Patent Application
20190217012
Embodiments of the present invention relate to a plunger for a syringe and to a syringe.
During use, the needle 16 is inserted into the medication to be administered which is dissolved in, or in suspension in, a liquid. The plunger is then drawn backwards (in the direction of arrow 22), thereby drawing the seal 20 backwards creating an under-pressure between the seal and the liquid. This, in turn, draws liquid into the cylinder 12.
During administration, the needle 16 is inserted into a vein or subcutaneously, the plunger 14 is depressed (pushed forwards in the direction of arrow 24), thereby forcing the seal 20 downwards which expels the liquid out of the needle 16 and into the patient.
As designated by reference numeral 30, a space exists between the seal 20 and the distal end of the syringe 10, e.g., tip of the needle 16. Generally, when the syringe 10 is filled, it is inverted so that the needle points upwards and the liquid is then drawn into the cylinder 12. The space 30 is filled with air prior to administration and this air, when the needle is inverted for administration, will be situated adjacent the tip of the needle. Therefore, unless any action is taken to avoid this, the aim would be injected first, prior to the liquid.
For these reasons, action of purging a syringe a well-known whereby the plunger 14 is depressed until the air has been expelled.
However, a user does not know that all of the air has been expelled until they observe liquid being expelled from the tip of the needle. Depending on the skill and dexterity of the user, this can lead to a lesser or greater expulsion of liquid. However, in each case, some of the liquid containing the medication will be expelled.
Besides that, re-usable needles like Insulin Pens keep on compiling air bubbles that are very hard to purge or get rid of totally.
This results in a significant waste of medication. Not only does this result in wasted costs, but there is an associated uncertainty regarding the dosage provided.
It is desirable to avoid or minimize the necessity to purge syringes of unwanted air, and/or provide means for improving the removal of air from the space containing the liquid to be administered.
PCT Application publication No WO 2004/039439 discloses a syringe assembly for discharging gaseous materials from a syringe. German Patent Application Publication No DE 10 2004 055 870 discloses a syringe device with a venting device. However, both these documents suffer from sub-optimal discharge of gas from the space of the syringe containing the liquid to be administered.
According to a first aspect, the invention provides a plunger for a syringe, the plunger comprising a head for reciprocating within a chamber of the syringe, the head comprising a seal which is impermeable to liquid, but permeable to gas.
In use, reciprocation of the plunger with the chamber, e.g., depression of the plunger into the chamber, allows the syringe to deliver a shot, e.g. a volume, of liquid contained within the chamber.
Provision of a seal which is impermeable to liquid, but permeable to gas, may permit any gas, e.g., air, to pass through the head, but may prevent liquid from doing so.
The seal may comprise a membrane which may be a semi-permeable membrane. The semi-permeable membrane may typically be permeable to gas, e.g. air, but not permeable to liquid(s), e.g. to an aqueous medium such as an aqueous solution or dispersion/emulsion.
Typically, the membrane may be made from a synthetic material, e.g., from a polymeric material. The membrane may be made from polyethylene, polypropylene, or the like. The membrane may be made from a nonwoven polypropylene material. For example, the membrane may be made from a material sold by Proctor Group Ltd (UK) under the trade name Roofshield. It will be appreciated that other types of semi-permeable membranes may be used, which may depend for example on the dimensions of the syringe, on the intended use for the syringe, on the liquid to be administered, and/or on the chemical and physical properties on the membrane.
Advantageously, the membrane may be located at or near an end portion of the head and/or seal. The membrane may be located at or near a portion of the head and/or seal nearest a needle end thereof. The plunger, head and/or seal may be configured such that the membrane may form or may define substantially the entire surface of the plunger and/or of the seal in contact with and/or exposed to the space, e.g. liquid and/or gas contained therein. The portion of the plunger, head and/or seal in contact with and/or exposed to the space may be defined by, e.g. may be exclusively defined by, the membrane, e.g. a surface of the membrane.
