U.S. patent application number 12/396619 was filed with the patent office on 2010-03-18 for syringe assembly having disabling mechanism.
This patent application is currently assigned to Becton, Dickinson and Company. Invention is credited to Richard James Caizza, Chad Smith, P. R. Samuel Suresh.
Application Number | 20100069840 12/396619 |
Document ID | / |
Family ID | 34108849 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100069840 |
Kind Code |
A1 |
Suresh; P. R. Samuel ; et
al. |
March 18, 2010 |
Syringe Assembly Having Disabling Mechanism
Abstract
A syringe assembly having passive disabling structure includes a
barrel and a plunger rod assembly. The plunger rod assembly
includes a plunger rod and a stopper connected by an indexing
locking element. The number of strokes of the syringe plunger
before the stopper is locked into the barrel rendering the syringe
assembly unusable is determined by the number of detents on the
plunger rod and stopper which engage the locking mechanism. Upon
completion of the final delivery stroke, any attempt to withdraw
the plunger rod from the barrel will cause the locking element to
engage the barrel and trap the stopper in the barrel preventing
further use of the syringe.
Inventors: |
Suresh; P. R. Samuel;
(Coimbatore, IN) ; Smith; Chad; (Oak Ridge,
NJ) ; Caizza; Richard James; (Vernon, NJ) |
Correspondence
Address: |
David W. Highet, VP & Chief IP Counsel;Becton, Dickinson and Company
(Diehl Servilla, LLC), 1 Becton Drive, MC 110
Franklin Lakes
NJ
07417-1880
US
|
Assignee: |
Becton, Dickinson and
Company
Franklin Lakes
NJ
|
Family ID: |
34108849 |
Appl. No.: |
12/396619 |
Filed: |
March 3, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12018865 |
Jan 24, 2008 |
7537582 |
|
|
12396619 |
|
|
|
|
10838687 |
May 4, 2004 |
7331934 |
|
|
12018865 |
|
|
|
|
60523490 |
Nov 20, 2003 |
|
|
|
60490939 |
Jul 30, 2003 |
|
|
|
Current U.S.
Class: |
604/110 |
Current CPC
Class: |
A61M 2005/5033 20130101;
A61M 5/502 20130101; A61M 5/5013 20130101; A61M 2005/5026
20130101 |
Class at
Publication: |
604/110 |
International
Class: |
A61M 5/50 20060101
A61M005/50 |
Claims
1. An operable syringe assembly having passive disabling structure
comprising: a barrel including a cylindrical side wall having an
inside surface defining a chamber for retaining fluid, an open
proximal end and a distal end including a distal wall having a
passageway therethrough in fluid communication with said chamber;
an elongate hollow plunger rod having a proximal end, an open
distal end and an interior surface, at least one detent on said
interior surface at said distal end of said plunger rod; a stopper
moveably engaged with the plunger rod, the stopper including a
circular shaped sealing element having a peripheral surface forming
a seal with said inside surface of said barrel, a boss member
projecting proximally from said sealing element, at least one boss
detent on said boss; a locking element including a central body
portion having an aperture therethrough, at least one cantilevered
leg extending distally outwardly from said body portion, and at
least one finger element extending proximally inwardly from said
aperture, said at least one leg having a sharp free end directed
outwardly for engaging said inside surface of said barrel; said
locking element being positioned with said sharp free end
contacting said interior surface of said plunger rod proximally of
said at least one detent, said boss member being positioned in said
aperture of said locking element wherein said at least one finger
element is contacting said boss proximally of said at least one
boss detent, so that applying a proximally directed force to said
plunger rod while holding said barrel causes said plunger rod to
move proximally with respect to said stopper until said free end of
said cantilevered leg moves distally along said inner surface of
said plunger rod to said at least one detent, and subsequently
applying a distally directed force to said plunger rod to discharge
fluid from said chamber through said passageway causing said
plunger rod to move in a distal direction along with said locking
element due to its engagement with said at least one detent until
said finger element of said locking element rides over said at
least one boss detent and into contact with said at least one boss
detent and said plunger rod contacts said stopper to move said
stopper distally to discharge fluid from said chamber, after which
applying a proximally directed force to said plunger rod will cause
said plunger rod to move proximally until said free end of said
cantilevered leg moves distally along said inner surface past said
distal end of said plunger rod so that said sharp end of said at
least one cantilever leg engages said inside of said barrel to help
prevent proximal movement of said stopper to render said syringe
assembly unusable.
