Syringe body, syringe and injection device for injecting a highly viscous medium

Description

[0001] The present invention relates to an injection device for injecting a highly viscous medium. In particular, the injection device can be used for injecting or administering highly viscous pharmaceutical media. Background of the invention

[0002] Syringes are used, for example, in the medical and cosmetic fields and are used to inject a medium contained in the syringe into a patient's body. For example, dermal fillers are injected beneath the patient's skin during a cosmetic skin treatment. Highly viscous media are typically used in cosmetic applications. Media contained in syringes can include various forms of fluids, pasty or liquid substances, and mixtures.

[0003] Document US 2010 / 152679 A1 discloses a syringe that can be connected to a needle assembly for injecting a viscous liquid. To ensure a sufficiently strong connection between the syringe body and the needle assembly and prevent detachment, document US 2010 / 152679 A1 proposes providing a thread of a connecting section between the syringe and the needle assembly with a pitch of 3 mm.

[0004] Document US 2003 / 220613 A1 also discloses a syringe with a syringe body that can be connected to a needle assembly at one end. Syringes with a circumferential bevel at the proximal end of the syringe body are known, among others, from US5554133A and US2016 / 184528A1.

[0005] To minimize the skin perforation required for injection and the associated pain for the patient, needles with a very small gauge are preferred. This is especially true for applications on the patient's face.

[0006] The combination of the smallest possible needle thickness and the high viscosity of the media to be injected places significant stress on the syringe or syringe body. In particular, high pressures within the syringe can lead to mechanical failure of the syringe assembly. However, since mechanical failure of the syringe is to be avoided, the possibilities for using needles with a thinner needle thickness are limited in existing syringes, which in turn results in the disadvantages for the patient described above.

[0007] It is therefore an object of the present invention to overcome the disadvantages of the prior art. In particular, an object of the invention is to provide an injection device that enables the use of needles with a small cannula thickness for injecting highly viscous media.

[0008] These objects are achieved by an injection device according to the independent patent claims. Further developments and embodiments of the injection device are the subject of the dependent claims and the following description. Description of the invention

[0009] One aspect of the invention relates to an injection device for injecting or applying a highly viscous medium, comprising a syringe with a syringe body and a needle assembly. In one embodiment, the highly viscous medium is characterized by a storage modulus G' of at least 30 Pa and at most 150 Pa, in particular at least 50 Pa and at most 100 Pa, or at least 70 and at most 90 Pa. The loss factor tan δ can be between 0.2 and 0.8, in particular between 0.3 and 0.6 or between 0.4 and 0.5. This can be, for example, hyaluronic acid fillers. The viscosity can be measured using a plate-on-plate measuring system at 25°C and an air pressure of 1013.25 hPa (e.g., rheometer from Anton Paar MCR 302), in particular at a frequency of 1 Hz. The measurement can be carried out, for example, using the method according to ISO standard 6721-10-2015-09. The syringe body comprises a distal end section and a proximal end section.The syringe body is hollow-cylindrical and forms a chamber for containing the highly viscous medium. The proximal end section has an opening through which a piston rod assembly can be inserted or is inserted into the chamber. The piston rod assembly is displaceable within the chamber along a longitudinal axis and is slidably guided within the syringe body.

[0010] A Luer-Lock connector is formed on the distal end portion of the syringe body, comprising an outer cone with a further opening for dispensing the highly viscous medium and a sleeve-shaped portion with an internal thread. The Luer-Lock connector forms part of a Luer-Lock connection system and is designed to interact with a Luer-Lock connector counterpart formed on a needle assembly. The outer cone can also be described as a conical nozzle extending beyond a distal end of the syringe body, through which the highly viscous medium can be discharged from the chamber. The outer cone also forms part of the Luer-Lock connection system and also interacts with a complementary counterpart of the needle assembly. In a Luer-Lock connection system, the outer cone and the sleeve-shaped portion surrounding it are arranged coaxially with one another.The Luer-Lock connector of the syringe body can be designed and dimensioned, in particular, in accordance with ISO Standard 80369-7:2016-12-01. This allows the syringe body according to the invention to be used with a variety of different needle arrangements standardized in the area of ​​Luer-Lock connections.

[0011] According to the invention, the syringe body has a minimum NPO resistance of between 90 N and 105 N, preferably between 95 N and 103.5 N, preferably between 98 N and 102 N. NPO stands for "needle pop off" and refers to the sudden detachment or popping off of a needle assembly from a syringe body, in particular a needle assembly connected to the syringe body via a Luer lock connection. Under high pressure (triggered by applying force to the syringe body via the piston rod assembly), the needle assembly begins to rotate and detach from the syringe body at high speed, i.e., an inner cone of the needle assembly, complementary to the outer cone of the syringe body, detaches.

[0012] The NPO minimum resistance ("needle pop off") specifies a threshold value of the force applied to a plunger rod assembly inserted into and operatively connected to the syringe barrel during the test procedure described below. The NPO minimum resistance is defined as a force below which no more than 1.8% of the tested syringe barrels experience a needle pop off. At least 56 measurements of syringe barrels of the same configuration and design are required to obtain a meaningful result for the NPO minimum resistance.

[0013] The test procedure for measuring NPO resistance, in particular the minimum NPO resistance and the average NPO resistance, requires that the syringe barrel to be tested is placed vertically in a testing machine and held in the area of ​​the proximal end of the syringe barrel. The testing machine used is a universal testing machine from "TesT", model "TesT 106.2 kN". This or a comparable universal testing machine must be used for the test procedure.

