CA2321906A1

CA2321906A1 - Device for hypodermic injection without needle of a medicine in liquid form

Info

Publication number: CA2321906A1
Application number: CA 2321906
Authority: CA
Inventors: Tino Dalto
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-03-03
Filing date: 1999-03-03
Publication date: 1999-09-10
Also published as: WO1999044658A1; FR2775603A1; FR2775603B1; AU3257599A; EP1064036A1

Abstract

The invention concerns a device comprising an injecting head (9) defining a chamber (11) capable of containing a volume of said medicine, the tubular body (10) being closed, at one end, by a transverse wall (12) traversed by microchannels (131, 132) emerging on an external surface of the head (9). At the other end, the body is closed by a mobile plunger (15). Means are provided for filling the chamber (11) and forcing the medicine outside the injecting head (9), through the microchannels (131, 132). The invention is characterised in that the filling means comprise a) means (25) for temporarily closing the microchannels (131, 132) and b) a passage (26) for injecting a medicine into the head (9), said passage being equipped with a non-return valve (32) preventing the medicine from leaking outside the passage at all.

Description

DEVICE FOR HYPODERMIC INJECTION WITHOUT NEEDLE OF A MEDICINE IN LIQUID
FORM
The present invention relates to a device for sub-cutaneous injection of a liquid medication without using a needle. It relates more particularly to a device of the above kind of the type which comprises a) an injection head consisting of a tubular body delimiting a chamber adapted to contain a volume of said medication and closed at one end by a transverse wall through which passes at least one microchannel opening onto an outside face of the head designed to be applied to the skin of a patient and at the other end by a piston mobile axially in said chamber, b) means for filling the chamber, and c) means for acting on said piston to force said medication out of the injection head via said microchannels.
A device of the above type is disclosed in international patent application WO 95/24176, which concentrates more particularly on the means for filling the chamber of the injection head with a volume of the medication to be administered. As shown in figure 1 of the appended drawing, those means essentially comprise a device 1 formed of a tubular cylindrical body 2 containing a cartridge 3 filled with medication and equipped at one end with a piston 4 that can slide in the cartridge 3 when pressure is applied to it by an operating rod 5 projecting from one end of the body. The other end of the cartridge 2 is closed by a seal 6.
The end of the body 2 opposite the end 5 is closed by a bush 7 through which passes axially a hollow needle 8 opening into the interior of the tubular body 1.
In a first position (not shown in figure 1), the cartridge 3 is spaced from the tip of the needle 8, which therefore does not pass through the seal 6. To discharge its contents into an injection head 9 mounted on the bush 7, the cartridge is pushed toward the needle 8 which pierces the seal and penetrates the cartridge, which at this time bears against the bush 7, as shown in figure 1. The contents of the cartridge 3 are then emptied into the injection head through the needle 8 by applying axial thrust to the actuator rod 5 of the piston 4.
The filling means described in WO 95/24176 are suitable for an injection head comprising a nozzle pierced with a single channel for discharging its contents after filling and through which the medication is forced to form a jet of medication which penetrates the skin of a patient by virtue of its momentum alone. The injection head is filled through this single channel, whose diameter is normally very small, for example of the order of a few hundred microns. Clearly this small diameter limits the flowrate of the medication into the injection head when filling it, which can take a long time.
An injection head known in the art which uses no needle comprises, like the head 9 shown in figure 1 of the accompanying drawing, a tubular body 10 delimiting a chamber 11 adapted to contain a volume of the medication and closed at one end by a transverse wall 12 through which pass microchannels 131, 132, etc parallel to the axis X
of the injection head. The channels open onto an external face 14 of the head designed to be applied to the skin of a patient to administer to the patient the medication contained in the chamber 11. The pain felt by the patient during administration is reduced by distributing the medication in this way through a plurality of microchannels which have a small diameter, for example a diameter less than 200 wm.
The other end of the injection head 9 is closed by a piston 15 mobile inside the chamber 11 along the axis X. A propulsion mechanism 16 which receives the injection head 9 can suddenly drive the piston 15 toward the wall 12 of the head, thereby forcing the liquid contained in the head through the microchannels 13;
and through the skin of a patient, to which the outside face of that wall is applied. In this case the filling device 1 is obviously separate from the injection head.
The means for filling a single microchannel injection head of the type described in WO 95/24716 are not suitable for fast filling of a head with multiple microchannels of the type shown in figure 1 of the accompanying drawing.
The object of the present invention is precisely to provide a device for sub cutaneous injection of a liquid medication without using a needle and including means for filling an injection head with said medication which does not have the disadvantages of the prior art devices and which in particular fills said head quickly.
The object of the invention, together with others that will become apparent in the course of the following description, is achieved by a device for sub-cutaneous injection of a liquid medication without using a needle of the type described in the preamble of this description, which device is noteworthy in that the means for filling the head of the device comprise means for temporarily blocking at least one microchannel for injecting the medication and at least one passage through a wall of the injection head, adapted to cooperate with a cartridge of medication to allow the head to be filled with a volume of medication from the cartridge and equipped with check valve means for preventing said medication leaking out of said head through said passage.
