INJECTION DEVICE

Abstract

An injection device includes a syringe having a body with a piston disposed therein with an open end along with a viscous fluid disposed in the body for injection by the piston. A needle assembly is provided which includes a cannula, for example a blunt tipped cannula, having a luer connection engageable with the syringe distal end with the luer connector including a hub. Mating engagement is provided by way of internal threads at the syringe distal end and external treads of a hub with a pitch sufficient to prevent detachment of the hub from the syringe distal end during ejection of the viscous fluid. In addition, a stepped cavity, disposed in the hub, further prevents detachment of the hub from the syringe distal end during ejection of the viscous fluid.

Description

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 12/629,480, filed on Dec. 2, 2009, which claims the benefit of U.S. Provisional Patent Application No. 61/119,298, filed on Dec. 2, 2008 and U.S. Provisional Patent Application No. 61/139,430, filed on Dec. 19, 2008, the entire disclosure of each of these applications being incorporated herein by this specific reference.

BACKGROUND

The present invention is generally directed to non-surgical devices for the correction of skin contour defects and aging and is more particularly directed to an injection device for enabling introduction of a dermal filler into peripheral locations of a human body through a cannula.

Dermal fillers such as, such as Juvederm™, a hyaluronic acid based formulation, have been used for the treatment of nasal labial folds, lip augmentation, tear troughs, and for facial volumizing through the use of very fine syringe needles.

The dermal fillers are of high viscosity and this provides for effective, and preferably substantially uniform, suspension of the dermal filler into a peripheral location.

A relatively small needle size, gauge, is preferred for delivery of the dermal filler in order to lessen complications and recovery time. However, in combination with the relatively high viscosity of the dermal filler, a problem can arise with regard to needle assembly separation from the syringe due to the high pressure generated by a piston reacting on the high viscosity dermal filler in order to eject the filler from the syringe through a fine needle and into the patient.

The present invention overcomes this problem by providing an ejection device which eliminates, or substantially reduces, the probability of needle assembly/syringe separation during a procedure.

SUMMARY OF THE INVENTION

An injection device in accordance with the present invention generally includes a syringe having a body with a piston disposed therein and an open distal end.

A needle assembly is provided which includes a cannula and a luer connector engagable with the syringe distal end. The needle or cannula, hereinafter “cannula”, has a gauge of about 18 to a gauge of about 25 or greater. The luer connector includes a hub with a distal end supporting the cannula and a proximal end matable with the syringe distal end.

In one embodiment, the present invention further includes a viscous fluid, for example, a hyaluronic acid-based dermal filler, disposed in the syringe's body and which is injectable by the piston into a peripheral location of a human or animal body through the cannula.

The mating engagement, for example, between the hub and the syringe distal end is provided by internal threads disposed in the syringe distal end and external threads disposed on the hub, as well as between a tapered syringe cone and a tapered inside surface of the hub. The internal threads have a pitch which is sufficient to prevent detachment of the hub from syringe distal end during injection of the viscous fluid into a peripheral location of a human or animal body.

More particularly, in one embodiment, the internal threads have a pitch of between about 2 mm and about 5 mm. For example, the internal threads have a pitch of about 3 mm. The internal thread may be double lead screw threads. In addition, the external threads disposed on the hub further may also be double lead screw threads and the double lead screw threads provide an advantage of enabling the hub to travel twice the distance into mating engagement with the syringe distal end with each single turn of the hub. In other embodiments, the internal threads have a pitch of about 2.0 mm, about 3.0 mm, about 3.5 mm, about 4 mm, about 4.5 mm or about 5 mm. In addition, the external threads may have a pitch of about 2.0 mm, about 3.0 mm, about 3.5 mm, about 4 mm, about 4.5 mm or about 5 mm.

In a specific embodiment, the external threads comprise single circumference double lead screw threads as will be hereinafter described in greater detail.

