Syringe

Abstract: A syringe (K1) comprising: a tubular body (1) which is provided, at its front end portion, with a portion for mounting an injection needle (10) thereon and opens at its rear end portion so as to have a rear end opening (1b); a gasket (2) for sealing the rear end opening (1b) of the tubular body (1), which is slidably inserted into the tubular body (1); and a plunger rod (3) which is detachably coupled with a rear end portion of the gasket (2) through the rear end opening (1b) of the tubular body (1); wherein a male screw (31) is formed at a front end portion of the plunger rod (3) and is circumferentially alternately divided into at least one male screw portion (31b) and at least one first recess portion (31a) ; wherein a female screw (21) is formed on a rear end face (2a) of the gasket (2) and is circumferentially alternately divided into at least one female screw portion (21b) and at least one second recess portion (21a); wherein in a state where the male screw portion (31b) and the first recess portion (31a) of the male screw (31) are, respectively, fitted into the second recess portion (21a) and the female screw portion (21b) of the female screw (21), the male screw (31) is rotated relative to the female screw (21) so as to be brought into engagement with the female screw (21) such that the plunger rod (3) is coupled with the gasket (2).

Description: The present invention generally relates to syringes and more particularly, to throwaway syringes such as disposable syringes and prefilled syringes, which are discarded after a single administration. In particular, the invention relates to a syringe comprising a tubular body which is provided, at its front end portion, with a portion for mounting an injection needle thereon and opens at its rear end portion so as to have a rear end opening; a gasket for sealing the rear end opening of the tubular body, which is slidably inserted into the tubular body; a plunger rod which is detachably coupled with a rear end portion of the gasket through the rear end opening of the tubular body; and an engageable projection member at a front end portion of the plunger rod. In the disposable syringes, injection liquid is not preliminarily filled in a tubular body and is sucked from an injection needle into the tubular body at the time of use by fixing the injection needle to the tubular body. Meanwhile, the prefilled syringes are classified into an ordinary type prefilled syringe in which injection liquid is preliminarily filled in a tubular body and a two-component type prefilled syringe in which by dividing a tubular body into two compartments by a movable sealing member, powder medicament, solid medicament such as microcapsules, granules and tablets or liquid medicament is filled in one of the compartments and vehicle such as dissolving agent and dispersing agent is filled in the other of the compartments such that the medicament and the vehicle are mixed with each other at the time of use by displacing the sealing member. As one example of the throwaway syringes such as the disposable syringes and the prefilled syringes, which are discarded after a single administration, a prefilled syringe is known from Japanese Patent Publication No. 49-14465 (1974) as shown in Figs. 1 to 3. In Figs. 1 to 3, a needle mounting portion for mounting an injection needle is provided at a front end portion of a tubular body 100 and a plunger rod 101 coupled in advance with a gasket 103 is inserted into the tubular body 100 from a rear opening of the tubular body 100 such that the prefilled syringe is used by pushing the plunger rod 101 into the tubular body 100. In the known prefilled syringe, a movable sealing member 102 is fitted into the tubular body 100 so as to divide interior of the tubular body 100 into first and second compartments 104A and 104B. Medicament is filled in the first compartment 104A, while dissolving agent is filled in the second compartment 104B. By pushing the plunger rod 101 into the tubular body 100, the sealing member 102 is advanced, so that the dissolving agent in the second compartment 104B is carried into the first compartment 104A through a bulge portion 105 so as to be mixed with the medicament in the first compartment 104A. By further pushing the plunger rod 101 into the tubular body 100, the mixed liquid is discharged from the injection needle fixed to the front end portion of the tubular body 100. In the known prefilled syringe referred to above, since the plunger rod projects out of the tubular body, such problems arise that the plunger rod may be inadvertently pushed during storage or on the market and space occupied by the known prefilled syringe is increased. Therefore, recently, in order to solve these problems, such a method is employed in which the plunger rod is separated from a syringe body formed by the tubular body during storage and on the market, while the plunger rod is fixedly coupled with a gasket mounted in the tubular body at the time of use. In order to secure the plunger rod to the gasket, it has been a common practice that a male screw is formed at a distal end of the plunger rod and is screwed into a female screw formed on a rear end face of the