As emerges in more detail later, the above passage can have dimensions enabling the injection head to be filled quickly, in contrast to what happens when the head is filled through the microchannel(s) for injecting the medication under the skin of 3 5 a patient.
Other features and advantages of the present invention will become apparent on reading the following description and referring to the accompanying drawing, in which:
figures 1 and lA show one embodiment of a device according to the invention already described in part in the preamble of this description, and figures 2, 2A and 3 show variants of the injection head of a device in accordance with the invention.
Figure 1 of the accompanying drawing shows, assembled in a linear arrangement along an axis X, a device 1 for filling an injection head 9 of an injection device in accordance with the invention mounted on the filler device and a propulsion mechanism 16 which is cocked manually and designed to actuate the injection head 9 to administer medication contained in the head. It is clear that at the time of actuation the filler device 1 must be demounted from the head to enable its external face 14 to be applied to the skin of a patient, which is then opposite the outlets of the microchannels 13;, which can also take the form of microslots. Similarly, the propulsion mechanism 16 is not mounted on the head 9 when filling the head.
The propulsion mechanism 16 injects under the skin of a patient medication previously loaded into the chamber 11 of the head 9 by the filling means in accordance with the present invention described in more detail later. The propulsion mechanism essentially comprises a cylindrical tubular body 17 in which slides a ram 18 spring-loaded by a spring 19. Balls 201, 202, etc spring-loaded by springs 211, 21z, etc in a 2 0 groove on the outside surface of the body 10 of the injection head 9 fix the latter removably to the propulsion mechanism 16. The ram 18 can be immobilized in a top position (as seen in figure 1), away from the head 9, by means that are not shown.
Pressing a trigger button 23 releases the ram 18 which is propelled suddenly by the compressed spring 19 toward the piston 15 of the head 10 without compressing the intermediate volume of air 24 (which is not sealed) and drives the piston 15 of the head 9 at constant speed toward the end of the head. The medication contained in the chamber 11 then exits the chamber at constant pressure, in the form of a spray, and penetrates under the skin of a patient to which the surface 14 of the head is applied, the skin of the patient taking the place of the device shown in figure 1 for filling the head.
The present invention is precisely concerned with new means for filling the head 9 quickly with medication to be administered in spray form.
In a first embodiment of those means, shown in figure 1, the filler means comprise means 25 for temporarily blocking the microchannels 13;, an axial passage 26 through the center of the wall 12 of the injection head, and a housing 27 between the ends of the passage 26 shaped to accommodate a tongue 28 of complementary shape (see figure lA).
The bush 7 mounted on the filling device 1 comprises an axial nozzle 29 which projects from the end of the bush and through the passage 26 and opens into the chamber 11 of the head 9 when the latter is mounted on the bush to be filled with medication. To this end the needle 8 passes axially through the nozzle 29.
The microchannels of the head 9 are advantageously distributed symmetrically about the axis of symmetry of the head. By way of illustrative and non-limiting example only, there can be two or more microchannels which can have a diameter of 100 to 300 ~.m, in a ratio to the diameter of the chamber 11 of 1/20 to 1/100.
According to one feature of the injection head according to the invention, a particular ratio is chosen between the diameter of the microchannels and the diameter of the cylindrical internal chamber 11 containing the liquid medication solution to guarantee the formation of a spray rather than a painful concentrated jet. The ratio is from 1/20 to 1/100 but must remain within the linear range of the propulsion mechanism and preserve a small overall size of the injection head to guarantee that it can be manufactured in the traditional way. The liquid to be injected must have a kinematic viscosity less than 3 centistokes, given the increase in pressure at the time thrust is applied to the liquid by the piston 15.
Good results have been obtained with a chamber 11 with a diameter of 8 mm and microchannels with a diameter of 200 microns (0.2 mm), in which case the 2 0 ratio is 8/0.2 = 40/1.
European patent EP 0 367 677 with the same applicant describes an injection head in which the liquid to be expelled under pressure enters oblique channels at an angle to one another and opening onto a rounded concave surface, producing turbulence and additional head losses. In contrast to that practice, in accordance with the invention, and to prevent any head loss, it is necessary to pass directly and without intermediate diameters from the inside diameter of the cylindrical chamber to that of the microchannels.
According to the invention, the microchannels are no longer at an angle to one another, must be perpendicular to the inside face of the chamber 11 and to the plane outside face 14 of the injection head which is in contact with the skin of the patient, and must be strictly parallel.
This feature is fundamental because it conditions the perfect regularity of the resulting spray. Similarly, any defect in terms of perpendicularity would be reflected in poor diffusion against the skin of the patient and much of the sprayed solution would escape from the sides of the injection head applied to the skin. The injection of the whole of the prescribed dose and effective treatment of the patient by the medication would not be guaranteed.