[0014] The syringe barrel to be tested is connected via the Luer-Lock connector to a needle assembly, which is screwed onto the distal end of the syringe barrel using a Luer-Lock connector counterpart to establish the Luer-Lock connection, applying a torque of 12 Ncm. Specifically, the described test procedure is to be performed with the "TSK STERiJECT Hypodermic Needle" needle assembly, Ref.: PRC-30013I, 30 G x 1 / 2, or a comparable needle assembly. The needle assembly used for the test procedure comprises an inner cone as the Luer-Lock connector counterpart and two fins arranged on the outer circumference of a needle hub of the needle assembly. The needle assembly used for the test procedure comprises a cannula or hollow needle with a thickness of 30 G and a length of 13 mm (30 G x 1 / 2). For testing purposes, the cannula must be flattened and closed using a hammer before carrying out the test procedure.For the test procedure, a dry Luer-Lock connection must be established by screwing the needle assembly onto the syringe barrel before a highly viscous medium is subsequently filled into the chamber. The test procedure must be performed using non-steam-sterilized components (syringe barrel, needle assembly, plunger rod assembly).

[0015] For this test procedure, a highly viscous medium with a storage modulus G' of approximately 84.5 Pa and a loss factor tan δ of approximately 0.48 must be selected. The viscosity can be measured using a plate-plate measuring system at 25°C and an air pressure of 1013.25 hPa (e.g. rheometer from Anton Paar MCR 302), in particular at a frequency of 1 Hz. The measurement can be carried out, for example, using the method according to ISO standard 6721-10-2015-09. The syringe barrel to be tested is, as intended, completely filled with the highly viscous material. Furthermore, a piston rod assembly is inserted into the syringe barrel at the beginning of the test procedure and is operatively connected to it. However, the syringe barrel and piston rod assembly are still in an initial position, i.e., in a non-actuated position, at the beginning of the test procedure.For this test procedure, a standard piston rod arrangement intended for the particular syringe barrel to be tested must be used. For example, for a syringe barrel with a 5 mm inner diameter of the chamber, a standard piston of type FM257 (e.g., from the manufacturer Daetwyler) can be used.

[0016] During the test procedure, a force is applied perpendicularly to the proximal end of the piston rod assembly via a test piston on the testing machine. The test piston moves at a constant test speed of 12.6 mm / min toward the distal end of the syringe body, continuously increasing the force acting on the piston rod assembly to a maximum of 420 N. The test piston is displaced by a distance of up to 15 mm during testing. The applied force is detected by a force sensor with a sampling rate of 200 Hz. The test piston continues to move, or the applied force is increased, until leakage (" Leakage ") and / or NPO occurs or until the maximum force of 420 N is reached. The test is stopped, ie leakage (" Leakage") and / or NPO is detected when the measured force suddenly drops by at least 30%. The force acting at the time of the occurrence of leakage and / or NPO is documented and linked to the information whether leakage and / or NPO occurred at this force. From the documented measurement results, the NPO minimum resistance described above and the average NPO resistance can then be determined. The leak examined here (" Leakage ") is the leakage between the syringe body and the needle assembly caused by the applied force and the resulting pressure. In other words, the force at which the highly viscous medium unintentionally escapes between the syringe body and the needle assembly in the area of ​​the Luer-Lock connection can be determined.

[0017] A mechanical failure to be avoided can be caused in particular by NPO, by leakage (" Leakage") between interconnected syringe components and / or due to a breakage of the syringe body. The inventors of the present invention have recognized that for the use of highly viscous media and a small cannula thickness of at least 31 G, a syringe body which has the above-defined NPO minimum resistance is advantageous. A smaller needle or cannula diameter (e.g. over 30 G) means less pain for the patient than larger needle or cannula diameters (e.g. diameters of 27 G conventionally used with highly viscous media), but at the same time requires a higher application of force than a larger needle or cannula diameter in order to dispense the highly viscous medium. The above inventive values ​​for the NPO minimum resistance take into account the recognition that male users, when used as intended, use a syringe orMale users can operate an injection device with an average maximum force (maximum finger force) of 95 N. Female users can operate a syringe or injection device with an average maximum force (maximum finger force) of 64 N when used as intended. The NPO minimum resistance defined above thus represents an optimal design of the syringe body structure, ensuring safe injection of a highly viscous medium with a very thin needle without being oversized.

[0018] In a further development, the syringe body can have an average NPO resistance of at least 100 N, preferably at least 105 N, preferably at least 110 N, more preferably at least 115 N, even more preferably at least 117 N. In particular, the average NPO resistance can be between 100 N and 120 N, preferably between 105 N and 120 N, preferably between 110 N and 120 N, more preferably between 115 N and 117 N.

[0019] The average NPO resistance indicates the mean force that must be applied to a plunger rod assembly inserted into and operatively connected to the syringe barrel during the test procedure described above for a needle pop-off to occur. Again, at least 56 measurements of syringe barrels of the same configuration and design are required to obtain a meaningful result for the average NPO resistance.

[0020] In one embodiment, the syringe body can have a minimum leakage resistance of at least 100 N. Preferably, the syringe body can have a minimum leakage resistance of more than 105 N, preferably more than 117.5 N, more preferably more than 125 N. In particular, the syringe body can have a minimum leakage resistance between 100 N and 130 N, preferably between 105 N and 120 N, preferably between 110 N and 115 N.

[0021] In a further development, the syringe body can have an average leakage resistance of at least 115 N, preferably at least 120 N, preferably at least 123 N, more preferably at least 125 N, even more preferably at least 127 N. In particular, the average leakage resistance can be between 110 N and 135 N, preferably between 115 N and 130 N, preferably between 120 N and 130 N, more preferably between 125 N and 130 N.

[0022] The minimum leakage resistance (MLR) indicates a threshold value of the force applied to a plunger rod assembly inserted into and operatively connected to the syringe barrel during the test procedure described above. The minimum leakage resistance is defined as the threshold value below which a leak occurs in less than 1.8% of the tested syringe barrels. At least 56 measurements of syringe barrels of the same configuration and design are required to obtain a meaningful result for the minimum leakage resistance.

[0023] Furthermore, the average leakage resistance indicates the average force that must be applied to a plunger rod assembly inserted into and operatively connected to the syringe barrel during the test procedure described above for a leak to occur. This also requires at least 56 measurements of syringe barrels of the same configuration and design to obtain a meaningful result for the average leakage resistance.

