Syringe system with defined maximum dose capacity

Abstract

The present application relates to syringe systems with defined maximum dose capacity. The syringe systems limit the aspiration capacity of a medical syringe to a maximum volume capacity or dose defined within the syringe cavity of the syringe barrel. A plunger pullback stop coupled to the syringe prevents additional aspiration of the medical fluid within the syringe cavity by blocking the syringe plunger pullback beyond a specified maximum dose volume. The plunger pullback stop includes a stop tip oriented within the syringe cavity between the inner barrel wall and the syringe plunger and intermediate the proximal and distal ends of the plunger. When the stop tip is in engaged contact with the plunger, it blocks further pullback of the plunger. In some embodiments of this syringe system, the maximum dose volume is selectively variable prior to drug administration, while in other embodiments it is fixed during syringe manufacture. Advantageously, use of such a syringe system with its pre-set maximum dose volume reduces the likelihood of patient drug overdosing.

Description

Technical Field

[0001] This disclosure generally relates to syringe assemblies for administering drug fluids to a patient. More specifically, aspects of this disclosure relate to a syringe system that limits the aspiration capacity of a medical syringe to a defined maximum volumetric capacity or dose. Background Technology

[0002] In the past, injectable medications were typically administered in licensed clinical settings such as medical offices, clinics, or hospitals. Whether the delivery was intravenous, subcutaneous, or intramuscular, it was administered to patients by trained medical professionals. These professionals adhered to injection protocols, including procedures to ensure the correct dosage was administered, to minimize the risk of overdose.

[0003] Drug research has driven the development of a growing number of medications for treating a wide range of conditions, including arthritis, cholesterol management, asthma, deep vein thrombosis, cardiovascular disease, osteoporosis, autoimmune diseases, infections, infertility, diabetes, and weight loss. Many of these newly developed drugs are administered via subcutaneous or intramuscular injection. Medical regulatory agencies permit self-administration of medications in non-clinical settings, administered directly by patients or home caregivers. Most patients and home caregivers administering medications outside of professionally supervised clinical facilities have not received formal training in medically recognized injection protocols. Due to insufficient medical training, negligence, or carelessness, self-administered medications pose a significant risk of overdose to patients. Some self-administered medications are pre-packaged in specialized delivery devices, administering only the prescribed dose per injection cycle, thus reducing the risk of overdose.

[0004] However, many self-injected medications are not packaged in specialized delivery devices that limit the maximum dose. Many of these medications are provided to patients in the form of multi-dose vials. Patients or caregivers must use a medical syringe to draw each individual dose from the vial and then inject it. Typical medical syringes provided for self-injection are capable of drawing a range of volumes of fluid smaller or larger than the patient's prescribed dose. Therefore, a potential cause of medication overdose is drawing an incorrect, larger volume of medication into the syringe – this could be due to excessively pulling back the syringe plunger, misreading the dosing markings on the syringe barrel, or misinterpreting the units of measurement. Summary of the Invention

[0005] An injector system limits the aspiration volume of a medical injector to a defined maximum volumetric volume or dose within the injector cavity of the injector barrel. This effectively presets the maximum deliverable dose of the injector. Limiting the maximum injector volume reduces the likelihood of patient overdose, particularly in home injections, self-injections, and other non-clinical settings where the injection administrator is not a licensed healthcare professional trained in extensive drug administration protocols. In the injector system of this disclosure, a plunger pull-back stop coupled to the injector includes a stop tip oriented within the pull-back path of the injector plunger. The pull-back stop prevents additional aspiration of drug fluid within the injector cavity by preventing the injector plunger from pulling back beyond the amount required to establish the specified maximum dose volume. The stop tip is oriented within the injector cavity between the inner barrel wall and the injector plunger, and is located between the proximal and distal ends of the plunger. During plunger retraction, when the stop tip engages with the plunger (engaging contact), it prevents further plunger retraction, thereby limiting the maximum volumetric capacity of the syringe used for drug aspiration. In some embodiments of this syringe system, the maximum dose volume is selectively variable, while in other embodiments, the maximum dose volume is fixed during syringe manufacturing.

[0006] One aspect of this disclosure relates to a syringe system with limited aspiration volume, comprising a syringe and a plunger pull-back stop. The syringe has a syringe barrel having a distal end defining an outlet, a proximal end opening, and an inner syringe wall therein defining a syringe cavity between its distal and proximal ends; and a syringe plunger inserted into the syringe cavity. The syringe plunger has a distal axial end and an outer peripheral surface that is in fluid-tight, abutting contact with the inner syringe wall. The plunger is translatable within the syringe cavity along a plunger pull-back path to selectively change the delivery volume within the syringe cavity between the distal end of the syringe barrel and the distal axial end of the plunger by the advancement or pull-back of the plunger. A plunger pull-back stop is coupled to the syringe. The plunger pull-back stop includes a stop tip oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and located between the proximal and distal ends of the plunger. The stop tip intersects the pull-back path of the syringe plunger and blocks further pull-back of the plunger when the stop tip engages with the plunger.

[0007] Another aspect of this disclosure relates to a syringe system with limited aspiration volume, comprising a syringe and a plunger pull-back stop. The syringe has a syringe barrel having a distal end defining an outlet, a proximal end opening, and an inner barrel wall therein defining a syringe cavity between its distal and proximal ends; a syringe flange on the proximal end of the syringe barrel; and a syringe plunger inserted into the syringe cavity. The syringe plunger has a distal axial end and an outer peripheral surface that is in fluid-tight, abutting contact with the inner barrel wall. The plunger is translatable within the syringe cavity along a plunger pull-back path to selectively change the delivery volume within the syringe cavity between the distal end of the syringe barrel and the distal axial end of the plunger by the advancement or pull-back of the plunger. The plunger pull-back stop is coupled to the syringe flange.

[0008] In some embodiments, the maximum dose regulated by the pull-back stop is fixed during the manufacture of the syringe system. In other embodiments, the maximum dose of the syringe can be selectively varied by repositioning the stop tip of the pull-back stop. Exemplary additional embodiments of the fixed and selectively variable maximum dose syringe systems of this disclosure are as follows.

