CA1195199A - Tamper-resistant hypodermic syringe - Google Patents
Tamper-resistant hypodermic syringeInfo
- Publication number
- CA1195199A CA1195199A CA000424005A CA424005A CA1195199A CA 1195199 A CA1195199 A CA 1195199A CA 000424005 A CA000424005 A CA 000424005A CA 424005 A CA424005 A CA 424005A CA 1195199 A CA1195199 A CA 1195199A
- Authority
- CA
- Canada
- Prior art keywords
- drive piston
- tubular member
- syringe
- retractable stopper
- hypodermic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/50—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests having means for preventing re-use, or for indicating if defective, used, tampered with or unsterile
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/178—Syringes
- A61M5/31—Details
- A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
- A61M5/31511—Piston or piston-rod constructions, e.g. connection of piston with piston-rod
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
- A61M5/178—Syringes
- A61M5/31—Details
- A61M5/315—Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
- A61M5/31511—Piston or piston-rod constructions, e.g. connection of piston with piston-rod
- A61M5/31515—Connection of piston with piston rod
Abstract
TAMPER-RESISTANT HYPODERMIC SYRINGE
ABSTRACT OF THE DISCLOSURE
Instances have been discovered in which a person has inserted the needle of a first hypodermic syringe through the soft rubber drive piston of a second hypodermic syringe to aspirate some of the narcotic fluid from the second syringe into the first syringe. To prevent this mode of pilfering, an impenetrable barrier is included in the second syringe to prevent the insertion of the needle of the first syringe. The impenetrable barrier may be a unitary portion of the screw that is normally included in the drive piston of the syringe, or the barrier may be a separate part molded into the drive piston.
ABSTRACT OF THE DISCLOSURE
Instances have been discovered in which a person has inserted the needle of a first hypodermic syringe through the soft rubber drive piston of a second hypodermic syringe to aspirate some of the narcotic fluid from the second syringe into the first syringe. To prevent this mode of pilfering, an impenetrable barrier is included in the second syringe to prevent the insertion of the needle of the first syringe. The impenetrable barrier may be a unitary portion of the screw that is normally included in the drive piston of the syringe, or the barrier may be a separate part molded into the drive piston.
Description
S~
T~iPER-~ESISTANT HYPODER~IC SYRINGE
BACKG~OUND OF THE INVENTION
Field of the Invention The present invention is in the field of medical apparatus ~nd more specifically relates to ~n improvement in a hypodermic syrin~e to render the syringe more tamper-resistant.
The novel features which are believed to be charQc'ceristic of the invention, both as to organization and method of operation, together witb further objects and advantages thereof, will be better understood from the followin~ description considered in connection with the sccompanyin~ dr~win~s in which several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.
8rief Descr;Ption of the_Drawin~
Fi~ure 1 is a fractional cross-sectional view showing s syringe of the prior art;
Figure 2 is a fractional crcss-sectional view showing an early embodiment of the syringe of the present inventiorl;
Fi~ure 3 is a frQctional cross-sectional view showing a first preferred embodiment of the syrin~e of the present invention;
Figure 4 is 8 fractional cross-sectional view showin~ a second preferred embodiment of the syrin~e of the present invention;
Figure 5 is a fractional cross-sectional view showin~ a third preferred e~nbodiment of the syrin~e of the present invention; and, Fi~ure 6 is a fractional cross-sectionQl view showin~ an alternative embodiment of the syrin~e of tbe present invention.
The Prior Art A fractional cross-seetional view throu~h a portion of a s7ringe of the prior art is shown in ~i~ure 1. Fi~ure 1 shows the end of the hypodermic syringe that is opposite the end to which the needle is ~ttached. As sho~n in Figure 1, the hypoderrnic syrin~e includes A tubular me~ber 12 of glAss oc other transparerlt materi~l which serves to contai~ the fluid 14. A drive piston 16 of 8 soft rubber is included within the tubular me~her 12 ~nd forms .~ ..
a slidable seal with the inside surface of the tubular member 12 A screw 18 -1- ~
is embedded in the drive piston 16 to permit an actuatin~ rod (not shown) to be connected to the drive piston 16. The actuating rod facilitates application of a force, directed leftward in Figure 1, to the drive piston 16 leftward for the purpose of e~pressin~ the fluid 14 from the syrin~e.
Instances ha~e been discovered in which a person has i~serted a needle 20 in the marlner shown in Fi~ure 1 throu~h the drive piston 16 to aspirate some of the fluid (narcotics). An object of the present invention is to prevent thls type of pilfering.
