Abstrict A process for filling and sealing a fluid-containing plastic disposable
syringe that is to be sterilized, wherein the disposable syringe
includes a barrel having a front end, a nozzle part having a sealing
element, a plunger plug, and a plunger stop element that is placed
in the area of a cylinder gripping plate, the process includes inserting
and pushing the plunger plug into the front end of the barrel, using
pressure and forcing a fluid medium into the barrel via the nozzle
part, whereby the fluid medium pushes the plunger plug in the direction
of the plunger stop element, and sealing the sealing element of
the nozzle part by plastic deformation after the barrel and the
nozzle part are filled.
Claims What is claimed is:
1. A fluid-containing plastic disposable syringe that is to be
sterilized, comprising:
a barrel having a front end and a gripping-plate end with a gripping
plate disposed thereon;
a nozzle part molded with said barrel at the front end of said
barrel; said nozzle part having a deformable sealing portion, a
connecting part, and an open free end, the free end adapted to receive
therethrough a pressurized fluid medium which fills the barrel;
a plunger-plug placed inside of said barrel; and
a plunger-stop element placed adjacent to said gripping plate,
the plunger-stop element engaging the plunger-plug to prevent the
plunger plug from being pushed out of the barrel at the gripping-plate
end by the pressurized fluid medium during filling of the barrel,
wherein the fluid medium is retained within the barrel by deforming
the sealing portion to close the nozzle part.
2. A disposable syringe according to claim 1 wherein said connecting
part comprises an outer cone.
3. A disposable syringe according to claim 2 wherein said connecting
part with said outer cone comprises a locking part.
4. A disposable syringe according to claim 1 further comprising
a protective cap with an attachment area, said protective cap being
removably attached to said nozzle part.
5. A diposable syringe according to claim 4 wherein outside of
its attachment area said protective cap has recesses therethrough.
6. A disposable syringe according to claim 1 wherein said sealing
portion is substantially tubular.
7. A disposable syringe according to claim 1 wherein said nozzle
part has a throat between said connecting part and said front area.
8. A disposable syringe according to claim 1 wherein said plunger-stop
element comprises at least one plunger support element extending
into said barrel and engaging behind said gripping plate with at
least one gripping element.
9. A disposable syringe according claim 1 further comprising a
protective cap with an attachment area, said protective cap being
removably attached to said barrel.
10. A disposable syringe according to claim 1 wherein said plunger-stop
element comprises at least one plunger support element covering
said barrel and engaging behind said gripping plate with at least
one gripping element.
11. A process for filling and sealing a fluid-containing plastic
disposable syringe that is to be sterilized, comprising:
providing a disposable syringe having a barrel with a front end
and an open rear end, a hollow nozzle part having a front area with
an open free end, a plunger plug and a plunger stop element that
is placed in the area of a cylinder gripping plate disposed at the
rear end of the barrel,
inserting and pushing the plunger plug from the open rear end to
the front end of the barrel;
forcing a fluid medium through the open free end of the nozzle
part by using pressure applied to the fluid medium, to thereby fill
the barrel as the fluid medium propelled by the pressure pushes
the plunger plug toward the plunger stop element at the rear end
of the barrel; and
after filling the barrel with the fluid medium, sealing said front
area of the nozzle part by plastic deformation.
12. The process according to claim 11 wherein the syringe is oriented
vertically during the process; wherein gas bubbles collect in the
front area of the nozzle part, and wherein sealing the front area
separates the gas bubbles from the fluid medium.
13. The process of claim 12 further including separating the front
area of the nozzle part from the syringe.
14. The Process according to claim 11 wherein scaling said front
area of the nozzle part by plastic deformation is achieved by heat
input applied to the nozzle part.
15. The process according to claim 11 further comprising: placing
a protective cap over the nozzle part and attaching the protective
cap to the nozzle part.
Description BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for filling and sealing a fluid-containing
plastic disposable syringe that is to be sterilized, whereby the
disposable syringe comprises a barrel with a nozzle part that is
molded at the front, an at least one-piece plunger or plunger plug,
and a plunger stop element that is placed in the area of the cylinder
gripping plate
2. Description of the Prior Art
To date, ampoules and injection vials have primarily been used
for parenteral administration of liquid pharmaceutical agents. In
addition, a hypodermic syringe with a matching injection cannula
is required to administer the liquid or free-flowing substances
that are decanted in these containers. This means, however, that
the pharmaceutical agent must be transferred to such a hypodermic
syringe before final use. This is not only time-consuming but also
creates considerable opportunities for contamination.
To keep the liquid pharmaceutical agent from being contaminated,
therefore, prefilled disposable syringes are already available on
the market. Such a disposable syringe is known from EP-B 0 227 401.
