Pressure indicator for medicament delivery device

Abstract

To provide a medicament delivery pen.SOLUTION: A medicament delivery pen comprises: a reservoir for holding a medicament; a pressurizing system for dispensing the medicament from the reservoir when operating; a needle hub for housing a hollow cannula, the hollow cannula having a distal end for insertion into a patient; a fluid delivery path disposed between the pressurizing system and the hollow cannula for communication therebetween; and a pressure sensor external to the pressurizing system and disposed in the hub to sense a back pressure in the fluid delivery path, and provide an indication when the back pressure drops below a predetermined threshold after the pressurizing system ceases the operation.SELECTED DRAWING: Figure 20

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under 35 USC § 119(e) from U.S. Provisional Patent Application Serial No. 62 / 799,420, filed January 31, 2019, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to medical equipment, and more particularly to a medical device including a cannula and a pressurization system. [Background technology]

[0003] After the drug pressurization system of the drug delivery device stops operating, the pressure in the fluid delivery path of the device does not immediately drop to zero. Drug delivery continues until the pressure in the fluid delivery path falls below a certain threshold. For example, during insulin injection when using the pump 14 (FIG. 1), residual pressure in the system builds up and may be present after the pump 14 stops operating. Premature removal or disconnection of the insulin infusion set or fluid connector 10 from the base or infusion site 80 inserted into the patient (see FIG. 1) may lead to insulin draining from the fluid connector 10 (see FIG. 2) after removal of the set. Thus, in such a situation, the user would not receive all of the intended dose.

[0004] The pressure required to deliver one unit of insulin is approximately equal to 0.7 psi. Thus, low residual pressure in an infusion set after removal or disconnection can mean a significant loss of therapy. For example, a loss of one unit from a 10 unit bolus results in the delivery of only 90% of the intended insulin dose. Improvement is desirable. Summary of the Invention

[0005] Accordingly, one aspect of the present invention provides a medication delivery device having an indicator to inform a user when it is safe to remove or disconnect the medication delivery device.

[0006] The foregoing and / or other aspects of the present invention are accomplished by providing a drug delivery device having a reservoir for holding a drug, a pressurization system that upon operation dispenses the drug from the reservoir, a hollow cannula for insertion into a patient, and a fluid delivery pathway disposed between the pressurization system and the hollow cannula for communicating the drug therebetween. The drug delivery device also has a pressure sensor external to the pressurization system for sensing backpressure in the fluid delivery pathway and providing an indication when the backpressure falls below a predetermined threshold after the pressurization system has ceased operation.

[0007] The foregoing and / or other aspects of the present invention are also accomplished by providing a medication delivery pen having a reservoir for holding a medication, a pressurization system that upon operation dispenses the medication from the reservoir, and a needle hub housing a hollow cannula, the hollow cannula having a distal end for insertion into a patient. The medication delivery pen also has a fluid delivery path disposed between the pressurization system and the distal end of the hollow cannula for communicating the medication therebetween, and a pressure sensor external to the pressurization system and disposed in the hub for sensing back pressure in the fluid delivery path and providing an indication when the back pressure falls below a predetermined threshold after the pressurization system has ceased operation.

[0008] The foregoing and / or other aspects of the present invention are also accomplished by providing a drug delivery syringe having a reservoir for holding a drug, a pressurization system that upon operation dispenses the drug from the reservoir, and a needle hub housing a hollow cannula, the hollow cannula having a distal end for insertion into a patient. The drug delivery syringe also has a fluid delivery path disposed between the pressurization system and the distal end of the hollow cannula communicating the drug therebetween, and a pressure sensor external to the pressurization system and disposed within the hub for sensing backpressure in the fluid delivery path and providing an indication when the backpressure falls below a predetermined threshold after the pressurization system has ceased operation.