~ sy~ cf` the~ Invention In accordance with the present invention, an impenetrable barrier is included iD the syrin~e to prevent the insertion of a needle in the msnner shown in Figure 1.
Detailed Description The present invention provides sn improved drive piston for a hypoder~ic syrin~e, of the type hnving a ri~id insert and having a resilient sealing element that can be advQnced and retracted within a tubular member and having a front surface facinK in the direction in which the resilient sealin~
element is advanced and n rear surface facin~ in the di~ection in which the resilient seQling element is retracted, and characterized in th~t the insert serves the multiple purposes of reducin~ stresses in the resilient sealin~
element when the drive piston is being moved, of rendering the drive piston impenetrable by a hypodermic needle and hence pilfer-proof, snd of providin~ a means for positively attachin~ an actuatin~ rod to the drive piston, sqid improved drive piston comprisin~:
a ri~id unitary insert havin~ a shan~ portion that extends rearward from the rear surface o~ the resilient seslin~ element, and havin~ a hesd portion whose diameter is less thaD the diameter of the bore of the tubular member by an amount not exceedin~ 0.018 inches and that is impenetrable by a hypodermic needle.
~0 In yet another aspect of the invention provides a tamper-resistant hypodermic syrin~e comprisin~ in combination:
Q tubular member navin~ 3 pro~imal end which is unobstructed and havin~ a distal end;
a drive piston positLoned within said tubular members;
a non-retractable stopper havin~ lon~itudinal passs~e to permit the
T~iPER-~ESISTANT HYPODER~IC SYRINGE
BACKG~OUND OF THE INVENTION
Field of the Invention The present invention is in the field of medical apparatus ~nd more specifically relates to ~n improvement in a hypodermic syrin~e to render the syringe more tamper-resistant.
The novel features which are believed to be charQc'ceristic of the invention, both as to organization and method of operation, together witb further objects and advantages thereof, will be better understood from the followin~ description considered in connection with the sccompanyin~ dr~win~s in which several embodiments of the invention are illustrated by way of example. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention.
8rief Descr;Ption of the_Drawin~
Fi~ure 1 is a fractional cross-sectional view showing s syringe of the prior art;
Figure 2 is a fractional crcss-sectional view showing an early embodiment of the syringe of the present inventiorl;
Fi~ure 3 is a frQctional cross-sectional view showing a first preferred embodiment of the syrin~e of the present invention;
Figure 4 is 8 fractional cross-sectional view showin~ a second preferred embodiment of the syrin~e of the present invention;
Figure 5 is a fractional cross-sectional view showin~ a third preferred e~nbodiment of the syrin~e of the present invention; and, Fi~ure 6 is a fractional cross-sectionQl view showin~ an alternative embodiment of the syrin~e of tbe present invention.
The Prior Art A fractional cross-seetional view throu~h a portion of a s7ringe of the prior art is shown in ~i~ure 1. Fi~ure 1 shows the end of the hypodermic syringe that is opposite the end to which the needle is ~ttached. As sho~n in Figure 1, the hypoderrnic syrin~e includes A tubular me~ber 12 of glAss oc other transparerlt materi~l which serves to contai~ the fluid 14. A drive piston 16 of 8 soft rubber is included within the tubular me~her 12 ~nd forms .~ ..
a slidable seal with the inside surface of the tubular member 12 A screw 18 -1- ~
is embedded in the drive piston 16 to permit an actuatin~ rod (not shown) to be connected to the drive piston 16. The actuating rod facilitates application of a force, directed leftward in Figure 1, to the drive piston 16 leftward for the purpose of e~pressin~ the fluid 14 from the syrin~e.
Instances ha~e been discovered in which a person has i~serted a needle 20 in the marlner shown in Fi~ure 1 throu~h the drive piston 16 to aspirate some of the fluid (narcotics). An object of the present invention is to prevent thls type of pilfering.
~ sy~ cf` the~ Invention In accordance with the present invention, an impenetrable barrier is included iD the syrin~e to prevent the insertion of a needle in the msnner shown in Figure 1.
Detailed Description The present invention provides sn improved drive piston for a hypoder~ic syrin~e, of the type hnving a ri~id insert and having a resilient sealing element that can be advQnced and retracted within a tubular member and having a front surface facinK in the direction in which the resilient sealin~
element is advanced and n rear surface facin~ in the di~ection in which the resilient seQling element is retracted, and characterized in th~t the insert serves the multiple purposes of reducin~ stresses in the resilient sealin~
element when the drive piston is being moved, of rendering the drive piston impenetrable by a hypodermic needle and hence pilfer-proof, snd of providin~ a means for positively attachin~ an actuatin~ rod to the drive piston, sqid improved drive piston comprisin~:
a ri~id unitary insert havin~ a shan~ portion that extends rearward from the rear surface o~ the resilient seslin~ element, and havin~ a hesd portion whose diameter is less thaD the diameter of the bore of the tubular member by an amount not exceedin~ 0.018 inches and that is impenetrable by a hypodermic needle.