In addition, a cavity, for example, a stepped cavity, is disposed in the hub. The cavity serves not only reduces dead space in the syringe but also significantly reduces the possibility of detachment of the hub from the syringe distal end during operation of the piston to eject the viscous fluid through the cannula. Thus, the cavity can be considered a hub retention cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will be better understood by the following description when considered in conjunction with the accompanying drawings in which:

FIG. 1 is an illustration of use of an injection device in accordance with the present invention for injecting a viscous fluid into a peripheral location of the human, generally showing a syringe having a body with a piston and a needle assembly;

FIG. 2 is a cross sectional view of the syringe shown in FIG. 1 illustrating more clearly showing the syringe body along with a needle assembly with a luer connector engagable with a distal end of the syringe along with a viscous fluid disposed in the syringe body;

FIG. 3 is an enlarged cross sectional view of the mating engagement between a luer connector hub and a distal end of the syringe specifically illustrating internal threads disposed in the syringe distal end and external threads along the hub for enabling the mating engagement, along with a cavity disposed in the hub configured as a hub retention cavity.

FIG. 4 is end view of the hub illustrating double lead screws;

FIG. 5 is an enlarged cross section view of the needle assembly and an open distal end of the syringe body showing a tapered syringe cone engageable with a tapered inside surface of the needle assembly hub;

FIG. 6 is a cross-section view of the needle assembly engaged with the syringe's open distal end; and

FIG. 7 is a cross-section view of another embodiment of the invention in which the needle assembly includes a cannula with a blunt tip and a side aperture.

DETAILED DESCRIPTION

With reference to FIG. 1, there is shown an injection device 10 in accordance with the present invention having a syringe 12 with a body 14 with a piston 18 disposed therein.

With additional reference to FIGS. 2 and 3, the syringe 14 includes an open distal end 22, and a needle assembly 26. The needle assembly includes a cannula 30 along with a sheath 34 and a luer connector 38 engagable with the syringe open distal end 22, which includes a hub 42 having a distal end 46 and a proximal end 50 matable with the syringe distal end 22.

Internal threads 52, 54 and external threads 56, 58 enable the mating engagement. Pitch (P) of the threads 52, 54 enables the ejection of viscous fluid 62 through the cannula 30 upon operation of the piston 18 without separation of the hub 42 from the syringe open distal end 22 during ejection of the viscous fluid 62 as illustrated in FIG. 1.

In some embodiments, the viscous fluid 62 is a dermal filler. In some embodiments, the viscous fluid is a hyaluronic acid-based fluid having a viscosity between about 50,000 cps and about 500,000 cps, measured at about 25° C. with a controlled stress rheometer (RS600 TA Instrument) and a cone plate geometry (40 mm, 2°). In some embodiments, the viscous fluid is a hyaluronic acid based dermal filler having a viscosity greater than about 130,000 cps.

When measured with a traction column test (Versatest, Mecmesin), at 13 mm/min (extrusion speed) and a needle with a gauge between 21G to 32G, the viscous fluid may have an extrusion force of between about 5N up to about 200N, more specifically, an extrusion force of between about 10N to about 150N.

In an exemplary embodiment, the pitch of the hub threads 56, 58 is between about 2 mm and about 5 mm. Preferably, the pitch is about 3 mm. The threads 52, 54 and 56, 58 are preferably at least double lead screw threads, although triple, and even quadruple lead threads may used. As most clearly shown in FIG. 4, in one particular embodiment, the threads 56, 58 have two thread starts 66, 68 at a 180° radial displacement from one another.

As hereinabove noted, this enables rapid engagement of the hub 42 with the syringe open distal end 22.

In one embodiment, the hub 42 is formed from a low elasticity material, for example, an acrylic or a polycarbonate, rather than polypropylene typically used for syringe hubs, as hereinafter described in connection with needle retention tests. This may further enhance the prevention of detachment of the hub 46 from the syringe open distal end 22.

With reference to FIGS. 5 and 6, hub 42 includes a hub retention cavity 80 defined by an inside surface 84, for example, a stepped interior surface, of the hub 42. For example, the inside surface 84 of the hub 42 may include a step 88. This configuration leads to a reduced space, sometimes referred to herein as a “reduced dead space” between the interior surface of the hub 42 and the distal connecting end of a syringe, relative to a conventional hub without the step configuration. It is believed that this configuration is effective, at least in part, to prevent detachment of said hub from the syringe distal end during ejection of a viscous fluid from the cannula outlet when the hub is engaged to the syringe distal end.