[0009] Additional and / or other aspects and advantages of the invention will be set forth in the description that follows, or will be obvious from the description, or may be learned by practice of the invention. [Brief description of the drawings]

[0010] BRIEF DESCRIPTION OF THE DRAWINGS Aspects and advantages of embodiments of the present invention will be more readily understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 illustrates the removal or disconnection of a drug infusion fluid connector. [Diagram 2] FIG. 2 illustrates the ejection of a drug from the fluid connector of FIG. [Diagram 3] FIG. 3 is various views of a fluid connector and associated base of the related art. [Figure 4] FIG. 4 is various views of a fluid connector and associated base of the related art. [Diagram 5] FIG. 5 is various views of a fluid connector and associated base of the related art. [Figure 6] FIG. 6 illustrates the location of a pressure sensor according to an embodiment of the present invention. [Figure 7] FIG. 7 illustrates the location of a pressure sensor according to an embodiment of the present invention. [Figure 8] FIG. 8 illustrates the location of a pressure sensor according to an embodiment of the present invention. [Figure 9] FIG. 9 illustrates a pressure sensor according to an embodiment of the present invention. [Figure 10] FIG. 10 illustrates a pressure sensor according to an embodiment of the present invention. [Figure 11] FIG. 11 illustrates a pressure sensor according to an embodiment of the present invention. [Figure 12] FIG. 12 illustrates a pressure sensor according to an embodiment of the present invention. [Figure 13] FIG. 13 is a graph illustrating pressure versus time conditions of a drug delivery device. [Figure 14] FIG. 14 is a graph illustrating pressure versus time conditions of a drug delivery device. [Figure 15] FIG. 15 illustrates a pressure sensor according to another embodiment of the present invention. [Figure 16] FIG. 16 illustrates a pressure sensor according to another embodiment of the present invention. [Figure 17] FIG. 17 illustrates a pressure sensor according to another embodiment of the present invention. [Figure 18] FIG. 18 illustrates a pressure sensor according to another embodiment of the present invention. [Figure 19] FIG. 19 illustrates a drug delivery pen. [Figure 20] FIG. 20 is an exploded view of the drug delivery pen of FIG. 19 in accordance with another embodiment of the present invention. [Figure 21] FIG. 21 illustrates a pressure sensor according to another embodiment of the present invention. [Figure 22] FIG. 22 illustrates a pressure sensor according to another embodiment of the present invention. [Figure 23] FIG. 23 illustrates a drug delivery syringe with a pressure sensor according to another embodiment of the present invention. [Figure 24] 24 is a cross-sectional view of the needle and needle hub of the syringe of FIG. 23. [Diagram 25] FIG. 25 illustrates a pressure sensor according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Reference will now be made to the embodiments of the present invention as illustrated in the accompanying drawings, in which like reference numerals refer to like elements throughout. The embodiments described herein illustrate, by way of example only and not by way of limitation, the present invention.

[0012] The embodiments are not intended to be mutually exclusive, and features of one embodiment can be combined with other embodiments unless they are mutually inconsistent.

[0013] It will be understood by those skilled in the art that the disclosure is not limited in its application to the details of construction and the arrangement of components described below or illustrated in the drawings. The embodiments herein are capable of other embodiments and can be practiced or carried out in various ways. Additionally, the phrases and terms used herein are for purposes of explanation and should not be considered as limiting. The use of "including," "comprising," or "having" and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless otherwise limited, the terms "connected," "coupled," and "mounted" and variations thereof herein are used broadly and encompass both direct and indirect connections, couplings, and mountings. Additionally, the terms "connected" and "coupled" and variations thereof are not limited to physical or mechanical connections or couplings. Additionally, terms such as "up," "down," "bottom," "top," "front," "back," "top," "bottom," "upward," "downward," and other orientation descriptors are intended to facilitate the description of exemplary embodiments of the present invention, and are not intended to limit the structures of exemplary embodiments of the present invention to any particular position or orientation. Terms of degree, such as "substantially" or "about," will be understood by those skilled in the art to refer to a reasonable range around and including a given value, as well as a range outside of a given value, such as the typical tolerance associated with the manufacture, assembly, and use of an embodiment. The term "substantially" when referring to a structure or characteristic includes a characteristic that is largely or completely within the structure.