[0024] In one embodiment, the internal thread of the Luer Lock connector can have an internal diameter of a maximum of 7.15 mm or a maximum of 7.12 mm. The internal diameter can preferably be at least 7.05 mm or at least 7.08 mm. In preferred embodiments, the internal diameter is between 7.05 mm and 7.15 mm, preferably between 7.08 mm and 7.12 mm, and most preferably a maximum of 7.1 mm. The internal diameter describes the smallest internal diameter of the sleeve-shaped end section, i.e., measured from thread crest to opposite thread crest of the internal thread. An internal diameter with this dimension can have a positive effect on a sufficiently tight connection between the syringe body and a needle arrangement connected to it, and thus advantageously influence the setting of the minimum NPO resistance as well as the average NPO resistance.The same applies to the minimum leakage resistance and the average leakage resistance.

[0025] According to one embodiment of the syringe body, the internal thread at the crest of the thread profile can have a width of at least 0.44 mm or at least 0.46 mm. Preferably, the width is a maximum of 0.52 mm or a maximum of 0.50 mm. In preferred embodiments, the width can be between 0.44 mm and 0.52 mm, preferably between 0.46 mm and 0.50 mm, preferably 0.48 mm.

[0026] Additionally or alternatively, the internal thread at the base of the thread profile can have a width of at least 0.85 mm or at least 0.875 mm. Preferably, the width is a maximum of 0.95 mm or a maximum of 0.925 mm. In preferred embodiments, the width can be between 0.85 mm and 0.95 mm, preferably between 0.875 mm and 0.925 mm, preferably 0.9 mm.

[0027] The internal thread can have an angle of between 22.5° and 27.5° on both sides of the thread profile, in particular an angle of 24° to 26° or approximately 25°. The angle can be described as the angle enclosed between a line orthogonal to the longitudinal axis of the syringe body and intersecting the thread profile and the flank of the thread profile.

[0028] By designing the thread profile parameters according to the dimensions described above, the contact area of ​​the threaded connection, i.e., the contact area between the internal thread of the syringe body and a complementary external thread of an associated needle assembly, can be adjusted. This can improve the Luer Lock connection with the associated needle assembly and have a beneficial effect on setting the minimum NPO resistance and the average NPO resistance. The same applies to the minimum leakage resistance and the average leakage resistance.

[0029] In a further development, a distal end face of the outer cone, which closes the outer cone and is provided with the further opening, can protrude beyond a distal collar of the sleeve-shaped section by a distance of at least 2.1 mm or at least 2.2 mm. In one embodiment, this distance is a maximum of 2.5 mm or a maximum of 2.4 mm. In a preferred embodiment, the distal end face of the outer cone protrudes beyond a distal collar of the sleeve-shaped section by a distance of 2.1 mm to 2.5 mm, preferably from 2.2 mm to 2.4 mm, preferably from 2.3 mm. This structural adaptation can also advantageously influence the setting of the minimum NPO resistance and the average NPO resistance. This applies analogously to the minimum leakage resistance and the average leakage resistance.

[0030] According to the invention, the syringe body comprises an inner circumferential surface with a chamfer at the proximal end portion, which tapers the inner circumferential surface from the proximal end portion toward the distal end portion. In other words, the inner circumferential surface tapers conically in the region of the chamfer toward the distal end portion. The chamfer can simplify the insertion of the piston rod assembly, more precisely the piston, into the chamber of the syringe body. The chamfer has a length of between 1.2 mm and 1.8 mm, preferably from 1.4 mm to 1.6 mm, preferably of approximately 1.5 mm, viewed in the direction of the longitudinal axis of the syringe body. In addition, the chamfer encloses an angle of at least 13°, preferably of at least 14°, preferably of at least 15° with the longitudinal axis. By forming a chamfer of such dimensions, the overall length of the syringe body can be reduced compared to known syringe bodies.This can have a beneficial effect on the ergonomics of the syringe body and its handling by the user. Nevertheless, a chamfer of this dimension can ensure sufficient stability and tightness (the so-called Container Closure Integrity, CCI) of the syringe. For example, a distance of at least 9 mm to a maximum of 10 mm, or approximately 9.5 mm, can be provided between the proximal end of the syringe and a proximal end of the piston of the piston rod assembly when the syringe is fully filled and not actuated.

[0031] In one embodiment, the syringe body can have a maximum total length of 80 mm and an inner chamber diameter of a maximum of 5 mm, wherein a volume of at least 1 ml can be accommodated in the syringe body. More precisely, a volume of at least 1 ml can be accommodated in the chamber and an adjoining chamber section formed by the outer cone. The total length can be measured from an end face of the syringe body delimiting the proximal end section to an end face of the syringe body delimiting the distal end section, i.e. the end face of the outer cone. The inner chamber diameter can be constant over the entire length of the chamber. For example, a volume of 1.073 ml can be accommodated in the chamber and the chamber section together in order to allow for overfilling of 2% and the inclusion of a 1 mm long air bubble in the chamber.It should be noted that the absorbable volume is not the same as the total volume formed by the entire chamber and the chamber section. In addition to the volume of medium to be absorbed, including the tolerances for overfilling and the air bubble described above, the chamber must also be able to accommodate part of the piston rod assembly in a non-actuated position and support it stably. To do this, the piston of the piston rod assembly must already be accommodated in the syringe body at a sufficient distance from the proximal end of the syringe body in a non-actuated position. For example, a distance of 9.5 mm can be provided between the proximal end of the syringe and a proximal end of the piston of the piston rod assembly.

[0032] The syringe body may preferably be designed and dimensioned within and in accordance with ISO Standard 11040-6:2012-04-01.

[0033] In a further embodiment, the syringe body can have a maximum total length of 60 mm and a maximum chamber inner diameter of 4.65 mm, wherein a volume of at least 0.5 ml can be accommodated in the chamber and the chamber section together.

[0034] In a further embodiment, the syringe body can have a maximum total length of 71 mm and a maximum chamber inner diameter of 5 mm, wherein the chamber and the chamber section together can hold a volume of at least 0.8 ml.

