DOUBLE-CHAMBER TYPE SYRINGE BARREL

Abstract: A double-chamber type syringe barrel which contains a frozen dry powdery medicine and dissolving liquid separately from each other but, when used, injects a mixture of said powdery medicine and dissolving liquid. The conventional double-chamber type syringe barrel causes turbidity in the liquid of mixture of powdery medicine and dissolving liquid which is not appropriate for medical use, and is unsatisfactory in operability during injection operation. A double-chamber type syringe barrel of this invention eliminates drawbacks in the prior art with improved silicone coating inside the syringe barrel and modified shape of the barrel, in which: the syringe barrel (3) is coated with silicone oil solution with a concentration of 0.3 % (W/V) or under on the part of the inner wall thereof with which the frozen dry medicine is in contact, and is provided with a layer coated with silicone oil solution with a concentration of 1 % (W/V) or more on the other part of the inner wall thereof substantially out of contact with the medicine; a stopper (14) is porvided for preventing a gasket from slipping off; and finger flanges (11), (12) are provided at two positions on the barrel. In this way, turbidity caused when dissolving the frozen dry medicine with dissolving solution in the syringe barrel can be suppressed to such a degree as is permitted in using the medicine and a syringe barrel is made excellent in operability.

Description: The present invention relates to a two-compartment syringe, and more particularly to a two-compartment syringe wherein freeze-dried powder and solvent are contained in a separate state in the syringe and, in use, the freeze-dried powder and solvent are mixed for injection. There are various dosage forms for medicines. In the case of aqueous preparations such as injections, it is desirable to put them in the form of solution, which is a final form, at a time of preparation. However, not a few medical substances are unstable in dissolved state. Therefore, such medical substances are generally dissolved at a time of use and applied, that is a dissolving method in use. Further, some medical substances cannot be obtained in crystals or are highly hygroscopic. In such cases, the medical substances are often practically used in the form of freeze-dried powder. In the case of injections, for example, a method is generally used in which freeze-dried powder is placed in a vial bottle or the like, dissolved by putting a solvent thereinto, and drawn up through an injection needle. However, it is more convenient to contain the solvent and freeze-dried powder in a syringe from the beginning. For use in a surgical operation, it is necessary to take maintenance of sterilized condition into consideration particularly. Methods have been proposed in which a medical substance and solvent are contained in a syringe from the beginning, and dissolution is effected within the syringe immediately before use. Specifically, in such methods, a medical substance in the form of freeze-dried powder or the like is placed in the bottom of a syringe adjacent an injection needle connecting portion, and a solvent for the medical substance is placed in a plunger rod attaching portion of the syringe. The medical substance containing chamber and solvent containing chamber are partitioned in an appropriate way. The solvent and medical substance are mixed in an appropriate way for dissolution at a time of use (Japanese Patent Publication No. 50-4992, Japanese Patent Publication Kokai No. 60-72561, Japanese Utility Model Publication No. 49-14465). However, freeze-dried powder tends to be charged with static electricity and often is in a trace quantity. Therefore, it is not easy to place the powder in the syringe accurately. In order to improve such drawbacks, it is conceivable to carry out freeze-drying in the syringe. Usually the syringe has an inner wall coated with a silicone oil solution having a concentration of 1-5% (W/V) in order to smooth movement of gaskets and a plunger rod in use. However, there is a problem that the product becomes turbid and is not suitable as a medicine when a solution of medicine to be freeze-dried is placed in the syringe silicone-coated in the above concentration, followed by freeze-drying and then the obtained freeze-dried powder is redissolved in a solvent. On the other hand, in a known form of such a two-compartment syringe, gaskets are used to partition between the power containing chamber and solvent containing chamber and between the solvent containing chamber and ambient air, respectively, as in the publications noted above. The objects of the present invention are to provide a two-compartment syringe capable of suppressing turbidity occurring when freeze-dried powder is dissolved in a solvent to a degree not obstructive to use while maintaining movement of the gaskets and plunger rod in a smooth condition with silicone coating applied to the inner wall of the syringe. In order to achieve the above objects, a characteristic construction of the present invention lies in a two-compartment syringe having freeze-dried powder obtained by freeze-drying a solution of medicine in a syringe inverted with a needle connecting side disposed below and contained in a bottom of the syringe barrel, a containing chamber for this freeze-dried powder partitioned by an elastic first gasket inserted into said syringe