US3320954A - Hypodermic syringe with breakable polypropylene needle adaptor - Google Patents

Description

May 23, 1967 c. COWLEY 3,320,954

HYPODERMIC SYRINGE WITH BREAKABLE POLYPROPYLENE NEEDLE ADAPTOR 2 Sheets-Sheet 1 Filed Dec. 30, 1965 F IG. 2,

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United States Patent Ofilice 3,320,954 Patented May 23, 1967 3,320,954 HYPODERMIC SYRINGE WITH BREAKABLE POLYPROPYLENE NEEDLE ADAPTOR Calvin C. Cowley, La Canada, Califi, assignor to Pharmaseal Laboratories, Glendale, Calif., a corporation of California Filed Dec. 30, 1963, Ser. No. 334,338 3 Claims. (Cl. 128218) This invention relates to a disposable hypodermic syringe. More particularly, it relates to a disposable hypodermic syringe which can accurately administer small doses of medicaments and which can be safely and easily mutilate-d immediately after use. Through mutilation the syringe can be rendered incapable of further injection should it fall into the hands of children or narcotic addicts.

Disposable hypodermic syringes are generally comprised of a barrel, a needle assembly mounted on an adapter attached to one end of this barrel, a plunger, and a resilient stopper mounted on one end of this plunger. The plunger and stopper are axially slidea ble within the barrel to inject medicaments from the barrel into the patient. These syringes have a problem in accurately administering small doses. This difi'iculty is caused by the resilient stopper, because the stopper has a higher coefficient of static friction than sliding friction with the barrel. Also, because the stopper must fit tightly enough within the barrel to form a seal, it may sometimes slightly deformv the barrel at the seal when stored for a length of time. The stopper must then be broken loose so it can freely slide within the barrel. Sometimes the stopper lunges forward a short distance when the static friction is broken. I have found a novel way to overcome this problem by locking the stopper to the plunger and pre venting the plunger from rotating relative to the stopper. When the stopper is so locked to the plunger the static friction between the stopper and the barrel can be broken by rotating the plunger and moving both the plunger and the stopper forward in the barrel with a screwing motion to administer small quantities, such as cc. or less, of the medicament. Previous syringes did not lock the stopper-to the plunger rotationwise and the stoppers were designed solely for axial movement within the barrel. 7 Once an injection has been made with a disposable hypodermic syringe it must be disposed of because it is contaminated with the medication and with the patients blood. Therefore, it must not be used for further injections. A common practice is to incinerate the used syringes; however, there is usually a time lag between the injection and the incineration. During this time lag it is possible that a used syringe may fall into the hands of a child or a narcotic addict. These syringes can be extremely dangerous. For instance, if the syringe has been used on a person having hepatitis, any person playing with or using this contaminated syringe could easily contact hepatitis. The safest way to avoid this is to mutilate the syringe immediately after use, but before incineration, so that it is incapable of further injections.

There are, however, certain problems involved in mutilating disposable syringes, especially syringes made of polypropylene. If the cannula is bent or broken off there is a danger of infecting the nurse or physician so mutilating the syringe and this method could also allow the syringe to be reuse-d with a mere resharpening of the cannula. Removing the plunger and stopper gives no guarantee that the syringe cannot be =re-used, and in addition, exposes the contaminated interior of the barrel. Syringes made of polypropylene further resist mutilation by breaking because of what is termed the hinge effect. Polypropylene does not easily break in two when bent,

but instead, goes through a molecular realignment at the surface and forms a hinge.

I have found a safe, effective way of mutilating a disposable polypropylene syringe immediately after an injection. This involves breaking the adapter extending from the forward end of the barrel and on which the needle assembly fits. This mutilation can be done without touching the needle or any portion of the syringe that has contacted medicaments. My syringe employs a protector that fits over the needle assembly and seats on some portion of the syringe. By cocking the protector to one side, it exerts a force on the needle assembly mounted on the adapter and thereby breaks the adapter at a score. This score has been found to overcome the polypropylene hinge effect.

An object of this invention is to provide a stopper and plunger assembly for a disposable hypodermic syringe that can accurately administer small amounts of medicaments.

Another object of this invention is to provide a disposable hypodermic syringe that can be easily and safely mutilated immediately after use.

Still another object of this invention is to provide a disposable polypropylene hypodermic syringe wherein the needle and protector for this needle can be separated from the syringe barrel to reduce the danger of others reusing the contaminated syringe.