There, a process for the production of filled, sterile plastic syringes
is described. The disposable syringe, whose design corresponds to
DIN 13 098 Part 2 is sterilized in a special process to preserve
its geometric shape. To prevent the plastic disposable syringe from
being deformed in an autoclave under the action of high internal
syringe pressure, the pressure is increased in the autoclave by
adding compressed air until the internal syringe pressure is reached.
In addition to a pneumatic pump, this process required a steam
generator with low inertia since although the compressed air that
is introduced into the autoclave raises the internal autoclave pressure,
it considerably lowers the temperature that is necessary for sterilization.
It is also disadvantageous that heat transfer is reduced by the
presence of air in the air/vapor mixture, which leads to a prolonged
retention time in the autoclave.
Another drawback arises from the design of the disposable syringe
that is used. It must be filled with the preparation through the
opening on its plunger rod side. With this method of filling, a
gas bubble is included in the barrel under the plunger plug that
is to be used which further increases the internal syringe pressure
during sterilization and thus forces the plunger plug to be pushed
out and/or the syringe body to deform.
This drawback also exists for a subcutaneous syringe with a partial
glass structure that is known from U.S. Pat. No. 5069670. The
syringe has a glass barrel, a mounted cylinder gripping plate with
an internal collar, a mounted head element with a standard connecting
part for attaching medical cannulae, a plunger plug, and a sealing
part. It cannot be sterilized in the filled state, however, since
its glass cylinder cannot withstand high internal pressure during
a sterilization process in the autoclave.
SUMMARY OF THE INVENTION
This invention therefore focuses on the problem of developing a
process for filling and sealing a fluid-containing plastic disposable
syringe that is to be sterilized, by which the disposable syringe
can be sterilized in the filled state in a standard type of autoclave,
without the danger arising of plastic deformation owing to the internal
syringe pressure of the syringe parts. In this case, the disposable
syringe is to be configured in such a way that largely gas-free
filling is made possible. Further, the syringe components are to
be simple to clean and to handle. Also, the drawbacks that are known
from the area of prior art are to be avoided.
The problem is resolved, i.e., by virtue of the fact that the plunger
or plunger plug, after insertion into the empty barrel, is inserted
all the way up to its front end with or without the specific plunger
rod and then the fluid medium is forced into the barrel under pressure
via the nozzle part, whereby the fluid medium pushes the plunger
or plunger plug in the direction of the plunger rod side up to the
plunger stop element. After filling, the front area of the nozzle
part is sealed by plastic deformation.
With this process, the disposable syringe can be filled almost
gas-free. The filling device is connected to the front, open end
of the sealing element to force the preparation that is subjected
to pressure via the nozzle part into the interior of the syringe
body. Because of the plunger plug that is attached in the nozzle
area, the preparation cannot flow freely into the barrel, but has
to push the plunger plug forward, optionally with the plunger rod.
As a result, i.e., foaming of the preparation is prevented, so that
after the filling device is detached, only a few gas bubbles are
present in the barrel. For the most part, the gas comes from the
cavity of the nozzle part. As the disposable syringe is being moved
to the next processing station, the gas rises and collects in the
upper area of the nozzle part. Theoretically, the liquid level should
then have to lie at the lower edge of the nozzle part when the disposable
syringes are arranged vertically. Since the preparation was filled
under pressure, however, on the one hand the syringe body has expanded
slightly, and, on the other hand the plunger plug has been minimally
compressed. Both elastic deformations heal themselves, causing the
liquid level in the nozzle part to rise almost to the upper edge.
Optionally, the rising of the gas bubbles into the front or upper
nozzle part is supported by an ultrasonic generator or the like.
The plunger plug can also partially project into the nozzle part,
thereby reducing the residual gas volume there.
Within the scope of the process, the disposable syringe is sealed
in such a way that the front area of the nozzle part, for example,
is plastically deformed with partial heat input. In this case, welding
and gluing processes can be used.
To complete the process, a protective cap is optionally put on
over the nozzle part. The protective cap is attached to the nozzle
part or the barrel by friction and/or clamping. It protects the
relatively thin and thin-walled nozzle part against mechanical damage.
In its rear area, the nozzle part preferably has the shape of a
connecting part with an outer cone according to German Industrial
Standard (Dentscre Industrie Normen) DIN 13 090 with or without
a locking part.
If the rear area of the nozzle part is only a conical connecting
part according to German Industrial Standard (Dentscre Industrie
Normen) DIN 13 090 Part 1 the above-mentioned protective cap is
pushed on to attach it to the outer cone of the connecting part.
The front area of the nozzle part is approximately a tubular sealing
element that projects over the standard connecting part. The so-called
sealing element is at least three times longer than the connecting
part. It is used, on the one hand, for adapting the syringe body
to the filling device and collecting the residual gas that remains
after filling in the syringe body and, on the other hand, for sealing
the syringe body on the nozzle side.