gasket. Meanwhile, in place of this conventional coupling practice based on threaded engagement, a syringe is proposed in Japanese Utility Model Laid-Open Publication No. 6-39005(1994) as shown in Figs. 4 and 5. In this prior art syringe, a rearwardly opening hollow 112 is formed on a rubber gasket 111 at a rear portion of a tubular body 110 and a reinforcing member 113 made of synthetic resin is fitted into the hollow 112. Furthermore, a cover 115 having a paid of opposed fitting slots 114 is formed integrally with the reinforcing member 113. On the other hand, a pair of opposite blade plates 117 are provided on outer periphery of a front portion of a plunger rod 116 and are inserted into the hollow 112. Then, by rotating the plunger rod 116, rear end portions of the blade plates 117 are fitted into the fitting slots 114 so as to bring the blade plates 117 of the plunger rod 116 into engagement with the fitting slots 114 of the cover 115 such that the plunger rod 116 is coupled with the gasket 111. However, in the known syringe in which the plunger rod is screwed into the gasket so as to be secured to the gasket, it is time-consuming to secure the plunger rod to the gasket. Furthermore, in case the plunger rod is screwed into the gasket out of alignment with the gasket, hermetic property of the gasket may be disrupted. If hermetic property is disrupted in the prefilled syringe, such a problem as leakage of medicament out of the tubular body arises. Therefore, in order to secure the plunger rod to the gasket, due care should be exercised to substantially bring the plunger rod into alignment with the gasket at all times. Meanwhile, in the prior art syringe, a rather large force is required for rotating the plunger rod 116 in order to fit the rear end portions of the blade plates 117 into the fitting slots 114. Therefore, a large frictional force is produced between the plunger rod 116 and inner periphery of the tubular body 110. Namely, sliding property of the plunger rod 116 relative to the tubular body 110 is downgraded, thereby resulting in deterioration of functions of the prior art syringe. On the other hand, in the prior art syringe of Figs. 4 and 5, since the resinous reinforcing member is embedded in the rubber gasket, such inconveniences are incurred that construction of the prior art syringe is complicated, thereby resulting in rise of its production cost. Meanwhile, both the plunger rod and the reinforcing member are made of synthetic resin and thus, have rigidity. Therefore, even if the blade plates and the fitting slots are brought out of alignment with each other only a little, the blade plates cannot be inserted into the fitting slots, so that the blade plates are brought into contact with the cover so as to depress the cover. As a result, the gasket is displaced forwardly and thus, the plunger rod may not be coupled with the gasket easily. A further syringe incorporating a plunger rod which is detachably coupled to a rear end portion of the gasket through the rear end opening of the tubular body of the syringe and which has an engageable projection member on a front end portion of the plunger rod is known from US patent 5 201 709. SUMMARY OF THE INVENTION In accordance with the invention, the syringe is characterised in that the engageable projection member protrudes radially outwardly so as to have a predetermined circular angle; and wherein a hollow for receiving the engageable projection member is formed on a rear end face of the gasket and a flange member having a recess means for inserting the engageable projection member of the plunger rod therethrough projects radially inwardly from a periphery of a mouth of the hollow so as to accommodate the engageable projection member. This construction can provide, with a view to eliminating the above mentioned drawbacks of the conventional syringes, a syringe in which a plunger rod having excellent sliding property relative to a tubular body can be positively secured to a gasket easily with least possibility of disruption of hermetic property of the gasket and operation of administering injection liquid after securing of the plunger rod to the gasket and operation of sucking the plunger rod so as to ensure that an injection needle is not stuck in a blood vessel in the case of hypodermic injection and intromuscular injection can be performed positively in the same manner as prior art. It is preferable that the engageable projection member includes a pair of engageable projections and the flange member includes a pair of flanges such that the recess means includes a pair of recesses formed between the flanges. Meanwhile, the number of the engageable projections is not restricted to two. Thus, three, four or more engageable projections may be formed at a regular angular interval, while the corresponding number of the recesses for receiving the engageable projections, respectively are formed on the gasket. In the above syringe, when the plunger rod is rotated after the plunger rod has been inserted into the hollow by bringing the engageable projections of the plunger rod into alignment with the recesses of the gasket, the engageable projections are retained by the flanges and thus, cannot be drawn