WO1988005315A1

WO1988005315A1 - Injection set with silicone-free piston

Info

Publication number: WO1988005315A1
Application number: PCT/CH1988/000008
Authority: WO
Inventors: Eckhard Schwöbel; Paul Zaugg
Original assignee: Intermedicat Gmbh
Priority date: 1987-01-27
Filing date: 1988-01-12
Publication date: 1988-07-28
Also published as: EP0301040A1; CH674942A5

Abstract

A new injection set is mainly used for the controlled injection of medicines; it is essentially composed of a cylindrical container (4.01) with attached injection hollow needles (4.02), hold-up plate (4.03) and piston rod guide (4.04), of a plastic piston (4.05) movable in the cylindrical container and with an automatic lip seal and of a piston rod (5.01) with pressure plate (5.04), separated from the piston. The cylindrical container has a rear section (4.06) - seen in the direction of the injection - with an enlarged inner diameter, compared with its front part, in which the piston is parked. The plastic piston has a front and a rear lip seal edge (4.051, 4.052), seen in the direction of the injection. This design dispenses with the use of silicon lubricants for the piston. The piston rod can be arranged in front of the hollow needle, protecting the same, or next to the injection.

Description

Syringe set with silicone-free plunger.

The invention described here relates to a syringe set, primarily for the controlled injection of medicaments, consisting essentially of a container cylinder with an attached injection cannula, counter plate and piston rod guide, made of a plastic provided movably in the container cylinder. Piston with automatic lip seal, which piston is parked in the back of the cylinder, and a piston rod with a pressure plate that is separate from the piston.

What is essential with generic syringes is their nature; the handling of the same should be sufficiently safe both in technically advanced machines and by medically untrained, for example older and / or poorly sighted persons, without the syringes causing excessive production costs. In addition, it should be noted that repeated use of the syringes cannot always be completely ruled out in the case of self-injections, so that the cleanliness of the syringe should also be taken into account if the syringe is used repeatedly, but always on the same person.

Similar syringes are known from the patent literature:

In CH Patent 366 126 (published 1/31/63) a piston is described in a plastic syringe, which is also made of thermoplastic material, such as polystyrene or polyethylene the piston mentioned has a round sealing lip at the front, possibly also at the rear, in the spraying direction. During spraying, the front sealing lip is pressed away from the piston body against the inner wall of the syringe body by the pressure in the liquid and thus seals itself automatically. The above-mentioned CH patent does not mention and therefore does not solve the problem of the relaxation of the tension in the round sealing lips even during the storage of such products, and thus the insufficient seal when used after a certain time.

FR patent 1,500,009 (published November 3, 677) teaches and claims a piston of the type described above in a plastic injection syringe. The plunger is usually present in the container cylinder of the syringe separately from the rod. Since it has a smaller outside diameter compared to the inside diameter of the cylinder mentioned, and is only expanded by the reception of the piston rod and then seals, the tension in the sealing lip is maintained. Incidentally, the piston rod is always in the container cylinder of this syringe.

The tightness problem of such pistons on the other hand - according to the European patent, Ver. No . 0 026 940, (published. 04/15/81) - solved by primarily specifying its material chemically and physically: The piston mentioned exists. from a dyeable, thermoplastic elastomer with a block-mixed polymer having an average molecular weight between 50,000 and 200,000 of the general formula

(St). (A) _n (St) _m ,

(in which: St = styrene units, A = a unit derived from at least one unsaturated hydrocarbon having 2 to 5 carbon atoms, with m, m 'and n = the molar percentage on the individual units, the sum of m and m 'being 2-20 mol%).

The long-term elasticity of these pistons is not dealt with in the EP described here.

Finally, the invention according to the international application PCT / HU 83/00060 with publication number WO 84/02278 (published June 21, 1984) describes a single-use plastic syringe with a plunger in the form of a flexible part, preferably made of polyethylene. The piston rod, which is made separately from the piston and is made of a material with a higher degree of rigidity, is always connected to the piston when using this syringe.