~0 In yet another aspect of the invention provides a tamper-resistant hypodermic syrin~e comprisin~ in combination:
Q tubular member navin~ 3 pro~imal end which is unobstructed and havin~ a distal end;
a drive piston positLoned within said tubular members;
a non-retractable stopper havin~ lon~itudinal passs~e to permit the
- 2 --~ ~5~
syrin~e to be used for aspiration, said non-retractable stopper located within said tubular member immediately adjncent the distal side of said driYe piston, but not connected to said drive piston;
a barrier impenetrable by a hypodermic needle and affi~ed to said non-retractable stopper whereby the attempted insertion of a hypodermic needle through said non-retractable stopper from the proximal end of said tubular membsr will c~use said non-retractable stopper to be pushed tow~rd the distal end, thereby givin~ a visual indication that the syringe has been tampered wit~l.
In another aspect the invention provides in ~ tamper--resistant hypodermic syrin~e of the type in which a fluid is expressed by advancin~ a drive piston within a tubular member and in which a non-retractable stopper h~ing a longit~dinal passa~e is pushed along within the tubular member by the drive piston, and in which the non-retractable stopper is not connected to the drive piston, so that ~hen the drive piston is retracted, the non-retractable stopper remains at its most advanced position to serve as a warning that fluid has been removed from the hypodermic syringe, the improvement comprisin~:
a barrier impenetrable by a hypodermic needle and affixed to the non-retractable stopper to prevent aspiration of the fluid by penetration of the non-retract~ble stopper.
Turnin~ now to the drawings, in which like parts are denoted by the sn~e reference numeral throughout, there is shown in Fi~ure 1 a cross-sectionsl vie~ of a portion of Q hypodermic syrin~e of the type known in th~ prior nrt. Specifically, Figure 1 shows the end of the syringe ~hich is opposite to the end to which the needle is attached. As discussed qbove, this type of syrin~e is s~sceptible to pilfering in the manner shown in Fi~ure 1.
Thnt is, the needle 20 of n second hypodermic syringe is inserted through the rubber drive piston 16 and the fluid 14 is then aspirated from the first syrin~e into the second syrin~e. Thereafter, the needle 20 is removed from the first syrin~e, and in many cases, the theft remains Indetected, particularly if care is taken to replace the pilfered fluid 14 with a saline solution or with water.
Clearly wh~t is needed is some kind of a barrier that cannot be penetrated by the needle 20 of the second hypodermic syringe. Initially, the present in~lentor attempted to devise a cap that would fit tightly over the end of the tubul~r member 12. ~lowever, it was not possible to design a CQp that would prevent tampering yet still be easily and rapidly removable by a ligitimate user.
Another unsatisfactory approach consid0red by the inventor was to attach a wssher to the screiJ 18 by 8~55-l 1 means of a nut. This approach had kwo problems. First, 2 the nut was exposed and therefore could also be tampered
syrin~e to be used for aspiration, said non-retractable stopper located within said tubular member immediately adjncent the distal side of said driYe piston, but not connected to said drive piston;
a barrier impenetrable by a hypodermic needle and affi~ed to said non-retractable stopper whereby the attempted insertion of a hypodermic needle through said non-retractable stopper from the proximal end of said tubular membsr will c~use said non-retractable stopper to be pushed tow~rd the distal end, thereby givin~ a visual indication that the syringe has been tampered wit~l.
In another aspect the invention provides in ~ tamper--resistant hypodermic syrin~e of the type in which a fluid is expressed by advancin~ a drive piston within a tubular member and in which a non-retractable stopper h~ing a longit~dinal passa~e is pushed along within the tubular member by the drive piston, and in which the non-retractable stopper is not connected to the drive piston, so that ~hen the drive piston is retracted, the non-retractable stopper remains at its most advanced position to serve as a warning that fluid has been removed from the hypodermic syringe, the improvement comprisin~:
a barrier impenetrable by a hypodermic needle and affixed to the non-retractable stopper to prevent aspiration of the fluid by penetration of the non-retract~ble stopper.
