GB2320195A

GB2320195A - Hypodermic syringe with resealable bung

Info

Publication number: GB2320195A
Application number: GB9704399A
Authority: GB
Inventors: Patrick Donough Moylan
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-12-13
Filing date: 1997-03-03
Publication date: 1998-06-17
Anticipated expiration: 2017-03-03
Also published as: GB9704399D0; GB2320195B; GB9625926D0

Abstract

The syringe comprises a barrel A with a nozzle, a plunger F and a hollow needle C which, prior to use, lies wholly within the chamber K of the barrel. The nozzle is hermetically sealed by a fixed, resealable bung B of rubber or the like which is penetrable by the needle, the tip of which (before use) lies just behind the bung. The hilt or base end E of the needle is immovably attached to the plunger and contains a hole G through which air or fluid can pass between the needle interior and the barrel chamber. The barrel chamber may serve as an ampoule or vial in which case a protuberance P is provided on the inside of the barrel to prevent the plunger falling out. If the plunger is forced beyond this protuberance, a further protuberance R retains it. In a further embodiment, both the needle and nozzle are off-centre so that the needle may be immobilised beneath the shoulder of the barrel by rotation of the plunger (Fig.3).

Description

AN IMPROVED SYRINGE The object of this syringe-needle assembly (which can also function long term as a storage vial or ampoule for the liquid medicament to be injected) is to enable a medical hypodermic injection to be given to a patient without the tip ofthe needle ever being exposed to the outside atmosphere during the preparation of the solution for injection, the administration of the injection, or during the subsequent disposal ofthe needle, thus making it impossible for the person giving the injection to get pricked and thereby transmitting infection from patient to injector or vice versa.

Hereinafter, the syringe-needle assembly will be known as the syringe and the two ends of the syringe will be referred to as the front or nozzle end and the back or handle end. The body ofthe syringe is called the barrel.

Basically the invention consists of modifying the barrel (A), the plunger (F) and the needle (C) of an ordinary hypodermic syringe as follows: I. The end ofthe syringe which would normally be occupied by the open nozzle has its nozzle hermetically sealed with a fixed immoveable rubber (or substance with similar retractile properties) bung (B) which is of such consistency and thickness that it reseals itself when a needle made to penetrate it during use is withdrawn.

2. The hollow injection needle (C) is made to lie lengthwise completely within the barrel of the syringe, its tip (D)being free been near the bung (B) end and its base or hilt (E) being immovably fixed to the front ofthe plunger head (F) at the other end.

3. The plunger (F) presses against the inside ofthe barrel and is free to be moved up and down inside the barrel by the handle (H) but is restrained from falling back out of the syringe on - its own by a small protuberance (P) on the inside of the barrel, which protuberance limits at rest the volume of the chamber (K) formed in the syringe between the bung and the plunger head and allowssufficient clearance at the shoulder (T) if the rotation method of immobilizing the needle after injection is used.

4. The base or hilt ofthe needle adjacent to the plunger is made to contain a hole (G) through which air or fluid can pass between the interior ofthe base ofthe needle and the adjacent inside ofthe barrel chamber (K) formed between the bung (B) and the plunger (F).

5. Just on the back or handle side ofthe Drotuberance P the wall of the syringe is Derforated with a small hole (S) (or indented with

that sub serves the same function) that establishes contact between the inside of the syringe and the outside atmosphere at that point.

6. At the back opening of the syringe there is another small protuberance (R) of similar size to protuberance P which prevents the plunger F falling out of the syringe on its own after it has been forcibly withdrawn beyond the protuberance P.

Usage & Functioning If the syringe is to be used as a syringe only - the barrel chamber K of the syringe will contain air before use. When required for use, the bung B ofthe syringe is pressed against the rubber cap (L) ofthe ampoule or vial (M) containing the solution for injection. The handle H ofthe plunger is depressed and the needle is driven through bung B and rubber cap L without contact with the outside air. As the plunger is driven home air from the barrel chamber K is driven through the hole in the base of the needle G into the lumen of the needle and hence into the vial M creating a positive pressure in the vial. As the needle is withdrawn again from the vial M, which is held in the usual inverted upright position relative to the syringe, the barrel chamber K is recreated and the fluid in vial M is sucked back through the needle into the recreated barrel chamber K When this manoeuvre is completed the needle is back again in the barrel chamber K and so also is the solution from vial M. The syringe is in effect the same as it was at the beginning but now contains the solution for injection. The pressure of bung B against rubber cap L can now be relaxed.