[0009] In some embodiments of this disclosure, the plunger pullback stop further includes a plunger pullback stop housing coupled to a syringe barrel, such as to a syringe flange of the syringe barrel, and defining a rack channel oriented to align with the proximal opening end of the syringe barrel. An elongated, translationally movable rack is held within the rack channel. The rack defines a first helical thread pattern between its proximal and distal ends, wherein the distal end of the rack defines a stop tip. The distal end of the rack and its stop tip are oriented within a syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger. A rotatable adjusting wheel is coupled to the plunger pullback stop housing. The adjusting wheel defines a second helical thread that engages with the first thread pattern such that rotation of the adjusting wheel advances or pulls back the stop tip of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotation of the adjusting wheel.

[0010] In some embodiments, the plunger pullback stop housing is coupled to the syringe barrel, such as to the syringe flange of the syringe barrel, and defines a rack channel oriented to align with the proximal opening end of the syringe barrel. An elongated, translationally movable rack is held within the rack channel. The rack defines a first tooth profile oriented between a proximal and a distal end of the rack, wherein the distal end of the rack defines a stop tip. The distal end of the rack and its stop tip are oriented within a syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger. A pinion profile and a rotatable adjusting wheel are coupled to the plunger pullback stop housing. The pinion adjusting wheel defines a second tooth profile that engages with the first tooth profile such that rotation of the pinion adjusting wheel advances or pulls back the stop tip of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotation of the pinion adjusting wheel.

[0011] In some embodiments of this disclosure, the plunger pullback stop further includes a plunger pullback stop housing coupled to a syringe barrel, such as to a syringe flange of the syringe barrel, and defining a rack channel oriented to align with the proximal opening end of the syringe barrel. An elongated, translationally movable rack is held within the rack channel. The rack defines a first hypoid-gear tooth pattern oriented between the proximal and distal ends of the rack, wherein the distal end of the rack defines a stop tip. A rotatable adjusting wheel is coupled to the plunger pullback stop housing, the adjusting wheel defining a second hypoid-gear tooth pattern on its outer circumferential surface, the second hypoid-gear tooth pattern engaging with the first hypoid-gear tooth pattern such that rotation of the adjusting wheel advances or pulls back the stop tip of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotation of the adjusting wheel.

[0012] In some embodiments of this disclosure, the plunger pullback stop further includes a plunger pullback stop housing, the distal end of which is inserted into the proximal end of the opening of a syringe barrel. The housing defines a plunger channel therethrough, which captures an axis of the syringe plunger that can translate. An elongated stop sleeve is oriented within a syringe cavity between the inner syringe wall and the plunger, thereby surrounding at least a portion of the plunger axis. The stop sleeve is inserted between the distal end of the plunger pullback stop housing and the distal axial end of the syringe plunger, wherein the distal end of the stop sleeve defines a stop tip. In some embodiments, the stop sleeve and the stop tip are integrally formed as a projection within the pullback stop housing. The maximum capacity of the syringe cavity is adjusted by the total axial length of the elongated stop sleeve.

[0013] In some embodiments of this disclosure, the plunger pullback stop further includes a plunger pullback stop housing coupled to a syringe barrel, such as to a syringe flange of the syringe barrel. The housing is oriented to align with the proximal opening end of the syringe barrel. A cantilevered pawl is coupled to the plunger pullback stop housing; the distal end of the pawl defines a stop end protruding into the syringe cavity. The syringe plunger defines an engagement surface that is biased and abuts against the stop end of the pawl. The plunger also defines a notch formed in the plunger engagement surface. The mutual engagement and trapping of the stop ends within the notch formed in the plunger engagement surface prevents further pullback of the plunger. For example, during the manufacture of the syringe system, the maximum capacity of the syringe cavity is selectively adjusted by the axial position of the notch in the plunger engagement surface.

[0014] Another aspect of this disclosure relates to a method for limiting the aspiration volume of a medical syringe having a syringe barrel, a retractable syringe plunger inserted into the syringe barrel along a retraction path, and a plunger retraction stop coupled to the syringe. The plunger retraction stop includes a stop tip oriented within the syringe barrel and intersecting the plunger retraction path. In this method, the stop tip is oriented in the syringe plunger retraction path to prevent plunger retraction beyond a position corresponding to the aspiration volume of the syringe for a dose of prescribed medication. A dose of prescribed medication is aspirated into the syringe barrel by retracting the syringe plunger. Further plunger retraction is blocked when the syringe plunger engages with the stop tip of the plunger retraction stop. When further plunger retraction is blocked, the syringe cannot aspirate any additional medication beyond the prescribed dose into the syringe barrel. Therefore, the use of the syringe system of this disclosure reduces the chance of patient overdose. Attached Figure Description

[0015] Exemplary embodiments of the present disclosure are further described in the following detailed description in conjunction with the accompanying drawings, wherein: Figure 1 This is an isometric view of an embodiment of the syringe system disclosed herein; Figure 2 yes Figure 1 A local axial cross section of the syringe system; Figure 3 yes Figure 1 Another local axial cross section of the syringe system; Figure 4 yes Figure 1 A partially exploded view of the syringe system; Figure 5 This is an isometric view of another embodiment of the syringe system disclosed herein; Figure 6This is an isometric view of an alternative embodiment of the syringe system disclosed herein; Figure 7 This is an isometric view of another embodiment of the syringe system disclosed herein, the syringe system including a plug-type housing stop; Figure 8-11 yes Figure 7 Isometric drawing of an alternative embodiment of the plug-type housing stop assembly of a syringe system; Figure 12 This is an isometric view of another embodiment of the syringe system disclosed herein; Figure 13 This is an isometric view of another embodiment of the syringe system disclosed herein; and Figure 14 yes Figure 13 The local axial cross section of the syringe system.

[0016] For ease of understanding, the same reference numerals have been used to represent the same elements as in the accompanying drawings, where possible. The accompanying drawings are not drawn to scale. Detailed Implementation

[0017] The various embodiments of the syringe systems disclosed herein limit the passive aspiration volume of the medical syringe to a defined maximum volumetric volume corresponding to the maximum volumetric volume of a prescription drug or other medical fluid to be administered to a patient. The aspiration volume limit is preset during syringe manufacturing or selectively preset prior to injection administration. Limiting the maximum syringe volume reduces the likelihood of patient overdose, particularly useful in home therapy and other non-clinical scenarios where the administration operator is not a licensed healthcare professional extensively trained in intravenous medication administration protocols. Each syringe system embodiment of this disclosure includes a plunger pull-back stop that prevents additional aspiration of the drug fluid into the syringe cavity by preventing the syringe plunger from pulling back by an amount required to establish a specified maximum dose volume. The plunger pull-back stop is coupled to the syringe, for example, by surrounding the exterior of the syringe barrel, by attaching to a flange of the syringe barrel, or by inserting as a plug into the open end of the syringe barrel cavity. The plunger pull-back stop includes a stop tip oriented within the pull-back path of the syringe plunger. More specifically, the stop tip is oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and is positioned between the proximal and distal ends of the syringe plunger. During plunger retraction, when the stop tip engages with the plunger, it prevents further retraction, thereby limiting the maximum volumetric capacity of the syringe corresponding to the prescribed drug dose. In some embodiments of this syringe system, the maximum dose volume is selectively variable, while in other embodiments, the maximum dose volume is fixed during syringe manufacturing. The plunger retraction stop embodiment of this disclosure is suitable for use with existing commercially available variable aspiration volume syringes.