Turnin~ now to the drawings, in which like parts are denoted by the sn~e reference numeral throughout, there is shown in Fi~ure 1 a cross-sectionsl vie~ of a portion of Q hypodermic syrin~e of the type known in th~ prior nrt. Specifically, Figure 1 shows the end of the syringe ~hich is opposite to the end to which the needle is attached. As discussed qbove, this type of syrin~e is s~sceptible to pilfering in the manner shown in Fi~ure 1.
Thnt is, the needle 20 of n second hypodermic syringe is inserted through the rubber drive piston 16 and the fluid 14 is then aspirated from the first syrin~e into the second syrin~e. Thereafter, the needle 20 is removed from the first syrin~e, and in many cases, the theft remains Indetected, particularly if care is taken to replace the pilfered fluid 14 with a saline solution or with water.
Clearly wh~t is needed is some kind of a barrier that cannot be penetrated by the needle 20 of the second hypodermic syringe. Initially, the present in~lentor attempted to devise a cap that would fit tightly over the end of the tubul~r member 12. ~lowever, it was not possible to design a CQp that would prevent tampering yet still be easily and rapidly removable by a ligitimate user.
Another unsatisfactory approach consid0red by the inventor was to attach a wssher to the screiJ 18 by 8~55-l 1 means of a nut. This approach had kwo problems. First, 2 the nut was exposed and therefore could also be tampered
3 with and probably unscrewed~ Secondly, 'che presence of
4 the washer and the nut on the exposed portion of the screw 18 seriously reduced ~he len~th of the remaininy 6 threaded portion so that the actuator rod could not be 7 adequately screwed on to the screw 180 Therefore, this second approach was deemed less attracti~e than the g techniques later d~veloped.
The present inventor found that it was necessary ~1 to give prop~r consideration to the fact that the rubber 12 of which ~he drive piston 16 was formed is extremely 13 soft, and also, the fact that the dimensions involved are ~4 qui~e smallO For example, the bore of the tubular member 12 typically only 7 millimeters. Thus, care must be taken 16 tha~ ~he modifications made to the drive piston 16 should 17 not unduly weaken the remaining rubber portions, or inter-18 fere with the ability of the drive piston 16 to seal against 19 the inside wall of the tubular member 12.
Figure 2 shows a first embodiment of the syringe 21 in accordance with the p.resent inv~ntion. I~ this first 22 embodiment, the screw 18 of Figure 1 nas been replacerl by 23 the screw 22 of Figure 2 which has a head of larger diameter.
24 Initially it was thought that if the difference between the radius oi the bore o~ the tubular member 12 and the 26 radius o the screw head 24 were less than the diameter 27 Gf the smallest needle, such as the needle 20 of Figure 1, 29 ~//
///
~1 ///
s~
1 then the syringe of Figure 2 would be pilfer-proofO
2 ~owever, the present inventor discovexed that this 3 criterion is not propex because the softness of ~he rubber 4 of ~he drive piston 16 permits the screw 22 to be de-flected laterally from khe center line of the tubular ~J~f lec~iD~J
6 member 12. Although some ~-~ec~ was to be expected, 7 the full extent of the deflection had not previously 8 been appreciated~ Accordingly, the present inventor g discovered tha~ a safer criterion is ~hat the difference between the diameter of the bore of the tubular member 12 1~ and the diameter of the screw head 24 should not exceed 1~ the diameter of the smallest needle that could be used 13 to pilEer the contents of the syringe.
1~ Although the design i~ Figure 2 is woxkable, the present inventor recognized that the screw head 24 ~6 almost divides the drive piston 16 into two parts, and 1~ that the parts are connected only by a relatively thin 18 band o~ the rubber of the drive piston 16 that ex~ends ~9 circumferentially around the screw head 24 at its widest 2~ diameter. Thus, the embodiment of Figure 2 is workable, 21 but it is probably not as desirable an embodiment as the 22 embodiments discussed belo~.
23 Fiyllre 3 shows a first preferred embodiment in 24 which the screw 18 of Figure 3 is comparable to the ~ screw 18 of Figure 1 used in the prior artO The embodl-26 me~t of Flgure 3 is distinguished by the presence of 27 a washer 26 tha~ i9 embedded in the drive piston 16 28 It should ~e noted that a central portiorl 17 of the drive 3~ ///
1 piston 16 of relatively large diam~ter connects the 2 portions of the d.rive piston that lie on o~posite sides 3 o~ the washer 26. ~ccordingly, the ~trength of the g drive piston 16 is not appreciably altered by the presence of the washer 26. Li~ewi~e, the portions of the drive 6 pist.on 16 that lie on opposite sides of the head of the 7 screw 18 are connected by an ~nnular region of appreci-able width, so that in ~his region the drive piston 16 9 of Figure 3 ls at least as strong as the corresponding 10 region of the prior art drive piston shown in Figure 1.
