FR2561925A3 - Disposable device for injecting predetermined and successive quantities of a medicine - Google Patents

Abstract

A device for injecting predetermined successive quantities of a medicine comprises a hollow cylinder 1 of which the lower end is adapted for the positioning of a double-ended hollow needle; a plunger rod 5, housed so as to slide and rotate in the said cylinder 1; as well as a pre-filled container 23 which is used as a fluid container for delivering the fluid which it contains. The cylinder 1 has a notched slide 7 provided with several slits which are respectively longitudinal and transverse. The said rod 5 is fitted with a guiding stud which engages in the said slide 7 of the cylinder and interacts with several projecting stop elements on the wall of the said cylinder 1.

Description

DISPOSABLE DEVICE FOR INJECTING PREDETERMINED QUANTITIES
AND SUCCESSIVE OF A DRUG
The present invention relates to a disposable device for administering successive predetermined amounts of a drug-containing liquid. This injection device is designed, in principle, like a hypodermic syringe, but it differs from it in that it makes it possible to deliver a predetermined quantity of the available drug, that it contains a separate reservoir, and that it dispenses very precise doses.

 Using a conventional syringe is relatively tedious, since it is necessary to draw each dose to be injected into the syringe, to verify that this syringe contains the correct amount, and then to inject said dose. Care should also be taken to expel the entire amount of air from the syringe before injecting.

 Syringes for administering successive predetermined quantities of a liquid are known, for example, from patents GB-1,517,462 and FR-1,156,296. These syringes however suffer from several drawbacks. Since they are intended to be refilled with the fluid to be injected, it is not possible to avoid an admission of air when filling these syringes. In addition, known syringes cannot dispense with necessary precautions consisting in expelling all the air present in the syringe by expelling a small quantity of liquid before each injection, or else do not allow the successive delivery of several doses without having first checked and carefully checked each time the point of departure, since a retrograde movement of the plunger is not prevented after it has been previously put in position to advance the piston. Problems inherent in hygiene and sterilization can also arise from the fact that the known syringes do not contain a separate reservoir containing the injection fluid, but trap this injection fluid in the internal space of the cylinder, between the piston and the lower end of this cylinder.

 Another notable disadvantage affecting known syringes consists in that the fluid to be injected is stored in the syringe for a long period, without it being possible to determine the compatibility between the fluid to be injected and the material constituting the syringe. This compatibility differs from one injection fluid to another # and must be determined for each specific preparation and for each material used for the syringe.

 An object of the present invention to provide a disposable injection device eliminating the aforementioned drawbacks, this device can be used to inject successive predetermined doses of a drug from a pre-filled reservoir contained by said device.

 The compliant injection device. the invention comprises a hollow cylinder, the lower part of which is suitable for putting in place: a hollow double-pointed needle, as well as a piston rod housed in sliding and rotation in said cylinder.

 The hollow cylinder is designed to enclose in its lower region a pre-filled reservoir to serve as a fluid reservoir for dispensing the fluid in question, and this cylinder is provided, in its lower region, with a threaded needle appendage supporting a hollow needle with double point which penetrates into the pre-filled tank and into the fluid.

 The cylinder is furthermore provided with a slot slide comprising several slots arranged longitudinally and delimiting a predetermined number of doses of medicament, as well as inclined transverse slots which communicate with two longitudinal slots, said transverse slots being inclined by approximately 20 per relative to the radial plane of the cylinder; both the longitudinal slots and the transverse slots are provided with stop elements which protrude beyond the wall of the cylinder and engage in the slot slide. The piston rod has a guide pin projecting outwards, which penetrates into the slotted cylinder slide and cooperates with the stop elements in this slide. Because the piston rod bears against a sliding piston housed in the reservoir, a progression of the said rod certainly pushes the said piston forward and expels the fluid out of the reservoir via the hollow double-pointed needle.

 The pre-filled reservoir is preferably a pre-filled cartridge and advantageously consists of a cartridge of a type known in the prior art and typically comprising a tube (made of glass) hermetically sealed at one of its ends by a diaphragm or a membrane intended to be perforated by the rear end of a hollow double-pointed needle, the other end of this tube being hermetically sealed by a stopper which is intimately fitted in said tube, but can slide there. This plug takes the form of a piston which runs the length of the tube and expels the fluid out of this tube through the needle. When using such a cartridge as a reservoir in the lower part of the hollow cylinder , the needle perforates the diaphragm and the piston rod bears against the sliding plug-piston, so as to express the fluid via the needle as said rod advances.

The use of a cartridge pre-filled as a reservoir in the injection device is advantageous, in that it allows-to administer a sterile injection fluid without the need to transfer this fluid beforehand. from any storage container to said tank. The use of a pre-filled cartridge also guarantees the presence of a closed system, safe from infection when the needle has been removed between two injections.

 In a preferred embodiment of the invention, the needle used in the injection device is a double-ended needle, mounted in a needle holder in the form of a cup whose internal face of the wall is tapped, of so that this needle holder can be screwed onto a threaded zone provided for this purpose at the lower end of the cylinder. Advantageously, the needle holder can be replaced from time to time as required.

