TWO COMPARTMENT SYRINGE AND METHOD OF MANUFACTURING

Abstract: The invention is dealing with a two compartment syringe having at least two by-passes (35,36) which allow an easy flow from one compartment (a) to the other compartment (b). Preferably the liquid (injection fluid) is in the "needle" compartment (a) and the solid medicament is in the "plunger" compartment (b).

Description: The present invention is directed to a two compartment syringe and more particularly to a two compartment syringe provided with a so-called by-pass. Injectable medicaments often show a rapid loss of potency when they are in their ready to use form. A solution of this problem is found in applying a two compartment syringe system, one compartment containing the solid medication (either in powder form or preferably in lyophilised form) and the other compartment containing the injection fluid. The oldest two compartment system usually consists of two vial with pierceable stoppers. However, this two vials system commonly presents problems with respect to sterility since only the interior of the vials are sterile and bacteria from the exterior of the vials may easily be introduced into the medication during the mixing procedure. The two compartment syringes as described is U.S. patent 2,607,344 and US-A-4 613 326 therefor embody a major improvement over the two vial system. The above-mentioned US-A-4 613 326 more particularly discloses a two compartment medication syringe that comprises: 1. a barrel having a chamber for retaining medication; 2. a tip extending from a distal end of said barrel having a passageway therethrough communicating with said chamber, said tip including means for accepting a hypodermic needle; 3. a by-pass stopper slidably positioned in fluid-tight engagement inside said barrel; 4. a raised peripheral portion of said barrel serving as a by-pass and defining a by-pass, said by-pass zone being longer along the longitudinal axis of said barrel than the length of said by-pass stopper along the longitydinal axis of said barrel, said by-pass positioned so that when said by-pass stopper is within said by-pass zone, the volume defined within said chamber between said by-pass stopper and said distal end of said barrel is approximately the volume of the combined components of the medication, said by-pass being raised enough to allow fluid flow around said by-pass stopper when said by-pass stopper is positioned within said by-pass zone; and 5. a stopper slidably positioned in fluid-tight engagement inside said barrel adapted to engage a plunger rod to facilitate its operation, said stopper capable of moving fluid from said chamber through said passageway upon its movement toward said distal end. This syringe minimizes sterility problems by allowing the mixing and administering steps to be performed without puncturing stoppers or transferring the medication compounds through surfaces which are exterior to the syringe assembly. The medication syringe according to the South African patent has a compartment [A] defined by the tip and the by-pass stopper, and a second compartment [B] defined by the by-pass stopper and the stopper adapted to engage the plunger rod. Hereinafter compartment A will be called the "needle-compartment" and compartment B the "plunger-compartment" indicating the relative position of the compartments in the barrel. The needle compartment of the syringe according to the US-A-4 613 326 is intended to contain the solid or lyophilised medicament and consequently the plunger compartment is filled up with the injection fluid. This syringe is, indeed, very suitable because lyophilisation of the medicament can be carried out directly in the needle compartment itself. The medication syringe according to the US-A-4 613 326 is, however, less suitable or even unsuitable for use of the injection fluid is to be stored in the needle compartment and the solid or lyophilised medicament in the plunger compartment, because efficient mixing of the two components is impossible. Under certain circumstances it is easier or even desired from a manufacturing point of view to fill the needle compartment with the injection fluid and to sterilize the syringe and then afterwards to add the medication either in powder or in lyophilised form aseptically into the plunger compartment. US-A-4 613 326 does not however disclose either "two by-passes" or means separate from the tip passageway for allowing escape of fluid during a lyophilization process in which the stopper is placed in the barrel, which means can be closed by moving the stopper in the direction of the tip. The present invention provides a medication syringe of the type is disclosed in the US-A-4 613 326 but especially suitable for use where the injection fluid is to be stored in the needle compartment and the medicament in powder or lyophilised form in the plunger compartment. The two compartment syringe according to the invention comprises: (1) a barrel; (2) a tip extending from a distal end of said barrel having a passageway therethrough connecting the interior of the barrel with the outside, said tip including means for accepting a hypodermic needle; (3) a by-pass stopper