[0014] FIG. 3 is a perspective view of a two-piece fluid connector 10 and associated base 80 of the related art as found in PCT Publication WO2013 / 086463, the disclosure of which is incorporated herein by reference for this purpose. FIG. 4 is a bottom view of the fluid connector 10, and FIG. 5 is a cross-sectional view of the fluid connector 10 connected to the base 80. The fluid connector 10 includes two components, a fluid path portion 12 and a latching portion 14. Together, the fluid path portion 12 and the latching portion 14 form a housing 15. The latching portion 14 includes an actuating lever 16, a fluid connector latch 18, and a rigid stop 21.

[0015] The fluid path portion 12 includes a tube connector portion 22 for connecting the fluid connector 10 to the tube 20. The fluid path portion 12 may be secured to the latch portion 14 via a snap-fit ​​engagement. As shown in FIG. 3, the tube 20 is connected to the pump 14 via the connector 22. The pump 14 has a reservoir 6 for the drug to be delivered. Although the reservoir 6 is shown as an internal reservoir, one skilled in the art will understand that the reservoir 6 may be an external reservoir 6, such as a drug vial, connected to the pump 14.

[0016] As shown in Figures 4-6, fluid path portion 12 has a blunt cannula 23 extending distally from a proximal inner surface of housing 15. When connected to a base 80 that corresponds to a patient cannula 84 inserted into a user's skin, blunt cannula 23 penetrates a septum 86 in a mushroom-shaped head 82 of base 80 to fluidly connect the pump to patient cannula 84 distal to base 80. Patient cannula 84 is flexible and is held in base 80 by a metal wedge. Typically, patient cannula 84 is inserted into the patient's skin using a known insertion device.

[0017] A pressure sensor according to an embodiment of the invention is external to a pressurizing system such as a pump and can be located in a number of locations. For example, as described below, the pressure sensor can be located in connector 17 or 19 or 22 connecting infusion line 20 to pump 14 (FIGS. 3 and 6), in line with tubing (e.g., location B), or in the flow path of a pen needle (FIG. 8) or syringe, in line with tubing 20 (FIG. 7), at the connection / disconnection site between set 10 and base 80 (e.g., location A).

[0018] 9-12 illustrate a pressure sensor 100 according to an embodiment of the present invention. Pressure sensor 100 is positioned external to a pressurized system (such as pump 14) and senses backpressure in a fluid delivery path. Pressure sensor 100 provides an indication when the backpressure falls below a predetermined threshold after the pressurized system has stopped operating.

[0019] The pressure sensor 100 illustrated in Figures 9-12 includes a body 102 with a primary fluid channel 104 passing through the pressure sensor 100. The primary fluid channel 104 is part of a fluid delivery path between a pressurized system (e.g., pump 14) and a hollow cannula (e.g., patient cannula 84). Opposite ends of the primary fluid channel 104 fluidly connect to an infusion line set 10 and / or tubing 20. For example, according to one embodiment, one end of the primary fluid channel 104 connects to tubing 20 and the opposite end of the primary fluid channel 104 connects to a set or fluid connector 10 (e.g., position A in Figure 7). According to another embodiment, both ends of the primary fluid channel connect to tubing 20 (e.g., position B in Figure 7).

[0020] As best seen in FIG. 10, the pressure sensor 100 includes a gauge chamber 106 fluidly connected to a primary fluid channel 104 and a gauge 108 movably disposed within the gauge chamber 106. The gauge or first gauge 108 senses backpressure within the primary fluid channel 104, which is part of a fluid delivery path, and when the backpressure exceeds a predetermined threshold, the gauge 108 extends outside the body 102. After the pressurizing system (e.g., pump 14) stops operating, the gauge 108 retracts into the body 102 when the backpressure falls below the predetermined threshold. According to one embodiment, the pressure sensor 100 includes a biasing member 110, such as a spring 110, that biases the gauge 108 inwardly relative to the body 102.