The nozzle part has a throat in the area between the connecting
part and the sealing element. In this throat is mounted the tool
for separating the connecting part and sealing element before the
preparation is administered. The throat is placed and configured
in such a way that after the sealing element is separated, the standard
connecting part for attaching the medical devices that are to be
connected later is created.
Despite the throat, the inner wall of the sealing element merges
without a seam and without a change in size into the inner wall
of the connecting part, so that there is no fluidic or bubble-forming
obstacle is created.
The throat can also be designed as a predetermined point of break
with high notching action, i.e., when brittle materials are used.
In this case, the sealing element can be separated from the connecting
part by being twisted off and/or broken off.
The plunger stop element is a separate component that projects
with at least one plunger support element into the barrel or covers
the barrel, and engages the cylinder gripping plate from behind
with at least one gripping element. With the aid of the plunger
stop element, the plunger or the plunger plug is kept from being
pushed out from the barrel during filling and autoclaving of the
disposable syringe. For this purpose, the plunger stop element can
be mounted on, for example, the cylinder gripping plate, whereby
locking elements secure the plunger stop element to the cylinder
gripping plate or the barrel.
Another alternative consists in shaping in the rear end of the
barrel knobs which project inward and on which the plunger can be
supported. To do this, the plunger must have recesses in the bottom
of the plunger or the plunger base that correspond to the knobs,
whereby the recesses are arranged spaced around the periphery of
the plunger like the knobs on the inner wall of the cylinder. After
insertion into the barrel, the plunger is swung around a half spacing
around its longitudinal axis, so that the plunger bottom areas without
a recess coincide with the knobs.
The plunger stop element is equipped with recesses at least in
the area of the barrel, so that there are no closed cavities between
the plunger and the plunger stop element. Such cavities could partially
produce heating that is inadequate for sterilization during autoclaving
owing to their thermal insulating action.
The same problem also exists for the protective cap with the subjacent
nozzle part. To ensure that the nozzle part is heated adequately,
the protective cap has recesses outside of its attachment area.
The recesses and breaks also make it possible for the disposable
syringe to dry completely after autoclaving.
Owing to the small volume flow due to factors related to the cross-section,
filling the disposable syringe via the nozzle part takes more time
than filling the barrel at the back. To ensure that the cycle time
of the conventional filling process is maintained, several filling
devices are preferably charged in parallel.
BRIEF DESCRIPTION OF THE DRAWINGS
Other details of the invention emerge from the embodiment that
is described and depicted diagrammatically below.
FIG. 1: Partially cut-away side view of the mounted disposable
syringe before filling;
FIG. 2: top view of the partially cut-away, mounted disposable
syringe;
FIG. 3: partially cut-away side view of the nozzle part with a
Luer lock connecting part before the disposable syringe is filled;
FIG. 4: partially cut-away side view of the nozzle part after the
disposable syringe is filled and sealed.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a large-volume disposable syringe, which, apart from
a special nozzle part (20) and a plunger stop element (40) of German
Industrial Standard (Dentscre Industrie Normen) DIN 13 098 Part
1 corresponds to a plastic disposable syringe. Accordingly, its
syringe body (10) consists of a barrel (11) with a cylinder gripping
plate (12) that is molded at the rear end and a lockable connecting
part (21) that is placed at the front end with an outer cone according
to German Industrial Standard (Dentscre Industrie Normen) DIN 13
090 Part 2. Connecting part (21), however, within the framework
of the invention, i.e., is designed extended. A plunger plug (30)
is located in barrel (11). This plunger plug (30) consists of a
plunger seal (33) that is put on plunger base (31) and has inner
threading (32). Inner threading (32) is used to attach the plunger
rod, not shown. Plunger base (31) projects at its rear end in the
longitudinal direction of the syringe over plunger seal (33) to
form a defined support for resting on plunger stop element (40).
In FIG. 3 nozzle part (20) of the unfilled disposable syringe
is presented in enlarged form. In addition to standard locking part
(22) and conical connecting part (21), it has, i.e., an extension
that is provided for filling. The extension, which is about 3 times
as long as connecting part (21), is a so-called sealing element
(25) which initially has an open free end 25a and a sealing portion
25b. A throat (26) separates sealing element (25) and connecting
part (21). Behind connecting part (21), the side of throat (26)
is an outer radius that is adapted to the shape of connecting part
(21). The base of the throat is cylindrical. There, the wall thickness
is less than a half millimeter. Behind sealing element (25), the
side of the throat is a 45.degree. bevel.
At its front end, sealing element (25) has an outer cone with a
1:4 slope. The inner wall of entire nozzle part (20) is approximately
cylindrical.