slidably positioned in fluid-tight engagement inside said barrel thus forming a compartment "a" between the tip and by-pass stopper; (4) at least two raised peripheral portions of said barrel serving as by-passes and defining possibly distinct by-pass zones, said by-pass zones each being longer along the longitudinal axis of the barrel than the length of said by-pass stopper (measured along the longitudinal axis of said barrel). said by-passes positioned so that when said by-pass stopper is moved in the direction of the said tip it comes within each by-pass zone simultaneously and then defines a volume of compartment "a", that is at least the volume of the combined medication components, said by-passes being raised enough to allow a fluid flow around the by-pass stopper when said by-pass stopper is positioned within the by-pass zones; and (5) a stopper slidably positioned in fluid-tight engagement inside the barrel and adapted to engage a plunger rod, thus forming a compartment "b" between said stopper and said by-pass stopper. The compartment "b" has means apart from the tip passageway for allowing the escape of a fluid therefrom during a lyophilization process which means can be closed by moving the stopper in the direction of the tip. In accordance with a preferred embodiment of the present invention the two compartment syringe includes an elongate substantially cylindrical barrel, and includes sealing means releaseably connected to the tip in order to close the passageway. Also provided are two raised peripheral portions of the barrel serving as by-passes and defining one by-pass zone, the two by-passes being positioned at approximately opposite sides of the barrel. The preferred embodiment further includes a liquid component (the injection fluid) being contained within the said compartment "a" and the solid medicament either in powder or in lyophilised form being contained in compartment "b". The means for allowing the escape of a fluid according to the invention renders it possible to lyophilise a solution of a medicament in the interior of compartment "b" in a very simple manner. For that purpose compartment "b" of the syringe of the invention is provided with a small opening in the wall, a bypass, or other means which provide an open connection with the outside. The syringe containing the injection fluid in compartment "a" and a solution of the medicament in a compartment "b" (that is provided with the open connection with the outside) is placed in a lyophiliser and lyophilised whereby the solvent in compartment "b" is allowed to escape through the opening, by-pass or the like. After the termination of the lyophilization process, compartment "b" is closed by simply moving the stopper (adapted to engage a plunger rod) in such a manner that it completely closes the connection with the outside resulting in a sealed compartment "b" containing the lyophilised residue. The present invention also provides a method of manufacturing a syringe of the invention, wherein a liquid is first placed into the first compartment, and then the solid medicament is placed into the second compartment. Drawings Fig. 1 is a cross-sectional view of the syringe according to the invention. Fig. 2 shows the same syringe as in Fig. 1 including the plunger rod and tip cap. Fig. 3 is an enlarged cross-sectional view of the syringe of Fig. 1 taken along line 2-2 with the by-pass stopper in the by-pass zone. Fig. 4 has the by-pass stopper within the by-pass zone and schematically shows the mixing of the medication components with closed tip, the lower by-pass allowing fluid flow from compartment "a" to compartment "b" and the upper by-pass allowing air flow from "b" to "a". Fig. 5 schematically shows the further mixing of the components started in Fig. 4 by gently moving the piston up and down to completely dissolve the solid or lyophilised medicament, wherby the tip must be kept tightly closed. Fig. 6 is a side elevation (and cross-sectional) view of the syringe which, after attachment of the needle, is ready for use. Fig. 7 illustrates a syringe according to the invention which is ready for lyophilising a solution of the medicament in compartment "b". Fig. 8 shows the syringe of Fig. 7 after the lyophilization process. The syringe according to the invention will now be described more in detail with a reference to figures 1 and 2. The two compartment syringe of fig. 1 includes an elongate substantially cylindrical barrel 30 with the tip 31 extending from a distal end of the barrel 30 and having a passageway 32 communicating with the outside. Tip cap 33 is releaseably connected to tip 31 and seals passageway 32 in an air-tight manner. A flexible by-pass stopper 34 is slidably positioned in fluid tight arrangement inside the barrel thus forming a compartment "a" between the tip 31 and by-pass stopper 34. The syringe barrel also includes two by-passes 35 and 36 defining in this embodiment one by-pass zone along the barrel. Both by-passes are large enough to allow fluid flow around the by-pass stopper when the by-pass is positioned within the by-pass zone. The by-passes as shown in fig. 3 effectively enlarges the inside diameter of the