[0021] According to another embodiment, as shown in Figures 9-12, the pressure sensor 100 also includes a second gauge chamber 112 fluidly connected to the primary fluid channel 104 and a second gauge 114 movably disposed within the second gauge chamber 112 that senses backpressure in the primary fluid channel 104 and extends outside the body 102 when the backpressure is greater than zero and retracts into the body 102 when the backpressure is zero or below zero.

[0022] Preferably, the pressure sensor 100 also includes a second biasing member 115, such as a second spring 115, that biases the second gauge 114 inwardly relative to the body 102. According to one embodiment, the springs 110, 115 have different spring constants to accommodate different predetermined thresholds. For example, the spring 115 that biases the second gauge 114 inwardly can be weaker than the spring 110 that biases the first gauge 108 inwardly. In such an embodiment, the second gauge 114 will extend from the body 102 within the primary fluid channel 104 with less back pressure than that required to extend the first gauge 108.

[0023] In such an embodiment, when the first gauge 108 is retracted into the body 102, the pressure sensor 100 provides an indication to the user that the back pressure has fallen below a predetermined threshold after the pressurization system (e.g., pump 14) has stopped operating and that it is safe to remove the fluid connector or set from the site or base 12. According to one embodiment, the predetermined threshold is about 0.5 psi or less. More preferably, the predetermined threshold is about 0.25 psi. Most preferably, the predetermined threshold is about 0.1 psi.

[0024] As shown in Figure 13, for one combination of pump, tubing, fluid connector, and base, after an initial spike while the pump is running, the pump provides 0.28 psi during delivery, and the pressure tapers off after the pump is stopped. During the waiting period after the pump is stopped, there is still the possibility of drug delivery, and therefore, for such a combination, the predetermined threshold is preferably about 0.1 psi to indicate that the intended dose has been received and it is safe to remove the fluid connector from the base.

[0025] In another combination of pump, tubing, fluid connector, and base, as shown in Figure 14, during operation of the pump, the pump provides approximately 0.4 psi before cutoff. For such combination, the predetermined threshold is preferably approximately 0.1-0.2 psi to indicate that the intended dose has been received and that it is safe to remove the fluid connector from the base.

[0026] 9-12, when the second gauge 108 is retracted into the body 102 and the pump is operating, the pressure sensor 100 provides an indication to the user that insertion of the base into the skin or connection of the fluid connector to the base is faulty due to the lack of backpressure in the primary fluid channel 104. In other words, if the cannula of the base is not inserted into the patient's skin or the fluid connector is not connected to the base, when the pump is operating, fluid will flow through the fluid supply path without resistance (e.g., other than the inherent resistance of the tubing) and therefore there will be little or no backpressure in the primary fluid channel 104.

[0027] When the pump is operating and the second gauge 108 extends from the body 102, the pressure sensor 100 provides an indication to the user that the base is fully inserted and that the connection between the fluid connector and the base is good because the backpressure in the primary fluid channel 104 is greater than zero.

[0028] According to one embodiment, the pressure sensor 100 includes a sliding cap 120 (best shown in FIGS. 11 and 12) for selectively covering either the gauge 108 or the second gauge 114, such that only the uncovered one of the gauges 108 and 114 is active at a given time. For example, while inserting the base into the user's skin and the pump is initially activated, the user may have the sliding cap covering the first gauge 108, such that the second gauge 114 can provide an indication of successful insertion. Subsequently, once the user is assured of successful insertion and connection, the user may slide the sliding cap 120 to cover the second gauge 114, thus monitoring the status of the first gauge 108 to determine when the fluid connector 10 can be safely removed from the base 80 to ensure proper dose delivery.