out of the hollow. As a result, the plunger rod is coupled with the gasket. Also in the syringes of the present invention, the gasket may be made of elastomer or rubber, while the plunger rod is made of a plastics material. The present invention can also be applied to an ordinary type prefilled syringe in which the tubular body injection liquid is preliminarily stored between the front end portion of the tubular body and the gasket. Meanwhile, the present invention can be suitably applied to a so-called two-component type prefilled syringe in which at least one movable sealing member is inserted into the tubular body as to be disposed between the front end portion of the tubular body and the gasket such that interior of the tubular body is divided by the sealing member into first and second compartments disposed at the front end portion and the rear end portion of the tubular body respectively. Specific medicament is stored in the first compartment, while liquid vehicle such as dissolving agent and dispersing agent is stored in the second compartment such that at the time the sealing member is depressed by the gasket through the plunger rod so as to be slidably displaced in the tubular body, the liquid vehicle in the second compartment flows into the first compartment via a bulge portion formed on a side wall of the first compartment. The above two-component type prefilled syringe preferably further comprises an engagement means for temporarily stopping advance of the plunger rod at a first position where the front end portion of-the plunger rod has been inserted into the gasket and at a second position where the sealing member has been depressed by the plunger rod through the gasket secured to the plunger rod so as to be advanced beyond a front end of the bulge portion. Specifically, a finger grip is mounted on the tubular body in the vicinity of the rear end portion of the tubular body and is formed with a protrusion projecting radially inwardly from an inner periphery of the tubular body, while a projection member is formed at a predetermined position of an outer periphery of the plunger rod such that advance of the plunger rod is temporarily stopped through contact of the projection member of the plunger rod with the protrusion of the finger grip. Thus, when the plunger rod is rotated relative to the finger grip, the projection member of the plunger rod is brought out of contact with the protrusion of the finger grip so as to enable advance of the plunger rod. More specifically, the protrusion of the finger grip is of an annular shape having a through-hole at its center and a pair of radially extending slots are formed on the finger grip so as to open to a periphery of the through-hole. The plunger rod includes a rod portion having a crossed sectional shape formed by a vertical frame and a horizontal frame, while the rod portion extends from a position of the plunger rod spaced a predetermined distance from the front end portion of the plunger rod to a rear end portion of the plunger rod and is divided into a front region, an intermediate region and a rear region. In the front region, the vertical frame and the horizontal frame are of such external shapes as to be inserted through the through-hole. Meanwhile, in the intermediate region, the horizontal frame is of such an external shape as to be inserted through the through-hole, while the vertical frame is of such an external shape as not to be inserted through the through-hole but to be inserted through the slots. Furthermore, in the rear region, the vertical frame is of such an external shape as to be inserted through the through-hole, while the horizontal frame is of such an external shape as not to be inserted through the through-hole but to be inserted through the slots. By the above described arrangements of the syringe of the present invention, when the front end of the plunger rod is inserted into the rear end opening of the tubular body, the engageable projection member provided at the front end of the plunger rod can be inserted, via the central through-hole of the finger grip, into the hollow of the gasket. At this insertion position, advance of the plunger rod is temporarily stopped through engagement of the front end of the intermediate region of the plunger rod with the protrusion of the finger grip. Therefore, at the time of coupling of the plunger rod with the gasket, such a phenomenon can be prevented that the gasket itself is advanced by the pushing force of the plunger rod. When the plunger rod is rotated through 90° in this temporary stop state of the plunger rod, a corresponding one of the frames is brought into alignment with the slots, so that the plunger rod can be further inserted into the tubular body and thus, the gasket can be pushed by the plunger rod so as to be advanced. When the movable sealing member is advanced to the bulge portion upon forward travel of the gasket, the medicament and the liquid vehicle separated from each other by the sealing member can be mixed with each other. When not only the sealing member has been advanced to a front end of the bulge portion but the gasket has been displaced to a rear end of the bulge portion, a corresponding one of the frames of the plunger rod is brought into engagement with the protrusion of the finger grip such that advance of the plunger rod is temporarily stopped. When the plunger rod is rotated through 90° in this temporary stop state of the plunger rod, the corresponding one of the frames retained by the protrusion of the finger grip is brought into alignment with the slots and thus, the plunger rod can be further inserted into the tubular body. As a result, the plunger rod is further advanced so as to forwardly feed the sealing member, so that the mixed injection liquid is discharged from the injection needle mounted on the front end of the tubular body so as to be administered to a living body. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention will now be described in detail, by way of example, with reference to the accompanying drawings, in which:- Figs. 1 to 3 are sectional views showing a prior art prefilled syringe at different pushing strokes of a plunger rod, respectively (already referred to) ; Fig. 4 is a fragmentary sectional view of another prior art syringe (already referred to); Fig. 5 is a rear end view of a gasket in the prior art syringe of Fig. 5 (already referred to); Fig. 6 is a rear end view of a gasket employed in a two-component type prefilled syringe according to a third embodiment of the present invention; Fig. 7 is a partly sectional front elevational view of the gasket of Fig. 6 ; Fig. 8 is a partly sectional fragmentary front elevational view of the prefilled syringe of Fig. 6 ; Fig. 9 is a side elevational view of a finger grip employed in the prefilled syringe of Fig. 8 ; Fig. 10 is a front elevational view of a plunger rod employed in the prefilled syringe of Fig. 8 ; Fig. 11 is a left side elevational view of the plunger rod of Fig. 10; Figs. 12, 13 and 14 are sectional views taken along the lines XXIII-XXIII, XXIV-XXIV and XXV-XXV in Fig. 10, respectively; Fig. 15 is a fragmentary sectional view showing coupling of the plunger rod of Fig. 10 with the gasket of Fig. 6 ; and Fig. 16 is a partially sectional view of an ordinary type prefilled syringe to which the present invention may be applied. Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings. DETAILED DESCRIPTION OF THE INVENTION The drawings show a two-component type pre-filled syringe having a generally tubular body 1. The tubular body 1 has a substantially uniformly cylindrical shape except for a bulge portion 1c to be described later. Opposite ends of the tubular body 1 open as a front end opening 1a and a rear end opening 1b, respectively. The front end opening 1a is sealed by a sealing member 7 fitted into inner periphery of the front end opening 1a and a cap 9 acting also as a member for holding a double-pointed needle 10 is fitted around outer periphery of the front end opening la. Meanwhile, a finger grip 11 is fitted around outer periphery of the rear end opening 1b of the tubular body 1. The gasket 2 is slidably inserted into the tubular body 1 in the vicinity of the rear end opening 1b so as to seal the rear end opening 1b. At least one movable sealing member 4 is also slidably inserted into the tubular body 1 between the gasket 2 and the sealing member 7. Thus, interior of the tubular body 1 is divided by the movable sealing member 4 into first and second compartments 5 and 6 disposed at front and rear portions of the tubular body 1, respectively. Powdery medicament P is stored in the first compartment 5, while liquid vehicle L such as dissolving agent and dispersing agent is stored in the second compartment 6. The bulge portion 1c is formed on a side wall of the first compartment 5 of the tubular body 1 so as to project outwardly from the side wall of the first compartment 5 over a predetermined width. An axial length L1 of the bulge portion 1c is so set as to be larger by a predetermined dimension than an axial thickness W1 of the movable sealing member 4 and smaller than a sum of a thickness W2 of the gasket 2 and the axial thickness W1 of the movable sealing member 4, namely, W1<L1<W1+W2. The gasket 2, the movable sealing member 4 and the sealing member 7 are made of rubber or elastomer. A plurality of annular ribs are provided on outer periphery of each of the gasket 2, the movable sealing member 4 and the sealing member 7 and are brought into pressing contact with inner periphery of the tubular body 1 so as to ensure sufficient sealing. Figs. 6 to 15 show a two-component type prefilled syringe K3 according to the present invention. In the prefilled syringe K3, a small-diameter rod portion 350 is provided at the front end of the base 3a of the plunger rod 3 and a pair of opposite sectoral engageable projections 351 each having a sectoral or circular or round angle of 90° are formed at a front end of the small-diameter rod portion 350 so as to extend radially outwardly. A pair of opposite ribs 352 extending from a rear end of the engageable projections 351 to the base 3a of the plunger rod 3 are provided on outer periphery of the small-diameter rod portion 350 so as to be disposed slightly circumferentially outwardly of the engageable projections 351. The plunger rod 3 is made of rigid plastics such as polypropylene or semirigid plastics. On