barrel, a solvent for the freeze-dried powder contained between said first gasket and an elastic second gasket inserted into said syringe barrel, and a plunger rod attached to said second gasket. Such a syringe is known from EP-A-0 328 699 (JP-A-02-5973) and from EP-A-0 144 551 (JP-A-60-72561). The present invention is further characterized in that coating layers are formed on an inner wall of the syringe barrel contacted by the solution of medicine to be freeze-dried, by coating with a silicone oil solution having a concentration not exceeding 0.3% (W/V), and on an inner wall of said syringe barrel substantially out of contact with the solution of medicine, by coating with a silicone oil solution having a concentration of at least 1% (W/V). Various studies have been made to find the cause of turbidity occurring when the freeze-dried powder is dissolved in the solvent, and it has been found as a result that the turbidity is caused by the silicone coating. Then, Inventors have made intensive researches for silicone coating concentrations not causing turbidity. A relationship between concentration and turbidity of the silicone oil solution and sliding force obtained through an experiment carried out in the course of the researches is shown in Table 1 noted hereinafter. As seen from the results of the experiment, it has been found that substantially no turbidity occurs where the silicone coating has a concentration not exceeding 0.3% (W/V) (% by weight per volume). Further, it has been found that movement of the gasket and plunger rod is substantially little affected by a lowered concentration of the silicone coating for the chamber accommodating the solution of medicine to be freeze-dried, i.e. the inner wall portion of the syringe barrel contacted by the solution of medicine. Thus, a two-compartment syringe is provided in which the silicone coating concentration of the coating layers applied to the inner walls of the syringe barrel is differentiated as above to be capable of suppressing the turbidity occurring when the freeze-dried powder obtained by freeze-drying the solution of medicine in the syringe is dissolved in the solvent in the syringe for use, to a degree not obstructive to use, while maintaining movement of the gasket and plunger rod in a smooth condition. Fig. 1 is a sectional side view showing a two-compartment syringe according to a preferred embodiment of the present invention. Fig. 2 is a sectional side view showing freeze-dried powder and solvent halfway through a mixing process, Fig. 3 is a perspective overall view, Fig. 4 is an exploded perspective overall view, Figs. 5 (a) and (b) are explanatory views showing Specific Example 1 of a silicone coating treatment method. Figs. 6 (a) and (b) are explanatory views showing Specific Example 2 of the silicone coating treatment method. A two-compartment syringe embodying the present invention will be described in detail hereinafter with reference to the drawings. Figs. 1 and 2 show a two-compartment syringe in one embodiment of the present invention, and Figs. 3 and 4 show an injector having the above two-compartment syringe. A cylindrical syringe 3 having a needle connecting side 2 for connecting a needle 1 includes two elastic, first gasket 4 and second gasket 5 slidably inserted therein through an opening 3a formed at the other end of this syringe 3. The first gasket 4 and second gasket 5 are formed of cylindrical halogenobutyl rubber having a diameter slightly larger than an inside diameter of the syringe barrel 3, and provide fluid-tight seals with the inner wall of the syringe barrel 3 upon insertion into the syringe 3. Of two chambers 3A and 3B partitioned in fluid-tight condition by the first gasket 4 and second gasket 5, the first chamber 3A disposed adjacent the needle connecting side 2 contains freeze-dried powder "a" obtained by freeze-drying a solution of medicine inside the syringe 3 in an inverted posture with the needle connecting side 2 lying below. On the other hand, the second chamber 3B disposed adjacent the opening 3a contains a solvent "b" for dissolving the freeze-dried powder "a". The second gasket 5 disposed adjacent the opening 3a of the syringe 3 has a plunger rod 6 detachably screwed tight thereto for sliding the second gasket 5 axially of the syringe 3. The plunger rod 6 has a thumb rest 7 formed at the top thereof and having a flatter shape larger than the inside diameter of the syringe barrel 3. The syringe 3 includes a flange 8 projecting diametrically outwardly from an outer peripheral surface thereof at the end where the opening 3a is formed. Further, the syringe 3 includes a ridge 3C formed in an axially intermediate position thereof and bulging radially outwardly. A bypass passage 9 is provided inside the ridge 3C for intercommunicating the first chamber 3A and second chamber 3B of the syringe 3. This bypass passage 9 has a length axially of the syringe barrel which is slightly greater than an axial length of the first gasket 4 disposed adjacent the needle connecting side 2. When, as shown in Fig. 2, the first gasket 4 lies in the region of the bypass passage 9 during an operation to push in the plunger rod 6, the solvent "b" in the second chamber 3B is led into the first chamber 3A through the bypass passage 9. A plug 15 of halogenobutyl rubber is mounted in a bore formed in the needle connecting side 2 of the syringe 3, which is perforated by the needle 1 attached