[0035] In a further embodiment, the syringe body can have a maximum total length of 95 mm and a maximum chamber inner diameter of 6.45 mm, wherein the chamber and the chamber section together can hold a volume of at least 2.25 ml.

[0036] In a further embodiment, the syringe body can have a maximum total length of 117 mm and a maximum chamber inner diameter of 6.45 mm, wherein the chamber and the chamber section together can hold a volume of at least 2.8 ml.

[0037] In a further embodiment, the syringe body can have a maximum total length of 56 mm and a maximum chamber inner diameter of 12.2 mm, wherein the chamber and the chamber section together can hold a volume of at least 2.8 ml.

[0038] In a further embodiment, the syringe body can have a maximum total length of 58 mm and a maximum chamber inner diameter of 12.2 mm, wherein a volume of at least 3.0 ml can be accommodated in the chamber and the chamber section together.

[0039] In a further embodiment, the syringe body can have a maximum total length of 115 mm and a maximum chamber inner diameter of 8.75 mm, wherein a volume of at least 5 ml can be accommodated in the chamber and the chamber section together.

[0040] The values ​​described above can be maximum dimensions or exact dimensions. A small inner chamber diameter has a positive effect on the application of a highly viscous liquid by applying finger force to the syringe or injection device. At the same time, however, care must be taken to ensure that the overall length of the syringe body, which also determines the overall length of the associated piston rod assembly, is not chosen too large to ensure manageability. The embodiments described above represent exemplary embodiments that indicate advantageous combinations of overall length and inner diameter for different syringe body volumes.

[0041] According to a further development, the syringe body can have a wall thickness of at least 1.7 mm, preferably at least 1.8 mm, preferably at least 2.0 mm, and more preferably at least 2.2 mm, at least in the chamber region. Forming such a wall thickness can positively influence the dimensional stability of the syringe body during use and thus reduce mechanical failure of the syringe body. The specified values ​​represent an optimized geometry with regard to the ratio between the inner and outer diameters.

[0042] For example, in the area of ​​the chamber, the syringe body may have an outer diameter of between 5 mm and 15 mm, in particular between 7.5 mm and 12.5 mm, or between 8.4 mm and 10 mm, in particular of approximately 9.4 mm.

[0043] The syringe body can be designed such that it has an extrusion force of less than 40 N when a standard piston is displaced at 10 mm / min in the chamber towards the distal end section. The syringe body can be designed such that it has an extrusion force of less than 75 N when a standard piston is displaced at 50 mm / min in the chamber towards the distal end section. The syringe body can be designed such that it has an extrusion force of less than 100 N when a standard piston is displaced at 100 mm / min in the chamber towards the distal end section. The above values ​​refer to the dispensing of a highly viscous medium with a storage modulus G' of approximately 84.5 Pa and a loss factor tan δ of approximately 0.48. Viscosity can be measured using a plate-plate measuring system at 25°C and an air pressure of 1013.25 hPa (e.g.Rheometer (Company: Anton Paar MCR 302), particularly at a frequency of 1 Hz. The measurement can be performed, for example, using the method according to ISO standard 6721-10-2015-09. The extrusion force describes the force with which the medium emerges from a cannula of a needle assembly connected to the syringe barrel. High-viscosity media generally require higher extrusion forces than low-viscosity media. The above values ​​apply to a test assembly with a needle assembly that includes a cannula with a thickness of 30 G and a length of 13 mm, i.e., a 30 G x 1 / 2 needle assembly, specifically the "TSK HYPODERMIC NEEDLE" needle assembly, Ref.: HPC-30013I-320, 30 G x 1 / 2. The cannula is open in this test procedure, allowing the high-viscosity medium to exit the cannula. The needle assembly includes a thread as a Luer Lock connector counterpart (in contrast to the needle assembly with fins).A syringe body with such comparatively low extrusion forces for highly viscous media requires less force from the user and enables improved dosing accuracy. Thus, such syringe bodies allow the use of needle assemblies with thin cannulas, i.e., a thickness of 30 G or more, despite the use of highly viscous media.

[0044] In one embodiment, the syringe body can be made of a plastic material that preferably has a Young's modulus between 2800 MPa and 3300 MPa, in particular between 2900 MPa and 3200 MPa (1 mm / min, ISO 527 Parts 1 and 2). The plastic material can have a tensile strength (5 mm / min, ISO 527 Parts 1 and 2) between 58 MPa and 65 MPa, in particular in the range of 60 MPa to 63 MPa. The plastic material can have a water absorption of less than 0.01% (ISO 62). Furthermore, the plastic material can have a ball indentation hardness between 180 and 195 N / mm² (30-s value at a load of 961 N according to ISO 2039 Part 1). The plastic material can have a heat deflection temperature between 120 and 180 °C (HDT / B 0.45 MPa, ISO 75 Parts 1 and 2). The linear thermal expansion coefficient of the plastic material can be 6.0 × 10 -4 < K -1 < (ISO 11 359 Parts 1 and 2).The elongation at break of the plastic material can be in the range of 2.5 to 2.7% (ISO 527 Parts 1 and 2). The impact strength of the plastic material can be approximately 15 kJ / m 2 < (ISO 179 / 1eU) and / or the notched impact strength can be in the range of 1.6 kJ / m 2 < to 1.8 kJ / m 2 < (ISO 179 / 1eA).

[0045] In a further development, the syringe body can comprise a flange at its proximal end portion. The flange can form a grip for supporting the index and middle fingers of a user when using the syringe body, or can be provided with such a grip.

[0046] The syringe for injecting a highly viscous medium with a syringe body of the type described above comprises a piston rod assembly. The piston rod assembly comprises a piston rod and a piston attached to a distal end of the piston rod. The piston is received in the chamber via the opening at the proximal end portion of the syringe body and is displaceably guided therein. The piston can, for example, comprise three sealing lips.