[0018] Before describing several exemplary embodiments of this disclosure, it should be understood that this disclosure is not limited to the details of the construction or process steps set forth in the following description. This disclosure can have other embodiments and can be practiced or carried out in a variety of ways.

[0019] In this disclosure, following convention, the distal end of the device is the end closest to the patient, for example, for delivering one or more medications to the patient, and the proximal end of the device is the end furthest from the patient and closest to the clinician or other practicing physician. The following definitions are provided regarding the terminology used in this disclosure.

[0020] As used in this article, the usage of “a”, “an” and “the” includes both singular and plural forms.

[0021] As used herein, the term "Luer connector" refers to a standard method of attaching syringes, catheters, needle hubs, intravenous tubing, etc., to each other. A Luer connector consists of interlocking male and female tubes with a slight taper to ensure a more secure connection through simple crimping / screwing. Optionally, Luer connectors may include additional external threaded edges for added strength. The male end of the Luer connector is associated with the syringe ejection tip and is interlocked with and connected to the female end, which is incorporated within the proximal end of a needle hub for drawing medication from a vial into a syringe. The female end of the Luer connector is typically located on a vascular access device (VAD).

[0022] As used herein, ISO 80369-7:2016 defines the specifications for standard Luer connectors, including a 6% taper between the distal and proximal ends. Male standard Luer connectors increase in diameter from the distal end of the opening towards the proximal end. Female standard Luer connectors decrease in diameter from the proximal end of the opening towards the distal end. According to ISO 80369-7:2016, the outer cross-sectional diameter of a male standard Luer connector, measured at 0.75 mm from the distal end, ranges between 3.970 mm and 4.072 mm. The length of the male standard Luer taper ranges between 7.500 mm and 10.500 mm. The outer cross-sectional diameter, measured at 7.500 mm from the distal end, ranges between 4.376 mm and 4.476 mm. As used herein, the phrases “male standard Luer connector” and “female standard Luer connector” refer to connectors having the dimensions described in ISO 80369-7, which are incorporated herein by reference in their entirety.

[0023] As will be readily understood by those skilled in the art, while descriptive terms such as “end,” “seat,” “thread,” “protrusion / insertion,” “plate,” “wall,” “top,” “side,” and “bottom” are used throughout the specification for ease of understanding, they are not intended to limit any components that can be used in combination or individually or to require a specific spatial orientation to implement various aspects of the embodiments of this disclosure.

[0024] The illustrations in this specification are provided to aid in a comprehensive understanding of the exemplary embodiments of this disclosure. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this disclosure. Furthermore, descriptions of well-known functions and constructions have been omitted for clarity and brevity.

[0025] In an exemplary embodiment of the embodiments of this disclosure, the syringe barrel includes a distal end having a needleless connection. In one or more embodiments, the needleless connection includes any and all combinations of at least one thread and other features, such that it interfaces with corresponding threads or threads of a corresponding connector.

[0026] According to another exemplary embodiment of the present disclosure, the construction of the structural element constituting the needleless connector includes a collar protruding from the distal end of the syringe barrel, the collar including at least one thread for connection to a corresponding thread or plurality of threads of a corresponding connector or needle holder.

[0027] According to another exemplary embodiment of the present disclosure, the collar or pinless connector can typically be bent or elastically deformed to allow for better interference fit compliance with the corresponding connector.

[0028] According to another exemplary embodiment of the present disclosure, a pinless connector may include a female thread sized to engage with a male fitting of type ISO 594-2 and / or a male thread sized to engage with a female fitting of type ISO 594-2. An example of an ISO 594-2 type connector is a Q-type connector.

[0029] The following non-limiting examples illustrate the principles of one or more embodiments according to this disclosure. Figure 1-4A first embodiment of a medical injection device or syringe system 20 is shown, the medical injection device or syringe system 20 having a syringe barrel 22 defining an inner syringe wall 23 and a syringe cavity 24 therein, the syringe barrel 22 having a proximal open end 26 and a syringe end or tip 28 terminating at a distal end of an outlet 30. In some embodiments, the syringe tip 28 includes a Luer connector 32. A needle hub and a needle 33 (shown in dashed lines) are coupled to the Luer connector 32 and are in fluid communication with the outlet 30. The syringe barrel 22 includes a syringe flange 34 at its proximal end. A syringe plunger 36 is inserted into the proximal open end 26 of the syringe barrel and is translatable along a translational path within the syringe cavity 24. The distal end of the plunger 36 has a plunger stop 38. As an assembly of the plunger 36, the plunger stop 38 defines a distal axial end 40 of the plunger 36 and an outer peripheral surface 42 that are in fluid-sealed, abutting contact with the inner syringe wall 23. In some embodiments, the plunger and plunger stop are integrally formed. The plunger contact surface 43 is oriented on the plunger 36 towards the proximal opening end 26 of the syringe barrel. A dose of medication or other medical fluid is contained in a syringe cavity 24 between the syringe tip or end 28 and the distal axial end 40 of the plunger stop 38. As is common in medical syringes, such as syringe system 20, the syringe cavity 24, syringe tip 28, and outlet 30 Luer connector 32 are in fluid communication with each other for administering the medical fluid through the needle tip 33 to the desired injection site within the patient. Medication is drawn into and dispensed from the syringe cavity 24 by finger manipulation and translation of the plunger shaft 44 and plunger tab 46 of the plunger 36 outside the syringe cavity 24 while the syringe flange 34 is grasped. A typical example of self-administered injection is a subcutaneous or intramuscular injection into the abdominal and / or muscle tissue site. The syringe barrel 22 and plunger 36 are capable of drawing in and dispensing multiple drug dose volumes, depending on the relative axial position of the distal axial end 40 of the plunger stop 38. The syringe barrel typically includes markings corresponding to the volume of liquid contained within the syringe barrel cavity 24. Overdosing may occur if the plunger 36 is pulled back beyond the marking corresponding to the prescribed drug dose during drug aspiration. For example, if the syringe has a 70 ml aspiration volume and the drug dose is 40 ml, pulling the plunger back beyond the 40 ml marking on the syringe will exceed the prescribed drug dose volume.