When torqued to the syringe and maximally seated as shown in FIG. 6, a tapered syringe cone 90 stops short of the step 88 and creates a dead space 92 which is reduced by the provision of step 88. Engagement between the cone 90 and inside surface 84, which is also tapered, provides a seal therebetween. Low dead space reduces the amount of fluid that cannot be administered. This is important in that the fluids to be administered, by injection, often are very expensive.

The step 88 unexpectedly prevents or substantially reduces the possibility of detachment of the hub 42 from the syringe cone 90 and syringe open distal end 22 during injection of the viscous fluid 62.

That is, the average detachment force is significantly greater with the step 88 formed in the cavity hub retention cavity 80 of the hub 42 as was discovered during comparison study as follows:

Test methods used in this study utilized equipment designed by Omnica Corporation specifically for torque setting and detachment testing.

The torque set unit utilizes a numerically controlled motor and torque sensor which tightens the needle hub 42 onto the syringe open distal end 22 and a pre-determined torque setting testing is shown that the static friction between the needle hub 42 and the syringe open distal end 22 materials causes more overshoot than observed with standard polypropylene hubs (not shown).

A detachment tester utilizes a numerically controlled motor driving linear carriage against a forced transducer.

In a comparison test, all of the hubs (not shown) were attached to the syringe open distal end 22 and cone 90 with a torque of 0.07 Nm (Newton meter). All of the tests were performed on 0.8 cc syringes having identical dimensions, for example, syringe open distal end 22 having an entry diameter D (see FIG. 6), of about 4 mm.

The results are shown in Table 1 for nominal torque static test needle retention with various design attribute combinations.

Table 1 shows that the conventional polypropylene hub mated to a syringe with 5 mm threads has an average detachment force 46.1 N (Newton) when the hub is attached to the syringe with a force of 0.07 Nm.

TABLE 1
Nominal torque Static Test Needle Retention
with Various Design Attribute Combinations
                                 Average Detachment
Needle Design                    Force (N)1 @ 0.07 Nm
Conventional Polypropylene Hub, Syringe 46.1
with 5 mm Threads
Conventional Polypropylene Hub, Syringe 56.2
with 3 mm Threads
Polycarbonate Hub and Syringe with 5 mm 83.2
Threads
Polycarbonate Hub and Syringe with 3 mm 96.0
Threads
Polycarbonate Hub and Syringe with 3 mm 200+
Threads and Stepped Cavity

Slight improvement shown in the conventional polypropylene hub attached to the syringe body with 3 mm threads, and an average detachment force of about 56.2 N.

Utilizing polycarbonate instead of polypropylene for the hub 42 results in an average detachment force of 83.2 N with 5 mm threads utilized for attachment.

Combination of polycarbonate hub 42 with 3 mm threads without a step 88 results in a 96 N average detachment force.

Surprisingly, the detachment force for the hub 42 with 3 mm threads incorporating the dead space reducing step 88 results in an average detachment force of more than 200 N.

It is contemplated that other structures may be useful in reducing dead space in a manner effective to increase detachment force relative to conventional syringe/needle combinations. For example, it is contemplated that reduced dead space can be accomplished, within the scope of the present invention, by reducing an outer diameter of the syringe luer tip, increasing an inner diameter of the hub cavity, and/or other ways effective to increase the engagement length of the syringe tip and the hub.

Example

A multi-center, double-blind, randomized parallel-controlled prospective comparison study was undertaken to test needle disengagement rates. This study tested needle disengagement rates of a Polycarbonate Hub and Syringe with 3 mm Threads and Stepped Cavity in accordance with the present invention (study device) in comparison to a conventional polypropylene hub and syringe with 5 mm threads (conventional device). Needles of each of the conventional devices and the study devices tested were all 30 G×½″ needles. The material injected for the study was Juvederm™ Ultra Injectable Gel (dermal filler).

There were up to 288 study participants. Each study participant underwent treatment for improving his or her bilateral nasolabial folds using 2 syringes of dermal filler packaged in either the conventional device or the study device.

The results demonstrated a significant difference in needle disengagement rates between the conventional device and the study device. No disengagements were reported for the study device. Between 3% and 7% of the needles of the conventional device unintentionally disengaged during injection.

