releasably engage a sleeve to limit axial movement of the plunger rod relative to the sleeve prior to a radially inward deflection which releases the plunger rod from the sleeve; and
a second opening configured to allow an inner portion of a distal side of the transverse portion to be viewable through the second opening when viewed along the longitudinal axis of the plunger rod from a distal end of the plunger rod,
wherein the distally-extending portion is sized to allow the compression spring to surround the distally-extending portion such that a substantially constant radial gap exists between the compression spring and the distally-extending portion along at least 25% of an axial length of the distally-extending portion.