[0029] According to one embodiment, the user must press down on the second gauge 114 to slide the sliding cap 120 over the second gauge 114. According to another embodiment, the sliding cap has ramps that engage with corresponding ramps on the second gauge 114, such that the act of sliding the sliding cap 120 over the second gauge 114 presses down on the second gauge 114, allowing the sliding cap 120 to cover the second gauge 114.

[0030] According to one embodiment, the sliding cap 120 can be positioned so as not to cover either of the gauges 108 and 114, and both gauges 108 and 114 can extend from the body 102 at the same time. According to another embodiment, there is no sliding cap, and both gauges 108 and 114 can extend from the body 102 at the same time.

[0031] According to another embodiment shown in FIG. 15, the pressure sensor 125 includes only a single gauge chamber 106 and a single gauge 108. Additionally, the pressure sensor 125 does not include a biasing member or spring. According to one embodiment, the pressure sensor 125 should be kept upright during operation, and after deactivation of the pressurizing system (e.g., pump 14), when the back pressure falls below a predetermined threshold, the weight of the gauge 108 retracts the gauge 108 within the body 102, thereby implying proper dose delivery and safe removal of the fluid connector 10 from the base 80. In other respects, the pressure sensor 125 operates similarly to the pressure sensor 100, and further description thereof will be omitted for the sake of brevity.

[0032] According to another embodiment shown in Figures 16-18, pressure sensor 130 also includes the functionality of the two gauges of pressure sensor 100 of Figures 9-12, but includes only a single gauge chamber 106 and a single gauge 138. More specifically, in this embodiment, gauge 108 has three bands 132, 134, and 136 of division, e.g., texture or color.

[0033] Similar to the second gauge 114 of the pressure sensor 100 described above, against the bias of the spring 110, the gauge 138 extends a first distance from the body 102 when the back pressure is greater than zero and retracts into the body 102 when the back pressure is zero or less. As shown in FIG. 16, when the gauge extends this first distance, only the first band 132 is visible outside the body 102.

[0034] When the backpressure meets or exceeds the predetermined threshold, the gauge 138 extends a second distance outside the body 102 and all three bands 132, 134, and 136 are visible outside the body 102 (FIG. 17). And when the backpressure in the gauge chamber 106 is less than the predetermined pressure but greater than the first non-zero pressure, after deactivation of the pressurizing system, when the backpressure falls below the predetermined threshold, the gauge 138 extends a third distance from the body 102 and only the first and second bands 132 and 134 are visible outside the body 102, as shown in FIG. 18. A pen injection device, such as an exemplary pen injector 250 as shown in FIGS. 19 and 20, typically includes a dosing knob / button 224, an outer sleeve 213, and a cap 221. The dosing knob / button 224 allows the user to set the dose of the medication to be injected. The outer sleeve 213 is gripped by the user when injecting the medication. Cap 221 is used by a user to securely hold pen injector 250 in a shirt pocket, purse, or other suitable location.

[0035] FIG. 20 is an exploded view of an exemplary drug delivery pen 250 shown in FIG. 19. The dosing knob / button 24 has a dual purpose and is used to both set the dose of drug to be injected and to inject the drug to be administered from a drug cartridge 212 attached to the drug delivery pen through a lower housing 217 via a lead screw 207 and a stopper 215. The drug cartridge 212 is typically a glass tube sealed at one end with a septum 216 and at the other end with a stopper 215. In a standard drug delivery pen, all of the dosing and delivery mechanisms are within an outer sleeve 213. These mechanisms are understood by those skilled in the art and will not be described in detail herein. According to one embodiment of the present invention, the pressure sensor 140 includes a pen needle hub 150.