[0047] The syringe can comprise a highly viscous medium accommodated in the chamber of the syringe body. In one embodiment, the highly viscous medium is characterized by a storage modulus G' of at least 30 Pa and at most 150 Pa, in particular at least 50 Pa and at most 100 Pa, or at least 70 and at most 90 Pa. The loss factor tan δ can be between 0.2 and 0.8, in particular between 0.3 and 0.6 or between 0.4 and 0.5. The viscosity can be measured using a plate-on-plate measuring system at 25°C and an air pressure of 1013.25 hPa (e.g., rheometer from Anton Paar MCR 302), in particular at a frequency of 1 Hz. The measurement can be carried out, for example, using the method according to ISO standard 6721-10-2015-09. For example, the syringe may contain hyaluronic acid fillers and / or other cosmetic compositions contained in the chamber of the syringe body.

[0048] The syringe can have a gripping length between 6 cm and 12 cm, in particular between 7.5 cm and 8 cm. The gripping length refers to the length between the proximal end of the syringe body and a proximal end of the plunger rod assembly. The plunger rod assembly can be provided with a handle at the proximal end.

[0049] The needle assembly comprises a needle hub and a cannula, wherein the needle hub comprises a Luer-Lock connector counterpart complementary to the Luer-Lock connector of the syringe body for establishing the Luer-Lock connection between the syringe body and the needle assembly. Accordingly, the needle hub comprises an inner cone complementary to the outer cone of the syringe body and preferably an external thread complementary to the internal thread of the syringe body. As an alternative to an external thread, the needle hub can comprise two fins arranged on the outer circumference of the needle hub.

[0050] The needle assembly may comprise a cannula with a thickness of at least 30 G (gauge), preferably at least 31 G, preferably at least 32 G, preferably at least 33 G, more preferably at least 34 G, even more preferably at least 35 G. The cannula may have a length of at least 10 mm, preferably at least 11 mm, preferably at least 12 mm, more preferably at least 13 mm. Alternatively, the cannula may have a length of 25 mm or more.

[0051] The needle hub of the needle assembly may comprise an inner cone having a length along a longitudinal axis of the needle assembly between 3 mm and 7 mm, preferably between 5.5 mm and 6.5 mm, preferably of about 6.1 mm.

[0052] In particular, the injection device may comprise the needle assembly "TSK HYPODERMIC NEEDLE", Ref.: HPC-30013I-320, 30 G x ½ or a comparable needle assembly.

[0053] Alternatively, the injection device may comprise the needle assembly "TSK STERiJECT Hypodermic Needle", Ref.: PRC-30013I, 30 G x ½ or a comparable needle assembly.

[0054] In one embodiment, the syringe body may be constructed from a plastic material comprising or consisting of a cycloolefin copolymer (COC) and / or a cycloolefin polymer (COP).

[0055] In a further development, the plastic material may comprise one or more additives, wherein an additive may preferably be a dye.

[0056] Although some aspects and features are described above and below only with respect to the syringe body, these aspects and features may apply accordingly to the syringe and / or the injection device and vice versa.

[0057] The invention also relates to a cosmetic method comprising applying a highly viscous cosmetic preparation using an injection device described herein. In one embodiment, the highly viscous cosmetic preparation is characterized by a storage modulus G' of at least 30 Pa and at most 150 Pa, in particular at least 50 Pa and at most 100 Pa, or at least 70 and at most 90 Pa. The loss factor tan δ can be between 0.2 and 0.8, in particular between 0.3 and 0.6 or between 0.4 and 0.5. The viscosity can be measured using a plate-on-plate measuring system at 25°C and an air pressure of 1013.25 hPa (e.g., rheometer from Anton Paar MCR 302), in particular at a frequency of 1 Hz. The measurement can be carried out, for example, using the method according to ISO standard 6721-10-2015-09. The application may comprise injecting the cosmetic preparation into an organism to be treated.Preferably, the preparation is administered to an application site on a human body. The application can be a subcutaneous injection. The application site can be a human face or a portion thereof. Short description of the characters

[0058] Embodiments of the present invention are explained in more detail below with reference to the accompanying schematic figures. They depict: Fig. 1 shows various perspective views of an injection device according to an embodiment of the invention. Fig. 2 shows a sectional view of the Luer-Lock connector of an embodiment of a syringe body. Fig. 3 shows a detailed view of a thread profile from Fig. 2 . Fig. 4 a sectional view of an embodiment of the syringe body with the piston rod assembly accommodated therein. Fig. 5 a detailed view of a bevel of the syringe body from Fig. 4Fig. 6 shows a diagram with test results for NPO and leakage of a syringe body according to the invention. Fig. 7 shows a diagram with test results for extrusion forces of a syringe body according to the invention. Character description

[0059] The same reference symbols in the figures indicate the same or analogous elements.

[0060] Figure 1 shows various perspective views of an injection device 10 according to an embodiment of the invention as exploded views and in the assembled state. The injection device 10 comprises a syringe body 12, a piston rod assembly 14, and a needle assembly 16.

[0061] The elongated syringe body 12 is hollow-cylindrical and forms a chamber for receiving a medium, in particular a highly viscous medium. The syringe body 12 has a distal end portion 18 and a proximal end portion 20. The proximal end portion 20 has an opening through which the piston rod assembly 14 can be inserted into the chamber (see views on the right side in Fig. 1 ). On the distal end portion 18 of the syringe body 12, a Luer-Lock connector 22 is formed, which is described in detail with respect to Fig. 2 The proximal end portion 20 of the syringe body 12 is provided with a flange 24 which serves as a grip for supporting the index and middle fingers of a user when using the syringe body 12.

[0062] The piston rod assembly 14 comprises a piston rod 26 and a piston 28, which in the exemplary embodiment is made of an elastic material and has three sealing lips. The piston 28 is attached to a distal end of the piston rod 26 and can be slidably guided over an inner circumferential surface of the chamber of the syringe body 12 and can be displaced in the direction of a chamber longitudinal axis. At a proximal end, the piston rod assembly 14 includes a handle 30, via which force can be exerted on the injection device 10 using the user's thumb.

