HK1131574A - Breech loaded fixed needle syringe and automatic injection device having the same - Google Patents

Abstract

A fixed needle syringe having a medicine compartment, a hypodermic needle, a piston, and a plunger is provided. The hypodermic needle is in fluid communication with the medicine compartment. The piston is slideably disposed in the medicine compartment. The plunger is secured to the piston. The plunger has a bore defined therethrough, where the bore allows access to the piston through the plunger.

Description

Syringe having fixed needle mounted at its tail and automatic injection device having the same

Cross reference to related applications

This application claims priority from U.S. provisional application 60/634,486 filed on 9/12/2004 and relates to commonly owned and assigned U.S. application 10/601,212 filed on 20/6/2003, the contents of both of which are incorporated herein by reference.

Technical Field

The present disclosure relates to fixed needle syringes. More particularly, the present disclosure relates to a syringe having a fixed needle mounted at the tail thereof and an automatic injection device having the same.

Background

Fixed needle syringes typically include a needle secured to and in flow communication with a medication chamber. A plunger, which typically acts on a resilient piston in a drug chamber, is used to fill the drug chamber by sucking or aspirating (hereinafter "aspirating") a drug solution from another container, such as a vial or ampoule, to expel air from the drug chamber, and to release the drug from the drug chamber into tissue at the injection site.

During aspiration, the needle of the syringe is inserted through the septum of the vial. The piston is then pulled to draw the drug from the vial into the drug compartment of the syringe. Thus, the needle of such fixed needle syringes is designed to withstand the pressure imparted during insertion through the septum and to allow sufficient fluid flow during aspiration.

The degree of pain and/or discomfort associated with the injection of the medication depends, at least in part, on the size or gauge ("gauge") of the needle. Unfortunately, the larger the needle gauge, the more damage to the tissue at the injection site and, thus, the more painful the person receiving the injection.

The needle gauge of a syringe filled at the time of use is generally limited by the needle tube strength of the needle when inserting and withdrawing the needle from the vial. Long, thin needles are more prone to bending when attempting to pierce the septum of a vial. Thus, fixed needle syringes filled by aspiration have a larger gauge needle than is required to avoid needle buckling.

In addition, needle gauge is also a limiting factor in drawing drug solution from another container because the flow of fluid from the vial into the syringe is determined in part by the inside diameter and length of the needle, the viscosity of the drug solution, and the available pressure differential that causes the fluid to flow; the maximum pressure during the pumping process is atmospheric pressure. A high viscosity drug requires a larger inner diameter needle, and thus a larger gauge needle, to aspirate the drug solution from the vial into the syringe in a reasonable amount of time compared to a low viscosity drug. Again, fixed needle syringes filled by aspiration typically have a larger gauge needle than is required to avoid filling delays.

Many drugs may be injected using automatic injection devices having fixed needle syringes therein. Typical automatic injection devices allow a medically untrained user to automatically inject a medicament by manually triggering the automatic injection device. Some existing automatic injection devices also automatically retract the needle after injection.

Accordingly, the present application recognizes that there is a continuing need for fixed needle syringes and automatic injection devices that overcome or mitigate the foregoing and other deficiencies of the prior devices.

Disclosure of Invention

It is an object of the present disclosure to provide a user-filled (user-filled) fixed needle syringe having a small gauge needle.

It is another object of the present disclosure to provide a fixed needle syringe that can be loaded with fluid medication without the need to aspirate the medication through the same needle that is later used to penetrate tissue and provide a conduit for flow into the injection site.

It is another object of the present disclosure to provide a fixed needle syringe that eliminates the size limitations of hypodermic needles associated with dual use hypodermic needles in the prior art, which requires the same needle to be used as both a conduit from the original vial into the fixed needle syringe and as a conduit from the fixed syringe into the subject being injected.

It is a further object of the present disclosure to provide a breech loadable medication chamber having a threaded interior region and a movable piston pierceable by a membrane.

It is a further object of the present disclosure to provide a fixed needle syringe having a movable piston with a self-sealing, pierceable membrane.

It is a further object of the present disclosure to provide a medication chamber having a syringe guide movably connected with a movable piston, the syringe guide having an inner diameter accommodating a hypodermic needle for piercing a piston membrane and filling the medication chamber by piercing through the membrane.