2. The syringe assembly of claim 1, wherein said at least one
detent in said plunger rod includes two axially spaced detents and
said at least one detent on said boss includes two axially spaced
boss detents so that said plunger rod can be moved distally two
times before proximal motion of said plunger rod causes said
locking element to engage said inside surface of said barrel.
3. The syringe assembly of claim 2, wherein said two axially spaced
detents in said plunger rod include two axially spaced steps each
having a blunt surface at its distal end extending inwardly from
said interior surface.
4. The syringe assembly of claim 2, wherein said two axially spaced
boss detents each include an inclined surface extending proximally
inwardly and a blunt surface at a distal end of each of said
inclined surfaces extending radially inwardly.
5. The syringe assembly of claim 2, wherein said at least one
cantilevered leg of said locking element includes two cantilevered
legs positioned on opposite sides of said central body portion and
two additional axially spaced detents are provided in said plunger
rod opposite said two axially-spaced detents.
6. The syringe assembly of claim 5, wherein said stopper further
comprises two radial projections positioned to engage and force
said two cantilevered legs outwardly when excessive proximally
directed force is applied to said plunger rod in an attempt to
overcome said locking element's engagement of said inside surface
of said barrel.
7. The syringe assembly of claim 1, further comprising a
discontinuity on said inside surface of said barrel sidewall
positioned to engage said sharp free end of said locking element
when said sharp free end is contacting said inside surface of said
barrel.
8. The syringe assembly of claim 1, wherein said distal wall of
said barrel further includes an elongate tip extending distally
therefrom having a passageway in fluid communication with said
passageway in said distal wall.
9. The syringe assembly of claim 1, further comprising a needle
cannula having a distal end, a proximal end and a lumen
therethrough, said proximal end of said needle cannula being
connected to said distal end of said barrel so that said lumen is
in fluid communication with said passageway.
10. The syringe assembly of claim 1, wherein said locking element
is made of sheet metal.
11. The syringe assembly of claim 1, wherein said stopper is
integrally formed of thermoplastic material.
12. An operable syringe assembly having passive disabling structure
comprising: a barrel including a cylindrical side wall having an
inside surface defining a chamber for retaining fluid, an open
proximal end and a distal end including a distal wall having an
elongate tip extending distally therefrom and a passageway
therethrough in fluid communication with said chamber; an elongate
hollow plunger rod having a proximal end, an open distal end and an
interior surface, said interior surface at said distal end of said
plunger rod including two pairs of axially spaced opposed steps,
each step extending inwardly from said sidewall and having a blunt
surface at its distal end and each recess having a distal face; a
stopper moveably engaged with the plunger rod, the stopper
including a circularly shaped sealing element having a peripheral
surface forming a seal within said inside surface of said barrel, a
boss member projecting proximally from said sealing element, two
axially spaced detents on said boss each having an inclined surface
extending proximally inwardly and a blunt surface extending
radially away from said boss; a locking element including a central
body portion having an aperture therethrough and two opposed
cantilevered legs extending distally outwardly from said body
portion, two finger elements extending proximally inwardly from
said aperture, said legs having free ends including a hook-shaped
portion, said hook-shaped portion having a sharp end directed
proximally outwardly from engaging said inside surface of said
barrel and said blunt surface in said plunger rod; said locking
element being positioned with said sharp ends of said hook-shaped
portions contacting said interior surface of said plunger rod
proximally of said blunt surface of said steps, said boss member
being positioned in said aperture of said locking element wherein
said finger elements contact said boss proximally of said blunt
surface of said detents, so that applying a proximally directed
force to said plunger rod while holding said barrel causes said
plunger rod to move proximally with respect to said stopper until
said hook-shaped portions of said cantilevered legs move distally
along said inner surface of said plunger rod and moves outwardly at
said blunt surface of proximal-most of said two steps to move said
stopper in a proximal direction for a selected distance, and
subsequently applying a distally directed force to discharge fluid
from said chamber through said passageway causes said plunger to
move in a distal direction with said locking element due to said
locking element's engagement with the proximal-most of said blunt
surfaces until said finger elements of said locking element ride
over said inclined surface of the proximal-most said two detents
and into contact with said blunt surface and said plunger rod
contacts said stopper to move said stopper distally to discharge
fluid from said chamber, an additional proximal and distal movement
of said plunger rod to draw fluid into said chamber and to deliver
fluid from said chamber will cause said locking element to be
repositioned so that said hook-shaped portions of said legs engage
the distal-most of said two steps and said finger elements engage
the distal-most of said blunt surfaces, after which applying a
proximally directed force to said plunger will cause said plunger
rod to move proximally until said hook-shaped portions of said
cantilevered legs move distally along said inner surface of said
plunger rod past said distal end of said plunger rod so that said
sharp ends of said hook-shaped projections engage said inside
surface of said barrel to help prevent proximal motion of said
stopper to render said syringe assembly unusable.
