Pen injection device having a multi-piece extendable plunger rod configuration - Patents.com

Abstract

The present disclosure provides a driver component and method of operating the driver component that reduces configuration factors for a pen injection device. In particular, various multiple telescoping plunger rod arrangements are disclosed that can be implemented within a pen injection device to achieve such improvements. The driver component replaces a single plunger rod that extends at least axially and has a fixed length that telescoping is controlled to inject fluid from a reservoir or cartridge.

Description

[Technical field]

[0001] The present invention relates generally to multi-use pen injection devices, and more particularly to drive components, systems and methods that facilitate reducing pen components, increasing fluid chamber / reservoir / cartridge capacity and improving dispensing accuracy in multi-use pen injection devices. [Background technology]

[0002] Some medications (e.g., insulin) are self-administered. A typical diabetic patient requires several doses of insulin throughout the week or day. The required dose of insulin varies from patient to patient and may vary throughout the day and from day to day. Usually, diabetic patients will establish a dosing regimen that suits their condition and their lifestyle. Dosing regimens include some combination of slow or medium acting insulin and rapid acting insulin. With each of these dosing regimens, diabetics may need to self-administer insulin periodically and in public places such as places of employment or restaurants. The need for standard subcutaneous injections and vials is inconvenient and not sufficient for users to administer individually in these public places.

[0003] Medication delivery or injection pens have been developed to facilitate self-administration of medication and are generally more discrete and convenient for the user than syringes. One example of such a medication delivery pen is described in U.S. Pat. No. 5,399,433 and includes a cartridge holder into which an insulin cartridge is inserted or into which another medication is injected. The overall size of an injection pen is influenced by the length of the cartridge and associated components in the cartridge assembly portion of the pen and the length of the plunger or piston rod in the pen body portion of the pen. Summary of the Invention

[0004] There is a need in the art for a pen injection device that has smaller components while providing accurate dosage injection and is therefore convenient for the user to carry. The above and other problems are solved and further advantages are realized by the embodiments described herein below.

[0005] An implementation of one exemplary embodiment is to provide a medication injection pen comprising a chamber having a drain port for holding and releasing fluid therefrom and a stopper configured to advance within the chamber to force the fluid from the chamber through the drain port to a patient, and a housing comprising a plunger rod assembly part coupled to the chamber and configured to be controllably moved axially to move the stopper a selected amount within the chamber to expel a selected dose of fluid, the plunger rod assembly part comprising at least two nested plunger rod members having a first plunger rod member slidably mounted within a second plunger rod member and controllably manipulated to move the first plunger rod member relative to the second plunger rod member to axially extend the plunger rod assembly part and push the stopper through a distal end of one of the nested plunger rod members.

[0006] In accordance with an implementation of an exemplary embodiment, the housing further comprises an administration set knob that rotates relative to the housing during administration set, and a driver that selectively engages the administration set knob and is threadably engaged with the plunger rod assembly components, the driver being rotatably fixed relative to the housing during administration set, the driver axially moving with the administration set knob during administration set and rotating with the administration set knob during injection to axially move at least one of the nested plunger rod members.

[0007] In accordance with an implementation of an exemplary embodiment, the chamber is a fluid cartridge comprising a stopper and a subchamber for holding fluid, the length of the plunger rod assembly component being less than the length of the subchamber when in an initial nested position and at least as long as the subchamber when extended from the nested position.

[0008] In accordance with an implementation of an exemplary embodiment, the first plunger rod member and the second plunger rod member are, respectively, a plunger rod and a plunger rod inner member, and are at least partially concentrically disposed with respect to one another such that the plunger rod at least partially encases the plunger rod inner member, and the plunger rod and the plunger rod inner member are controllably manipulated to telescopically move relative to one another.