to the needle connecting side 2. In the two-compartment syringe constructed as above, the inner wall of the syringe barrel 3 contacted by the solution of medicine to be freeze-dried has a coating layer formed by a coating treatment with a silicone oil solution having a concentration not exceeding 0.3% (W/V). On the other hand, the inner wall of the syringe barrel 3 substantially free from contact with the solution of medicine has a coating layer formed by a coating treatment with a silicone oil solution having a concentration of at least 1% (W/V). The silicone oil solutions are prepared by dissolving silicone oil in desired concentrations in a highly volatile liquefied gas of chlorofluorocarbon (flon) or the like. While specific examples of coating treatment method will be described later, in a common method of manufacturing the syringe 3 of the present invention, the entire inner wall of the syringe barrel 3 is first coated with a silicone oil solution having a concentration not exceeding 0.3% (W/V), and then the inner wall of the syringe barrel 3 outside the part containing the solution of medicine is coated with a silicone oil solution having a concentration of at least 1% (W/V). It is of course possible to coat only the inner wall of the syringe barrel 3 containing the solution of medicine with the silicone oil solution having a concentration not exceeding 0.3% (W/V) and thereafter to coat the inner wall of the syringe barrel 3 outside the part containing the solution of medicine with the silicone oil solution having a concentration of at least 1% (W/V). However, the former is more convenient. Examples of the coating methods are a method in which the silicone oil solutions are sprayed, a method in which the solutions are drawn through the bore formed in the needle connecting side 2 of the syringe 3, and a method in which the syringe 3 is immersed in tanks of the silicone oil solutions, but not to be limited to the above methods. While the area for coating the silicone oil solution having a concentration not exceeding 0.3% (W/V) is the inner wall of the syringe barrel 3 contacted by the solution of medicine to be freeze-dried, a coating area may be slightly smaller than a surface area of the inner wall of the syringe barrel 3 contacted by the solution of medicine to be freeze-dried as long as the turbidity occurring at a time of dissolution inside the syringe 3 of the freeze-dried powder "a" obtained by freeze-drying the solution of medicine inside the syringe 3 and the solvent "b" presents no obstacle in use. In practice, it is desirable that the inner wall including the part to which the solution of medicine may splash is coated with the silicone oil solution having a concentration not exceeding 0.3% (W/V). The syringe 3 thus obtained is inverted with the needle connecting side 2 disposed below where the rubber plug 15 is inserted into and seals the bore of the needle connecting side 2, and the solution of medicine is placed and freeze-dried in the syringe 3. Next, the first gasket 4 is inserted into the syringe barrel 3, thereafter the solvent "b" is placed, and the upper end is sealed tight with the second gasket 5. In use, the plunger rod 6 is attached to the second gasket 5, and the needle 1 is attached to the needle connecting side 2 of the syringe 3. The plunger rod 6 may of course be attached to the second gasket 5 at the beginning. Specific examples of the coating treatment method will be described next. [Specific Example 1] As shown in Figs. 5 (a) and (b), the syringe 3 is inverted with the needle connecting side 2 disposed above and a silicone oil solution having a concentration of 0.1% (W/V) [a solution prepared by dissolving silicone oil (SH-200 manufactured by Toray-Dow Corning) in Flon 113 (CCl 2 F-CClF 2 : Freon TF manufactured by Mitsui Dupont Fluorochemical)] is sprayed through a nozzle 16 inserted through the opening 3a in this state. Next, a nozzle 18 carrying a partition at a top thereof is inserted through the opening 3a of the syringe 3 so that the solution will not spread to the portion contacted by the solution of medicine to be freeze-dried, and a silicone oil solution having a concentration of 3% (W/V) (prepared in the same way as the 0.1% solution) is applied to the inner wall of the syringe barrel 3 substantially free from contact with the solution of medicine, which is followed by a drying treatment. [Specific Example 2] As shown in Figs. 6 (a) and (b), the syringe 3 is inverted with the needle connecting side 2 disposed above, and immersed slightly in a tank 19 containing a silicone oil solution having a concentration of 0.1% (W/V) (prepared in the same way as in Specific Example 1 above). The silicone oil solution in the tank 19 is drawn up to the needle connecting side 2 of the syringe 3 by applying suction through the bore formed in the needle connecting side 2 of the syringe 3, Next, the tank 19 is replaced by a tank 20 containing a silicone oil solution having a concentration of 3% (W/V) (prepared in the same way as in Specific Example 1 above). The syringe 3 is again immersed slightly therein in the inverted posture with the needle connecting side 2 disposed above, and thereafter suction is applied through the needle connecting side 2 of the syringe 3. At this time, the silicone oil solution in the tank 20 is drawn up to a position just short of the section contacted by the solution of medicine to be freeze-dried, while