13. The syringe assembly of claim 12, wherein said stopper further
comprises two radial projections positioned to engage and force
said two cantilevered legs outwardly when excessive proximally
directed force is applied to said plunger rod in an attempt to
overcome said locking element's engagement of said inside surface
of said barrel.
14. The syringe assembly of claim 12, further comprising a
discontinuity on said inside surface of said barrel sidewall
positioned to engage said sharp free end of said locking element
when said sharp free end is contacting said inside surface of said
barrel.
15. The syringe assembly of claim 12, further comprising a needle
cannula having a distal end, a proximal end and a lumen
therethrough, said proximal end of said needle cannula being
connected to said distal end of said barrel so that said lumen is
in fluid communication with said passageway.
16. The syringe assembly of claim 12, wherein said locking element
is made of sheet metal.
17. The syringe assembly of claim 12, wherein said stopper is
integrally formed of thermoplastic material.
Description
STATEMENT OF RELATED CASES
[0001] This application is a continuation of U.S. application Ser.
No. 12/018,865, filed Jan. 24, 2008, which is a continuation of
U.S. application Ser. No. 10/838,687, filed May 4, 2004, which
claims the benefit of U.S. Provisional Application No. 60/490,939,
filed Jul. 30, 2003 and U.S. Provisional Application No.
60/523,490, filed Nov. 20, 2003, the disclosures of which are
incorporated herein in their entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to syringe assemblies and
particularly to syringe assemblies having an automatic disabling
mechanism.
[0003] Throughout the world the multiple use of hypodermic syringe
products which are intended for single-use only, is instrumental in
drug abuse and in the transfer of contagious diseases. Intravenous
drug users who routinely share and re-use syringes are a high-risk
group with respect to the AIDS virus. Also, the effects of multiple
use are a major concern in some countries where repeated use of
syringe products during mass immunization programs may be
responsible for the spread of many diseases. Re-use of single-use
hypodermic syringe assemblies is also instrumental in the spread of
drug abuse even in the absence of infection or disease.
[0004] Many attempts have been made to remedy this problem. Most
notable are early contributions which relied on a specific act to
destroy the syringe after use either by using a destructive device
or providing a syringe assembly with frangible zones so that the
syringe could be rendered inoperable by the application of force.
Other attempts involve the inclusion of structure which would allow
the destruction or defeating of the syringe function to a conscious
act by the syringe user. Although many of these devices work quite
well, they do require the specific intent of the user followed by
the actual act to destroy or render the syringe inoperable. These
devices are not effective with a user having the specific intent to
re-use the hypodermic syringe. Accordingly, there was a need for a
single-use hypodermic syringe which after use will become
inoperable or incapable of further use automatically without any
additional act on the part of the user. The automatic function is
much harder to provide because the means for rendering the syringe
inoperable must not prevent its filling or use under normal
conditions.
[0005] A single-use syringe which automatically disables after
injection is taught in U.S. Pat. No. 4,973,310 to Kosinski. This
syringe contains a locking element positioned in the syringe barrel
between the plunger rod and the inside surface of the barrel. In
use, the syringe allows the user to draw a pre-selected amount of
medication into the chamber of the barrel and deliver this
medication, as through injection, into the patient. Any attempt to
withdraw the plunger to use the syringe a second time will cause
the locking element to embed itself into the inside surface of the
syringe barrel to prevent proximal motion of the plunger rod.
[0006] There is still a need for a single-use syringe which will
allow a pre-selected number of plunger rod strokes before the
automatic disabling mechanism activates. For example, four strokes
of the plunger may be required to complete the injection process.
Such as when the syringe assembly is used to draw a diluent into
the syringe barrel, dispense the diluent into a vial containing the
substance to be reconstituted, drawing back the reconstituted
medication into the syringe and then delivering the contents of the
syringe into the patient.