These and other objects of the present disclosure are achieved by a fixed needle syringe having a medication chamber, a hypodermic needle, a plunger and a piston. A hypodermic needle is in flow communication with the medication chamber. A piston is slidably disposed in the medication chamber. The plunger is movably fixed with the piston. The plunger has a bore defined therethrough that allows access to the piston through the plunger.

There is also provided a method of injecting a drug, the method comprising pushing the drug from a drug delivery needle into a drug chamber of a fixed needle syringe through a hollow plunger and piston element of the fixed needle syringe; removing the hollow plunger from the piston; inserting a fixed needle syringe into the first assembly such that the hypodermic needle is proximate to the lower seal of the first assembly; the second assembly is secured with the first assembly such that the driven rod of the second assembly is proximate the piston member.

An injection kit is also provided. The injection kit includes an injection assembly, a retraction assembly, and a tail loadable fixed needle syringe.

The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims.

Drawings

FIG. 1 is a cross-sectional view of an exemplary embodiment of a fixed needle syringe according to the present disclosure;

FIG. 2 is a partially exploded perspective view of the fixed needle syringe of FIG. 1 in use with an automatic injection device; and

fig. 3 is a cross-sectional view of the fully assembled automatic injection device of fig. 2.

Detailed Description

Referring to the drawings, and in particular to fig. 1, one exemplary embodiment of a fixed needle syringe 10 according to the present disclosure is shown. Syringe 10 includes a hypodermic needle 12 in flow communication with a medication chamber 14. In some embodiments, syringe 10 may include a removable protective sheath 16 disposed over hypodermic needle 12.

The injector 10 further includes a plunger 18 slidably disposed in the medication chamber 14. Preferably, syringe 10 includes a syringe end cap 20 at a trailing end 22 of medication chamber 14 to prevent accidental withdrawal of plunger 18 from the medication chamber.

Advantageously, the syringe 10 is arranged such that the chamber 14 can be filled with medicament via the piston 18.

The disclosure of the present application has identified: the size of the hypodermic needle is limited by the force exerted on hypodermic needle 12 during aspiration. Advantageously, syringe 10 decouples the force exerted on hypodermic needle 12 during aspiration from the force exerted on hypodermic needle 12 during injection. In this way, the size of the hypodermic needle can be reduced.

Thus, hypodermic needle 12 need not be sized with sufficient syringe strength to withstand the pressure generated by inserting the hypodermic needle into the vial. Furthermore, the tip of hypodermic needle 12 does not risk becoming dulled as a result of insertion into the vial. In view of the above results, hypodermic needle 12 can be reduced in size while still maintaining adequate flow during injection into a patient.

Syringe 10 has a hypodermic needle 12 with a small inner and outer diameter, and hypodermic needle 12 reduces user discomfort during needle insertion and injection. Hypodermic needle 12 preferably has an inner diameter and an outer diameter that match the viscosity of the injected drug and the needle force exerted on the hypodermic needle during injection-not the force exerted on the hypodermic needle during aspiration.

In some embodiments, hypodermic needle 12 has a slenderness ratio that minimizes discomfort associated with needle insertion into a user. As used herein, the slenderness ratio is defined as the length of the hypodermic needle in inches divided by the outer diameter of the hypodermic needle in inches. Here, the slenderness ratio of hypodermic needle 12 is limited only by the strength required to penetrate tissue at the injection site. Hypodermic needle 12 can have a slenderness ratio of at least about 60. In some embodiments, hypodermic needle 12 can have a slenderness ratio of up to about 120. Hypodermic needle 12 preferably has a slenderness ratio of about 85. Thus, hypodermic needle 12 can have a slenderness ratio of between about 60 and about 120, and any subranges therebetween.

In other embodiments, hypodermic needle 12 has a flow ratio that is below the level at which medication chamber 14 can be filled through the needle cannula via aspiration over a certain period of operation. As used herein, the flow ratio is defined as the maximum flow rate in cubic centimeters per minute (cc/min) through the hypodermic needle during aspiration divided by the length of the hypodermic needle in inches. At atmospheric pressure, the maximum pressure differential during suction is about 14.7 pounds per square inch above sea level. As used herein, a certain operating time is less than about 30 seconds. Thus, if it takes longer than 30 seconds to fill the medication chamber 14 via aspiration, it may be considered impractical for the purposes of this application.