Another object of this inveniton is to provide a disposable hypodermic syringe which a physician or nurse can mutilate immediately after an injection without the danger of being exposed to either the needle or portions of the syringe that have contacted the administered medica- Inent.

Another object of this invention is to provide a hypodermic hyringe having a set of calibrations on its barrel in which the set is separated into two sections, one section indicating the normal filling capacity and the other section indicating the maximum filling capacity.

Other objects of this invention will become apparent upon further description of my invention of which the following are illustrations:

FIGURE 1 is a side elevational view partially in section of the hypodermic syringe;

FIGURE 2 is an enlarged side elevational view partially in section of the front portion of the syringe of FIG- URE 1. This figure shows the syringe before it has been mutilated and a portion of the stopper has been cut away to show the locking means between the stopper and plunger;

FIGURE 3 is an enlarged side elevational view partially in section of the syringe of FIGURE 1 showing the syringe immediately after it has been mutilated;

FIGURE 4 is a side elevational view partially in section of the front portion of the stopper and plunger assembly showing a modification of the locking means between the stopper and plunger;

FIGURE 5 is a sectional view taken along line 5-5 of FIGURE 4;

FIGURE 6 is a sectional view taken along line 66 of FIGURE 2;

FIGURE 7 is a side elevational view partially in section of a modification of my syringe;

FIGURE 8 is a side elevational view partially in section of the syringe of FIGURE 7 showing it immediately mounted within this barrel is a plunger 9 with a resilient stopper 8 attached to its forward end. Attached to the adapter 3 is a needle hub 6 which has a cannula 7 extending from one end. Enclosing both the hub and the cannula is a protector S which seats on the hub 6 in one embodiment of my invention. The protector may be provided with sterilizing vents where it seats on the syringe or a port with a filter may be included in the protector so the syringe can be sterilized with the protector on the syringe. Between the partially closed end of barrel 2 and hub 6 is a score 4 on adapter 3 which aids in breaking the adapter.

Breaking the adapter of the disposable syringe renders it incapable of further injections, but breaking the adapter cen be diificult if the syringe including the adapter is molded of a material such as polypropylene. The desirability of using poly-propylene in disposable syrings stems from the fact that it is more compatible with drugs than for instance polystyrene.

To overcome the resistance to breaking of polypropylene, the score 4 is cut into the outer surface of the adapter 3 after the syringe has been molded. This score is small enough so as not to cause the adapter to break prematurely. For the purposes of this application, a score is defined as any non-molded scratch, recess, or notch cut into the outer surface or skin of the adapter. A molded indentation or recess in the adapter 3 would tend to aggravate the hinging effect of polypropylene as illustrated by the fact that in the manufacture of polypropylene hinges, a molded recess is employed to make the hinges more flexible. The score 4 is preferably a 360 score around the adapter but it is possible to break the adapter 3 if the score is only along a portion of the circumference of the adapter. One way of doing this is to provide two score sections each on opposite sides of the adapter. However, in this latter case it is necessary to orient the syringe barrel when breaking the adapter so as to snap it at the score. I have found that the adapter breaks very well if the wall thickness of the adapter is from .030 to .050 inch thick and the depth of the score is from .001 to .020 inch.

The procedure for using and mutilating the described disposable hypodermic syringe is as follows. The syringe is removed from its sterile package (not shown) and the protector 5 removed from the needle hub 6. Next, the syringe is filled from a medicament vial in the normal manner and the patient is then given the injection. Upon completion of the injection the protector 5 is replaced on the syringe by pushing it onto the hub from the forward end and forcing the protector down upon hub 6 until the protector 5 seats against a flange 11 at the rearward end 19 of the hub. The nurse or physician then snaps the adapter at the score 4 by cocking the protector to one side. This is usually done by holding the protector in one hand and the syringe barrel 2 in the other. With the adapter 3 broken as shown in FIGURE 3, the cannula 7 and hub 6 are still encased in the protector 5 and the barrel 2, plunger 9 and stopper 8 are rendered incapable of further injections. Throughout the above procedure the nurse or physician touched only the outer surface of protector 5, syringe barrel 2, and plunger 9. There was no contact with either the cannula 7 or the interior of barrel 2 which had contained the medicament.