SUMMARY OF THE INVENTION
[0007] An operable syringe assembly having a passive disabling
structure includes a barrel having a cylindrical sidewall with an
inside surface defining a chamber for retaining fluid, an open
proximal end and a distal end including a distal wall having a
passageway therethrough in fluid communication with the chamber. An
elongate hollow plunger rod having a proximal end, an open distal
end, and an interior surface is provided. A stopper has a
circular-shaped sealing element having a peripheral surface forming
a seal with the inside surface of the barrel and a boss member
projecting proximally from the sealing element. A locking element
interacts between the stopper and the plunger rod. The locking
element includes a central body portion having at least one
cantilevered leg extending distally outwardly from the body portion
wherein the leg includes a sharp free end directed outwardly for
engaging the inside surface of the barrel. The locking element is
movably connected to the boss of the stopper and movably connected
to the plunger rod interior surface. Structure for indexing the
locking element distally in the plunger rod during proximal motion
of the plunger rod to draw fluid into the chamber and for indexing
the locking element distally on the boss of the stopper during
distally-directed motion of the plunger rod for delivering fluid
from the chamber through the passageway and means for engaging the
locking element with the inside surface of the barrel sidewall for
preventing reuse of the syringe assembly is provided.
[0008] Structure for engaging the locking element with the inside
surface of the barrel sidewall may include an opening in the distal
end of the plunger rod to shorten the axial length of the interior
surface area of the opening for allowing the sharp free end to
project outwardly past the plunger rod and onto the inside surface
of the barrel.
[0009] The structure for indexing includes at least one detent on
the interior surface of the distal end of the plunger rod, at least
one boss detent on the boss and at least one cantilevered arm on
the stopper having an outwardly extending rib near its free end
sized to engage a recess in the inside surface of the plunger rod.
The indexing structure further includes the locking element having
at least one finger element extending inwardly from an aperture in
the central body portion of the locking element. The locking
element is positioned with its sharp free end contacting the
interior surface of the plunger rod proximally of the at least one
detent and the boss member is positioned in the aperture of the
locking element wherein the at least one finger element is
contacting the boss member proximally of the at least one boss
detent and the outwardly extending rib is positioned in the recess
of the plunger rod.
[0010] The syringe assembly may be configured so that the at least
one detent in the plunger rod includes two axially-spaced detents
and the at least one detent in the boss includes two axially-spaced
boss detents so that the plunger rod can be moved distally one or
two times before proximal motion of the plunger rod causes the
locking element to engage the inside surface of the barrel,
depending on the initial position of the locking element at the
time of use. The two axially-spaced detents in the plunger rod may
include two axially-spaced steps each having a blunt surface at its
distal end extending inwardly from the interior surface of the
plunger rod. The two axially-spaced boss detents may each include
an inclined surface extending proximally inwardly and a blunt
surface at a distal end of each of the inclined surfaces extending
radially inwardly.
[0011] The at least one cantilevered leg of the locking element may
include two cantilevered legs positioned on opposite sides of the
central body portion. The stopper may further include two radial
cam projections positioned to contact and force the two
cantilevered legs outwardly when excessive proximally-directed
force is applied to the plunger rod in an attempt to overcome the
locking element's engagement to the inside surface of the
barrel.
[0012] The at least one cantilevered arm of the stopper may include
two cantilever arms positioned on opposite sides of the boss and
said at least one recess in the inner surface of the plunger rod
may include two recesses positioned on opposite sides of the
plunger rod and configured to receive the outwardly extending ribs
of the two cantilevered arms.
[0013] The syringe barrel may further include an elongate tip
extending distally from the distal wall and having a passageway
therethrough in fluid communication with the chamber of the syringe
barrel. The syringe assembly may also include a needle cannula
having a distal end, a proximal end and a lumen therethrough,
wherein the proximal end of the needle cannula is connected to the
distal end of the syringe barrel so that the lumen is in fluid
communication with the passageway of the barrel. The syringe
assembly may include a locking element made of sheet metal such as
stainless steel. Further, the stopper and all its elements may be
integrally formed of thermoplastic material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a side-elevational view of the syringe assembly of
the present invention.
[0015] FIG. 2 is a side-elevational end view of the proximal end of
the syringe assembly of FIG. 1.
[0016] FIG. 3 is a cross-sectional view of the syringe assembly of
FIG. 1 taken along line 3-3.
[0017] FIG. 4 is a perspective view of the plunger rod of the
syringe assembly viewed from its distal end.
[0018] FIG. 5 is a perspective view of the locking element of the
syringe assembly viewed from its distal end.