The invention will now be described in more detail by way of non-limiting examples, with reference to the appended drawings in which
Figure 1 is a longitudinal section of the injection device, along the line AA of Figure 2
Figures 2 and 3 are side elevations of two embodiments of this injection device
Figure 4 is a side elevation of the cylinder of Figure 2
Figure 5 is a side elevation of the piston rod; and
Figure 6 is a side elevation of an embodiment of the device, showing in more detail the notched slide and the stop elements.

 A hollow cylinder 1 is provided at its upper end with a gripping rim 3 and, at its lower end, with a threaded appendage 2 with needle allowing the establishment of a needle holder 13 having the shape of a cup, and provided with a plug 21 in which a needle 12 is fixed and through which this needle 12 extends right through. The cup-shaped needle holder 13 is tapped on the internal face of its wall, so that it can be screwed onto the threaded appendage 2 with a needle. In the upper part, the hollow cylinder 1 also has a slide 7 with slots of stepped configuration, which extends longitudinally on this cylinder as illustrated in FIG. 2. This slide 7 comprises several slots 9 arranged longitudinally and, on the one hand and on the other side of each longitudinal slot, inclined transverse slots 8 communicating with two longitudinal slots. These transverse slots 8 are inclined by about 20 relative to the radial plane of the cylinder, and can occupy from about 750 to about 900 of the circumference of this cylinder. Furthermore, said cylinder is provided with a stop element 11 which protrudes beyond the wall of the cylinder and engages either in the longitudinal slots or in the transverse slots of the slide 7.

 The preferred configuration of the slide 7 is illustrated in FIG. 2. Another possible configuration of this slide is shown in FIG. 3.

 In its lower region, the cylinder has a window 14 allowing the inspection of a cartridge 23. As shown in FIG. 1, a window can be made on the opposite sides of the cylinder.

 The injection device also has a piston rod 5.

This rod 5 is slidably and rotatably housed inside the cylinder 1, and is equipped with a guide pin 10 projecting outwards, which penetrates the slot 7 with slots of the cylinder 1 and cooperates with the elements stop 11.

 Figure 5 shows a preferred embodiment of the piston rod. This rod has an upper region 18 whose cross section corresponds to the cavity of the hollow cylinder, so that the upper part of this piston rod is in sliding contact with the internal face of the cavity of the cylinder. In its lower region 19, the piston rod has a cross section corresponding to the upper opening of the cartridge 23 housed in the lower end of the cylinder 1 (see FIG. 1), an extreme rear end 20 of said rod bearing against a piston 6 incorporated in said cartridge.

 The guide pin 10 provided on the piston rod 5 preferably has a rectangular configuration corresponding to the configuration of the slot slide 7, and is certainly applied by sliding against opposite zones of the wall of said slide when a rotation or a forward push is printed on the piston rod in the direction of an arrow 22 in FIG. 2 or 3. At its upper end, this rod is provided with a flange 16 making it possible to manually push said rod towards the front, in the direction of arrow 22.

 The cartridge 23 (see FIG. 1) is a pre-filled cartridge of a type known in the prior art, consisting of a tube 4 made of hermetically sealed glass> at one of its ends, by a diaphragm or membrane 17 intended to be pierced by the rear side of the hollow needle 12 with double point and hermetically closed, at its other end, by the piston-stopper 6 intimately adjusted, but sliding.

 The injection device according to the present invention is delivered to the patient with the pre-filled cartridge inserted into the cylinder and the piston rod 5 occupying its extreme external position as illustrated in FIG. 1. An involuntary retraction of this piston rod prior to use is prevented - by means of an elastic projection 15 extending downwards from the underside of the grip rim 3, as illustrated in FIG. 2. When the device is assembled, the piston rod is introduced so that its guide pin 10 comes into engagement with the upper part of the notched slide, then it is pushed from top to bottom. The elastic projection 15 allows movement of the guide pin forward, but prevents involuntary retraction of the piston rod, because said stud is suddenly stopped by this projection 15 if an attempt is made to retract said rod. In this way, a system is obtained which certainly prohibits false maneuvers. A inadvertent forward movement of the piston rod before the first injection is prevented by a first stop element 11a (illustrated in FIGS. 2 and 4) which, together with the projection 15, blocks the guide stud in its starting position.

 In service, the needle holder 13 provided with the needle 12 is installed on the threaded appendage 2 to the needle. Then, the piston rod is pressed forward so as to release the stop member 11a, after which it is given a rotation during which the guide pin moves transversely along the first inclined transverse slot , until it reaches the posterior end of this first transverse slot. This rotation of the piston rod, during which the stud runs along the inclined transverse slot, causes said rod to advance in the longitudinal direction, by a distance corresponding to the inclination of approximately 20 of the transverse zone of the slide. Because this progression of the rod causes the piston 6 to advance into the cartridge, a small amount of liquid and / or air likely to be in the system is certainly expelled. Consequently, the rotation of the piston rod prior to injection rids the system of its air in a very convenient manner. The device is now ready for injection, which is indicated by an audible click generated mechanically when the guide pin crosses a stop element. It is not necessary to check or check the starting point before injection, because a retrograde movement of the piston rod is prohibited since the guide pin is prevented from moving back by the stop it located in the first transverse slot.