[0030] The syringe system 20 includes a plunger pullback stop mechanism 48 that prevents the plunger 36 from pulling back and the corresponding increase in the volume of the syringe barrel 24 (exceeding the increase in the prescription drug dose). The pullback stop mechanism 48 is calibrated to correspond the volume of the syringe barrel 24 to the volume of the prescription drug dose. For example, if the prescription drug dose is 40 ml, the pullback stop mechanism 48 is also calibrated to prevent the plunger from pulling back beyond the corresponding 40 ml volume in the syringe barrel 24.

[0031] exist Figure 1-4 In one embodiment, the plunger pull-back stop mechanism 48 includes a plunger pull-back stop housing 50 having axially separated proximal retaining plate 52 and distal retaining plate 54 for capturing the syringe flange 34 therebetween. An anti-clocking channel 56 captures the outer edge of the cross-shaped plunger shaft 44 therein. The housing 50 includes a rack channel 58 and a pair of first retaining flanges 60 and second retaining flanges 62, the rack channel 58 being oriented to align with the proximal opening end 26 of the syringe barrel 22.

[0032] The plunger pullback stop mechanism 48 also includes an elongated, translationally movable rack 64 having an axial central axis parallel to the axial central axis of the syringe plunger 36 and a fan-shaped cross-section, the outer circumference of which defines a first helical thread type 66 between its proximal and distal ends, and defines an outer radial edge of an anti-rotation step 68 parallel to the axial central axis of the rack. The rack 64 is slidably captured within a rack channel 58 having a planar profile perpendicular to the central axis of the plunger 36, the planar profile conforming to the cross-section of the rack 64. The rack 64 is oriented and protrudes into the syringe barrel cavity 24 between the inner wall 23 of the syringe barrel 22 and the syringe plunger 36 (i.e., between the plunger shaft 44 and the syringe barrel), between the proximal and distal ends of the plunger. The distal end of the rack 64 forms a stop tip 70, which protrudes into the syringe cavity 24 with an orientation opposite to that of the plunger contact surface 43 of the plunger 36. The stop tip 70 intersects the pull-back path of the syringe plunger 36. Once the plunger 36 pulls back a sufficient axial distance to cause the plunger contact surface 43 to contact the stop tip 70, the pull-back of the plunger 36 is blocked. The axial translation and positioning of the stop tip 70 adjusts the maximum pull-back of the plunger 36, thereby adjusting and presetting the maximum volume of drug fluid in the aspirable plunger syringe cavity 24.

[0033] exist Figure 1-4In embodiment 20 of the syringe system, the axial positioning of the stop tip 70 can be selectively altered through the interaction of a translational rack 64 and an annular rotatable adjusting wheel 72. The annular rotatable adjusting wheel 72 is defined as coaxial with the axial central axis of the syringe plunger 36 and rotatably connected to the axis of rotation of the plunger pull-back stop housing 50. The adjusting wheel 72 surrounds the syringe plunger 36 and the rack 64; the adjusting wheel 72 defines a second helical thread type 74 on its annular inner peripheral surface that engages with a first helical thread type 66 of the rack 64. The selective rotation of the adjusting wheel 72 causes its rotational movement (i.e., Figure 1 The double arrow R in the image is converted to a linear translation of the rack 64 (i.e., Figure 1 and 3 The double arrow L in the diagram causes the stop tip 70 of the rack to advance or retract within the syringe barrel 22. Separation of the corresponding first thread type 66 and second thread type 74 is limited and prevented by the interaction of an annular groove 76 formed on the inner circumferential surface of the adjusting wheel 72 with the radially outwardly oriented first retaining flange 60 and second retaining flange 62 of the plunger pullback stop housing 50. The interaction of the annular groove 76 and the retaining flanges 60, 62 prevents relative axial separation of the adjusting wheel 72 from the plunger pullback stop housing 50. In some embodiments, the annular groove is formed on the outer circumferential surface of the adjusting wheel, and the corresponding retaining flange is radially inwardly oriented and positioned outside the adjusting wheel. In some embodiments, a single retaining flange is present, while in other embodiments, more than two retaining flanges are present.

[0034] Figure 5 and 6 Other embodiments of a syringe system utilizing a plunger pull-back stop mechanism with a rotation-to-linear motion conversion element are shown. Figure 1-4 Similar to the embodiments described above, these other syringe system embodiments are capable of variable adjustment of the position of the stop tip within the syringe barrel in order to selectively change and limit the maximum aspiration volume capacity of the syringe. Figure 5 and 6 The syringe system embodiments include those with Figure 1-4 The embodiments use the same syringe barrel 22 and syringe plunger 36, therefore, for the sake of brevity, common structural elements in all these embodiments are described with the same structural names and reference numbers.

[0035] Figure 5 The syringe system 80 includes a rack and pinion plunger return stop mechanism 82, which includes a plunger return stop housing 84 connected to the syringe flange 34 and a rack channel 86, which is used in conjunction with... Figure 1The plunger pullback stop housing 50 and rack channel 58 are oriented in the same manner to align with the proximal opening end of the syringe barrel 22. The plunger pullback stop mechanism 82 also includes an elongated, translationally movable rack 88 held within the rack channel 86. The rack 88 defines a first tooth profile 90 between its proximal and distal ends, wherein the distal end of the rack 88 defines a stop tip 92. The distal end of the rack 88 and its stop tip 92 are oriented within the syringe barrel cavity 24 between the proximal and distal ends of the plunger 36 and its internal syringe barrel wall 23. The stop tip 92 protrudes into the syringe cavity 24 with an orientation opposite to that of the plunger contact surface 43 of the plunger 36. The stop tip 92 intersects the pullback path of the syringe plunger 36. Once the plunger 36 pulls back a sufficient axial distance to cause the plunger contact surface 43 to contact the stop tip 92, the pullback of the plunger 36 is blocked. The axial translation of the stopper tip 92 and the maximum pullback of the positioning adjustment plunger 36 adjust and pre-set the maximum volume of drug fluid in the aspirable plunger syringe cavity 24.