[0019] FIG. 6 is a perspective view of the locking clip viewed from
its proximal end.
[0020] FIG. 7 is a perspective view of the stopper of the syringe
assembly viewed from its distal end.
[0021] FIG. 8 is a perspective view of the stopper viewed from its
proximal end.
[0022] FIG. 9 is an exploded side-elevational view of the plunger
assembly.
[0023] FIG. 10 is a cross-sectional view of the plunger assembly of
FIG. 9 taken along line 10-10.
[0024] FIG. 11 is an enlarged partial cross-sectional view of the
syringe assembly of FIG. 1 taken along line 3-3 showing the syringe
assembly before use.
[0025] FIG. 11A is an enlarged partial cross-sectional view similar
to FIG. 11 but rotated 90.degree.
[0026] FIG. 12 is an enlarged partial cross-sectional view of the
syringe assembly of FIG. 1 taken along line 3-3 showing the syringe
assembly after a first aspiration stroke.
[0027] FIG. 12A is an enlarged partial cross-sectional view similar
to FIG. 12 but rotated 90.degree.
[0028] FIG. 13 is an enlarged partial cross-sectional view of the
syringe assembly of FIG. 1 taken along line 3-3 showing the syringe
assembly during a first dispensing stroke.
[0029] FIG. 13A is an enlarged partial cross-sectional view similar
to FIG. 13 but rotated 90.degree.
[0030] FIG. 14 is an enlarged partial cross-sectional view of the
syringe assembly of FIG. 1 taken along line 3-3 showing the syringe
assembly at the start of a second aspiration stroke.
[0031] FIG. 14A is an enlarged partial cross-sectional view similar
to FIG. 14 but rotated 90.degree.
[0032] FIG. 15 is an enlarged partial cross-sectional view of the
syringe assembly of FIG. 1 taken along line 3-3 showing the syringe
assembly after a second dispensing stroke.
[0033] FIG. 15A is an enlarged partial cross-sectional view similar
to FIG. 15 but rotated 90.degree.
[0034] FIG. 16 is an enlarged partial cross-sectional view of the
syringe assembly of FIG. 1 taken along line 3-3 showing a position
of the internal components in the event of an attempt to withdraw
the plunger rod after the second dispensing stroke.
[0035] FIG. 16A is an enlarged partial cross-sectional view similar
to FIG. 16 but rotated 90.degree.
[0036] FIG. 17 is an enlarged partial cross-sectional view similar
to the syringe assembly of FIG. 16 showing the interaction of
additional structure to prevent reuse.
[0037] FIG. 17A is an enlarged partial cross-sectional view similar
to FIG. 17 but rotated 90.degree.
[0038] FIG. 18 is an enlarged partial cross-sectional view similar
to the syringe assembly of FIG. 17 showing a discontinuity in the
syringe barrel for engaging the locking element.
DETAILED DESCRIPTION OF THE INVENTION
[0039] The present invention is directed to a syringe assembly
having a passive disabling mechanism. The disabling mechanism
enables variable dosages by the syringe assembly and enables a
selected number of cycles or strokes by the plunger rod before
being automatically disabled. In one preferred embodiment, the
disabling mechanism provides two aspirating and two dispensing
cycles before being automatically disabled. The assembly enables
the aspiration and dispensing of a selected volume of a diluent
into a vial to reconstitute a drug, pharmaceutical agent, or other
substance and then aspirating the reconstituted substance back into
the syringe. A selected volume of the reconstituted substance can
be injected or delivered to a patient where the volume of the
substance that is delivered can be the same or different than the
volume of the substance aspirated into the syringe barrel. The
syringe is automatically disabled after the injection or delivery
stroke by retracting the plunger rod, which activates the disabling
mechanism.
[0040] The disabling mechanism is actuated by the axial movement of
the plunger rod with respect to the syringe barrel and to the
stopper, by moving the plunger rod in the aspirating direction. The
stopper is coupled to the plunger rod to allow limited axial
movement of the stopper with respect to the plunger rod. The
disabling mechanism moves through a series of stages by reversing
the direction of the axial movement of the plunger rod with respect
to the stopper to move the mechanism in a step-wise manner to the
disabling position. The disabling position of the mechanism is
attained by the relative movement between the plunger rod and the
stopper and is not dependent on the position of the stopper within
the syringe barrel or the length of the stroke by the stopper. In
this manner, the syringe assembly is able to dispense a desired
volume of the drug or other substance, and the disabling mechanism
can be actuated after the final dispensing or injection stroke
regardless of the position of the stopper in the syringe barrel. By
actuating the disabling mechanism, the stopper cannot be retracted
to aspirate a substance into the syringe barrel but allows any
substance remaining in the syringe barrel to be dispensed.