[0009] According to implementation of an exemplary embodiment, the housing includes a lead screw driver that is operated to controllably rotate when a dosage of fluid is to be delivered. The plunger rod inner member includes internal threads that engage and rotate with external threads on the lead screw driver as the lead screw driver rotates. The plunger rod inner member includes external threads that engage with internal threads in the plunger rod. The internal and external threads of the plunger rod inner member, the internal threads in the plunger rod, and the external threads on the lead screw driver have the same pitch.

[0010] In accordance with an exemplary embodiment implementation, the plunger rod inner member includes a distally disposed external thread that engages with an internal thread in the plunger rod, the external thread being one of a male and female thread, and the internal thread being the other of a male and female thread.

[0011] According to an implementation of an exemplary embodiment, the plunger rod is disposed within the housing and prevented from rotating within the housing and relative to the plunger rod inner member. The housing further comprises a lead screw driver that is controlled to rotate by operation when a dosage of fluid is to be delivered. The plunger rod comprises a counterbore at its proximal end to prevent the distal end of the plunger rod inner member from disengaging from the plunger rod. The plunger rod inner member comprises a cap at its distal end and internal threads that engage and rotate with external threads on the lead screw driver as the lead screw driver rotates, and a coupling mechanism configured to provide a temporary engagement between the plunger rod inner member and the lead screw driver until rotation of the plunger rod inner member moves the plunger rod axially to a point where the cap abuts the counterbore of the plunger rod and creates a force to disengage the plunger rod inner member from the lead screw driver and allow the plunger rod inner member to move axially.

[0012] In accordance with an exemplary embodiment implementation, the coupling mechanisms on the plunger rod inner member include at least one detent on their proximal ends that is correspondingly shaped and configured to frictionally engage with a snap-fit ​​notch provided on a distal face of the lead screw driver.

[0013] According to an implementation of an exemplary embodiment, the housing includes a brake tower axially and rotatably secured thereto. The brake tower includes a plurality of slots. The plunger rod includes at least one tang that extends into one of the slots to engage the plunger rod with the brake tower. The plunger rod inner member includes at least one tang on its proximal end that enters the nearest slot after the plunger rod inner member is disengaged from the lead screw driver, further stopping rotation of the plunger rod and the plunger rod inner member and advancing axially as the lead screw is rotated.

[0014] According to an implementation of the exemplary embodiment, the housing includes a brake tower axially and rotatably secured thereto. The proximal end of the plunger rod inner member and the brake tower have mutually engaging same-turn threads, the same-turn thread being one of a clockwise thread and a counterclockwise thread. The distal end of the plunger rod inner member and the plunger rod have mutually engaging same-turn threads, the other of a clockwise thread and a counterclockwise thread, such that when a lead screw driver engaged with the brake tower and the plunger rod inner member rotates, the plunger rod and the plunger rod inner member move simultaneously.

[0015] According to an implementation of the exemplary embodiment, the threads on the plunger rod inner member, the plunger rod, and the brake tower have the same pitch.

[0016] In accordance with an implementation of an exemplary embodiment, the housing further includes an anti-rotation sleeve disposed between the brake tower and the plunger rod, the anti-rotation sleeve including a slot, and the brake tower and the plunger rod each including a stop member received in the slot.

[0017] In accordance with implementation of the exemplary embodiment, the axial cross section of the lead screw driver has at least a portion thereof shaped to key into the inner portion of the plunger rod inner member.

[0018] Additional and / or alternative aspects and advantages of the exemplary embodiments will be set forth in and will be apparent from the description that follows, or may be learned by practice of the exemplary embodiments. The exemplary embodiments may include one or more of the embodiments and / or apparatus having one or more of the features and combinations thereof. The exemplary embodiments may include one or more of the features and / or combinations of the above recited embodiments, for example, as set forth in the appended claims.