The microchannels have a length equal to 5 to 10 times their diameter to prevent them bursting at the time of the injection and to prevent risk of injury.
The microchannels must also be perfectly cylindrical to guarantee at their outlet a perfect well aligned spray. This rules out fabrication techniques such as some 5 laser beams (which act on the material in the manner of small torches), because the resulting holes would be irregular. Microdrilling is currently the most reliable technique.
The head is then filled with a volume of medication in the following manner.
With the device 1 separated from the head, axial pressure is applied to the operating rod 5 of the piston 4 of the cartridge 3 of medication placed in the device 1 to bring the seal 6 of the cartridge into contact with the needle 8, which then pierces the seal, as already explained. Axial movement of the cartridge 3 ends when the cartridge abuts against the bush 7. The medication fills the needle 8, expelling the air previously contained in it.
The head 9 is then fitted to the bush 7 of the filling device 1. To this end the bush 7 includes spring claws 301, 302, etc which engage an annular shoulder farmed on the injection head 9. The blocking means 25 are installed at the end of the bush to block the microchannels 131, 132 when the nozzle 29 passes through the passage 26.
Further movement of the piston 4 into the cartridge empties the latter into the chamber 11 of the injection head 9. The piston 15 of the injection head moves from an initial position in which it bears on the end of the chamber, in contact with the nozzle 29, to a final position defined by the quantity of medication received. This procedure ensures that the chamber 11 contains only medication and not unwanted air. Because of the blocking means 25, the medication injected into the chamber 11 cannot escape from it via the microchannels 131, 132.
Clearly the quantity of medication injected into the chamber 11 can be precisely varied by various means known in the art, for example by micrometer adjustment of the travel of the piston 4 in the cartridge 3. The head 9 can also be transparent and graduated for this purpose.
With the head filled with a metered quantity of medication and the nozzle 29 removed from the passage 26, in accordance with the present invention, the tongue 28 is inserted into the housing 27 to prevent the medication contained in the chamber escaping from it via the passage 26, which is now blocked by the tongue, which thus constitutes a check device. In the embodiment shown in figure 1 by way of example only, the wall 12 of the head 9 incorporates a transverse passage constituting the housing 27 and whose cross section in the plane of the drawing conforms to that of the tongue 28.
The head 9 can then be removed from the filling device 1 and installed on the propulsion mechanism 16.
If there is a risk of loss of medication by capillary action in the microchannels 131, 132, the blocking means 25 remain at the outside ends of the microchannels. Those means can then take the form of a peel-off adhesive film applied to the face 14 of the injection head. In this case, the seal can be applied before filling the head. It is then removed just before administering the medication. The presence of this seal also satisfies hygiene requirements.
According to the invention, it is the diameter D of the injection needle 8 which limits the flowrate of the medication into the chamber 11 when it is being filled, not that of the very fine microchannels 131, 132, because the latter are not used for filling, in contrast to what is described in WO 95/24176. The diameter D can then be chosen so that filling can be carried out as quickly as required. For example, the diameter D can be in the order of 1 mm, whereas the diameter of the microchannels 131, 132 is of the order of 100 to 300 wm.
It is now clear that the embodiment of the invention shown in figures 1, lA
achieves the stated object. Note, however, that using a removable tongue 28 which must be installed in the head after filling it makes this embodiment somewhat difficult to use. Using a tongue of this kind can also give rise to sealing problems during injection of the medication, because of the high pressure in the chamber 11 at this time.
Figures 2, 2A and 3 shown variants of the above embodiment adapted to solve these problems. In these figures, reference numbers identical to those used in figure 1 correspond to identical or similar items or units.
In the figure 2 variant, the tongue 28 of the figure 1 embodiment is replaced by a check valve 32, which is shown in more detail in figure 2A, Where it is clear that the valve comprises a central stem 33 and a transverse flexible skirt 34. The central stem is designed to be forced into the passage 26 with the skirt 34 pressed against an inside face of the end wall 12 of the injection head 9 by the pressure of the medication contained in the chamber 11. However, the skirt 34 is flexible and can be lifted off that inside face by the pressure of the liquid medication injected through the nozzle 29 projecting axially from the end of the bush 7, to allow the medication to enter the chamber 11 when filling the head 9. To this end, the stem 33 carries splines 351, 352, etc between which are formed spaces through which the medication passes around the stem 33. This arrangement is well known in the art for this type of valve.