[0041] Referring to the drawings, a syringe assembly 100 having a
disabling mechanism includes a syringe barrel 102 and a plunger
assembly 104. Barrel 102 includes a cylindrical sidewall 106 having
an inside surface 107 defining a chamber 109 for retaining fluid,
an open proximal end 113 and a distal end 115 including a distal
wall 117 having a passageway 119 therethrough in fluid
communication with the chamber. In this embodiment, the distal wall
of the barrel includes an elongate tip extending distally therefrom
and having a passageway in fluid communication with the passageway
in the distal wall. In this embodiment barrel 102 also includes a
needle cannula 170 having a proximal end 171, a distal end 172 and
a lumen 173 therethrough. The proximal end of the needle cannula is
attached to elongate tip 103 so that the lumen of the needle
cannula is in fluid communication with passageway 119 in the
barrel.
[0042] Plunger assembly 104 includes an elongate hollow plunger rod
108, a stopper 128 and a locking element 130. Plunger rod 108
includes a proximal end 111, an open distal end 110 and an interior
surface 116 and at least one aperture or recess 114 in the interior
surface at the distal end of the plunger rod. The recess includes a
distal face 121. In this embodiment, there are two recesses 114
having distal faces 121. The interior surface at the distal end of
the plunger rod includes at least one detent. In this embodiment
the at least one detent on the interior surface of the distal end
of the plunger rod includes four axially spaced detents 118 with
two detents on each side of the plunger rod. Each pair of detents
is shaped to form axially spaced steps 120 with each step having a
blunt surface 122 at its distal end extending inwardly from the
interior surface of the plunger rod.
[0043] Stopper 128 includes a circularly-shaped sealing element 144
having a peripheral surface 145 forming a seal with the inside
surface of the barrel. A boss member 134 extends proximally from
the sealing element and includes at least one boss detent and in
this embodiment, contains two boss detents 136. At least one
cantilevered arm extends proximally from the sealing element and in
this embodiment there are two cantilever arms 140 extending
proximally from the sealing element. Each of the cantilevered arms
includes an outwardly extending rib 142. The rib is sized to fit
within recess 114 in the plunger rod. The axially spaced boss
detents 136 each include an incline surface 137 extending
proximally inwardly and a blunt surface 138 at the distal end of
each of the inclined surfaces. The stopper is preferably integrally
formed of thermoplastic material such as polyethylene. The
circularly-shaped sealing element and/or the peripheral sealing
surface thereon may be made of elastomeric materials such as
thermoplastic elastomers, natural rubber, synthetic rubber and
combinations thereof
[0044] Locking element 130 includes a central body portion 148
having an aperture 152 therethrough and at least one cantilevered
leg 150 extending distally outwardly from the body portion and at
least one finger element 154 extending inwardly from the aperture.
In this embodiment, at least two cantilevered legs with each of the
cantilevered legs having a sharp free end 155 directed outwardly
for engaging the inside surface of the barrel. The configuration of
sharp free end 155 can be any configuration capable of engaging the
inside surface of the barrel, such as a sharp edge or one or more
pointed teeth and the like. The locking element may be made of a
variety of materials, or combinations of materials, however, it is
preferred to have the sharp free ends made of metal and it is also
preferred that the entire locking element be made of integrally
formed from sheet metal such as stainless steel.
[0045] In this preferred embodiment plunger assembly 104 is
assembled by inserting locking element 130 into the distal end of
plunger rod 108. Boss 134 of stopper 128 is then inserted into the
distal end of the plunger rod through aperture 152 of locking
element 130 so that cantilevered legs 150 extend toward
circularly-shaped sealing element 144 of the stopper as illustrated
in FIGS. 9 and 10.
[0046] As will be explained in more detail hereinafter, the plunger
assembly is then inserted into barrel 102 through open proximal end
113 to the initial position illustrated in FIGS. 11 and 11A. In the
initial position of the syringe element, locking element 130 is
positioned with its sharp free ends 155 contacting the interior
surface of the plunger rod proximally of axially spaced steps 120.