In addition to causing safe mutilation of the syringe, the hub 6 and protector 5 fit together in such a manner that during assembling of the syringe the hub and cannula can be handled while in the protector 5. The hub 6, cannula 7, and protector 5 can be assembled in a subassembly and the whole unit forced onto adapter 3 by means of an axial force on the protector itself. Flange 11 prevents the protector 5 from becoming too tightly engaged on hub 6 and insures that the frictional engagement between the protector and the hub will be less than the frictional engagement between the hub and the adapter. Thus, once the entire syringe is assembled the protector may be pulled off hub 6 without disengaging the hub from adapter 3.

A modification of the protector and adapter is shown in FIGURES 7, S, 9 and 10. Here the protector 20 seats not on the hub 6 but on a protector support 21 mounted on the partially closed end of barrel 2. The protector 20 is flexible enough to be cocked to one side while it is still on the protector support 21 and thereby break the adapter 3 at score 4.

FIGURES 9 and 10 show the configuration of the protector support 21. Protector support 21 is substantially cylindrical in shape and is held by a series of ribs 26 in concentric relationship around the outside surface of adapter 3. In between ribs 26 are cavities 22 which reduce the amount of material at the forward end of the syringe barrel and thereby reduce the molding shrinkage the interior of the barrel with the lumen of the cannula is shown in FIGURE 9. Passage 27 has a reduced diameter section 24 near its rearward end. Forward of this reduced diameter section 24 is an enlarged diameter section 28 of the passage. different diameters in the passage include reduction of medicament loss in the adapter and at the same time having a thin wall section of the adapter on which the hub seats. This thin walled section provided by enlarged diameter section 28 causes the tapered outer surface of the adapter to be less affected by shrinkage after molding, so that a leakproof fit can be obtained between hub 6 and adapter 3. For added strength at the forward end of the adapter, an inturned. lip 25 has been provided at mouth 23.

Besides reducing the medicament loss in the adapter, it is often desired to very accurately administer small doses of medicament. This can be done by locking the stopper to the plunger. In FIGURES 2, 4, 5, and 6 I have shown two ways of locking the stopper to the plunger. One method involves providing one or more prongs 14 on the plunger neck 15 which will engage the stopper and prevent it from rotating relative to the plunger 9. A backing plate 16 and a plunger head 12 including a flange 13 lock the stopper 8 against axial movement relative to the plunger 9. FIGURE 6 shows two of these prongs 14 and illustrate how they grip stopper 8 and lock it to plunger 9.

A modification of the locking means between the stopper 8 and plunger 9 is shown in FIGURES 4 and 5. Here the flange 13 of head 12 of the plunger has about its periphery an enlarged section 19 and this enlarged section is designed to grip the stopper 8 and lock it to plunger 9. The enlarged section 19 is small enough so as not to affect the functioning of sealing rings 17 and 18 but at the same time is large enough to effectively lock the stopper on the plunger.

As the stopper is axially moved within the barrel by a plunger, the amount of medicament to be administered, or the amount already administered, is usually indicated by the position of the stopper relative to a set of calibrations on the syringe barrel. The normal capacity of the syringe many times is less than the maximum capacity. For instance, a 2 cc. syringe can administer 2 /2 cc. If calibrated to only 2 cc., any dose slightly over 2 cc. would require a much larger 5 cc. syringe. However, only rarely is 2 /2 cc. needed, and to calibrate the barrel continuously from zero to 2 /2 cc. would cause confusion, particularly with operators accustomed to administering the more common 2 cc. dose. It would be quite easy for a person using the syringe for a 2 cc. dose to pull the stopper to the end of the calibrations and give a 2 /2 cc. dose.

As shown in FIGURE 1, this problem is solved by a set of calibrations 29 divided into two sections. The first section 30 begins at zero and terminates at 2 cc. and the second section 31 Which is laterally offset from the The advantages of having two first section extends from 2 cc. to 2 /2 cc. Since there is a definite break in the scale at 2 cc. caused by the offset second section 31, there is little chance of mistaking a 2 /2 cc. dose for a 2 cc. dose. Also, the offset second section 31, calibrates discardable overfill in a 2 cc. dose and thus tends to minimize the drug loss through overfill.

I have used the embodiments of my invention for illustrative purposes only. It is understood that those skilled in the art can make certain modifications to these embodiments Without departing from the spirit and scope of this invention.