the other hand, a rearwardly opening hollow 210 is formed on the gasket 2 and a pair of radially inwardly projecting flanges 212 having a central through-hole 211 extend from a mouth of the hollow 210 to periphery of the hollow 210. As shown in Fig. 6, a pair of sectoral recesses 213 each having a predetermined sectoral angle of 90° are formed between the flanges 212. The flanges 212 are not formed up to the bottom face of the hollow 210 and thus, a receiving space 215 having a circular cross section is formed in the hollow 210 so as to receive a pair of the engageable projections 351 and a portion of the small-diameter rod portion 350 of the plunger rod 3. Thus, by rotating the plunger rod 3 after a pair of the engageable projections 351 of the plunger rod 3 have been, respectively, inserted through the recesses 213 of the gasket 2 so as to be received in the receiving space 215, the engageable projections 351 are fitted into the receiving space 215 so as to be gripped between the bottom face of the hollow 210 and an inner face of the flanges 212. At this time, in order to prevent the plunger rod 3 from being rotated excessively, the ribs 352 are brought into contact with edges of the flanges 212, respectively so as to stop rotation of the plunger rod 3. As a result, the plunger rod 3 is coupled with the gasket 2. Therefore, a depth F of the receiving space 215 is so set as to be equal to or slightly larger than an axial length G of the engageable projections 351. The gasket 2 including the flanges 212 as a whole is integrally formed from rubber or elastomer. Meanwhile, as shown in Fig. 8 , a pair of opposite ribs 400 having a function identical with that of the ribs 352 may be provided on the bottom of the hollow 210 of the gasket 2 in place of or in addition to the ribs 352. Namely, when the plunger rod 3 is rotated after the engageable projections 351 have been inserted into the hollow 210 through the recesses 213, the engageable projections 351 are brought into contact with the ribs 400, respectively such that rotation of the plunger rod 3 is stopped. Furthermore, as shown in Fig. 9 , a finger grip 11 is attached to a rear end of the tubular body 1 and has a protrusion 110a radially inwardly projecting from inner periphery of the tubular body 1. The protrusion 110a is of an annular shape having a through-hole 110b at its center and a pair of opposed radially extending slots 110c for receiving a vertical frame 361 or a horizontal frame 362 of a rod portion 360 of the plunger rod 3 to be described later are formed at predetermined locations of periphery of the through-hole 110b of the finger grip 11 so as to open to the through-hole 110b. The plunger rod 3 is inserted into the tubular body 1 from the rear end opening through the through-opening 110b of the protrusion 110a of the finger grip 11. At this time, in order to temporarily stop the plunger rod 3 at a first position where the plunger rod 3 is coupled with the gasket 2 and at a second position where the medicament is mixed with the dissolving agent upon advance of the movable sealing member by pushing the plunger rod 3 in a state of coupling between the plunger rod 3 and the gasket 2, the plunger rod 3 is shaped as shown in Figs. 21 to 25. Namely, the rod portion 360 extends continuously from the rear end of the base 3a of the plunger rod 3 and includes the vertical frame 361 and the horizontal frame 362 so as to have a crossed sectional shape. A diameter of the base 3a is larger than a diameter R1 of the engageable projections 351 and is smaller than a diameter R2 of the through-hole 110b of the finger grip 11. Furthermore, as shown in Fig. 12, the vertical frame 361 and the horizontal frame 362 in a front region S1 of the rod portion 360 have a diameter r1 equal to that of the base 3a such that a front portion of the plunger rod 3, which extends from the engageable projections 351 to the front region S1 of the rod portion 360, can be passed through the through-hole 110b of the finger grip 11. As shown in Fig.13, in an intermediate region S2 of the rod portion 360 abutting on the front region S1, the horizontal frame 362 has the diameter r1 but the vertical frame 361 has a diameter r2 larger than the diameter r1. Thus, the vertical frame 361 cannot be passed through the through-hole 110b but can be inserted through the finger grip 11 when the vertical frame 361 is aligned with the slots 110c by rotating the plunger rod 3 through about 90°. Furthermore, as shown in Fig. 25, in a rear region S3 of the rod portion 360 adjoining rearwardly the intermediate region S2, the vertical frame 361 has the diameter r1 but the horizontal frame 362 has the diameter r2. Therefore, if the horizontal frame 362 is aligned with the slots 110c by rotating the plunger rod 3 through about 90°, the horizontal frame 362 can be inserted through the finger grip 11. The large-diameter push plate 3d is provided at a rear end of the rear region S3. When the plunger rod 3 is coupled with the gasket 2 in order to use the prefilled syringe K3 of the above described arrangement, the front portion of the plunger rod 3 is inserted into the tubular body 1 from the rear end opening via the through-hole 110b of the