 During the injection, the piston rod is moved in the longitudinal direction by grasping the grip flange 3 by two fingers, placing the thumb on the collar 16 and exerting, using this thumb, a pressure from top to bottom on the piston rod 5. This rod is then moved longitudinally by a distance corresponding to the length of the first longitudinal zone of the slide, until the guide pin is stopped by the rear end of this longitudinal zone, and that a corresponding quantity medication contained in the cartridge is delivered through the needle.

 At the same instant, an audible click is heard when the guide pin crosses the next stop element, which assures the user that an injection has been delivered. The above process is repeated for the next injection, that is to say that the piston rod is rotated, then moved in the longitudinal direction by a distance corresponding to the next longitudinal area of the slide.

 Between two injections, both rotation and retraction of the piston rod are prohibited, because the guide pin is blocked between two stop elements, as shown in Figure 2. After replacing the needle beforehand on the next injection, a rotation is imparted to the piston rod by pushing U forcibly the guide pin beyond the stop element extending up and down in the transverse slot, so that a any amount of air is expelled as described above.

The result is a 100% air-free system, which eliminates the risk of air embolism by intravenous injection.

The stop elements preferably consist of elastic protuberances molded integrally with the cylinder wall and having a configuration which allows the guide pin to pass a stop element from the rear to the front. , but prohibits its retrograde movement. The preferred configuration of the stop elements is shown in FIG. 6. The latter does not, however, illustrate the preferred embodiment of the upper region of the notched slide, comprising the elastic projection 15
As is apparent from the above description, the injection device according to the invention makes it possible, on the basis of a very simple principle, to inject successive predetermined quantities of the drug. This device, consisting for example of a plastic material, is very simple to manufacture and can compete with usual disposable syringes, because it can be used for several injections. In addition, a sterile fluid is delivered directly to the patient, since the device is supplied with a pre-filled cartridge. In addition, since the injection fluid is administered to the patient in a standardized pre-filled cartridge, there is no problem of compatibility between the injected fluid and the material constituting the device. The use of a cartridge for performing successive injections using a disposable device has not been described previously.

 It is obvious that the present invention is not limited to the embodiments described above and illustrated in the drawings.

Thus, the stop elements can be arranged differently and the slide can have a configuration different from those shown in FIGS. 2 and 3.

 It therefore goes without saying that numerous modifications can be made to the device described above, without departing from the scope of the invention.

Claims (3)

RFVENDIGATIONS  1. Disposable device for injecting, using a needle, successive predetermined quantities of a liquid containing a medicament, device characterized in that it comprises a hollow cylinder (1) whose lower end is adapted to the placement of a hollow needle (12) with double point, as well as a piston rod (5) housed in sliding and rotation in said cylinder (1), this cylinder being designed to contain in its lower region a reservoir pre-filled (23) to serve as a fluid reservoir for delivering the fluid it contains; by the fact that said cylinder (1) is provided, in its lower region, with a needle appendage (2) supporting a hollow needle (-12) with double point which penetrates into said pre-filled reservoir C239 and into the fluid ; by the fact that said cylinder (1) is moreover provided with a slot slide (7) comprising several slots (9) arranged longitudinally and several inclined transverse slots (8) which communicate with two longitudinal slots, these transverse slots (8 ) being inclined by about 20 relative to the radial plane of the cylinder (1), both the longitudinal slots (9) and the said transverse slots (8) being provided with stop elements (11) projecting beyond from the wall of the cylinder (1) and engaging in the slot slide (7); and by the fact that the piston rod (5) has a guide pin (10) which projects outwards, penetrates into said slot slide (7) formed in the cylinder (1) and cooperates with the elements of stop (11) in this slide, said rod (5) bearing against a sliding piston (6) housed in said pre-filled reservoir (23), so that the progression of this rod in the longitudinal direction, accompanied by a movement of said guide pin (10) along a longitudinal slot (9), undoubtedly pushes said piston (6) forward by a predetermined distance corresponding to the length of a longitudinal slot (9), and expels a corresponding amount of fluid out of said reservoir (23), via said hollow double-pointed needle (12).  2. Device according to claim 1, characterized in that the stop elements (11, lia) consist of elastic protrusions integrally molded with the wall of the cylinder (1).  3. Device according to claim 1, characterized by the tool fact contains a reservoir consisting of a pre-filled cartridge (23) hermetically sealed, which is in the form of a tube (4) filled with a liquid and provided, at one of its ends, a diaphragm (17) which can be perforated by a hollow needle (12) with a double point and, at its other end, with a sliding plug or piston (6); and by the fact that the piston rod (5) bears against said piston (6), so that the progression of this rod (5) certainly pushes said piston (6) forward and expels the fluid contained by said cartridge (23).