Hypodermic needle 12 can have a flow ratio of less than about 2.0. In some embodiments, hypodermic needle 12 can have a flow ratio of less than about 1.8. Preferably, hypodermic needle 12 has a flow ratio of less than about 1.5. Since medication chamber 14 is not filled via aspiration through hypodermic needle 12, syringe 10 is advantageously not limited to a high flow ratio, but may have a flow ratio of less than about 2.0.

For example, at a flow ratio of less than about 2 and a needle length of about 1 inch, hypodermic needle 12 has a maximum flow rate during aspiration of less than about 2 cc/min.

The syringe 10 includes a plunger 24 movably disposed through an opening 26 in the syringe end cap 20. In some embodiments, plunger 24 is removably secured with piston 18. For example, piston 18 may include internal threads 28, and plunger 24 may include corresponding external threads 38. In this manner, threads 28, 38 may be used to selectively secure and/or unsecure plunger 24 and piston 18.

The plunger 24 includes a hollow bore or bore 30 defined therethrough. Advantageously, the hole 30 allows access to the plunger 18 through the rod body 24 (rod). Preferably, the bore 30 includes one or more needle guide surfaces 32 defined therein. In use, a delivery needle (not shown) for withdrawing a drug solution from a supply container in place of the injected hypodermic needle 12 is inserted into the bore 30, through the piston 18 and into the drug compartment 14. Piston 18 is made of a self-sealing, pierceable material such as those commonly used as a septum for a vial, and may include, but is not limited to, materials such as silicone or butyl rubber.

In this manner, chamber 14 may be filled at trailing end 20 by piston 18. Guide surface 32, if present, may assist in guiding the delivery needle into piston 18.

Once the medication chamber 14 is filled, the delivery needle (not shown) may be withdrawn from the medication chamber 14 through the piston 18 from the bore 30. Any air or other gas within medication chamber 14 may be removed by simply rotating syringe 10 so that the air is proximate hypodermic needle 12 (e.g., hypodermic needle 12 is vertically oriented), and depressing plunger 24 to expel the air through hypodermic needle 12. In use, the user simply removes protective sheath 16, inserts hypodermic needle 12, if present, into the body, and depresses plunger 24 to inject the desired dose of medicament from chamber 14.

In some embodiments, plunger 24 may include one or more handle portions 34. Handle portion 34 may be used to stabilize plunger 24 during filling and/or use of syringe 10.

In addition to being useful during manual injection as described above, it is contemplated by the present disclosure for injector 10 to be used with an automatic injection device and retraction device 40, such as shown in fig. 2 and 3.

Some automatic injection devices have the ability to generate more force than is normally applied by hand on the piston, which allows the same injection flow rate to be achieved using a smaller hypodermic needle than can be achieved by a human hand. The disclosure of the present application has identified: the design features of the present application make it easier to take advantage of the ease of injection if the above limitations associated with aspirating drugs through small gauge hypodermic needles are eliminated.

As shown in FIGS. 2 and 3, device 40 includes power injection assembly 42 and power retraction assembly 44. By using syringe 10 with hypodermic needle 12 having a smaller outer diameter as described above with respect to the syringe, device 40 reduces tissue damage and discomfort from the injection.

When it is desired to use the device 40, the syringe 10 may be filled in the manner described above. Next, plunger 24 may be removed from syringe 10 and, once sheath 16 is removed, the syringe may be operably disposed in device 40.

Preferably, device 40 is an automatic injection device that extends hypodermic needle 12 from within the device, injects a single, predetermined dose of medication from chamber 14 into the user, and automatically retracts the hypodermic needle into the assembly after the injection is completed.

The injection assembly 42 may operate substantially as disclosed in commonly owned and assigned U.S. application No. 10/601,212, filed on 20/6/2003, the contents of which are incorporated herein by reference.

Alternatively, injection assembly 42 may be as shown in fig. 2 and 3. Here, injection assembly 42 includes an injection spring 46, a driven rod 48, an activation button 50, a disengagement device 52, and a coupling 54.

Injection spring 46 is disposed about driven rod 48 between a spring retainer 49 and a coupling 54 that selectively engages the injection spring with driven rod 48.