11 In the second prefexred embodiment shown in 1~ Figuxe 4, the screw 18 of Figure 1 has been replaced 13 by an improved screw 28 which extends through the drive 14 piston 16 to terminate in a circular head 30 that is 15 comparable to the head of a nail. It should be noted JhD~rY
16 that the structure of the screw 28 ~w~ in Figure 4 17 not only does not weaken the drive piston 16~ bu~ instead, 18 actuall~ reduces the stre~ses on the rubber, at least i9 when the drive piston is drawn to the righ~ as viewed 20 in Figure 40 As discussed above in connection with 21 the mbodiment of Figure 2, the inventox has found that 22 th~ difference between the diameter of ~he bore of the 23 tubular member 12 and the diameter of the circular head 30 24 should not exceed the diameter of the smallest needle that 25 might be used to aspirate the conten~ of the syringe.
26 ; Figure 5 shows a third pre~erred embodiment o 27 a syringe in accordanee with the present invention~ In 2~ ///
~9 ///
3(~ ///
~1 ///
1 the embodiment of Figure 5, the screw 18 of Figure 1 X is replaced by the screw 32 of Figure 5. The screw 32 3 includes an integral disc 34 which serves as an 4 impenetrable barrier. When the drive piston 16 is pushed to the left in Figure 5, the disc 34 di6tributes the 6 force more or less uniformly over the right hand end of 7 the drive piston 16, khereby relievlng the stresses that would otherwise develop in ~he region of ~he head of the 9 screw 32. ~onsistent with the a~ove ~iscussions, the diameter of the integral disc 34 should not be less than ll the diameter of the tubular member 12 by an amount l~ exceeding the diameter of the smallest needle that might 13 be used to pil~er the contents of the syringeO
14 Figure 6 shows a~ embodiment of the present invention that is intended for use with a syringe having, 16 in addition to the normal drive piston 16, a non-17 retractable stopper 36 having a longitudinal passage 38.
18 In the known prior use of such a syringe, as the l9 drive piston 16 is pushed to the left as viewed in ~igure 6, 20 i~ pushes the non-re~ractable stopper 36 along in front of 21 ~i. However, when the drive piston 16 is retracted to the 22 right, the non retractable stopper 36 remains at it5 most 23 advanced position. The longitudinal passage 38 permits 24 some of the fluid 14 ~o flow through the non-retxactable stopper 36 in~o the space between the drive piston 16 and 2~ thë non-re~ractable stopper. In thls manner, the non~
27 retrac~able stopper serves as an indica~or of whether the ~9 ///
3~ ///
s~
1 drive piston 16 has ever been advanced.
2 Initially, the drive piston 16 and the non-3 retractable stopper 36 are in end-to-end contac-t, and it 4 is not impossible for a thief to inser~ a thin hypodermic
The present inventor found that it was necessary ~1 to give prop~r consideration to the fact that the rubber 12 of which ~he drive piston 16 was formed is extremely 13 soft, and also, the fact that the dimensions involved are ~4 qui~e smallO For example, the bore of the tubular member 12 typically only 7 millimeters. Thus, care must be taken 16 tha~ ~he modifications made to the drive piston 16 should 17 not unduly weaken the remaining rubber portions, or inter-18 fere with the ability of the drive piston 16 to seal against 19 the inside wall of the tubular member 12.
Figure 2 shows a first embodiment of the syringe 21 in accordance with the p.resent inv~ntion. I~ this first 22 embodiment, the screw 18 of Figure 1 nas been replacerl by 23 the screw 22 of Figure 2 which has a head of larger diameter.
24 Initially it was thought that if the difference between the radius oi the bore o~ the tubular member 12 and the 26 radius o the screw head 24 were less than the diameter 27 Gf the smallest needle, such as the needle 20 of Figure 1, 29 ~//
///
~1 ///
s~
1 then the syringe of Figure 2 would be pilfer-proofO
2 ~owever, the present inventor discovexed that this 3 criterion is not propex because the softness of ~he rubber 4 of ~he drive piston 16 permits the screw 22 to be de-flected laterally from khe center line of the tubular ~J~f lec~iD~J
6 member 12. Although some ~-~ec~ was to be expected, 7 the full extent of the deflection had not previously 8 been appreciated~ Accordingly, the present inventor g discovered tha~ a safer criterion is ~hat the difference between the diameter of the bore of the tubular member 12 1~ and the diameter of the screw head 24 should not exceed 1~ the diameter of the smallest needle that could be used 13 to pilEer the contents of the syringe.