[0036] 21 and 22 illustrate the pressure sensor 140 in more detail, with the needle 211 omitted for clarity. The pressure sensor 140 has a primary fluid channel 152 through the pressure sensor 140, a gauge chamber 154, and a gauge 156 movably disposed within the gauge chamber 154. Preferably, the pressure sensor 140 also includes a biasing member 158 that inwardly biases the gauge 156 relative to the hub 150. According to one embodiment, the needle 211 has a sharpened distal patient end for insertion into a patient and a sharpened proximal end for penetrating, for example, a septum of the cartridge 212. Both ends of the needle 211 are in fluid communication with each other. In such an embodiment, the needle 211 has a lateral opening in communication with the gauge chamber 154. According to another embodiment, the needle 211 has only a sharpened distal patient end in communication with a fluid pathway (e.g., the primary fluid channel 152) that communicates with the cartridge 212, for example via a spike. In such an embodiment, the gauge chamber is in fluid communication with the fluid path.

[0037] The operation of pressure sensor 140 is substantially similar to the operation of pressure sensors 100, 125 or 130, and therefore has been omitted for brevity. Like pressure sensor 100, in other embodiments pressure sensor 140 may also include a second gauge chamber, a second gauge, a second biasing member, and a sliding cap, but preferably does not, since a user can typically determine whether the pen needle has been inserted successfully.

[0038] FIG. 23 illustrates an exemplary embodiment of a drug delivery device, such as a plastic disposable syringe 300, having a needle 302 at a proximal end disposed within a molded needle hub 304 that includes a pressure sensor 350. FIG. 24 is a cross-sectional view of the needle 302, needle hub 304, and pressure sensor 350. The needle hub 304 is fastened to an open proximal end of a molded cylindrical barrel 306, and a plunger 308 is disposed in an open distal end of the cylindrical barrel 306. The plunger 308 includes a stopper 110 configured to seal the distal end of the barrel 306. The stopper 310 may be integral with the plunger 108. The distal end of the plunger 308 includes a thumb press 311, providing an interface for a user to move the plunger 308 axially of the barrel 106. By pulling or pushing the plunger, a user can transfer fluid to or from the syringe 300 through the needle 302 at the proximal end of the syringe 300 .

[0039] The pressure sensor 350 has a primary fluid channel 352 through the pressure sensor 350, a gauge chamber 354, and a gauge 356 movably disposed within the gauge chamber 354. Preferably, the pressure sensor 350 also includes a biasing member 358 that inwardly biases the gauge 356 relative to the hub 304.

[0040] The operation of pressure sensor 350 is substantially similar to the operation of pressure sensors 100, 125, 130, or 140, and thus has been omitted for brevity. Like pressure sensor 100, in other embodiments pressure sensor 350 may also include a second gauge chamber, a second gauge, a second biasing member, and a sliding cap, but preferably does not, since a user can typically verify whether needle 302 has been inserted successfully.

[0041] A connector 402 for connecting tubing 20 to a pump (e.g., pump 14) is illustrated in FIG. 25 and includes a pressure sensor 400 according to another embodiment of the present invention. Pressure sensor 400 has a primary fluid channel 452 through pressure sensor 400 that includes a spike 453 for penetrating a septum of pump 14 or a reservoir. Pressure sensor 400 also includes a gauge chamber 454 and a gauge 456 movably disposed within gauge chamber 454. Preferably, pressure sensor 400 also includes a biasing member 458 that inwardly biases gauge 456 relative to connector 402.

[0042] The operation of pressure sensor 400 is substantially similar to the operation of pressure sensors 100, 125, 130, or 140, and thus has been omitted for brevity. Similar to pressure sensor 100, in other embodiments, pressure sensor 400 can also include a second gauge chamber, a second gauge, a second biasing member, and a sliding cap.

[0043] Although only a few embodiments of the present invention have been shown and described, the present invention is not limited to the described embodiments. Instead, it will be understood by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the present invention. Any of the embodiments and / or elements disclosed herein may be combined with each other to form various additional embodiments not specifically disclosed, unless they are mutually inconsistent. It is particularly noted that those skilled in the art may easily combine various technical aspects of the various elements of the various exemplary embodiments described above in many other ways, all of which are considered to be within the scope of the present invention and are defined by the appended claims and their equivalents.