barrel within the by-pass zone. A flexible stopper 37 is slidably positioned in fluid tight engagement inside the barrel thus forming a compartment "b" between stopper 37 and by-pass stopper 34. Stopper 37 is furthermore adapted to engage the plunger rod 38 preferably provided with the rod flange 39 (see fig. 4) as a convenient structure for applying forces to move the plunger rod. The preferred embodiment of the instant invention contains two components of the medication which will be mixed at the time of use. A liquid, usually the injection fluid, is contained within the compartment "a" and a medicament in powder- or lyophilised form in compartment "b". The figs. 4 and 5 clearly show the best way of handling in order to mix the medication components. This handling can be carried out while the passageway 32 is being kept sealed. Fig. 7 shows a syringe of the invention, in which compartment "b" is provided with an opening 40. This opening (which also can be any other means that provides an open connection with the outside, such as a by-pass) allows an easy lyophilisation of a solution of the medicament in compartment "b". Fig. 8 illustrates the syringe of fig. 7 after the lyophilization process whereby opening 40 is now closed by the stopper 37. The syringe barrel may be constructed of thermoplastic material or glass, while the stopper, by-pass stopper and tip cap may be made of a wide variety of materials such as natural and synthetic rubbers. Obviously the materials used must be compatible with the medication to be stored. The syringe according to the present invention includes advantages over the prior art syringe in that for a given volume of powder and solution, the required volume of the syringe can be much smaller (25-40 %); hence this syringe is cheaper and easier to handle by the doctor and in pharmaceutical processing it is now possible to fill the (cheap) injection fluid and afterwards (after quality control) to add the (expensive) solid medicament. with a simple modification (opening in the wall of compartment "b") of the syringe it is moreover possible to carry out the lyophilising process in the interior of compartment "b".

Claims: A two compartment syringe for containing and combining separated medication components, said syringe being of the type having a barrel (30); a tip (31) extending from a distal end of said barrel, said tip having a first passageway (32) therethrough connecting the interior of the barrel with the outside, said tip including means for accepting a hypodermic needle; a by-pass stopper (34) slidably positioned in fluid tight engagement inside the barrel thus forming a first compartment (a) between the tip (31) and the by-pass stopper (34); the barrel having at least two raised peripheral portions (35, 36) serving as by-passes and defining possibly distinct by-pass zones, said by-pass zones each being longer along the longitudinal axis of the barrel than the length of the by-pass stopper measured along the longitudinal axis of said barrel, said by-passes positioned so that when said by-pass stopper is moved in the direction of the tip, it comes within each by-pass zone simultaneously, said by-passes being raised enough to allow fluid flow around the by-pass stopper when said by-pass stopper is positioned within the by-pass zones; and a stopper (37) slidably positioned in fluid tight engagement inside said barrel and adapted to engage a plunger rod (38), thus forming a second compartment (b) between said stopper and said by-pass stopper, said second compartment having means (40) separate from said tip passageway for allowing escape of fluid therefrom during a lyophilization process in which the stopper is placed in said barrel, which means can be closed by moving the stopper in the direction of the tip (FIG. 8). The syringe of claim 1 wherein said barrel is elongate and substantially cylindrical and further including means (33) for sealing said passageway releasably connected to the tip. The syringe of claim 2 having two by-passes defining one by-pass zone along the barrel said by-passes being positioned at approximately opposite sides of the barrel. The syringe of claims 1, 2 or 3 wherein a liquid is contained within the first compartment, and a solid medicament is contained within the second compartment. The syringe of claim 4 wherein the solid medicament is lyophilized. The syringe of claim 1, 2 or 3 wherein said means for allowing escape of fluid from said second compartment is a small opening in the wall of the barrel associated therewith. The syringe of claim 1 wherein said means for allowing the escape of solvent from the second compartment is a by-pass for providing an open connection exterior to the syringe. A method of manufacturing a syringe according to claim 4 characterized in that a liquid is first placed into the first compartment, and then the solid medicament is placed into the second compartment. A method of manufacturing a syringe according to claim 5 characterized in that the solid medicament is lyophilized in the second compartment.

Inventors: YSEBAERT, WILLEM MARIE
Applicants: AKZO N.V.
Application year: 1987
Main classification: A61M5
IPC codes: A61M5