[0036] The plunger pullback stop mechanism 82 also includes a pinion profile and a rotatable adjusting wheel 94 connected to the plunger pullback stop housing 84 via a shaft 96. The pinion adjusting wheel 94 defines a second tooth profile 98 that engages with a first tooth profile 90 of the rack 88. Rotation of the pinion adjusting wheel 94 causes the stop tip 92 of the rack 88 to advance or retract within the syringe cavity 24. The maximum capacity of the syringe cavity 24 is selectively adjusted by rotation of the pinion adjusting wheel 94.

[0037] Figure 6 The syringe system 100 includes a quasi-hyperboloid rack and pinion plunger pull-back stop mechanism 102, which includes a plunger pull-back stop housing 104 coupled to the syringe flange 34 and a rack channel 106, which is connected to... Figure 1The plunger pull-back stop housing 50 and rack channel 58 are oriented in the same manner to align with the proximal opening end of the syringe barrel 22. The plunger pull-back stop mechanism 102 also includes an elongated, translationally movable rack 108 retained within the rack channel 106. The rack 108 defines a first quasi-hyperboloidal tooth profile 110 between its proximal and distal ends, wherein the distal end of the rack 108 defines a stop tip 112. The distal end of the rack 108 and its stop tip 112 are oriented within the syringe barrel cavity 24 between its internal syringe wall 23 and the syringe plunger 36, and between the proximal and distal ends of the plunger. The stop tip 112 protrudes into the syringe cavity 24 with an orientation opposite to that of the plunger contact surface (not shown) of the plunger 36. The stop tip 112 intersects the pull-back path of the syringe plunger 36. Once the plunger 36 is pulled back a sufficient axial distance to cause the plunger contact surface to contact the stop tip 112, the pullback of the plunger 36 is blocked. The axial translation and positioning of the stop tip 112 adjusts the maximum pullback of the plunger 36, thereby adjusting and presetting the maximum volume of drug fluid in the aspirable plunger syringe cavity 24.

[0038] The plunger pullback stop mechanism 102 also includes a rotatable adjusting wheel 114, which is connected to the plunger pullback stop housing 104 via a shaft 116. The adjusting wheel 114 defines a second quasi-hyperboloid tooth profile 118 that engages with a first tooth profile 110 of the rack 108. Rotation of the adjusting wheel 114 causes the stop tip 112 of the rack 108 to advance or retract within the syringe cavity 24. The maximum capacity of the syringe cavity 24 is selectively adjusted by the rotation of the adjusting wheel 114.

[0039] Figure 7-14 Additional embodiments of a syringe system with a fixed maximum capacity plunger pull-back stop mechanism are shown. In these additional embodiments, the position of the stop tip within the syringe barrel is pre-set during manufacturing. Figure 7-12 The syringe system embodiments include those with Figure 1-4 The embodiment uses the same syringe barrel 22 and syringe plunger 36. Similarly, Figure 13 and Figure 14 The syringe system embodiments include those with Figure 1-4 The same syringe syringe 22 is used in the embodiment. For the sake of simplicity, Figure 1-14 The common structural elements of all these embodiments are described with the same structural names and reference numbers.

[0040] Figure 7-11The syringe system 120 includes a plunger pull-back stop mechanism 122 with a fixed-length stop sleeve 124, the fixed-length stop sleeve 124 pre-setting the maximum pull-back limit of the syringe plunger 36. In general overview, the plunger pull-back stop mechanism 122 includes a plug-like plunger pull-back stop housing 126 having a distal end 128 inserted into the proximal end 26 of the syringe barrel 22. The housing 126 defines a plunger channel 130 therethrough, which captures a shaft 44 capable of translating the syringe plunger 36. As shown, the elongated stop sleeve 124 is oriented within a syringe cavity 24 between the inner syringe wall 23 and the plunger 36, surrounding at least a portion of the plunger shaft 44. The stop sleeve 124 is inserted between the distal end 128 of the plunger pull-back stop housing 126 and a plunger contact surface 43 located at the distal axial end of the syringe plunger 36. Piston stop 38 Figure 7 Not shown in the figure, but an enlarged view of the figure is shown. The distal end of the stop sleeve 124 defines a stop tip 132. As in the previously described embodiment, once the contact surface 43 of the plunger 36 abuts against the stop tip 132, the retraction of the plunger 36 is blocked. Therefore, the maximum dose capacity of the syringe cavity 24 is adjusted by the entire axial length of the elongated stop sleeve 124. The syringe system 120 maintains the ability to aspirate doses smaller than the maximum dose capacity by partially retracting the syringe plunger 36 within its maximum translational range to a smaller dose volume indicated by the marked dosing mark 133 on the syringe barrel 22.

[0041] To facilitate the manufacture of a syringe system 120 with a range of maximum capacities for the syringe cavity 24, the stop sleeve 124 further includes a telescopic sleeve assembly of a first nested sleeve segment 134 and a second nested sleeve segment 136, which are rigidly connected to each other during syringe manufacturing at a desired total axial length (e.g., via pin 138). In other embodiments, the sleeve segments are connected by adhesive or thermal welding, or by pawls, or by lanced piercings, or by threaded engagement. In some embodiments, stop sleeves with different axial lengths are incorporated within a plunger pull-back stop mechanism 122 to adjust the dosage capacity of the syringe system 120.

[0042] exist Figure 7 and Figure 8In this configuration, the plunger pull-back stop housing 126 also includes a necked-off bushing 140, the distal neck 128 of which inserts into the proximal opening 26 of the syringe barrel 22. The bushing 140 has two abutting first bushing halves 142 and a second bushing half 144 that capture the plunger shaft 44 within a commonly defined plunger channel 130. The abutting axial faces of the bushing halves are aligned parallel to the central axis of the plunger shaft 44 and are joined together by a weld 146 or adhesive.

[0043] Figure 9-11 An alternative embodiment of the plug-like plunger pull-back stop housing is shown. Figure 9 In the middle, the plunger pull-back stop housing 150 has an abutting first bushing half 152 and a second bushing half 154, which are connected to opposing mating pins 156 and pin receiving holes 158. Figure 10 In the middle, the plunger pull-back stop housing 160 has an abutting first bushing half 162 and a second bushing half 164, which are connected to opposing mating snap fasteners 166 and snap receiving holes 168. Figure 11 In the middle, the plunger pull-back stop housing 170 includes a half bushing, whose plunger channel 172 captures three of the four flange segments of the cross-shaped plunger shaft 36, such as Figure 7 As shown. Hooks 174 formed in housing 170 prevent the plunger shaft from radially separating from plunger channel 172.