[0063] The needle assembly 16 comprises a needle hub 32 and a cannula 34 in the form of a hollow needle. In the illustrated embodiment, the cannula 34 has a thickness of at least 30 G and a length of 13 mm. However, cannulas with other dimensions can also be used. The needle hub 32 has a Luer-Lock connector counterpart 36, which can establish a tight Luer-Lock connection with the Luer-Lock connector 22 of the syringe body 12 in order to connect the syringe body 12 to the needle assembly 14. The Luer-Lock connector counterpart 36, more precisely the needle hub 32, in the illustrated embodiment comprises an inner cone and two fins formed on an outer circumferential surface of a proximal end of the needle hub 32. It is understood that in further embodiments, the needle hub can be provided with an external thread or an external thread section instead of fins.Using such an external thread design, an even more secure Luer-Lock connection can be realized.

[0064] In order to close the syringe body 12, for example during transport, it can be closed in the area of ​​the Luer-Lock connector 22 by means of the Figure 1 The syringe body 12 can be closed by the cover 38 shown. This cover 38 is designed to complement the Luer lock connector 22 of the syringe body 12. The cover 38 is removed from the syringe body 12 before the needle assembly 16 is connected to the syringe body 12.

[0065] In the assembled state, in which the syringe body 12, the piston rod assembly 14, and the needle assembly 16 are structurally connected and operatively connected to one another, the injection device 10 can be moved from a non-actuated position to an actuated position by displacing the piston 28 within the chamber from the proximal end portion 20 toward the distal end portion 18. This allows a highly viscous medium, for example, hyaluronic acid, held in the chamber to be injected through the cannula 34 beneath the skin surface of a patient.

[0066] In the embodiment shown, the syringe body 12 is made of cycloolefin polymer (COP) or cycloolefin copolymer (COC).

[0067] Figure 2shows an enlarged sectional view of the Luer-Lock connector 22 of the syringe body 12. The Luer-Lock connector 22 comprises an outer cone 40 with a further opening 42 for dispensing the highly viscous medium contained in the chamber. As can be seen in Figures 1 and 2, the outer cone 42 protrudes as a conically shaped nozzle beyond a distal end of the syringe body 12. The Luer-Lock connector 22 also comprises a sleeve-shaped portion 44 provided with an internal thread 46. The outer cone 40 is surrounded by the sleeve-shaped portion 44, wherein the outer cone 40 and the sleeve-shaped portion 44 are arranged coaxially with one another.

[0068] The internal thread 46 has a smallest internal diameter I 1 of 7.1 mm, measured from the thread crest 50 to the opposite thread crest 50' of the internal thread 46. The largest internal diameter I 2 , measured from the thread root 54 to the opposite thread root 54' of the internal thread 46, is 8.0 mm in the illustrated embodiment. The outer diameter AH of the sleeve-shaped section 44 is 10.0 mm. Accordingly, the sleeve-shaped section 44 has a wall thickness of 1 mm.

[0069] As from Figure 2 and in particular from the detailed view of the thread profile of the internal thread 46 in Figure 3As can be seen, the internal thread 46 has a width BK of 0.48 mm at the crest 50 of the thread profile. Furthermore, the internal thread 46 has a width BG of 0.9 mm at the base 54 of the thread profile. The internal thread has an angle α and β of 25° on both sides of the thread profile. A thread profile designed with these dimensions serves to optimally define the common contact surface with the complementary external thread of the associated needle assembly. This can contribute to the targeted adjustment of the minimum NPO resistance, the average NPO resistance, the minimum leakage resistance, and the average leakage resistance.

[0070] The outer cone 40 comprises a distal end face 56 in which the further opening 42 is formed. The distal end face 56 protrudes a distance A of 2.3 mm beyond a distal collar 58 of the sleeve-shaped portion 44, viewed in the direction of the longitudinal axis L of the syringe body 12. Furthermore, the distal end face 56 of the outer cone 40 is spaced from a bottom side of the first complete thread profile facing away from the end face 56 by a distance B of 3.1 mm. In the illustrated embodiment, the outer cone 40 has a total cone length C of 8.9 mm.

[0071] In particular, the Figure 3The parameters BK, BG, α and β of the thread profile shown, the smallest inner diameter I 1 and / or the distance A can be provided with these dimensions for syringe bodies with different chamber volumes in order to achieve optimal values ​​for the minimum NPO resistance, for the average NPO resistance, for the minimum leakage resistance and for the average leakage resistance of the syringe body 12.

[0072] In Figure 4is a sectional view of the syringe body 12 with a piston rod arrangement 14 accommodated therein, wherein the piston rod arrangement 14 is not shown in full for reasons of clarity. The syringe body 12 of the exemplary embodiment shown has a total length L SK of 80.0 mm. The total length L SK is made up of the length of a section of the syringe body forming the chamber and the total cone length C of the outer cone 40. The inner chamber diameter IK of the chamber is 5 mm in the example shown. This means that a medium, in particular a highly viscous medium, with a volume V of 1073 mm 3< can be accommodated in the chamber of the syringe body 12 and the adjoining chamber section formed by the outer cone 40. This absorbable volume V results from the considerations and resulting design measures according to which the syringe body 12 should provide a highly viscous medium with a volume of 1 ml.In addition, the chamber must allow for overfilling of 2% and the inclusion of an air bubble 1 mm long (see length s). In addition to the volume of medium to be accommodated, including the tolerances for overfilling and the air bubble described above, the chamber must be able to accommodate part of the piston rod assembly even in a non-actuated position and support it stably. To this end, a proximal end of the piston 28 of the piston rod assembly 14 should already be spaced a distance u of 9.5 mm from the proximal end of the syringe body 12 in a non-actuated position. Furthermore, a third (proximal) sealing lip of the piston 28 of the piston rod assembly 14 is spaced a distance o of 9.5 mm from a chamfer 60 of the syringe body 12 in this non-actuated position. The piston 28 has, for example, a length t of 6.9 mm.