Accordingly, the medication, pushed into the needle 8 in the direction of the arrow F by device of the type shown in figure 1 can pass through the valve 32 into the chamber 11. When the chamber 11 has been filled with a metered quantity of the medication to be administered, the valve 32 prevents the medication flowing out again through the central passage 26. The microchannels 131, 132 are blocked by means 25 analogous to those described with reference to figure 2.
This variant accelerates filling and can facilitate automation of filling, because it eliminates the operation of inserting the tongue 28 of the embodiment shown in figures l, lA, after filling the chamber 11. Also, the skilled person knows how to make skirt-type valves providing the required seal at the high pressures encountered in the chamber 11 of the head 9 during injection of the medication.
In the figure 3 variant, the valve 32, which is identical to that of the figure 2 variant, is introduced into a passage 26' formed along the axis of the piston 15 instead of in the end 12 of the head 7.
The nozzle 29 is modified so that it can hook onto the piston 15 during filling. For this purpose it has a ring of spring claws 361, 362, etc adapted to hook removably into a groove in an annular housing 37 of the piston 15. In this position, the nozzle 29 can expel a volume of medication that enters the chamber 11 by a mechanism analogous to that described with reference to figures 2, 2A. A
stopper 38 equipped with blocking means 25 is then applied to the face 14 of the head 9.
The figure 3 variant simplifies the structure of the wall of the head 9 because the arrangements needed to accommodate the check valve are transferred to the piston 15.
It is clear that the figure 1 embodiment, like the figure 2 and 3 variants, enables either manual filling of the injection head with the medication just before administering the medication to a patient or automatic filling in the factory, in which case the heads are shipped ready for use. It is also clear that the figure 2 and 3 variants are better suited to fast filling of the injection heads than the figure 1 embodiment, for the reasons indicated above.
Of course, the invention is not limited to the embodiments described and shown, which are described and shown by way of example only. Accordingly, although the invention has been described in its application to an injection head including a plurality of microchannels, it is obviously applicable to an injection head including only one medication injection microchannel. Equally, check valves other than those described above, for example ball valves, can be used. Thus a self-healing material tongue can be substituted for the tongue 28 shown in figure 1. In this case the tongue is permanently installed on the head, before filling the head. When the head is fitted to the filling device, a needle of the same type as the needle 8 pierces the self-healing tongue to enable the medication to flow into the head. On removing the head from the device, the needle is removed from the tongue, which "heals" itself automatically, preventing any return flow of the liquid. By shaping this tongue appropriately, the high pressure applied by the medication to the scar in the tongue during administration of the medication does not re-open the scar, but instead closes it more strongly.
Equally, the cartridge can be replaced by a flask containing the liquid medication or by any other form of packaging, the bush 7 being adapted accordingly.
For automatic filling in the factory, an appropriate automated system renders the operation repetitive at a high rate of throughput in order to obtain injection heads prefilled with a predetermined dose and shipped in sterile packaging.
It is also possible to check the volume of medication in the internal chamber 11 visually if the injection head 9 is transparent and graduated like a syringe. This simplifies filling it.
In a disposable version, the head can be made from a material that can be injection molded. In a non-disposable version, the head can be made of steel and sterilized before use. The valve is still disposable and interchangeable in this case.
According to another feature of the invention, in some applications, in particular in the specific and particular field of vaccination, total puncturing of the skin is not required.
In this case, it is necessary to carry out a superficial injection into the surface layer of the skin, like "scarification". To this end, it is sufficient to replace the microchannels 13; with microslots whose characteristics are within the following tolerances, depending on the product used and its kinematic viscosity, which is again less than 3 centistokes, as well as the required effect, the pressure again being constant. For example, a microslot can have a width from 10 w to 500 w, a length from 100~to5000wandadepthfrom 100~.to5000w.