I claim:

1. A hypodermic syringe comprising: a polypropylene barrel With a transverse partially closed end Wall at one end and an open opposite end; a plunger axially slideable Within the barrel; a polypropylene tubular adapter connected to and extending longitudinally outwardly from the partially closed end wall of the barrel to a hub receiving forward section of the adapter; said tubular adapter having a breakable section between the hub receiving section and the partially closed end Wall of the barrel; said breakable section including a score extending radially inwardly from the adapters outer surface through a skin of the polypropylene adapter to insure the adapter will break apart and not hinge at the breakable section, said skin of the adapter having an abrupt discontinuity at the score with opposed edges of the skin spaced apart across the score; a needle assembly including a cannula and hub joined together, said hub connected to the adapters hub receiving section to join the needle assembly and the barrel whereby longitudinal piercing force applied by pushing the barrel can be transmitted across the adapters breakable section to the cannula; and a protector encas ing said cannula, said protector connected to the needle assembly and barrel combination, said protector, needle and hub receiving section of the adapter capable of being laterally cocked relative to the barrel to break apart the adapter at its score, thus separating the hub receiving section of the adapter from the syringe barrel.

2. A hypodermic syringe as set forth in claim 1 wherein the score extends 360 about the adapter.

3. A hypodermic syringe as set forth in claim 1 wherein the adapter has a Wall thickness from .030 to .050 inch and the score extends into this Wall a depth of .001 to .020 inch.

References Cited by the Examiner UNITED STATES PATENTS 1,343,085 6/1920 Lerch 128-218 2,676,591 4/1954 Fox -1 128-216 2,902,995 9/1959 Loper 128-221 X 2,971,509 2/1961 Cohen 128-21'6 2,972,991 2/1961 Burke 128-218 3,008,570 11/1961 Roehr et a1 128-218 X 3,021,942 2/1962 Hamilton 128-218 X 3,118,448 1/1964 Gottschalk 128-218 RICHARD A. GAUDET, Primary Examiner. D. L. TRULUCK, Assistant Exalm'ner

Claims (1)

1. A HYPODERMIC SYRINGE COMPRISING: A POLYPROPYLENE BARREL WITH A TRANSVERSE PARTIALLY CLOSED END WALL AT ONE END AND AN OPEN OPPOSITE END; A PLUNGER AXIALLY SLIDEABLE WITHIN THE BARREL; A POLYPROPYLENE TUBULAR ADAPTER CONNECTED TO AND EXTENDING LONGITUDINALLY OUTWARDLY FROM THE PARTIALLY CLOSED END WALL OF THE BARREL TO A HUB RECEIVING FORWARD SECTION OF THE ADAPTER; SAID TUBULAR ADAPTER HAVING A BREAKABLE SECTION BETWEEN THE HUB RECEIVING SECTION AND THE PARTIALLY CLOSED END WALL OF THE BARREL; SAID BREAKABLE SECTION INCLUDING A SCORE EXTENDING RADIALLY INWARDLY FROM THE ADAPTER''S OUTER SURFACE THROUGH A SKIN OF THE POLYPROPYLENE ADAPTER TO INSURE THE ADAPTER WILL BREAK APART AND NOT HINGE AT THE BREAKABLE SECTION, SAID SKIN OF THE ADAPTER HAVING AN ABRUPT DISCONTINUITY AT THE SCORE WITH OPPOSTED EDGES OF THE SKIN SPACED APART ACROSS THE SCORE; A NEEDLE ASSEMBLY INCLUDING A CANNULA AND HUB JOINED TOGETHER, SAID HUB CONNECTED TO THE ADAPTER''S HUB RECEIVING SECTION TO JOIN THE NEEDLE ASSEMBLY AND THE BARREL WHEREBY LONGITUDINAL PIERCING FORCE APPLIED BY PUSHING THE BARREL CAN BE TRANSMITTED ACROSS THE ADAPTER''S BREAKABLE SECTION TO THE CANNULA; AND A PROTECTOR ENCASING SAID CANNULA, SAID PROTECTOR CONNECTED TO THE NEEDLE ASSEMBLY AND BARREL COMBINATION, SAID PROTECTOR, NEEDLE AND HUB RECEIVING SECTION OF THE ADAPTER CAPABLE OF BEING LATERALLY COCKED RELATIVE TO THE BARREL TO BREAK APART THE ADAPTER AT ITS SCORE, THUS SEPARATING THE HUB RECEIVING SECTION OF THE ADAPTER FROM THE SYRINGE BARREL.

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