finger grip 11. At this time, the plunger rod 3 is oriented such that the vertical frame 361 extends orthogonally to the lateral slots 110c. Therefore, when the engageable projections 351 disposed at the front end of the plunger rod 3 and the front region S1 of the rod portion 360 have been inserted through the through-hole 110b of the finger grip 11 and then, the front end of the intermediate region S2 of the rod portion 360 reaches the finger grip 11, the plunger rod 3 is stopped. Thus, the plunger rod 3 is inserted into the tubular body 1 and the engageable projections 351 are aligned with the recesses 213 of the gasket 2 as described above. When the engageable projections 351 have reached the receiving space 215 in the hollow 210 beyond the flanges 212 so as to be fitted into the receiving space 215, the plunger rod 3 is rotated until the ribs 352 come into contact with the edges of the flanges 212 such that the engageable projections 351 are retained by the flanges 212. As a result, the engageable projections 351 cannot be drawn out of the hollow 210 and thus, the plunger rod 3 is coupled with the gasket 2. Since the depth F of the receiving space 215 is substantially equal to the axial length G of the engageable projections 351, the plunger rod 3 and the gasket 2 have substantially no axial play in the coupling state of Fig. 15 and thus, the gasket 2 is positively moved together with the plunger rod 3 in response to longitudinal travel of the plunger rod 3. Meanwhile, at the time the engageable projections 351 of the plunger rod 3 have been fitted into the receiving space 215 of the hollow 210 of the gasket 2, the front end of the intermediate region S2 of the rod portion 360 of the plunger rod 3 reaches the finger grip 11. At this time, the vertical frame 361 of the rod portion 360 is brought into contact with the protrusion 110a of the finger grip 11 such that insertion of the plunger rod 3 into the tubular body 1 is temporarily stopped. Since insertion of the plunger rod 3 into the tubular body 1 is temporarily stopped when the plunger rod 3 has been inserted into the tubular body 1 to such a position as to be coupled with the gasket 2, the gasket 2 is not pushed by the plunger rod 3 and thus, it becomes possible to positively prevent such a phenomenon that in a state where the gasket 2 is not sufficiently coupled with the plunger rod 1, the gasket 2 is pushed by the plunger rod 3 so as to be advanced in the tubular body 1. When the engageable projections 351 of the plunger rod 3 have been fitted into the receiving space 215 of the gasket 2 such that the plunger rod 3 is temporarily stopped by the finger grip 11 as described above, the plunger rod 3 is rotated through 90°. By this rotation of the plunger rod 3, the engageable projections 351 are brought into engagement with the flanges 212. As a result, not only the plunger rod 3 is positively coupled with the gasket 2 but the vertical frame 361 of the plunger rod 3 is oriented laterally so as to be aligned with the slots 110c of the finger grip 11. Accordingly, the plunger rod 3 can be further advanced in the tubular body 1. Thus, the intermediate region S2 of the plunger rod 3 is passed through the finger grip 11 so as to be further pushed into the tubular body 1 in the coupling state between the plunger rod 3 and the gasket 2. When the gasket 2 is advanced, the movable sealing member 4 is advanced by liquid pressure of the liquid vehicle L filled in the second compartment 6 defined between the gasket 2 and the movable sealing member 4. Therefore, the liquid vehicle L in the second compartment 6 is forced into the first compartment 5 through the bulge portion 1c and thus, the powdery medicament P in the first compartment 5 is mixed with the liquid vehicle L. At the time a first half portion of the movable sealing member 4 is advanced beyond the bulge portion 1c and a last half portion of the gasket 2 is held in close contact with inner periphery of the tubular body 1 without reaching the bulge portion 1c, the front end of the rear region S3 of the plunger rod 3 reaches the finger grip 11. At this time, the horizontal frame 362 of the rear region S3 of the plunger rod 3 is brought into contact with the protrusion 110a of the finger grip 11 and thus, the plunger rod 3 is temporarily stopped by the finger grip 11. At this time, length of the intermediate region S2 is set such that the sealing member 4 is disposed forwardly of a front end of the bulge portion 1c. Accordingly, thereafter, back-flow of the mixed liquid does not happen in the bulge portion 1c. In this state, the tubular body 1 is shaken so as to promote mixing between the powdery medicament P and the liquid vehicle L. Subsequently, the plunger rod 3 is rotated through 90° so as to bring the horizontal frame 362 of the rear region S3 into alignment with the slots 110c of the finger grip 11 such that the plunger rod 3 can be further advanced in the tubular body 1. Hence, the rear region S3 of the plunger rod 3 is passed through the finger grip 11 so as to be pushed into the tubular body 1 and thus, the mixed liquid stored in the first compartment 5 defined between the front end of the tubular body 1 and the movable sealing member 