[0044] Figure 12 The syringe system 180 includes a plunger pull-back stop mechanism 182 with a fixed-length stop rod 184, which pre-sets the maximum pull-back limit of the syringe plunger 36. In general overview, the plunger pull-back stop mechanism 182 includes a plug-like plunger pull-back stop housing 186 having a distal end 187 inserted into an opening proximal end 26 of the syringe barrel 22. The housing 186 defines a plunger channel 188 therethrough, which captures a shaft 44 capable of translating the syringe plunger 36. The elongated stop rod 184 is oriented within a syringe cavity 24 between the inner syringe wall 23 and the plunger 36. The stop rod 184 is coupled to the distal end 187 of the plunger pull-back stop housing 186. The distal end of the stop rod 184 defines a stop tip 190. As in the previously described embodiments, once the contact surface 43 of the plunger 36 abuts against the stop tip 190, the retraction of the plunger 36 is blocked. Therefore, the maximum dose capacity of the syringe cavity 24 is adjusted by the entire axial length of the elongated stop rod 184.

[0045] Figure 13 and Figure 14The syringe system 200 embodiment includes a pawl and toothed plunger pull-back stop mechanism 202, which presets the maximum pull-back limit of the syringe plunger 204. Figure 14 In the middle, the plunger 204 is compared to Figure 13 The syringe is inserted deeper into the syringe barrel. The maximum dose capacity of the syringe system 200 is preset during syringe manufacturing. Similar to... Figure 1 The plunger pullback stop housing 50 and the plunger pullback stop housing 206 are coupled to the syringe flange 34 in a manner aligned with the proximal opening end 26 of the syringe barrel 22. The housing 206 also includes an anti-rotation groove 208, similar to... Figure 1 and 4 Anti-rotation groove 56. A cantilevered pawl 210 is formed within the anti-rotation groove 208. The distal end of the pawl 210 defines a stop end 212; the stop end projects radially inward into the syringe barrel cavity 24. The pawl 210 is integrally formed within the plunger pull-back stop housing 206. In other embodiments, the pawl is formed separately and coupled to the housing. The syringe plunger 204 defines an engagement surface 216 on the outer edge of one of the cross-shaped flanges of the plunger shaft. The engagement surface 216 is biased and abuts against the stop end 212 of the pawl 210. The engagement surface 216 defines an outwardly projecting toothed notch 218 formed thereon, the notch projecting radially outward toward the stop end 212. In some embodiments, the plunger notch is a recess formed in the engagement surface, and the stop end is biased into the notch when they are axially aligned. In some embodiments, the syringe system 200 has more than one pair of opposing slots and stop tips in its plunger pull-back stop mechanism 202. The stop tip 212 intersects the pull-back path of the slot 218 of the syringe plunger 204. For example... Figure 14 As shown, once the plunger 204 is pulled back a sufficient axial distance to cause the notch 218 to contact the stop tip 212 of the pawl 210, the pullback of the plunger 204 is blocked. The maximum dose capacity of the syringe cavity 23 is preset during the manufacturing of the axial position of the notch 218 along the plunger engagement surface 216 in the syringe system 200. The corresponding different dose capacities of the syringe system 200 require specific associated syringe plungers with notch positions corresponding to the desired dose.

[0046] The following discloses exemplary methods for using one or more previously described embodiments of a syringe system. A pharmacy or other authorized drug distributor provides a patient or designated caregiver with one or more doses of a prescription drug and a sufficient number of syringes to dispense those doses. The patient's administration operator prepares the medication for injection according to the prescription instructions, such as by mixing a diluent with powdered medication in multiple doses in a vial. When using one of the syringe system embodiments of this disclosure, the risk of drug overdose is reduced as long as the prescription dose matches the maximum preset or adjusted aspiration volume of the provided syringe system. For example, in the case of a prescription drug dose of 40 ml, the pharmacy provides the patient syringe of this disclosure, which is preset or adjusted to match the maximum aspiration volume of 40 ml.

[0047] In some dispensing scenarios, each supplied syringe includes a preset, maximum-capacity, fixed plunger pull-back stop, which is connected to, for example... Figure 7 , 12 The syringes in Examples 120, 180, or 200 of 13 and 14. These provided syringe systems prevent additional aspiration of drug fluid from the syringe cavity by preventing further retraction of the plunger beyond a preset maximum dose volume when the plunger retraction stop is blocked at the end of the stop of the plunger retraction stop. While following an approved drug administration protocol, the patient's administration operator prepares the syringe, aspirates the prescribed dose volume by retracting the plunger to its blocked retraction position, and injects the drug into the patient.

[0048] In other distribution scenarios, each provided syringe includes a variable maximum capacity and a plunger pull-back stop, which is connected to, for example... Figure 1-6The syringes in embodiments 20, 80, or 100. Before dispensing the medication, the adjusting wheel of any of these syringe system embodiments is adjusted to match the prescribed medication dose. In some embodiments, the adjusting wheel is pre-adjusted during manufacturing. In other embodiments, the pharmacy or other dispenser adjusts the adjusting wheel before transferring the medication to the patient or dosage manager. In yet another embodiment, the administration operator adjusts the adjusting wheel of the syringe at home before injecting the patient. After adjusting the adjusting wheel of the syringe system, these provided syringes prevent additional aspiration of medication fluid from the syringe cavity by preventing further retraction of the plunger beyond a preset maximum dose volume when the stopper of the syringe plunger retraction stop prevents further retraction of the plunger. While following an approved medication injection protocol, the patient's administration operator prepares the syringe, aspirates the prescribed dose volume by retracting the plunger to its blocked retraction position, and injects the medication into the patient. It is advantageously disclosed that variable maximum volume syringe systems are capable of administering different medication dose volumes. When prescribing multiple injectable drugs or other medical fluids to a patient, each prescription can be dispensed using a single syringe system model that allows for the administration of each individual drug prescription dose via a dedicated and adjustable separate syringe.

[0049] Throughout this specification, references to "one embodiment," "some embodiments," "various embodiments," "one or more embodiments," or simply "embodiment" refer to a particular feature, structure, material, or characteristic described in connection with an embodiment that is included in at least one embodiment of this disclosure. Therefore, the appearance of phrases such as "in one or more embodiments," "in some embodiments," "in various embodiments," "in one embodiment," or "in an embodiment" throughout this specification does not necessarily refer to the same embodiment of this disclosure. Furthermore, in one or more embodiments, particular features, structures, materials, or characteristics may be combined in any suitable manner.