During use of the syringe, when the syringe is inverted after having filled, any gas, e.g. air, may be located adjacent to the seal, e.g. membrane thereof. When a user depresses the plunger, the action may cause the seal, e.g. membrane, to press against the gas, e.g. air, located in the space. This force causes the gas to pass through the membrane of the seal. In this manner, some or all of the gas may be removed without having to purge the syringe before administration, thereby avoiding waste of any of the medication involved and/or saving time. Further, when the membrane defines the entire surface of the plunger, head and/or seal contact with and/or exposed to the space, no further part of the plunger may interfere with evacuation of the gas through the seal, thus optimising the gas removal performance of the present arrangement.
In an embodiment, any gas having passed through the seal and/or membrane may be evacuated from the syringe.
In an embodiment, any gas having passed through the seal and/or membrane may be contained in a cavity defined by the syringe and/or plunger.
In an embodiment, the syringe, e.g. plunger, may include a reservoir located near its head, e.g. adjacent to the seal, e.g. on a side thereof opposite the membrane. This may provide a means for storing any gas having passed through the seal and/or membrane.
In an embodiment, a portion of the head and/or seal may be configured to receive, accommodate, and/or store gas which may be located in the space between the seal and the liquid in the chamber, and which may pass through the membrane. The head and/or seal, e.g. a portion of the seal in contact with the membrane, may be made from a porous material. The head and/or seal, e.g. a portion of the seal in contact with the membrane, may be made from a foam material capable of receiving, accommodating, and/or storing gas that passes through the membrane. By such provision, the syringe may advantageously provide effective purging and storing of any gas contained in the space. The head and/or seal, e.g. a portion of the seal in contact with the membrane, may be made from foam plastic and/or foam rubber.
The membrane may be attached to a support member of the plunger, e.g. head thereof. In an embodiment, the membrane may be permanently attached to the support member, e.g. may be bonded, welded, or the like, to the support member. Advantageously, the membrane may be ultrasonically welded to the support member. By such provision, effective bonding of the membrane to the support member may be achieved, without compromising the effectiveness of the membrane or requiring the use of adhesives.
The support member may be provided by an end portion of the plunger, e.g. head. In such instance the seal may be defined by the membrane. The support member may be provided by an end portion of the plunger, e.g. seal. In such instance the seal may further comprise the membrane and be act as a/the support member for the membrane.
A further embodiment of the invention extends to a syringe comprising a chamber for receiving a liquid to be dispensed and a piston for reciprocating with the chamber so that liquid contained within the chamber is expelled by movement of the piston, the piston comprising a plunger as herein described.
The membrane may be dimensioned in accordance with a size of the chamber to accommodate gas which may be stored in the chamber together with the liquid.
Embodiments of the invention are described with reference to the accompanying schematic diagrams in which:
Embodiments of the invention are described hereafter with reference to the accompanying diagrams.
Typically, the membrane 41 is made from a synthetic material, e.g. from a polymeric material. The membrane 41 may be made from polyethylene, polypropylene, or the like. The membrane 41 may be made from a nonwoven polypropylene material. In this embodiment, the membrane is a material sold by Proctor Group Ltd (UK) under the trade name Roofshield.
Advantageously, the membrane 41 is located at or near an end portion of the seal. The membrane is located on a portion/surface of the seal 40 nearest a needle end thereof. The plunger 14 and/or seal 40 is configured such that the membrane 41 forms or defines the entire surface of the plunger in contact with the space 30, e.g. with a liquid and/or gas contained therein.
During use of the syringe 100, when the syringe is inverted after having filled, the air will be located adjacent to the seal 40. When a user depresses the plunger 14, the action causes the seal 40 to press against the air located in space 30. This force creates the force necessary for the gas to pass through the membrane 41 of the seal 40. In this manner, all the gas may be removed without having to purge the syringe and thereby avoiding the waste of any of the medication involved.
The seal 40 of the embodiment of
The embodiment of
It will be appreciated that the dimensions of the seal 40 as illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 93154 | Jul 2016 | LU | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/068232 | 7/19/2017 | WO | 00 |