4 is delivered from the prefilled syringe K3 so as to be administered to a living body. As described above, the engagement means is provided between the plunger rod 3 and the finger grip 11. Thus, when the plunger rod 3 has been inserted into the tubular body 1 through a dimension necessary for coupling the plunger rod 3 with the gasket 2, the plunger rod 3 is stopped temporarily. Furthermore, in a state where the liquid vehicle L in the second compartment 6 has been carried to the first compartment 5, the plunger rod 3 is stopped temporarily. Accordingly, operation of coupling the plunger rod 3 with the gasket 2, operation of mixing the liquid vehicle L with the powdery medicament P and operation of administering the mixed liquid (injection liquid) can be performed quite separately. The prefilled syringe of the present invention is not restricted to the above described embodiment but, needless to say, can be modified to an arrangement in which a cap carrying an injection needle is mounted on the tubular body in place of the double-pointed needle. Furthermore, the above mentioned embodiment of the present invention is applied to a two-component type prefilled syringe. However, it goes without saying that the present invention can be likewise applied to an ordinary type prefilled syringe in which injection liquid Q is preliminarily filled in the tubular body 1 as shown in Fig. 16 and a disposable syringe in which injection liquid is not preliminarily stored in the tubular body 1. Namely, the present invention can be properly applied to an arrangement in which at the time of use, the plunger rod is coupled with the gasket fitted preliminarily into the tubular body. Furthermore, in the syringe according to the present invention, since the engageable projections provided at the front end of the plunger rod are inserted into the hollow of the gasket through the recesses of the gasket, there is no resistance against insertion of the plunger rod into the hollow of the gasket and thus, the plunger rod can be inserted into the hollow of the gasket without applying any load to the gasket. Meanwhile, if the plunger rod is rotated through the predetermined angle after the plunger rod has been inserted into the hollow of the gasket, the engageable projections of the plunger rod are retained by the flanges of the gasket and thus, the plunger rod can be positively coupled with the gasket. As a result, the syringe having a favorable balance between liquid tightness and sliding property can be obtained. Meanwhile, the present invention can be properly applied to not only an ordinary type prefilled syringe but a two-component type prefilled syringe. During storage and transport of the syringe of the present invention, since the plunger rod is separated from the tubular body, the syringe of the present invention is not bulky and thus, space occupied by the syringe of the present invention can be reduced. Furthermore, during storage and transport of the syringe of the present invention, since the plunger rod is separated from the tubular body, such a phenomenon can be prevented positively that the plunger rod is inadvertently pushed so as to displace the gasket. In addition, in the syringe according to the present invention, since the engagement means is provided between the plunger rod and the finger grip attached to the rear end of the tubular body, the plunger rod to be inserted into the hollow of the gasket can be temporarily stopped at the predetermined position. If the plunger rod is temporarily stopped at the time the front end of the plunger rod has been inserted into the hollow of the gasket, such a phenomenon can be prevented positively at the time of coupling of the plunger rod with the gasket that the gasket is pushed by the plunger rod so as to be displaced in the tubular body.

Claims: A syringe (K3) comprising: a tubular body (1) which is provided, at its front end portion, with a portion for mounting an injection needle (10) thereon and opens at its rear end portion so as to have a rear end opening (1b); a gasket (2) for sealing the rear end opening (1b) of the tubular body (1), which is slidably inserted into the tubular body (1); and a plunger rod (3) which is detachably coupled with a rear end portion of the gasket (2) through the rear end opening (1b) of the tubular body (1); and an engageable projection member (351) characterised in that the engageable projection member (351) protrudes radially outwardly at a front end portion of the plunger rod (3) so as to have a predetermined circular angle; and wherein a hollow (210) for receiving the engageable projection member (351) is formed on a rear end face (2a) of the gasket (2) and a flange member (212) having a recess means (213) for inserting the engageable projection member (351) of the plunger rod (3) therethrough projects radially inwardly from a periphery of a mouth of the hollow (210) so as to accommodate the engageable projection member (351). A syringe (K3) as claimed in Claim 1, wherein the engageable projection member includes a pair of engageable projections (351) and the flange member includes a pair of flanges (212) such that the recess means includes a pair of recesses (213) formed