Activation button 50 is configured to selectively release energy in injection spring 46 to driven rod 48. In the illustrated embodiment, the driven rod 48 includes a locking end 56 and a driving end 58. Driving end 58 is configured to act on piston 18 to expel drug from chamber 14, as will be described in detail below.

In one embodiment, locking end 56 includes two or more tines 60, with tines 60 resiliently biased outwardly to move the tines away from each other. When biased against each other, tines 60 engage a locking surface 62 on spring retainer 49. Activation button 50 includes a release surface 64. Force applied to activation button 50 in injection direction 66 causes release surface 64 to compress tines 60 relatively to disengage driven rod 48 from locking surface 62.

Injection spring 46 is held in a normally compressed or stressed condition between spring seat 49 and coupling 54. Upon release of tines 60, the stored energy in spring 46 acts on spring retainer 49 and coupling 54 to drive driven rod 48 in an injection direction 66.

Injection spring 46 drives driven rod 48 in injection direction 66 until coupling 54 abuts distractor 52. The force of the disengagement means 52 on the coupling 54 disengages the coupling from the driven rod 48. Disengagement of coupling 54 from driven rod 48 frees the driven rod from the force of injection spring 46, thereby allowing the driven rod to be moved in a direction opposite injection direction 66 by power-retraction assembly 44.

Device 40 may be configured to inject drugs intramuscularly, interocularly, subcutaneously, and/or intradermally from chamber 14. For example, separation device 52 may be secured within injection assembly 42 for movement in injection direction 66. Changing the position of splitter device 52 in injection direction 66 by changing the point at which the splitter device decouples injection spring 46 from driven rod 48 may change the stroke of injection assembly 42.

In the illustrated embodiment, injection assembly 42 includes a cap 68 disposed on activation button 50. Cap 68 may mitigate inadvertent depression of activation button 50, thereby preventing premature activation of injection assembly 42.

In a preferred embodiment, injection assembly 42 and retraction assembly 44 are secured to one another in a snap-fit manner such that the assemblies cannot move relative to one another after assembly. For example, injection assembly 42 may include one or more outwardly supported protrusions 68, which protrusions 68 are received in a corresponding number of openings 70 defined in retraction assembly 44. As injection assembly 42 is inserted into retraction assembly 44, protrusions 68 act on the retraction assembly to elastically deform the inner dimension of the tube. Once opening 70 receives protrusion 68, the inner dimension of retraction assembly 44 returns to its original dimension to secure the protrusion within the opening.

In the assembled state, injection assembly 42 and retraction assembly 44 preferably maintain chamber 14 sealed therebetween. For example, injection assembly 42 may include a seal 72, such as, but not limited to, a 0-ring. Once injection assembly 42 and retraction assembly 44 are secured together, seal 72 cooperates with the interior of the retraction assembly to form a radial seal. In the illustrated embodiment, the seal 72 is disposed below the opening 70 to provide a seal below the snap-fit connection between the protrusion 68 and the opening 70.

Power-retraction assembly 44 includes a second or retraction spring 74 and a lower seal body 76. Retraction spring 74 is substantially weaker than injection spring 46. When assembled, needle 12 is disposed proximate lower seal 76. During use, injection spring 46 overcomes the force of retraction spring 74 to compress the retraction spring and move chamber 14 in injection direction 66 to cause needle 12 to pierce lower seal 76 and tissue at the injection site. In addition, injection spring 46 urges driving end 58 of driven rod 48 in an injection direction 66 to expel drug from chamber 14 through needle 12.

At the point where piston 18 has moved to complete the injection of medicament from chamber 14, driven rod 48 has moved in injection direction 66 a sufficient distance to bring coupling 54 into contact with disengaging device 52, which disengages the coupling from the driven rod and terminates the influence of injection spring 46 on the driven rod. Once injection spring 46 is disengaged, the now compressed retraction spring 74 urges needle 12, chamber 14, and driven rod 48 in a direction opposite injection direction 66 until after the needle has retracted back into lower seal 76.

In the illustrated embodiment, when injection assembly 42 and retraction assembly 44 are permanently secured to one another, retraction of needle 12 into the retraction assembly prevents device 40 from causing accidental injury from needle 12, thereby allowing device 40 to be safely disposed of.