[0019] The above and / or other aspects and advantages of the exemplary embodiments will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0020] [Figure 1A] FIG. 1A is a side view of an exemplary injection pen constructed in accordance with an exemplary embodiment. [Figure 1B] FIG. 1B is a side view of an exemplary injection pen configured to a reduced length in accordance with an exemplary embodiment. [Figure 2A] FIG. 2A is a side view of an exemplary injection pen in an administration set according to an exemplary embodiment. [Figure 2B] FIG. 2B is a side view of an exemplary injection pen configured with a shortened length in accordance with an exemplary embodiment. [Figure 2C] FIG. 2C is a side view of an exemplary injection pen configured with a shortened length in accordance with an exemplary embodiment. [Figure 3A] FIG. 3A is a partial cross-sectional view of an exemplary injection pen constructed in accordance with an exemplary embodiment. [Figure 3B] FIG. 3B is a partial cross-sectional view of an exemplary injection pen configured to have a shortened length in accordance with an exemplary embodiment. [Figure 3C] FIG. 3C is a partial cross-sectional view of an exemplary injection pen configured to have a shortened length in accordance with an exemplary embodiment. [Figure 4A] FIG. 4A is an enlarged cross-sectional view of an exemplary injection pen. [Figure 4B] FIG. 4B is an enlarged cross-sectional view of an exemplary injection pen. [Diagram 5] FIG. 5 is a partial cross-sectional view of a pen body assembly of an exemplary injection pen. [Figure 6] FIG. 6 is a partial cross-sectional view of a pen body assembly of an injection pen constructed in accordance with an exemplary embodiment. [Figure 7A] 7A-7C are partial cross-sectional views of an injection pen constructed in accordance with the exemplary embodiment of FIG. 6 at various stages of axial movement. [Figure 7B] 7A-7B are partial cross-sectional views of an injection pen constructed in accordance with the exemplary embodiment of FIG. 6 at various stages of axial movement. [Figure 7C] 7A-7C are partial cross-sectional views of an injection pen constructed in accordance with the exemplary embodiment of FIG. 6 at various stages of axial movement. [Figure 8] FIG. 8 is a perspective view of a plunger rod and brake tower assembly constructed in accordance with the exemplary embodiment of FIG. [Figure 9] FIG. 9 is a partial side view of a plunger rod and lead screw assembly configured in accordance with the exemplary embodiment of FIG. [Figure 10] FIG. 10 is a cross-sectional view of a plunger rod and brake tower assembly constructed in accordance with the exemplary embodiment of FIG. [Figure 11] FIG. 11 is a partial cross-sectional view of a pen body assembly of another exemplary injection pen. [Figure 12A] 12A-12C are partial cross-sectional views of an injection pen constructed in accordance with the exemplary embodiment of FIG. 11 at various stages of axial movement. [Figure 12B]12B are partial cross-sectional views of an injection pen constructed in accordance with the exemplary embodiment of FIG. 11 at various stages of axial movement. [Figure 12C] 12C are partial cross-sectional views of an injection pen constructed in accordance with the exemplary embodiment of FIG. 11 at various stages of axial movement. [Figure 13] FIG. 13 is a perspective view of a plunger rod and brake tower assembly constructed in accordance with the exemplary embodiment of FIG. [Figure 14A] 14A is an enlarged cross-sectional view of a plunger rod and lead screw assembly constructed in accordance with the exemplary embodiment of FIG. [Figure 14B] 14B is an enlarged cross-sectional view of a plunger rod and lead screw assembly constructed in accordance with the exemplary embodiment of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Throughout the drawings, reference numerals and the like may be understood to refer to components, functions, structures, and the like.

[0022] Exemplary embodiments illustrated in the accompanying drawings will now be described in detail. The embodiments described herein are illustrative and are not limited to the exemplary embodiments referred to in the drawings. The matters illustrated in this description are provided to facilitate a complete understanding of the exemplary embodiments of this disclosure. Thus, those skilled in the art will understand that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of this disclosure. Furthermore, descriptions of well-known functions and configurations are omitted for the sake of clarity and conciseness.

[0023] Injection pens typically have a plunger rod similar to that found in a syringe. The plunger rod is tightened via a threaded mechanism against a linear force. The length of the plunger in existing pens is approximately equal to the length of the cartridge or barrel that filters the delivered fluid to expel all of the fluid (e.g., medication) therefrom.