[0050] While the disclosure herein provides for descriptions of specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of this disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to this disclosure without departing from the spirit and scope thereof. Therefore, this disclosure is intended to include modifications and variations within the scope of the appended claims and their equivalents.

Claims

1. A syringe system with limited aspiration volume, comprising: A syringe having: a syringe barrel having a distal end defining an outlet, a proximal end opening, and an inner barrel wall therein defining a syringe cavity between the distal and proximal ends of the syringe barrel; And a syringe plunger inserted into the syringe cavity, the syringe plunger having a distal axial end and an outer peripheral surface, the outer peripheral surface being in fluid-sealed, abutting contact with the inner syringe wall, the plunger being translatable along a plunger pull-back path within the syringe cavity to selectively change the delivery volume within the syringe cavity between the distal end of the syringe syringe and the distal axial end of the plunger by the advancement or pull-back of the plunger; as well as A plunger pullback stop is coupled to the syringe, the plunger pullback stop including a stop tip oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and located between the proximal and distal ends of the plunger. The stop tip intersects the pullback path of the syringe plunger and, when the stop tip engages with the plunger, prevents further pullback of the plunger.

2. The syringe system with limited suction capacity according to claim 1, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe barrel, the plunger pullback stop housing defining a rack channel oriented to align with the proximal opening end of the syringe barrel; An elongated, translationally movable rack is held within the rack channel, the rack defining a first helical thread type between its proximal and distal ends, wherein the distal end of the rack defines the stop tip, the distal end of the rack and its stop tip being oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger. as well as A rotatable adjusting wheel is connected to the plunger pullback stop housing, the adjusting wheel defining a second helical thread that engages with the first thread type, such that rotation of the adjusting wheel advances or pulls back the stop end of the rack within the syringe cavity; The maximum capacity of the syringe cavity is selectively adjusted by rotating the adjusting wheel.

3. The syringe system with limited suction capacity according to claim 2, wherein the plunger pull-back stop further comprises: An annular adjusting wheel surrounds the syringe plunger and the rack, wherein the second helical thread type and the annular groove are oriented on the inner peripheral surface of the adjusting wheel; as well as At least one flange is formed on the proximal surface of the plunger pull-back stop housing, the at least one flange engaging within the annular groove to prevent the adjusting wheel from axially separating from the plunger pull-back stop.

4. The syringe system with limited aspiration capacity according to claim 3, further comprising: The rack has an axial central axis parallel to the axial central axis of the syringe plunger and a fan-shaped cross section, the outer radius of which defines the first thread type, and at least one radial edge defines an anti-rotation step parallel to the axial central axis of the rack. The cross-section of the rack channel conforms to the cross-section of the rack; and The adjusting wheel has a rotation axis that is coaxial with the axial central axis of the syringe plunger.

5. The syringe system with limited suction capacity according to claim 1, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe barrel, the plunger pullback stop housing defining a rack channel oriented to align with the proximal opening end of the syringe barrel; An elongated, translationally movable rack is held within the rack channel, the rack defining a first tooth profile between its proximal and distal ends, wherein the distal end of the rack defines the stop tip, the distal end of the rack and its stop tip being oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger. as well as A pinion profile rotatable adjustment wheel is connected to the plunger pull-back stop housing. The pinion adjustment wheel defines a second tooth profile that engages with the first tooth profile, such that rotation of the pinion adjustment wheel advances or pulls back the stop end of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotating the pinion adjusting wheel.

6. The syringe system with limited suction capacity according to claim 1, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe barrel, the plunger pullback stop housing defining a rack channel oriented to align with the proximal opening end of the syringe barrel; An elongated, translationally movable rack is held within the rack channel, the rack defining a first hypoid gear tooth profile between its proximal and distal ends, wherein the distal end of the rack defines the stop tip, the distal end of the rack and its stop tip being oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger; as well as A rotatable adjusting wheel is connected to the plunger pull-back stop housing. The adjusting wheel defines a second hypoid gear tooth profile on its outer peripheral surface that engages with the first hypoid gear tooth profile, such that rotation of the adjusting wheel advances or pulls back the stop end of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotating the adjusting wheel.

7. The syringe system with limited suction capacity according to claim 1, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing having a distal end that inserts into the proximal end of the opening of the syringe syringe, the plunger pullback stop housing defining a plunger channel therethrough, the plunger channel therein capturing the axis of the translational syringe plunger; as well as An elongated stop sleeve is oriented within the syringe cavity between the inner syringe wall and the plunger, thereby surrounding at least a portion of the plunger shaft. The stop sleeve is inserted between the distal end of the plunger pull-back stop housing and the distal axial end of the syringe plunger, wherein the distal end of the stop sleeve defines the stop tip. The maximum capacity of the syringe cavity is adjusted by the total axial length of the elongated stop sleeve.

8. The syringe system with limited suction capacity according to claim 7, wherein the elongated stop sleeve further comprises a telescopic sleeve assembly consisting of at least two nested sleeves rigidly connected to each other with a required total axial length.

9. The syringe system with limited suction capacity according to claim 7, wherein the plunger pull-back stop housing further includes a necked-off bushing, wherein the distal end of the bushing is inserted into the proximal end of the opening of the syringe barrel, the bushing having two abutting halves, the abutting surfaces of the bushing halves being aligned parallel to the central axis of the plunger shaft and joined together by welding, or by adhesive, or by opposing mating pins and pin receiving holes, or by opposing mating snap fasteners and snap receiving holes.

10. The syringe system with limited suction capacity according to claim 1, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe barrel, and the plunger pullback stop housing is oriented to align with the proximal opening end of the syringe barrel; A cantilevered pawl, the cantilevered pawl being connected to the plunger pullback stop housing, the distal end of the pawl defining a protrusion into the stop end within the syringe cavity; and The plunger defines an engagement surface that is offset from and abuts against the end of the stop of the pawl, and also defines a groove formed in the plunger engagement surface. The stop tip engages and captures within the groove formed in the plunger engagement surface, preventing further retraction of the plunger, and the maximum capacity of the syringe cavity is selectively adjusted by the axial position of the groove in the plunger engagement surface.