In one embodiment of the present disclosure, device 40 and syringe 10 may be provided in an unassembled state for assembly and use in a terminally sterilized kit (not shown). Here, the kit may include injection and retraction assemblies 42, 44 and syringe 10. Furthermore, for the convenience of the user, the kit may include one or more injection site cleaning swabs, such as a prepackaged alcohol swab. For example, injection assembly 42, retraction assembly 44, and syringe 10 may be contained in a sealed package, such as a plastic or TYVEC package. In some embodiments, the packet may be terminally sterilized.

It should also be noted that the terms "first," "second," "third," "upper," "lower," and the like as used herein are used to modify various elements. These modifiers do not imply a spatial, sequential, or hierarchical order to the modified elements unless specifically stated.

While the disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims (22)

1. A fixed needle syringe, the fixed needle syringe comprising:

a medication chamber;

a hypodermic needle in flow communication with the medication chamber;

a piston slidably disposed in the medication chamber; and

a plunger fixed with the piston, the plunger having a bore defined therethrough, the bore allowing access to the piston through the plunger.

2. The fixed needle syringe of claim 1 further comprising an end cap at the trailing end of the medication chamber, the end cap preventing withdrawal of the piston from the medication chamber.

3. The fixed needle syringe of claim 1 wherein the plunger is movably fixed with the piston.

4. The fixed needle syringe of claim 3 wherein the plunger is movably secured to the piston by a threaded connection.

5. A fixed needle syringe as recited in claim 1, further comprising one or more needle guide surfaces defined in the bore of the plunger.

6. The fixed needle syringe of claim 1 wherein the piston is a self-sealing, pierceable material.

7. A fixed needle syringe, the fixed needle syringe comprising:

a medication chamber;

a self-sealing piston slidably disposed in the medication chamber; a hypodermic needle in flow communication with the medication chamber; the hypodermic needle has a slenderness ratio of between about 60 and about 120; and

a plunger secured with the self-sealing piston, the plunger having an aperture defined therethrough that allows access to the self-sealing piston through the plunger.

8. The fixed needle syringe of claim 7 wherein the slenderness ratio is about 85.

9. The fixed needle syringe of claim 7 wherein the hypodermic needle has a flow ratio of less than about 2.

10. A fixed needle syringe, the fixed needle syringe comprising:

a medication chamber;

a self-sealing piston slidably disposed in the medication chamber; a hypodermic needle in flow communication with the medication chamber; a flow rate ratio of the hypodermic needle is less than about 2; and

a plunger secured with the self-sealing piston, the plunger having an aperture defined therethrough that allows access to the self-sealing piston through the plunger.

11. The fixed needle syringe of claim 10 wherein the flow ratio is less than about 1.8.

12. The fixed needle syringe of claim 10 wherein the flow ratio is less than about 1.5.

13. The fixed needle syringe of claim 10 wherein the hypodermic needle has a slenderness ratio of between about 60 and about 120.

14. A method of injecting a drug, the method comprising:

introducing a drug delivery needle into a drug chamber of the fixed needle syringe through a hollow plunger and piston of the fixed needle syringe; and

pushing a drug from the drug delivery needle into the drug chamber.

15. The method of claim 14, further comprising:

removing the hollow plunger from the piston;

inserting the syringe in a first assembly such that a hypodermic needle of the fixed needle syringe is proximate to a lower seal of the first assembly; and

securing a second component to the first component such that a rod of the second component is proximate to the piston.

16. The method of claim 15, further comprising:

placing the lower seal over an injection site; and

releasing an injection spring in the second assembly to drive the stem in an injection direction, the stem pushing the hypodermic needle through the lower seal into the injection site and pushing the piston to expel the drug from the drug chamber through the hypodermic needle.

17. The method of claim 16, further comprising urging a retraction spring of the first component to a compressed state when the stem is moved in the injection direction.

18. The method of claim 17, further comprising: disengaging the injection spring from the stem such that the retraction spring urges the hypodermic needle through the lower seal in a direction opposite the injection direction.

19. An injection kit, comprising:

a fixed needle syringe loadable at the tail;

an injection assembly; and

a retraction assembly, the injection assembly and retraction assembly being arranged to be operably secured with the syringe.

20. The injection kit of claim 19, further comprising one or more injection site cleaning swabs.

21. The injection kit of claim 19, further comprising a package containing the syringe, the injection assembly, and the retraction assembly.

22. The injection kit of claim 21, wherein the packet is terminally sterilized.