All of the prior art syringes just discussed have in common that they are optimized in terms of material, construction and / or cost.

In contrast, in the case of syringes, application-related optimization comes to the fore primarily for use in automatic infusion machines and / or for injections; Significantly, there are no syringes dealt with above as a set.

Thanks to the novel arrangement of the components, the syringe set according to the invention now creates the application safety necessary for the purpose of reliable, controlled injection of medication, which is not readily derivable even for the person skilled in the art.

The syringe set mentioned, primarily for the controlled injection of medicaments, essentially consists of a container cylinder 4.01 with an attached injection cannula 4.02, support plate 4.03 and piston rod guide 4.04, a movable one in the container cylinder and a rear one Cylinder section with expanded diameter, parked plastic pistons 5.05 with automatic lip seal as well a piston rod 5.01 separated from the piston with pressure plate 5.04, and is characterized in that the container cylinder in the rear section in the spraying direction has a compartment 4.06 with an enlarged inside diameter compared to its front part, that the piston in the compartment with an enlarged inside ¬ diameter is parked, the piston in the direction of injection front and rear one sealing lip edge 4.051; Comprises 4.052 whose maximum outside diameter greater than the inner diameter of the front portion, but smaller than that of ^"lter cylinder of the parking compartment of the CONT in the rest position and that the piston-rod either disposed in front of the cannula as a protection for the same or adjacent to the syringe, in the latter case the cannula is otherwise protected 4.07 and the piston rod tip 5.05 and the piston rear part 4.08 are designed in such a way that they can be securely connected to one another for aspiration and injection, but can also be easily separated again.

In the same syringe set, the other protection of the cannula 4.07 can include a protective tube and a filter 4.071, through which, when the protection is attached, while the plunger is pulled back into the parking position without aspirating, dust-free air is sucked into the container cylinder.

It is also important that the edge of the lip seal 4.051 on the piston 4.05 and the transition zone between the section with a larger inner diameter and the space 4.09 in the container cylinder 4.01 are rounded and matched to one another such that when the piston is pushed into the cavity 4.09 Container cylinder 4.01 the sealing lips are pressed against the inner wall of the piston and do not fold backwards.

With the new syringe set, the outside diameter of the piston rod 5.01 has to be smaller than the inside diameter of the cavity 4.09 to avoid contamination. The above-mentioned, other protection 4.07 should be able to be accommodated in the rear cavity 5.03 of the piston rod 5.01, and the connection between the tip 5.05 of the piston rod 5.01 is to be accomplished by means of a guided fit and / or bayonet seat.

All components of the new syringe set, in particular also the piston 4.05, consist of injection-molded, sterilizable thermoplastic material, in particular of alkene polymers, such as polyethylene or propylene. This fundamentally solves the problem of medication being influenced by silicone oils which are used to increase the ease of movement of rubber pistons according to the prior art.

When manufacturing the syringe set described above, it should be noted that the set with the plunger parked is made sterile using gas or jets, especially to obtain sterile air in the cavity 4.09 for the storage of the set.

The syringe set according to the invention is preferably used in automatic infusion machines, but also for single injections. This combination of preferred uses is based on the fact that in both cases the delivery of a controlled amount of medication is essential.

Only through the arrangement of the components according to the syringe set defined in detail can the problems in manufacture and storage as well as those in use for the controlled injection be really satisfactorily solved.

Especially with regard to the known syringes already described above, the differences from the syringe set according to the invention are as follows:

The plastic syringe according to CH Patent 366 126 shows the automatically sealing pistons also made of plastic - however, the problem of the temporary sealing capacity of such arrangements is not mentioned. And especially in the case of single-use syringes, as specified in the above-mentioned CH patent - ie syringes that are manufactured in large quantities and some of which are stored - the mastery of this problem is a decisive factor in achieving a sufficiently high level of application safety.