1~ Although the design i~ Figure 2 is woxkable, the present inventor recognized that the screw head 24 ~6 almost divides the drive piston 16 into two parts, and 1~ that the parts are connected only by a relatively thin 18 band o~ the rubber of the drive piston 16 that ex~ends ~9 circumferentially around the screw head 24 at its widest 2~ diameter. Thus, the embodiment of Figure 2 is workable, 21 but it is probably not as desirable an embodiment as the 22 embodiments discussed belo~.
23 Fiyllre 3 shows a first preferred embodiment in 24 which the screw 18 of Figure 3 is comparable to the ~ screw 18 of Figure 1 used in the prior artO The embodl-26 me~t of Flgure 3 is distinguished by the presence of 27 a washer 26 tha~ i9 embedded in the drive piston 16 28 It should ~e noted that a central portiorl 17 of the drive 3~ ///
1 piston 16 of relatively large diam~ter connects the 2 portions of the d.rive piston that lie on o~posite sides 3 o~ the washer 26. ~ccordingly, the ~trength of the g drive piston 16 is not appreciably altered by the presence of the washer 26. Li~ewi~e, the portions of the drive 6 pist.on 16 that lie on opposite sides of the head of the 7 screw 18 are connected by an ~nnular region of appreci-able width, so that in ~his region the drive piston 16 9 of Figure 3 ls at least as strong as the corresponding 10 region of the prior art drive piston shown in Figure 1.
11 In the second prefexred embodiment shown in 1~ Figuxe 4, the screw 18 of Figure 1 has been replaced 13 by an improved screw 28 which extends through the drive 14 piston 16 to terminate in a circular head 30 that is 15 comparable to the head of a nail. It should be noted JhD~rY
16 that the structure of the screw 28 ~w~ in Figure 4 17 not only does not weaken the drive piston 16~ bu~ instead, 18 actuall~ reduces the stre~ses on the rubber, at least i9 when the drive piston is drawn to the righ~ as viewed 20 in Figure 40 As discussed above in connection with 21 the mbodiment of Figure 2, the inventox has found that 22 th~ difference between the diameter of ~he bore of the 23 tubular member 12 and the diameter of the circular head 30 24 should not exceed the diameter of the smallest needle that 25 might be used to aspirate the conten~ of the syringe.
26 ; Figure 5 shows a third pre~erred embodiment o 27 a syringe in accordanee with the present invention~ In 2~ ///
~9 ///
3(~ ///
~1 ///
1 the embodiment of Figure 5, the screw 18 of Figure 1 X is replaced by the screw 32 of Figure 5. The screw 32 3 includes an integral disc 34 which serves as an 4 impenetrable barrier. When the drive piston 16 is pushed to the left in Figure 5, the disc 34 di6tributes the 6 force more or less uniformly over the right hand end of 7 the drive piston 16, khereby relievlng the stresses that would otherwise develop in ~he region of ~he head of the 9 screw 32. ~onsistent with the a~ove ~iscussions, the diameter of the integral disc 34 should not be less than ll the diameter of the tubular member 12 by an amount l~ exceeding the diameter of the smallest needle that might 13 be used to pil~er the contents of the syringeO
14 Figure 6 shows a~ embodiment of the present invention that is intended for use with a syringe having, 16 in addition to the normal drive piston 16, a non-17 retractable stopper 36 having a longitudinal passage 38.
18 In the known prior use of such a syringe, as the l9 drive piston 16 is pushed to the left as viewed in ~igure 6, 20 i~ pushes the non-re~ractable stopper 36 along in front of 21 ~i. However, when the drive piston 16 is retracted to the 22 right, the non retractable stopper 36 remains at it5 most 23 advanced position. The longitudinal passage 38 permits 24 some of the fluid 14 ~o flow through the non-retxactable stopper 36 in~o the space between the drive piston 16 and 2~ thë non-re~ractable stopper. In thls manner, the non~
27 retrac~able stopper serves as an indica~or of whether the ~9 ///
3~ ///
s~
1 drive piston 16 has ever been advanced.