between the flanges (212). A syringe (K3) as claimed in Claim 1, wherein the gasket (2) is made of elastomer or rubber, while the plunger rod (3) is made of a plastics material. A syringe (K3) as claimed in Claim 1, wherein in the tubular body (1) injection liquid (Q) is preliminarily stored between the front end portion of the tubular body (1) and the gasket (2). A syringe (K3) as claimed in any of Claims 1 to 4 further comprising: at least one movable sealing member (4) which is inserted into the tubular body (1) so as to be disposed between the front end portion of the tubular body (1) and the gasket (2) such that the interior of the tubular body (1) is divided by the sealing member (4) into first and second compartments (5, 6) disposed at the front end portion and the rear end portion of the tubular body (1), respectively; wherein specific medicament (P) is stored in the first compartment (5), while liquid vehicle (L) such as dissolving agent and/or dispersing agent is stored in the second compartment (6) such that at the time the sealing member (4) is depressed by the gasket (2) via the plunger rod (3) so as to be slidably displaced in the tubular body (1), the liquid vehicle (L) in the second compartment (6) flows into the first compartment (5) via a bulge portion (1c formed on a side wall of the first compartment (5). A syringe as claimed in Claim 5, further comprising: an engagement means (360, 110b, 110c) for temporarily stopping advance of the plunger rod (3) at a first position where the front end portion of the plunger rod (3) has been inserted into the hollow (210) of the gasket (2) and at a second position where the sealing member (4) has been depressed by the plunger rod (3) through the gasket (2) secured to the plunger rod (3) so as to be advanced beyond a front end of the bulge portion (1c). A syringe as claimed in Claim 6, wherein a finger grip (11) is mounted on the tubular body (1) in the vicinity of the rear end portion of the tubular body (1) and is formed with a protrusion (110a) projecting radially inwardly from an inner periphery of the tubular body (1), while a projection member (361, 362) is formed at a predetermined position of an outer periphery of the plunger rod (3) such that advance of the plunger rod (3) is temporarily stopped through contact of the projection member (361, 362) of the plunger rod (3) with the protrusion (110a) of the finger grip (11); wherein when the plunger rod (3) is rotated relative to the finger grip (11), the projection member (361, 362) of the plunger rod (3) is brought out of contact with the protrusion (110a) of the finger grip (11) so as to enable advance of the plunger rod (3). A syringe as claimed in claim 7, wherein the protrusion (110a) of the finger grip (11) is of an annular shape having a through hole (110b) at its center and a pair of radially extending slots (110c) are formed on the finger grip (11) so as to open, to a periphery of the through-hole (110b); wherein the plunger rod (3) includes a rod portion (360) having a crossed sectional shape formed by a vertical frame (361) and a horizontal frame (362); wherein the rod portion (360) extends from a position of the plunger rod (3) spaced a predetermined distance from the front end portion of the plunger rod (3) to a rear end portion of the plunger rod (3) and is divided into a front region (S1), an intermediate region (S2) and a rear region (S3); wherein in the front region (S1), the vertical frame (361) and the horizontal frame (362) are of such external shapes as to be inserted through the through-hole (110b); wherein in the intermediate region (S2), the horizontal frame (362) is of such an external shape as to be inserted through the through-hole (110b), while the vertical frame (361) is of such an external shape as not to be inserted through the through-hole (110b) but to be inserted through the slots (110c); wherein in the rear region (S3), the vertical frame (361) is of such an external shape as to be inserted through the through-hole (110b), while the horizontal frame (362) is of such an external shape as not to be inserted through the through-hole (110b) but to be inserted through the slots (110c). A syringe as claimed in Claim 1, wherein a first rib (352) projects from a rear portion of the engageable projection member (351) of the plunger rod (3); wherein when the plunger rod (3) is rotated after the engageable projection member (351) has been inserted into the hollow (210) through the recess means (213), the first rib (352) is retained by an edge of the flange member (212) so as to stop rotation of the plunger rod (3). A syringe (K3) as claimed in Claim 1 or 9, wherein a second rib (400) is provided in the hollow (210) of the gasket (2); wherein when the plunger rod (3) is rotated after the engageable projection member (351) has been inserted into the hollow (210) through the recess means (213), the engageable projection member (351) is retained by the rib (400) so as to stop rotation of the plunger rod (3).

Inventors: MATSUDA TERUMI, TANAKA NOBUO, MATSUDA, TERUMI, TANAKA, NOBUO
Applicants: TAKEDA CHEMICAL INDUSTRIES LTD, TAKEDA CHEMICAL INDUSTRIES, LTD.
Application year: 1995
Main classification: A61M5
IPC codes: A61M5