Boss member 134 is positioned in aperture 152 of locking element
130 so that finger elements 154 contact boss member proximally of
boss detents 136. Outwardly extending ribs 142 of cantilever arms
140 are positioned in recesses 114 in the plunger rod. Ribs 142 are
configured to complement the recesses 114 for allowing limited
axial movement of the stopper with respect to the plunger rod. The
stopper 128 further includes stabilizing member 146 positioned
proximally with respect to sealing element 144 and has an outer
dimension complimenting the other dimension of the sealing element
as shown in FIG. 11A, stabilizing member 146 has an outer dimension
to contact the inner surface of the syringe barrel and is spaced
from sealing element 144 to assist in stabilizing stopper 128 to
maintain the stopper and boss member 134 in an orientation
substantially parallel to the axis of the syringe barrel. In the
position illustrated in FIGS. 11 and 11A, syringe assembly 100 is
ready to use for drawing liquid into the chamber of the barrel.
[0047] As will now be shown, the operation of the plunger assembly
of this embodiment includes a first aspiration stroke followed by a
first dispensing stroke, a second aspiration stroke and a final
dispensing stroke after which the syringe is disabled. The
disabling elements prevent or inhibit movement of stopper 128 in a
proximal aspirating direction thereby limiting the function of the
syringe assembly to a single use. The maximum number of strokes
being limited by a number of axially positioned detents in the
plunger rod and the number of axially positioned boss detents on
the stopper. However, the actual number of strokes the syringe may
make will be determined by the position of the locking element with
respect to the detents in the plunger rod and the detents on the
stopper at the time of first use. For example, a syringe with two
plunger detents and two stopper detents can be supplied to the end
user as a syringe capable of two strokes or four strokes. This is
an important feature of the present invention since a single
syringe assembly can be provided with different stroke limitations
before disabling.
[0048] The syringe assembly may now be used to draw liquid, such as
a sterile water diluent into the chamber of the barrel by applying
a proximally directed force to a thumb press 123 on the proximal
end of the plunger rod while holding the syringe barrel. As
illustrated in FIGS. 12 and 12A, this causes the plunger rod to
move proximally with respect to the stopper until the free end of
cantilevered legs 150 moves distally along inner surface 116 of the
plunger rod and snaps past blunt surface 122 of the proximal most
axially spaced steps 120, as best illustrated in FIG. 12. Also,
during this first aspiration stroke outwardly extending ribs 142
engage distal surface 121 of the recesses 114 in the plunger rod as
best illustrated in FIG. 12A. When ribs 142 engage distal surface
121 the stopper is drawn proximally with respect to the barrel as
the plunger rod moves. The stopper is now moved proximally, through
action of the plunger rod, until the desired volume of liquid is in
the chamber as determined by the user.
[0049] The liquid diluent in the chamber may now be discharged into
a vial of dry medication such as lyophilized medication, for
reconstitution. This first dispensing stroke is accomplished by
moving the plunger rod in a distal direction while holding the
barrel. A barrel flange 124 is provided on the proximal end of the
barrel to help control motion of the barrel during use of the
syringe assembly. As best illustrated in FIGS. 13 and 13A, as the
plunger rod moves distally, locking element 130 moves with the
plunger rod dragging the locking element with it so that finger
elements 154 on the locking element slide from the proximal most to
the distal most boss detent by riding up inclined surface 137 and
falling into the second detent. When the plunger rod contacts the
stopper, the stopper will begin moving in a distal direction along
with the plunger rod to discharge liquid diluent from the chamber
into, for example, a vial of lyophilized medication.
[0050] When the diluent and the lyophilized medication are mixed
the syringe assembly of the present invention may now be used to
withdraw the reconstituted, ready-to-inject medication into the
chamber of the syringe barrel, as best illustrated in FIGS. 14 and
14A, by applying a proximally directed force to the plunger rod
while holding the syringe barrel. Proximally directed force will
cause the plunger rod to move in a proximal direction while locking
element 130 will remain relatively stationary due to its connection
to the boss detent on the stopper. Proximal motion of the plunger
causes the locking element to move distally along the inside
surface of the plunger rod so that the sharp free end 155 of the
cantilever legs moves from the proximal-most axially-spaced steps
120 in the plunger rod to the second more distal axially-spaced
steps 120. Proximal motion of the plunger rod also causes outwardly
extending ribs 142 of cantilever arms 140 to engage distal surfaces
121 of recesses 114 in the plunger rod so that the stopper now
moves proximally with the plunger rod drawing the reconstituted
medication into the chamber of the syringe barrel to an amount
determined by the user. An advantage of the present invention is
that the amount of medication drawn into the chamber, and therefore
the maximum amount of medication that can be delivered, is
determined by the user at the time of use and not by the placement
of the components at the time of manufacture.