The technical teaching according to FR Patent 1,500,009 covers the problem mentioned, but solves it in a different and rather complex manner from the invention described here; especially the embodiment according to FIGS. 5 and 6 does not appear to be easy to understand. An important problem is also practically not dealt with: the question of materials. A deformation of a piston to the extent of FIGS. 1 to 4 within the container cylinder of a plastic syringe with the plugging in and loosening of the piston rod in or from the piston is very likely to result in special plastic materials; however, these are not mentioned in the FR patent mentioned.

With the plunger material of the ^* syringe according to EP, Ver. No. 0026 940, since it is defined in a very complex manner with regard to its monomer composition and its compressibility, compared to commercially available alkene polymers such as especially polyethylene or propylene, control and thus increased cost problems arise. Such syringes may be suitable for very special applications.

Finally, regarding the plunger of the syringe in accordance with PCT / HU 83/00060, WO 84/02278, the problem of the loss of sealing capacity must be pointed out again (see above, FR Patent 1,500,009).

The arrangement of the components in the syringe set according to the invention specified above, on the other hand, permits both the automated manufacture of the syringe from proven, application-inert plastic materials and the preservation of the sealing capacity of the Plunger while the syringe is in storage and not in use (plunger parked) and the syringe is sufficiently safe to use for the same in infusion machines as well as by medically untrained and elderly people; yes, even using the two or three times

Syringes on the same patient during self-injection should not lead to any risk of infection.

With regard to the practical application of the syringe set according to the invention, the following essential points should be noted:

Syringes with plastic pistons are currently available, which are parked in the front in the spraying direction in the cylinder containers, also in sections with enlarged diameters. As a result, however, a little air (from behind) is aspirated at the start of the absorption of liquid medications; the tightness of the piston is only given after it has entered the cylinder space with a reduced diameter compared to the parking space.

In many cases, the usual syringes currently on the market still have elastic rubber stoppers which are treated with silicone agents in order to increase the ease of movement of such pistons in plastic cylinders. However, modern studies have shown that silicone-containing agents are not always safe with regard to influencing the pharmaceutical effects of medication.

The syringe set according to the invention therefore has two major advantages, also with regard to its practical use, compared to the products on the market: The aspiration of air when sucking up medication is completely avoided and siliconization of the plunger is generally no longer necessary .

The syringe set according to the invention will now be described in detail on the basis of exemplary embodiments which are illustrated in the attached FIGS. 1 to 5: Figures 1 to 3 show specifically plunger shapes to be used in the syringe set according to the invention,

FIGS. 4 and 5 show an overall arrangement of an embodiment of the set mentioned in a schematic representation.

According to Figures la, 1b, 2a and 2b, the sealing lips are designed so that the 1.06;

2.06 during the spraying process due to the excess pressure in the spray liquid 1.03; 2.03 towards the air behind the seal.

1.04; 2.04 and the one behind in the direction of spraying; 2.07, during the suction process due to the overpressure of the air 1.04; 2.04 against the suction liquid against the inner wall of the syringe barrel. In the parking space 15, the sealing lips then expand outwards.

According to FIGS. 3a and 3b, the sealing lips in the front spraying direction 3.06 during spraying and the sealing lips in the rear spraying direction 3.07 are pressed against the inner wall of the syringe cylinder body by the position of the rod body 3.02 in the sealing and delivery piston.

FIGS. 4 and 5 show a preferred embodiment of the syringe set according to the invention. The piston rod 5.01 25 can be attached to the syringe separately from the syringe or, with or without an additional filter 4.07, as protection over the cannula 4.02 at the front.

In the container cylinder 4.01 of the syringe of the 30 set according to the invention, the metal cannula 4.02 is applied at the front in the spraying direction. These cannulas are usually glued in today. An additional protective filter can be placed over the cannula

4.07 with the filter material 4.071. In the rear part, the container cylinder has a section 4.06

35 enlarged inner diameter, which section at the rear end through the end part with counter sheath plate 4.03 and piston rod guide 4.04 is completed. In section 4.06, the plunger made of plastic 4.05 is parked during storage and during the non-use of the syringe set according to the invention. This piston has the fitting seat opening 4.08 (for the piston rod tip 5.05) at the rear end. At the front and also at the back, it shows circular sealing lips 4.051 and 4.052. When spraying, the sealing lips are pressed by the liquid pressure at the front, away from the piston body - against the inner wall of the cylinder, ie they seal automatically. The same happens with the rear sealing lips when aspirating air and / or when aspirating liquids. In the former case, the additional protective filter 4.07 can be attached in order to ensure that no dust particles are sucked into the syringe.