2 Initially, the drive piston 16 and the non-3 retractable stopper 36 are in end-to-end contac-t, and it 4 is not impossible for a thief to inser~ a thin hypodermic
5 n~edle through bot.h ~he drive piston 16 and the non-
6 retractable stopp~r 36 to pilEer the 1uid 14. Clearly,
7 the measures shown in ~igures 2-5 would prevent such
8 pilfering. Tha embodiment ~hown in Figure 6 would not
9 prevent pilferi~g but would leave a vislble indication
10 that the syringe has been tampered with, and would have
11 the added advantage of requiri.ng no modification what-
12 soever to the drive piston 16 and the screw 18 eurrently
13 in use. In the embodiment of Figure 6, an impenekrable
14 washer 40 is bonded to one end of the non retractable 1$ stopper 360 In Fi~ure 6~ the washer 40 is bonded to the 16 end of the non-retractable s~opper that faces the drive 17 piston 16. With ~he impenetrable washer 40 in place, 18 any aktempt to pilfer ~he fluid 14 will result in the 19 non~retractable stopper 36 being advanced to the left 20 as viewed in Figure 6 where the non-retractable stopper 36 21 will remain to serve as a signal that the syringe has been 22 tampered witho FuEth~r, as discussed above~ the difference 23 between the diameter of the bor2 of the tubular member 12 and 24 the diameker of the impenetrable washer 40 should not exceed 2g ///
~2 //~
_9 1 the diameter of the smallest ~eedle that could be used 2 to pilfer the fluid 14.
3 Thus, there have been described several 4 embodiments of an invention which should materially reduce the pilferage of narcotics and other fluids from 6 hypodermic syringes by penetration of the drive pis~on 7 by the needle of a second hypodermic s~ringe. In each 8 of these embodiments described herein, an impenetrable 9 barrier is placed in the path of the needle of the second 10 hypodermic syringe to deny access of ~hat needle to the 11 fluid within the syringe.
1~ The foregoing detailed description lllustrates 13 several embodimen~s of the invention, and it is to be 14 understood that additional embodiments thereof will be
~2 //~
_9 1 the diameter of the smallest ~eedle that could be used 2 to pilfer the fluid 14.
3 Thus, there have been described several 4 embodiments of an invention which should materially reduce the pilferage of narcotics and other fluids from 6 hypodermic syringes by penetration of the drive pis~on 7 by the needle of a second hypodermic s~ringe. In each 8 of these embodiments described herein, an impenetrable 9 barrier is placed in the path of the needle of the second 10 hypodermic syringe to deny access of ~hat needle to the 11 fluid within the syringe.
1~ The foregoing detailed description lllustrates 13 several embodimen~s of the invention, and it is to be 14 understood that additional embodiments thereof will be
15 obvious to ~hose skilled in the art. The e~bodiments
16 described herein to~ether with those additional 1~ embodiments are considered to be within ~he scope of 18 th~ invention.
~2 ~6 ' 2g ~10--
~2 ~6 ' 2g ~10--
Claims (9)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An improved drive piston for a hypodermic syringe, of the type having a rigid insert and having a resilient sealing element that can be advanced and retracted within a tubular member and that have a front surface facing in the direction in which the resilient sealing element is advanced and a rear surface facing in the direction in which the resilient sealing element is retracted, and characterized in that the insert serves the multiple purposes of reducing stresses in the resilient sealing element when the drive piston is being moved, of rendering the drive piston impenetrable by a hypodermic needle and hence pilfer-proof, and of providing a means for positively attaching an actuating rod to the drive piston, said improved drive piston comprising:
a rigid unitary insert having a shank portion that extends rearward from the rear surface of the resilient sealing element, and having a head portion whose diameter is less than the diameter of the bore of the tubular member by an amount not exceeding 0.018 inches and that is impenetrable by a hypodermic needle.
a rigid unitary insert having a shank portion that extends rearward from the rear surface of the resilient sealing element, and having a head portion whose diameter is less than the diameter of the bore of the tubular member by an amount not exceeding 0.018 inches and that is impenetrable by a hypodermic needle.
2. The improved drive piston of claim 1, wherein said shank portion includes a threaded portion.
3. In a tamper-resistant hypodermic syringe of the type in which a fluid is expressed by advancing a drive piston within a tubular member and in which a non-retractable stopper having a longitudinal passage is pushed along within the tubular member by the drive piston, and in which the non-retractable stopper is not connected to the drive piston, so that when the drive piston is retracted, the non-retractable stopper remains at its most advanced position to serve as a warning that fluid has been removed from the hypodermic syringe, the improvement comprising:
a barrier impenetrable by a hypodermic needle and affixed to the non-retractable stopper piston to prevent aspiration of the fluid by penetration of the non-retractable stopper.
a barrier impenetrable by a hypodermic needle and affixed to the non-retractable stopper piston to prevent aspiration of the fluid by penetration of the non-retractable stopper.
4. The improvement of claim 3 wherein the diameter of said barrier is less than the inside diameter of the tubular member by an amount not exceeding 0.018 inches.