[0051] The syringe assembly of the present invention is now ready
for a second and final dispensing stroke which is best illustrated
in FIGS. 15-15A. The medication is delivered to the patient by
applying a distally directed force to the plunger rod causing the
plunger rod to move in a distal direction with respect to the
barrel. As the plunger rod advances in a distal direction the
engagement of sharp free ends 155 of the locking element in with
the distal-most blunt surfaces 122 of axially-spaced steps 120
moves the locking element distally so that finger elements 154 of
the locking element ride over the distal-most inclined surface 137
of the boss detents distally past the most distal boss detent 136.
When the distally moving plunger rod contacts the stopper, both the
stopper and the plunger rod move toward the distal end of the
barrel to discharge the contents of the chamber through the
passageway.
[0052] The syringe assembly has now been used and is ready to be
discarded. Any attempt to move the plunger rod in a proximal
direction to refill the syringe assembly for further use will cause
the locking element to disable the syringe. Specifically, as best
illustrated in FIGS. 16 and 16A, moving the plunger rod in a
proximal direction will allow the plunger rod to move a short
distance until the sharp free ends 155 of the locking clip snap
past the end of the plunger rod and engage the inside surface 107
of the barrel side wall. Further proximal motion of the plunger
will be resisted by the locking element's engagement to the inside
surface of the barrel sidewall. In addition, as illustrated in FIG.
17, cam surface 125 on the stopper is positioned to force sharp
free ends 155 further into the syringe barrel wall as more
proximally directed force is used in an attempt to improperly reuse
the syringe. Accordingly, increased force to pull the plunger rod
out of the syringe barrel results in increased force of engagement
of the sharp free ends of the locking element into the barrel. It
is desirable to provide a cut-out area 126 in the distal end of the
plunger rod along the path of the sharp free ends of the locking
element for supporting the locking element and allowing it to
engage the inside surface of the barrel. Further, the area at the
end of the plunger rod on the area around the cutout can be
configured to support the locking element so that if the user
accidentally withdraws the plunger rod a second time before
delivering the final dose of medication the medication may still be
delivered even though the locking element sharp free ends are
touching the barrel so long as they are moved in a distal direction
and urged not to engage the inside surface of the barrel by the
cut-out area and the plunger rod. In this case the area around the
cutout supports and limits the motion and helps prevent deformation
of the sharp free end of the locking element.
[0053] It is also within the purview of the present invention to
provide a discontinuity such as a recess or projection on the
interior surface of the barrel, as illustrated in FIG. 18, to
further improve the engagement of the sharp free end of the locking
element with the interior surface of the barrel. In FIG. 18 syringe
barrel 102 includes a discontinuity in the form of an inwardly
directed projection 127 on inside surface 107 of the barrel. In
this embodiment, projection 127 is an annular ring projecting into
the barrel and extending 360.degree. around the inside surface. The
discontinuity may be in the form of an annular projection, an
annular recess or one or more projections or recesses shaped to
engage locking element, all positioned within the barrel to engage
sharp free end 155 of locking element 130 to further increase the
grip of the locking element on the barrel and inside surface.
[0054] The present syringe assembly provides an improvement over
prior art devices by allowing a variable dose of diluent, chosen by
the user at the time of use, to be drawn into the syringe,
dispensing the diluent into a vial containing a substance to be
reconstituted, drawing a selected amount of the reconstituted
substance back into the syringe and then delivering the contents of
the syringe. The selected amount of the reconstituted substance may
be equal or less than the full volume reconstituted at the
discretion of the user. The syringe assembly is automatically
disabled after the final injection stroke by reversing the
direction of the movement of the plunger rod from the dispensing
direction to the aspirating direction. After the injection stroke
of the syringe plunger the plunger rod is retracted to activate the
disabling mechanism to prevent axial movement of the stopper toward
the proximal end of the syringe barrel thereby preventing the
stopper from being removed and preventing reuse of the syringe.
[0055] When the present syringe assembly has two or more detents on
the stopper and in the plunger rod, the maximum number of strokes
the syringe assembly will allow can be varied by the initial
position of the locking element with respect to the stopper detents
and the plunger rod detents.
[0056] While various embodiments have been chosen to illustrate the
invention, it will be appreciated that changes and modifications
can be made without departing from the scope of the invention.
* * * * *