detecting the draw-up position by means of an optical sensor 21. Thereafter the syringe 3 is removed from the tank 20 for a drying treatment. Next, Inventors have carried out an experiment to show a relationship among concentration of a silicone oil solution, turbidity and sliding force. In this experiment, a 10% aqueous solution of mannitol was used as an example of solution of medicine to be freeze-dried, and purified water as an example of solvent. The needle connecting sides 2 of the syringes 3 manufactured by the above two specific method examples were sealed tight with rubber covers, the syringes 3 were inverted with the needle connecting sides 2 disposed below, and the 10% aqueous solution of mannitol was placed and freeze-dried therein. Then the first gaskets 4 of halogenobutyl rubber were inserted into the syringes 3, and after placing purified water therein, the second gaskets 5 of halogenobutyl rubber were mounted in place Syringes containing the 10% aqueous solution of mannitol and purified water were prepared in this way. Then, observation was made of degrees of turbidity occurring when the freeze-dried powder of the 10% aqueous solution of mannitol was dissolved in the purified water, and resistance (sliding force) occurring when the plunger rod 6 was pushed down. Results of the experiment are shown in Table 1. In Table 1, "-" in the degrees of turbidity shows that no turbidity occurred, "+" shows occurrence of turbidity, and "± " shows degrees presenting no practical problem, "-" in the sliding forces shows that the plunger rod 6 was pushed down smoothly, "+" shows strong resistance, and "±" shows degrees of resistance presenting no practical problem. Silicone Coating Concentration (%) Degrees of Turbidity Sliding Force Medicine Contact Section Medicine Non-Contact Section 0.1 0.1 - + 0.3 0.3 ± + 0.5 0.5 + + 0.1 1.0 - ± 0.1 2.0 - - 0.1 5.0 - - 1.0 1.0 + ± 5.0 5.0 + - It has been found from these results of the experiment that the syringe 3 in accordance with the present invention is obtained by silicone coating the solution of medicine contact section in a concentration not exceeding 0.3% (W/V) and silicone coating the solution of medicine non-contact portion in a concentration of 1% or more (W/V), preferably in a concentration of 1-5% (W/V). Other embodiments are shown below. (1) In the foregoing embodiment, the silicone coating concentration for the inner wall of the syringe barrel 3 contacting the solution of medicine is set to a value not exceeding 0.3% (W/V). However, where the solution of medicine is in a small quantity, hardly any obstacle substantially occurs to movement of the gaskets 4 and 5 and plunger rod 6 without the silicone coating. In other words, the concentration not exceeding 0.3% (W/V) in the claims set out hereinbefore includes 0%. (2) Application of the syringe 3 according to the present invention is not limited by the type of solution of medicine, but covers all solution of medicines to be freeze-dried for use. (3) In the foregoing embodiment, the silicone oil solutions having predetermined concentrations are prepared by adding silicone oil to a liquefied gas of chlorofluorocarbon (flon) or the like. Instead of using chlorofluorocarbon, silicone oil suspended in water may be used. Further, there is no specific limitation to silicone oil used as long as it is applicable to the syringe barrel interior, and may be dimethylpolysiloxane, cyclic polydimethylsiloxane or the like. (4) In the foregoing embodiment, the solvent in the second chamber 3B is led to the freeze-dried powder in the first chamber 3A through the bypass passage 9 formed in the syringe barrel 3. However, the first gasket 4 itself may include a valve structure for leading the solvent in the second chamber 3B to the freeze-dried powder in the first chamber 3A when the plunger rod 6 is pushed in. In short, any structure may be used as long as it is capable of leading the solvent in the second chamber 3B to the freeze-dried powder in the first chamber 3A when the plunger rod 6 is pushed in.

Claims: A two-compartment syringe having freeze-dried powder (a) obtained by freeze-drying a solution of medicine in a syringe (3) inverted with a needle connecting side (2) disposed below and contained in a bottom of said syringe barrel (3), a containing chamber for this freeze-dried powder (a) partitioned by an elastic first gasket (4) inserted into said syringe barrel (3), a solvent (b) for said freeze-dried powder (a) contained between said first gasket (4) and an elastic second gasket (5) inserted into said syringe barrel (3), and a plunger rod (6) attached to said second gasket (5), characterized in that coating layers are formed on an inner wall of said syringe barrel (3) contacted by the solution of medicine to be freeze-dried, by coating with a silicone oil solution having a concentration not exceeding 0.3% (W/V), and on an inner wall of said syringe barrel (3) substantially out of contact with the solution of medicine, by coating with a silicone oil solution having a concentration of at least 1% (W/V). A two-compartment syringe as set forth in claim 1, wherein said silicone oil solutions are solutions prepared by dissolving silicone oil in chlorofluorocarbon (flon).

Inventors: KUSU YUKIO, UEMURA OSAMU, KUSU, YUKIO, UEMURA, OSAMU
Applicants: SANTEN PHARMA CO LTD, SANTEN SEIYAKU KABUSHIKI KAISHA
Application year: 1991
Main classification: A61M5
IPC codes: A61M5