Claims

1. A device for sub-cutaneous injection of a liquid medication without using a needle, which device comprises a) an injection head (9) consisting of a tubular body (10) delimiting a chamber (11) adapted to contain a volume of said medication and closed at one end by a transverse wall (12) through which passes at least one microchannel (13 1, 13 2) opening onto an outside face of the head (9) designed to be applied to the skin of a patient and at the other end by a piston (15) mobile axially in said chamber, b) means for filling the chamber, and c) means (16) for acting on said piston (15) to force said medication out of the injection head (9) via said microchannels (13 1, 13 2), which device is characterized in that said filling means comprise b1) means (25) for temporarily blocking said microchannel and b2) at least one passage (26) through a wall of said injection head (9), adapted to cooperate with a cartridge (3) of medication to allow said head (9) to be filled with a volume of medication from the cartridge (3) and equipped with check valve means (28; 32) for preventing said medication leaking out of said head (9) through said passage (26).

2. A device according to claim 1, characterized in that said check valve means comprise a tongue (28) adapted to block said passage (26) and installed in the passage (26) after filling said chamber (11) of the injection head (9).

3. A device according to claim 1, characterized in that said check valve means (32) comprise a central stem (33) adapted to be forced into the passage (26) with passages between said stem and the wall of said passage (26) and a flexible skirt (34) extending transversely to the axis of said stem (33) and be mobile between a position in which it blocks said passage (26) because of the pressure of the medication contained in the chamber (11) and another position in which it opens said passage (26) because of the pressure of the medication entering that chamber during filling thereof.

4. A device according to either claim 2 or claim 3, characterized in that said passage (26) is formed in said end wall (12) of the injection head.

5. A device according to either claim 2 or claim 3, characterized in that said passage (26') is in said piston (15) moving in said chamber (11) of said injection head (9).

6. A device according to any of claims 1 to 5, characterized in that said blocking means (25) comprise a peel-off adhesive seal applied to the outside face (14) of the head (9) onto which one end of said microchannel (131, 132) opens.

7. A device according to claim 1, characterized in that said check valve means comprise a ball valve.

8. A device according to claim 1, characterized in that said check valve means comprise a tongue made from a material that can be pierced by a needle forming part of said filler means for injecting said medication into the chamber (11) and that heals itself automatically on withdrawing said needle.

9. A device according to any of claims 1 to 8, characterized in that said head (9) comprises a plurality of microchannels (13 1, 13 2).

10. A device according to any of claims 1 to 9, characterized in that it comprises a propulsion mechanism (16) for pushing the medication out of the injection head (9) by operating on the piston (15) and operating in a linear range to guarantee a constant pressure and constant spraying of the medication through the microchannels (13 1, 13 2).

11. A device according to claim 9, characterized in that said head (9) is removable.

12. A device according to claim 11, characterized in that said microchannels (13 1, 13 2) have a diameter of 100 to 300 µm in a ratio to the diameter of the chamber (11) of 1/20 to 1/100.

13. A device according to claim 12, characterized in that to guarantee a good spray the head is filled with liquid medication having a kinematic viscosity less than about 3 centistokes.

14. A device according to any of claims 11 to 13, characterized in that the inside and outside faces (14) of the wall (12) through which the microchannels (13 1, 13 2) pass are parallel.

15. A device according to claim 14, characterized in that the diameter of the microchannels (13 1, 13 2) is constant throughout their passage through the wall (12).

16. A device according to either claim 14 or claim 15, characterized in that the axes of the microchannels (13 1, 13 2) are perpendicular to the inside and outside faces of the wall (12).

17. A device according to any of claims 14 to 16, characterized in that the outside face (14) of the wall (12) is perfectly plane.

18. A device according to any of claims 11 to 17, characterized in that the microchannels (13 1, 13 2) are perfectly cylindrical.

19. A device according to any of claims 11 to 18, characterized in that the microchannels (13 1, 13 2) have a length 5 to 10 times their diameter.

20. A device according to any of claims 11 to 19, characterized in that the axes of the microchannels (13 1, 13 2) are parallel to the axis of the chamber (11).

21. A device according to any of claims 11 to 20, characterized in that the components of the head are injection molded.

22. A device according to any of claims 11 to 21, characterized in that the microchannels (13 1, 13 2) take the form of microslots whose width, length and depth are respectively in the ranges 10 to 500 µm, 100 to 5 000 µm and 100 to 5 000 µ.