As already mentioned above, the parking of the plastic piston 4.05 in the room 4.06 is essential in the arrangement according to the invention. By using the syringe set according to the invention, both the disadvantages of the plastic pistons parked in front - the aspiration of air during the suction of liquids which cannot be avoided thereby - as well as those of the elastic rubber pistons - the siliconization and the thus possible impairment of the injected medication - basically avoided.

The piston rod 5.01 has the pressure plate 5.04 on the back and the recess 5.03 for receiving the additional filter 4.07. The tip 5.05 of the piston rod fits, e.g. by means of a fit with a bayonet catch, in the rear opening 4.08 of the piston 4.05.

Claims

PA 86/78

PATENT CLAIMS

Syringe set, primarily for the controlled injection of medicaments, consisting essentially of a container cylinder

(4.01) with attached injection cannula (4.02), counter plate (4.03) with piston rod guide (4.04), made of a plastic piston provided movably in the container cylinder and parked in a rear cylinder section with an enlarged diameter ( 4.05) with automatic lip seal and from a piston rod (5.01) with pressure plate (5.04) separate from the piston, characterized by,

that the container cylinder (4.01) has a compartment (4.06) in the rear section in the spraying direction with an enlarged inside diameter compared to its front part,

that the piston (4.05) is parked in the compartment with an enlarged inside diameter (4.06), the piston having a sealing lip edge (4.051; 4.052) in the injection direction at the front and rear, the maximum outside diameter of which in the rest position is larger than the inside diameter of the front Partially, but smaller than that of the parking compartment of the container cylinder and

that the piston rod is arranged either in front of the cannula as protection for the same or next to the syringe, the latter in the latter If the cannula is protected in some other way (4.07) and the piston rod tip (5.05) and the piston rear part (4.08) are designed in such a way that they can be safely connected to one another for aspiration and injection, but can also be easily separated again .

2 ^

Syringe set according to claim 1, further characterized in that the other protection of the cannula (4.07) comprises a protective tube and a filter (4.071), through which, when the protection is attached, the aspirator is pulled back into the parking position without being aspirated , dust-free air is sucked into the container cylinder. •

! __.

Syringe set according to claim 1, further characterized in that the edges of the lip seal (4.051) on the piston (4.05) and the transition zone between the section with an enlarged inner diameter and the space (4.09) in the container cylinder (4.01) are rounded off in this way and are coordinated so that when the piston is pushed into the cavity (4.09) of the container cylinder (4.01) the sealing lips are pressed against the inside wall of the piston and do not fold backwards.

Syringe set according to claim 3, further characterized in that, in order to avoid contamination, the outside diameter of the piston rod (5.01) is smaller than the inside diameter of the cavity (4.09). _5__.

Syringe set according to claim 4, further characterized in that the other protection (4.07) can be accommodated in the rear cavity (5.03) of the piston rod (5.01).

6 _

Syringe set according to claim 5, further characterized in that the connection between the tip (5.05) of the piston rod (5.01) and the rear opening (4.08) in the piston is achieved by means of a guided fit and / or bayonet seat becomes.

7_ ^ Syringe set according to claim 1, characterized in that all the components thereof, including the plunger (4.05), are made of injection-molded, sterilizable thermoplastic material, in particular alkene polymers, such as polyethylene or propylene.

__

Method for producing the syringe set according to claim

1, whereby in addition to the usual manufacturing steps, the set is sterilized with a parked piston using gases or jets in order to obtain sterile air in the cavity (4.09) for storing the set.

9 ^ Use of the syringe set according to claim 1 for in infusion machines or for single injections.