Plunger stop element (40) is located at the other end of the disposable
syringe in barrel (11), see. FIGS. 1 and 2. It comprises a base
plate (41), on which, on the one hand, four plunger support elements
(46) that project into barrel (11) are located, and, on the other
hand, there are two gripping elements (43), which at least partially
engage cylinder gripping plate (12) on the outside. Plunger support
elements (46) are molded at equidistant intervals around a central
hole (42) of base plate (41). Each of the plunger support elements
(46) has, over its entire length, a cross-section that largely corresponds
to the shape of a circular ring section. The outer contour of the
circular ring cross-section has about the length of 1/8 the circumference.
The uncurved lateral surfaces of plunger support elements (46) form
planes that run parallel around half the width of plunger support
elements (46), offset to the assumed center line of the disposable
syringe. Plunger support elements (46) that are aligned parallel
to the wall of barrel (11) do not touch the wall itself. This has,
i.e., the advantage that after sterilization, these zones dry quickly.
Centering elements (47) are located between plunger support elements
(46) and the wall of barrel (11). The centering elements are located
on the outer contour of plunger support elements (46) in the area
of cylinder gripping plate (12). They are aligned parallel to the
center line of the syringe and midway to respective plunger support
element (46). Their cross-section is approximately semi-circular.
Base plate (41), whose center hole (42) is also used to guide the
plunger rods, not shown, completely covers cylinder gripping plate
(12) from the outside. In this case, it projects slightly over the
edge of cylinder gripping plate (12). The projecting edge is designed
to be circular in sections in the area that is the farthest from
the center line of the syringe. In this edge area, gripping elements
(43) are molded-on. In both halves of cylinder gripping plate (12),
the shapings also extend, as FIG. 2 shows, in the direction of barrel
(11). Corresponding to FIG. 2 this is on the right half in the
lower area and in the left half in the upper area. Gripping elements
(43) partially engage the lower side of cylinder gripping plate
(12) from the outside, so that the lower side on both halves is
obliquely covered in each case. The shape of the plunger stop element
is partially determined by the type of assembly. Plunger stop element
(40) is, like a bayonet catch, first inserted into the barrel and
then brought into the gripping position, relative to the direction
of insertion, by a clockwise rotation by 90.degree.. To this end,
plunger stop element (40) is used in barrel (11) rotated by 90.degree.
relative to the center line of the syringe in the assembly compared
to the illustrations in FIGS. 1 and 2. Plunger stop element (40)
reaches the position shown only by clockwise rotation. For attaching
in this gripping position, in each case two safety knobs (44) are
placed on the edge of two gripping elements (43). They prevent any
unintentional reversal of plunger stop element (40).
Before the disposable syringe is filled and after the sterilization
of the individual parts and the application of lubricant on the
inner wall of the barrel, plunger plugs (30) are inserted into syringe
body (10) and pushed up to the front end of the barrel. Then, plunger
stop element (40) is inserted and swiveled to secure it. When plunger
plug (30) and/or plunger stop element (40) is inserted, depending
on design, the original plunger rod can also be mounted. When plunger
plug (30) is inserted, plunger stop element (40) can even sit loosely
on the plunger rod.
For filling the disposable syringe, for example, the filling nozzle
of the decanting machine that is equipped with an inner cone is
mounted on the outer cone of sealing element (25). During the filling
process, plunger plug (30) is pushed by the liquid preparation that
is pressed into barrel (11) in the direction of plunger stop element
(40). As soon as plunger plug (30) rests on plunger stop element
(40), the filling process is completed, and the filling nozzle rises
from sealing element (25). As the disposable syringe is being moved
to the next processing position, gas bubbles that are included in
the preparation by shaking during shipment or by any additional
vibration rise and collect in the front area of sealing element
(25). As heat is input, the front part is crushed, twisted off,
or similarly tightly sealed with plastic deformation.
Deformed sealing element (25') is shown in FIG. 4. A frustum-like
protective cap (50) is put over sealing element (25') and screwed
tight with the aid of the threading that is integrated in locking
part (22). To this end, two short threaded sections (51) are located
on the lower edge of protective cap (50), as indicated by, for example,
German Industrial Standard (Dentscre Industrie Normen) DIN 13 090
Part 2 compare connecting part Luer-Lock (LLS) with shapes set
forth in the Germnan Industrial Standard. Protective cap (50) has
a wall (52) and four recesses (53) that are arranged symmetrically
to the center line of the syringe and extend over 3/4 of the length
of the protective cap.
To prepare the disposable syringe for use, protective cap (50)
is screwed off, and sealing element (25') is separated from conical
connecting part (21). The separation in the area of throat (26)
can be done with the aid of shears, a knife, a scalpel, or the like.
After sealing element (25') is separated, nozzle part (20) to is
available for attaching an injection element. |