[0073] The chamfer 60 is formed on the inner peripheral surface of the proximal end portion 20 of the syringe body 12. The chamfer 60 tapers the inner peripheral surface of the syringe body 12 from the proximal end portion 20 toward the distal end portion 18.

[0074] The chamfer 60 is in Figure 5 Enlarged. It has a length w of 1.5 mm, viewed in the direction of a longitudinal axis L of the syringe body 12, and forms an angle γ of 15° with the longitudinal axis L. A radius R of 0.5 mm is provided in a transition region of the chamfer 60 to the proximal end of the syringe body 12.

[0075] The syringe body 12 of the illustrated embodiment has a wall thickness of 2.2 mm in the area of ​​the chamber, which provides sufficient stability against breakage of the syringe body.

[0076] Figure 6shows a diagram with test results for a syringe body according to the invention, showing various measured resistances of the syringe body against NPO and leakage. The underlying tests were carried out with the syringe body 12 of the Figures 1 to 5 The x-axis of the diagram represents the various measurements from the series shown (56 individual measurements). The y-axis indicates the measured force applied to the syringe at the time of failure of the syringe barrel due to NPO or leakage.

[0077] For the test procedure, the syringe body 12 to be tested was positioned vertically in the universal testing machine from "TesT", model "TesT 106.2 kN" and held in the area of ​​the proximal end of the syringe body 12. Before starting the test, the tested syringe body 12 was connected via the Luer-Lock connector 22 to the needle assembly "TSK STERiJECT Hypodermic Needle", Ref.: PRC-30013I, 30 G x 1 / 2. This needle assembly comprises an inner cone and two fins arranged on the outer circumference of a needle hub of the needle assembly to establish the Luer-Lock connection. The Luer-Lock connector 22 of the syringe body 12 was screwed to the Luer-Lock connector counterpart of the needle assembly with a torque of 12 Ncm. The cannula of the needle assembly, which has a thickness of 30 G and a length of 13 mm (30 G x ½), was flattened with a hammer and thus closed before carrying out the test procedure.For the test procedure, a dry Luer-Lock connection was created by screwing the needle assembly onto the syringe barrel before a highly viscous medium was subsequently filled into the chamber. The test procedure was carried out using non-steam-sterilized components (syringe barrel, needle assembly, piston rod assembly). A highly viscous placebo medium was used for this test procedure. The highly viscous placebo medium had a storage modulus G' of approximately 84.5 Pa and a loss factor tan δ of approximately 0.48. The viscosity was measured using a plate-on-plate measuring system at 25°C and an air pressure of 1013.25 hPa (e.g., rheometer from Anton Paar MCR 302). The frequency was 1 Hz. The measurement was carried out according to ISO standard 6721-10-2015-09. The tested syringe body 12 was completely filled with this material, ie with a volume of 1073 mm 3< .A standard piston type FM257 from the manufacturer Daetwyler was used for the piston arrangement.

[0078] A force was applied perpendicularly to the proximal end of the piston rod assembly via a test piston on the testing machine. The test piston was moved at a constant test speed of 12.6 mm / min toward the distal end of the syringe body, while the force acting on the piston rod assembly was continuously increased. A maximum force of 420 N was set, at which the test would have been terminated. The applied force was detected by a force sensor with a sampling rate of 200 Hz. The test piston was continuously moved until leakage ( "Leakage ") and / or NPO was detected, ie until the measured force suddenly dropped by at least 30%.

[0079] The force acting at the time of occurrence of leakage and / or NPO was documented for each measurement and recorded in the Figure 6 shown diagram. The diagram of the Figure 6 shows the results of a series of 56 measurements. The results presented in the diagram demonstrate that no syringe barrel failure due to NPO or leakage occurred under a force of 100 N for any of the 56 measurements. Performing 56 measurements ensures that a minimum NPO resistance can be determined, which is defined as a "needle pop-off" occurring in no more than 1.8% of the tested syringe barrels below this threshold.

[0080] Since the maximum finger force with which syringes are operated in practice is on average 95 N, the occurrence of NPO and / or leakage can be avoided with the syringe body according to the invention.

[0081] In Figure 7 This is another diagram showing test results for extrusion forces of a syringe barrel according to the invention compared to extrusion forces of a known product from the prior art. The various measurements are plotted along the x-axis of the diagram. The y-axis indicates the measured extrusion force. The diagram shows measurements at three different test speeds.

[0082] A syringe body was compared according to the Figures 1 to 5The example shown used a "SCHOTT COC Standard" syringe barrel with a 1 ml filling volume (designation "TopPac 1 ml long"). A standard plunger of type FM257 from the manufacturer Daetwyler was used for the plunger assembly with both syringe barrels. The needle assembly used with both syringe barrels was the "TSK HYPODERMIC NEEDLE" needle assembly, Ref.: HPC-30013I-320, 30 G x ½ with an open (non-flattened) cannula with a thickness of 30 G and a length of 13 mm. A highly viscous medium was used as the extruded medium. The highly viscous medium had a storage modulus G' of approximately 84.5 Pa and a loss factor tan δ of approximately 0.48. Viscosity was measured using a plate-on-plate measuring system (e.g., Anton Paar MCR 302 rheometer) at 25°C and an air pressure of 1013.25 hPa. The frequency was 1 Hz. The measurement was conducted according to ISO 6721-10-2015-09.

[0083] Testing was carried out at test speeds of 100 mm / min, 50 mm / min and 10 mm / min, at which the piston in the syringe body was displaced from proximal to distal. The test results show that at a test speed of 100 mm / min the extrusion force of the syringe body according to the invention was reduced from 172.3 N to 94.9 N compared to the syringe body from the prior art. Furthermore, the test results show that at a test speed of 50 mm / min the extrusion force of the syringe body according to the invention was reduced from 136.4 N to 73.9 N compared to the syringe body from the prior art. Furthermore, the test results show that at a test speed of 10 mm / min the extrusion force of the syringe body according to the invention was reduced from 73.5 N to 38.3 N compared to the syringe body from the prior art.