5. A tamper-resistant hypodermic syringe comprising in combination:
a tubular member having a proximal end which is unobstructed and having a distal end;
a drive piston positioned within said tubular member;
a non-retractable stopper having a longitudinal passage to permit the syringe to be used for aspiration, said non-retractable stopper located within said tubular member immediately adjacent the distal side of said drive piston, but not connected to said drive piston;
a barrier impenetrable by a hypodermic needle and affixed to said non-retractable stopper whereby the attempted insertion of a hypodermic needle through said non-retractable stopper from the proximal end of said tubular member will cause said non-retractable stopper to be pushed toward the distal end, thereby giving a visual indication that the syringe has been tampered with, the diameter of said barrier being less than the inside diameter of said tubular member by an amount not exceeding 0.018 inches.
a tubular member having a proximal end which is unobstructed and having a distal end;
a drive piston positioned within said tubular member;
a non-retractable stopper having a longitudinal passage to permit the syringe to be used for aspiration, said non-retractable stopper located within said tubular member immediately adjacent the distal side of said drive piston, but not connected to said drive piston;
a barrier impenetrable by a hypodermic needle and affixed to said non-retractable stopper whereby the attempted insertion of a hypodermic needle through said non-retractable stopper from the proximal end of said tubular member will cause said non-retractable stopper to be pushed toward the distal end, thereby giving a visual indication that the syringe has been tampered with, the diameter of said barrier being less than the inside diameter of said tubular member by an amount not exceeding 0.018 inches.
6. The improved drive piston of claim 1 wherein the head portion of said rigid unitary insert substantially covers the front surface of the resilient sealing element.
7. The improved drive piston of claim 1 wherein the head portion of said rigid unitary insert substantially covers the rear surface of the resilient sealing element.
8. A tamper-resistant hypodermic syringe comprising in combination:
a tubular member having a proximal end which is unobstructed and having a distal end;
a drive piston positioned within said tubular members, a non-retractable stopper having a longitudinal passage to permit the syringe to be used for aspiration said non-retractable stopper located within said tubular member immediately adjacent the distal side of said drive piston, but not connected to said drive piston;
a barrier impenetrable by a hypodermic needle and affixed to said non-retractable stopper whereby the attempted insertion of a hypodermic needle through said non-retractable stopper from the proximal end of said tubular member will cause said non-retractable stopper to be pushed toward the distal end, thereby giving a visual indication that the syringe has been tampered with.
a tubular member having a proximal end which is unobstructed and having a distal end;
a drive piston positioned within said tubular members, a non-retractable stopper having a longitudinal passage to permit the syringe to be used for aspiration said non-retractable stopper located within said tubular member immediately adjacent the distal side of said drive piston, but not connected to said drive piston;
a barrier impenetrable by a hypodermic needle and affixed to said non-retractable stopper whereby the attempted insertion of a hypodermic needle through said non-retractable stopper from the proximal end of said tubular member will cause said non-retractable stopper to be pushed toward the distal end, thereby giving a visual indication that the syringe has been tampered with.
9. The improved drive piston of claim 1 wherein the difference between the diameter of the bore of the tubular member and the diameter of said barrier does not exceed the diameter of the smallest hypodermic needle that could be used to pilfer the contents of the hypodermic syringe.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US36401182A | 1982-03-31 | 1982-03-31 | |
| US06/364,011 | 1982-03-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1195199A true CA1195199A (en) | 1985-10-15 |
Family
ID=23432658
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000424005A Expired CA1195199A (en) | 1982-03-31 | 1983-03-18 | Tamper-resistant hypodermic syringe |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS58173560A (en) |
| CA (1) | CA1195199A (en) |
| GB (1) | GB2117645B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU709617B2 (en) * | 1995-10-24 | 1999-09-02 | Astra Pharmaceuticals Pty Ltd | Tamper evident syringe design |
| AUPN615095A0 (en) | 1995-10-24 | 1995-11-16 | Astra Pharmaceuticals Pty Ltd | Tamper evident syringe design |
-
1983
- 1983-03-17 JP JP58043267A patent/JPS58173560A/en active Pending
- 1983-03-18 CA CA000424005A patent/CA1195199A/en not_active Expired
- 1983-03-28 GB GB08308489A patent/GB2117645B/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2117645B (en) | 1986-01-15 |
| GB8308489D0 (en) | 1983-05-05 |
| JPS58173560A (en) | 1983-10-12 |
| GB2117645A (en) | 1983-10-19 |
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|---|---|---|---|
| MKEC | Expiry (correction) | ||
| MKEX | Expiry |