It is to be appreciated that needles other than traditional sharp-tipped hypodermic type needles such as that shown in FIGS. 1-6 may make up suitable components of the present needle assemblies. For example, turning now to FIG. 7, a needle assembly 126 in accordance with another embodiment of the invention is shown. The needle assembly 126 may be identical to needle assembly 26 described and shown elsewhere herein, with like elements being represented by like numbers increased by 100. Needle assembly 126 includes hub 142 and hub retention cavity 180 defined by an inside surface 184 of the hub 142 and a step 188, thus providing a unique stepped interior surface and reduced dead space. Instead of sharp-tipped needle 30, a blunt-tipped cannula 98 is provided. Cannula 98 includes a relatively rounded tip 99 and an outlet, for example, a side aperture 101, space apart from the tip 99. The presently described hub 142, by being advantageously structured to resist “pop-off” even under high extrusion forces, enables injection of viscous fluids, for example, dermal fillers, from a relatively fine, narrow cannula 98. For example, in some embodiments, the cannula 98 has a gauge greater than 21, greater than 25, greater than 30 and in some embodiments, the cannula has a gauge of up to about 32.

Needle assembly 126 may be used to inject dermal fillers in any suitable manner known to those of skill in the art.

Although there has been hereinabove described a specific injection device in accordance with the present invention for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. That is, the present invention may suitably comprise, consist of, or consist essentially of the recited elements. Further, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims.

Claims

1. A injection device comprising:

a needle assembly comprising a cannula and a luer connector engageable with a distal end of a syringe, said cannula having a rounded distal tip and an outlet spaced apart from said tip, and said luer connector comprising a hub with a distal end supporting said cannula and a proximal end mateable with the syringe distal end;

a cavity, defined by a stepped interior surface of the hub, effective to prevent detachment of said hub from the syringe distal end during ejection of a viscous fluid from the cannula outlet when the hub is engaged to the syringe distal end; and

external threads disposed on an exterior surface of said hub enabling mating engagement between the hub and the syringe distal end.

2. The device of claim 1 wherein the stepped cavity provides a reduced dead space relative to an otherwise identical needle assembly without the stepped interior surface.

3. The device according to claim 1 wherein the external threads has a pitch of about 3 mM.

4. The device according to claim 3 wherein the external threads comprise double lead screw threads.

5. The device according to claim 4 wherein the external threads comprise single circumference double lead screw threads.

6. The injection device of claim 7 wherein the cannula has a gauge greater than 21.

7. The injection device of claim 1 wherein the cannula has a gauge greater than 25.

8. The injection device of claim 1 wherein the cannula has a gauge greater than 30.

9. The injection device of claim 1 wherein the cannula has a gauge of up to about 32.

10. An injection device comprising:

a syringe having a body with a piston disposed therein and a distal end;

a needle assembly comprising a cannula and a luer connector engageable with the syringe distal end, said cannula having a rounded distal tip and an outlet spaced apart from said tip, and said luer connector comprising a hub with a distal end supporting said cannula and a proximal end mateable with the syringe distal end;

a cavity, defined by a stepped interior surface of the hub, effective to prevent detachment of said hub from the syringe distal end during ejection of a viscous fluid from the cannula outlet when the hub is engaged to the syringe distal end; and

external threads disposed on an exterior surface of said hub enabling mating engagement between the hub and the syringe distal end.

11. The injection device of claim 10 wherein the cannula has a gauge greater than 21.

12. The injection device of claim 10 wherein the cannula has a gauge greater than 25.

13. The injection device of claim 10 wherein the cannula has a gauge greater than 30.

14. The injection device of claim 10 wherein the cannula has a gauge of up to about 32.

15. The injection device of claim 10 further comprising viscous fluid disposed in said body and injectable by said piston through said cannula.

16. The injection device of claim 15 wherein the fluid is a dermal filler.

17. The injection device of claim 10 further comprising internal threads disposed in the syringe distal end enabling mating engagement of the hub external threads and the syringe distal end.

18. The injection device of claim 10 wherein the external threads have a pitch of about 3 mM.

19. The device according to claim 10 wherein the external threads comprise double lead screw threads.

20. The device according to claim 10 wherein the external threads comprise single circumference double lead screw threads.