Injection is now given as follows: The bung B end ofthe syringe is pressed against the skin of the patient and the plunger is driven home delivering the contents of the barrel chamber K through the hole G into the needle and thence to the patient. When all the fluid is injected the plunger and needle is withdrawn. The pressure ofthe bung against the patients skin is not relaxed until the needle is completely drawn back into the syringe barrel. However, the syringe chamber is now a vacuum and to prevent the tip of the needle being redriven forward through the bung when the pull on the handle is relaxed the rubber of the bung would have to be of such consistency and thickness as to withstand the vacuum pull on the plunger; or, alternatively, the nozzle could be off centre on the front of the syringe and the needle base off centre on the plunger head, in which case the withdrawn plunger could be rotated so that the needle tip is made to engage the shoulder (T) of the front of the syringe where it would be immobilized (Fig. 3) or, alternatively again, the plunger can be further withdrawn with a little force beyond the protuberance P so that the chamber side of the plunger reaches the hole S thereby establishing contact between the barrel chamber K and the outside atmosphere and thereby restoring the barrel chamber to atmospheric pressure. The plunger F is then prevented from falling out of the syringe by the small protuberance R The syringe is now ready for discard.

The syringe can also be used long term as a vial or ampoule to house or store a solution for injection at a later date where such solution is stable; or it can be used to store the excipient only where the active drug and excipient must not be mixed until immediately before injection. In this latter case the vial M would contain the active drug and the barrel chamber K of the syringe would contain the water or other excipient.

Regarding the materials used in the construction of the syringe - the barrel, plunger and handle can be made of plastic and the plunger head can have an adherent rubber circumferential band (Fo) that establishes an airtight junction between the plunger and the inner wall ofthe syringe, which circumferential band is of such consistency and thickness as to allow itself to be so compressed that the plunger can be pulled back over the protuberance P with a little force.

While the syringe would normally be used only once and then discarded, it could be reused without any special reassembly as long as the seal on the bung continues to function.

Claims

CLAIMS:

1. A medical syrrngneedle assembly for hypodermic injections which would normally be used once and then discarded but which could be reused without any special reassembly, a syringe which enables an injection to be prepared, administered and the needle subsequently discarded without the needle ever being exposed to the outside atmosphere where it could cause needleprick, a syringe which can also function as a longterm storage vial (ampoule) for the medicament to be injected - which syringe is so constructed that at rest in the pre use state its hollow injection needle lies longitudinally in and is completely enclosed in the chamber formed in the barrel of the syringe between the plunger and the nozzle, which nozzle is hermetically sealed (stoppered) with a fixed immovable bung made of rubber or substance with similar retractile properties to rubber and which automatically reseals itself when the needle made to penetrate it during use is withdrawn back into the syringe after use, which said needle has its tip end lying free just behind the nozzle bung and its hilt or base end immovably attached to the front barrel chamber side of the plunger head, which hilt end of needle contains a hole which establishes continuity between the lumen of the needle and the inside of the barrel chamber adjacent to the plunger.

2. A syringe according to Claim 1 in which a small protuberance on the inside of the barrel on the handle side of the plunger head prevents the plunger falling back out of the syringe, unless some force is used, and so maintains the size of the barrel chamber when used as an ampoule or vial.

3. A syringe according to Claims 1 & 2 in which a small perforation is present in the wall of the barrel on the back or handle side of the proturberance mentioned in Claim 2 and beyond which the plunger may be further pulled, using a little force, after use and before discard, the said plunger being then prevented form falling out of the barrel altogether (and thereby causing needleprick) by another small protuberance on the inside wall of the barrel at or near its handle end.

Amendments to the claims have been filed as follows AN IMPROVED SYRINGE 1.A medical Syringe-Needle assembly for hypodermic injections comprising a barrel with a nozzle, a plunger with a handle and a hollow needle, the needle prior to use lying longitudinally in and being completely enclosed by the chamber formed in the barrel between the plunger and the nozzle, the nozzle being hermetically sealed with a fixed, immovable bung which can be penetrated by the needle during the process of injection, which said needle has its tip end lying free just behind the nozzle bung and its hilt or base end immovably attached to the front barrel chamber side of the plunger head, which hilt end of needle contains a hole which establishes continuity between the lumen of the needle and the inside ofthe barrel chamber adjacent to the plunger.

2. A Syringe-Needle assembly according to Claim 1 in which the nozzle bung is made of rubber or substance with similar retractile properties to rubber and which automatically reseals itself when the needle made to penetrate it during use is withdrawn back into the syringe after use.

3. A Syringe-Needle assembly according to Claims 1 and 2 in which a small protuberance on the inside of the barrel on the handle side of the plunger head prevents the plunger falling back out ofthe syringe, unless some force is used, and so maintains the size ofthe barrel chamber when the latter is used as a long-term storage ampoule on vial.

4. A Syringe-needle assembly according to claims 1,2 and 3 in which a small perforation is present in the wall ofthe barrel on the back or handle side ofthe protuberance mentioned in Claim 3 and beyond which the plunger may be further pulled, using a little force, after use and before discard, the said plunger being then prevented from falling out of the barrel altogether (and thereby causing needleprick) by another small protuberance on the inside wall ofthe barrel at or near its handle end.