11. A syringe system with limited aspiration volume, comprising: A syringe comprising: a syringe barrel having a distal end defining an outlet, a proximal end opening, and an inner syringe wall, and a syringe flange on the proximal end of the syringe barrel, the inner syringe wall defining a syringe cavity between the distal and proximal ends of the syringe barrel; and a syringe plunger inserted into the syringe cavity, the syringe plunger having a distal axial end and an outer peripheral surface in fluid-sealed, abutting contact with the inner syringe wall, the plunger being translatable along a plunger pull-back path within the syringe cavity to selectively change the delivery volume within the syringe cavity between the distal end of the syringe barrel and the distal axial end of the plunger by means of the advancement or pull-back of the plunger; as well as A plunger pull-back stop is connected to the syringe flange, the plunger pull-back stop including a stop tip oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and located between the proximal and distal ends of the plunger. The stop tip intersects the pull-back path of the syringe plunger and blocks further pull-back of the plunger when the stop tip engages with the plunger.

12. The syringe system with limited suction capacity according to claim 11, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe flange, the plunger pullback stop housing defining a rack channel oriented to align with the proximal opening end of the syringe barrel; An elongated, translationally movable rack is held within the rack channel, the rack defining a first helical thread type between its proximal and distal ends, wherein the distal end of the rack defines the stop tip, the distal end of the rack and its stop tip being oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger. as well as A rotatable adjusting wheel is connected to the plunger pullback stop housing, the adjusting wheel defining a second helical thread that engages with the first thread type, such that rotation of the adjusting wheel advances or pulls back the stop end of the rack within the syringe cavity; The maximum capacity of the syringe cavity is selectively adjusted by rotating the adjusting wheel.

13. The syringe system with limited suction capacity according to claim 12, wherein the plunger pull-back stop further comprises: An annular adjusting wheel surrounds the syringe plunger and the rack, wherein the second helical thread type and the annular groove are oriented on the inner peripheral surface of the adjusting wheel; And at least one flange formed on the proximal surface of the plunger pull-back stop, the at least one flange engaging within the annular groove to prevent the adjusting wheel from axially separating from the plunger pull-back stop.

14. The syringe system with limited aspiration capacity according to claim 13, further comprising: The rack has an axial central axis parallel to the axial central axis of the syringe plunger and a fan-shaped cross section, wherein the outer circumferential radius of the fan-shaped cross section defines the first thread type, and at least one radial edge defines an anti-rotation step parallel to the axial central axis of the rack. The cross-section of the rack channel conforms to the cross-section of the rack; and The adjusting wheel has a rotation axis that is coaxial with the axial central axis of the syringe plunger.

15. The syringe system with limited suction capacity according to claim 11, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe flange, the plunger pullback stop housing defining a rack channel oriented to align with the proximal opening end of the syringe barrel; An elongated, translationally movable rack is held within the rack channel, the rack defining a first tooth profile between its proximal and distal ends, wherein the distal end of the rack defines the stop tip, the distal end of the rack and its stop tip being oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger. as well as A pinion profile rotatable adjustment wheel is connected to the plunger pull-back stop housing. The pinion adjustment wheel defines a second tooth profile that engages with the first tooth profile, such that rotation of the pinion adjustment wheel advances or pulls back the stop end of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotating the pinion adjusting wheel.

16. The syringe system with limited suction capacity according to claim 11, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe flange, the plunger pullback stop housing defining a rack channel oriented to align with the proximal opening end of the syringe barrel; An elongated, translationally movable rack is held within the rack channel, the rack defining a first hypoid gear tooth profile between its proximal and distal ends, wherein the distal end of the rack defines the stop tip, the distal end of the rack and its stop tip being oriented within the syringe cavity between the inner syringe wall and the syringe plunger, and between the proximal and distal ends of the plunger; as well as A rotatable adjusting wheel is connected to the housing of the plunger pull-back stop. The adjusting wheel defines a second hypoid gear tooth that engages with the first hypoid gear tooth on its outer circumferential surface, such that rotation of the adjusting wheel advances or pulls back the end of the stop of the rack within the syringe cavity. The maximum capacity of the syringe cavity is selectively adjusted by rotating the adjusting wheel.

17. The syringe system with limited suction capacity according to claim 11, wherein the plunger pull-back stop further comprises: A plunger pull-back stop housing having a distal end inserted into the proximal end of the opening of the syringe syringe, the plunger pull-back stop housing defining a plunger channel therethrough, the plunger channel therein capturing the axis of the translational syringe plunger; as well as An elongated stop sleeve is oriented within the syringe cavity between the inner syringe wall and the plunger, thereby surrounding at least a portion of the plunger shaft. The stop sleeve is inserted between the distal end of the plunger pullback stop housing and the distal axial end of the syringe plunger, wherein the distal end of the stop sleeve defines the stop tip. The maximum capacity of the syringe cavity is adjusted by the total axial length of the elongated stop sleeve.

18. The syringe system with limited suction capacity according to claim 17, wherein the elongated stop sleeve further comprises a telescopic sleeve assembly consisting of at least two nested sleeves rigidly connected to each other with a desired total axial length.

19. The syringe system with limited suction capacity according to claim 11, wherein the plunger pull-back stop further comprises: A plunger pullback stop housing is connected to the syringe flange, the plunger pullback stop housing being oriented to align with the proximal opening end of the syringe barrel; A cantilevered pawl is connected to the plunger pullback stop housing, the distal end of the pawl defining a protrusion into the stop end within the syringe cavity; as well as The plunger defines an engagement surface that is offset from and abuts against the end of the stop of the pawl, and also defines a groove formed in the plunger engagement surface. The stop tip engages and captures within the groove formed in the plunger engagement surface, preventing further retraction of the plunger, and the maximum capacity of the syringe cavity is selectively adjusted by the axial position of the groove in the plunger engagement surface.

20. A method for limiting the aspiration volume of a medical syringe, comprising: A syringe is provided, the syringe having: a syringe barrel; a syringe plunger inserted into the syringe barrel and retractable along a retraction path; and a plunger retraction stop coupled to the syringe, the plunger retraction stop including a stop tip oriented within the syringe barrel and intersecting the plunger retraction path; The stop tip is oriented in the syringe plunger pullback path to prevent the plunger from pulling back beyond a position corresponding to the syringe aspiration volume of the prescription drug dose. The prescription drug dose is aspirated into the syringe syringe by pulling back the syringe plunger; as well as When the plunger engages with the end of the stop of the plunger pull-back stop, it prevents further pull-back of the plunger, thereby preventing the aspiration of an additional volume of drug exceeding the prescribed drug dose into the syringe.

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