[0084] The extrusion forces of the syringe body 12 according to the invention are thus significantly lower than the extrusion forces of known syringe bodies. The syringe body according to the invention thus requires less force from the user to dispense highly viscous media, thereby enabling improved dosing accuracy. Thus, despite the use of highly viscous media, the syringe bodies according to the invention allow the use of needle assemblies with thin cannulas, i.e., a thickness of 30 G or more. List of reference symbols

[0085] 10 Injection device A Distance 12 syringe body B Distance 14 Piston rod arrangement C Total cone length 16 Needle arrangement I 1 smallest inner diameter 18 distal end section I 2 largest inner diameter 20 proximal end section UH Outer diameter 22 Luer-Lock connector BK Wide comb 24 flange BG Width base 26 piston rod α Angle on the thread profile 28 Pistons β further angle on the thread profile 30 Handle Y Angle of the bevel 32 Needle attachment IK Chamber inner diameter 34 Cannula V absorbable volume 36 fin L SK Total length 38 Lid o Distance 40 Outer cone s Length of the air bubble 42 opening t Piston length 44 sleeve-shaped section u Distance 46 internal thread w Length of the bevel 50, 50' Comb 54, 54' Reason 56 frontal surface 58 distal collar 60 chamfer L Longitudinal axis

Claims

1. Injection device (10) for injecting a highly viscous medium, comprising a syringe for injecting a highly viscous medium having a syringe body (12) and a piston rod assembly (14) and a needle assembly (16) comprising a needle hub (32) and a cannula (34), wherein the syringe body (12) comprises a distal end portion (18) and a proximal end portion (20), wherein the syringe body (12) is hollow cylindrical and forms a chamber for receiving the highly viscous medium, wherein the proximal end portion (20) comprises an opening through which a piston rod assembly (14) is insertable into the chamber, wherein the piston rod assembly (14) comprises a piston rod (26) and a piston (28) attached to a distal end of the piston rod (26), wherein the piston (28) is received in and displaceably guided within said chamber via said opening at the proximal end portion (20) of the syringe body (12), wherein a Luer lock connector (22) is formed at the distal end portion (18) of the syringe body (12), which connector (22) comprises an outer cone (40) having a further opening (42) for dispensing the highly viscous medium and a sleeve-shaped portion (44) comprising an internal thread (46), wherein the needle hub (32) comprises a Luer lock connector counterpart (36) complementary to the Luer lock connector (22) of the syringe body (12) for establishing a Luer lock connection between the syringe body (12) and the needle assembly (16), and wherein for a Luer lock connection of the Luer lock connector (36) with the Luer lock connector counterpart (36) the syringe body (12) has a minimum NPO resistance between 90 N and 105 N, as measured according to the method specified in the description on pages 3 to 5, wherein the syringe body at the proximal end portion (20) comprises an inner peripheral surface having a chamfer (60) which causes the inner peripheral surface to taper as viewed from the proximal end portion (20) in the direction of the distal end portion (18), characterized in that, the chamfer (60) as viewed in the direction of a longitudinal axis (L) of the syringe body (12) has a length (w) between 1.2 mm and 1.8 mm, preferably from 1.4 mm to 1.6 mm, more preferably of 1.5 mm, and / or wherein the chamfer (60) forms an angle (y) of at least 13°, preferably at least 14°, more preferably at least 15°, with the longitudinal axis (L).

2. Injection device (10) according to claim 1, wherein the syringe body (12) has an average NPO resistance of at least 110 N, preferably at least 115 N, more preferably at least 117 N.

3. Injection device (10) according to claim 1 or 2, wherein the internal thread (46) has a smallest internal diameter (I1) between 7.05 mm and 7.15 mm, preferably between 7.08 mm and 7.12 mm, more preferably 7.1 mm.

4. Injection device (10) according to any one of the preceding claims, wherein the internal thread (46) has a width (BK) between 0.44 mm and 0.52 mm, preferably between 0.46 mm and 0.50 mm, more preferably 0.48 mm at the ridge (50) of the thread profile.

5. Injection device (10) according to any one of the preceding claims, wherein the internal thread (46) has a width (BG) between 0.85 mm and 0.95 mm, preferably between 0.875 mm and 0.925 mm, more preferably 0.9 mm at the root (54) of the thread profile.

6. Injection device (10) according to any one of the preceding claims, wherein a distal end face (56) of the outer cone (40) projects by a distance (A) of 2.1 mm to 2.5 mm, preferably from 2.2 mm to 2.4 mm, more preferably from 2.3 mm, beyond a distal collar (58) of the sleeve-shaped portion (44).

7. Injection device (10) according to any one of the preceding claims, wherein the syringe body has a maximum overall length (LSK) of 80 mm and a chamber inner diameter (IK) of at most 5 mm, wherein a volume (V) of at least 1 ml can be received in the syringe body (12).

8. Injection device (10) according to any one of the preceding claims, wherein the syringe body has a wall thickness of at least 1.7 mm, preferably at least 1.8 mm, more preferably at least 2.0 mm, further preferably at least 2.2 mm, at least in the region of the chamber.

9. Injection device (10) according to any one of the preceding claims, wherein the syringe body is made of a plastic material which preferably has a modulus of elasticity between 2800 MPa and 3300 MPa, in particular between 2900 MPa and 3200 MPa.

10. Injection device (10) according to any one of the preceding claims, wherein the cannula (34) has a thickness of at least 31 G, preferably at least 32 G, more preferably at least 33 G, still more preferably at least 34 G, further preferably at least 35 G, and / or the needle hub (32) comprises an inner cone having a length along a longitudinal axis of the needle assembly (16) between 3 mm and 7 mm, preferably between 5.5 mm and 6.5 mm, more preferably 6.1 mm.

11. Cosmetic method comprising applying a highly viscous cosmetic preparation by use of an injection device according to any one of claims 1 to 10.