[0044] The various aspects of the embodiments may be used independently or in combination.

Claims

1. a reservoir for holding a medicament; a pressurization system that upon actuation dispenses medicament from the reservoir; a needle hub housing a hollow cannula, the hollow cannula having a distal end for insertion into a patient; a fluid delivery pathway disposed between the pressurization system and the distal end of the hollow cannula, communicating a medicament therebetween; a pressure sensor external to the pressurized system and disposed in the hub, the pressure sensor sensing backpressure in the fluid delivery path and providing an indication when the backpressure falls below a predetermined threshold after the pressurized system has ceased operation; 1. A medication delivery pen comprising:

2. the hub comprising a primary fluid channel passing therethrough, the primary fluid channel being part of the fluid delivery path and connected to a distal end of the hollow cannula; The pressure sensor is a gauge chamber fluidly connected to the primary fluid channel; a gauge movably disposed within the gauge chamber, the gauge sensing the back pressure in the fluid supply path, the gauge extending outwardly of the hub when the back pressure exceeds the predetermined threshold after deactivation of the pressurization system, and retracting into the hub when the back pressure falls below the predetermined threshold; Equipped with The medication delivery pen of claim 1 .

3. The medication delivery pen of claim 2 , wherein the pressure sensor further comprises a biasing member that inwardly biases the gauge relative to the body.

4. a second gauge chamber fluidly connected to the primary fluid channel; and a second gauge movably disposed within a second gauge chamber, the second gauge sensing the backpressure in the fluid delivery path and extending outwardly of the hub when the backpressure is greater than zero and retracting into the hub when the backpressure is equal to or less than zero; and The medication delivery pen of claim 2 further comprising:

5. a biasing member for inwardly biasing the gauge relative to the hub; a second biasing member inwardly biasing the second gauge relative to the hub; The medication delivery pen of claim 4 , wherein the pressure sensor further comprises:

6. a reservoir for holding a medicament; a pressurization system that upon actuation dispenses the agent from the reservoir; a needle hub housing a hollow cannula, the hollow cannula having a distal end for insertion into a patient; a fluid delivery pathway disposed between the pressurization system and the distal end of the hollow cannula, communicating the agent therebetween; a pressure sensor external to the pressurized system and disposed in a hub for sensing back pressure in the fluid delivery path and providing an indication when the back pressure falls below a predetermined threshold following deactivation of the pressurized system; A drug delivery syringe comprising:

7. the hub comprising a primary fluid channel passing through the hub, the primary fluid channel being part of the fluid delivery path and connected to the hollow cannula; The pressure sensor is a gauge chamber fluidly connected to the primary fluid channel; a gauge movably disposed within the gauge chamber, the gauge sensing the back pressure in the fluid supply path, the gauge extending outwardly of the hub when the back pressure exceeds the predetermined threshold after deactivation of the pressurization system, and retracting into the hub when the back pressure falls below the predetermined threshold.

7. The drug delivery syringe of claim 6.

8. The drug delivery syringe of claim 7 , wherein the pressure sensor further comprises a biasing member that inwardly biases the gauge relative to the body.

9. a second gauge chamber fluidly connected to the primary fluid channel; a second gauge movably disposed within the second gauge chamber, the second gauge sensing the backpressure in the fluid delivery path and extending outwardly of the hub when the backpressure is greater than zero and retracting into the hub when the backpressure is equal to or less than zero; and The drug delivery syringe of claim 7 further comprising:

10. a biasing member for inwardly biasing the gauge relative to the hub; a second biasing member inwardly biasing the second gauge relative to the hub; The drug delivery syringe of claim 9 , wherein the pressure sensor further comprises:

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