[0024] 1A, 4AB, and 4B respectively show a side view, a close-up view, and a cross-sectional view of an exemplary injection pen 200 that does not employ an exemplary embodiment of a telescoping plunger rod configuration to reduce pen form factor. The exemplary injection pen 200 may be enhanced in accordance with exemplary embodiments described herein that employ a respective telescoping plunger rod configuration to reduce its form factor, maintain or increase its delivered fluid volume, and also maintain increased dosing accuracy (e.g., exemplary injection pen 300 shown in FIG. 1B).

[0025] The exemplary injection pen 200 shown in Figures 1A, 4A and 4B comprises a pen upper body or housing 201 that houses a number of administration sets and injection components. The pen upper body 201 is coupled to a cartridge housing 214 that houses a medication cartridge 215, as shown in Figures 4A and 4B. The injection pen 200 may also comprise a lower pen cap 212 that covers the cartridge 215 and the cartridge housing 214 (e.g., insulin cartridge assembly part 219) when the injection pen is not in use. As shown in Figure 2A, the injection pen 200 comprises an administration set knob 202 that comprises a knob-like portion that is rotated by the user to set the desired dose visible at a window 213.

[0026] 4B shows a cross-sectional view of an exemplary injection pen 200. The references of the individual parts may be more easily understood in view of the enlarged assembly shown in FIG. 1B. As shown, a push button 203 is provided at the proximal end of the pen upper body 201, which is most proximal to the user and most distant from the needle attached to the insulin cartridge assembly 219. The push button 203 houses a spring 210 and is configured with a friction fit such that the push button 203 is pushed into the administration set knob 202 to inject a set dose, while the force of the button spring 210 keeps the push button 203 in a biased position on the administration set knob 202. The interior of the push button 203 houses a setback bearing insert 208 that is placed on an inner surface at the proximal end of a setback member or driver 209. The push button 203 is designed to rotate freely on the setback bearing insert 208. The double click car body 222 provides auditory feedback and is surrounded by the administration set knob 202. The double click car may provide a ratchet mechanism that prevents rotation (e.g., clockwise) of the administration set knob 202 relative to the setback member 209 during administration set rotation (e.g., clockwise).

[0027] The setback member or driver 209 is a cylindrical member coaxially and surrounded by the administration set knob 202. The setback member 209 is coaxially provided around the brake tower 205, which is axially and rotatably fixed to the pen upper body 201. The brake tower 205 coaxially surrounds the piston rod 206, as shown in FIG. 4A. A wave clip or spring 211 is provided between the distal end of the brake tower 205 and the cartridge 215, as shown in FIG. 4A, to bias the cartridge 215 distally to prevent any movement of the cartridge 215 during injection, and thereby ensure that an accurate dose is injected. As will be discussed in more detail below, due to its threaded engagement with a lead screw, the piston rod 206 is moved into the cartridge 215 during injection and pushes on a stopper 216 provided inside the cartridge 215 to expel a dose of medication.

[0028] More specifically, the brake tower core 220 is surrounded by and rotatably fixed coaxially to the brake tower 205. The brake tower core 220 is provided with a plurality of teeth on an enlarged surface 223 near its proximal end. The plurality of teeth may extend axially toward a distal end and are configured to engage with corresponding teeth 225 provided on the proximal end of the brake tower 205. The engagement of the corresponding teeth prevents relative rotation between the brake tower core 220 and the brake tower 205. The brake tower 205 is rotatably fixed to the pen upper body 201, both coaxially, in the same manner as described above. As shown, the brake tower core 220 is a substantially cylindrical element having an open side 224 extending along the axial length of the brake tower core 220. The open side 224 may, for example, comprise approximately one-fifth to one-quarter of the circumference of the cross section of the brake tower core 220. Thus, the open side 224 forms two longitudinally extending edges at each end of the open side 224 .

[0029] The brake tower core 220 functions to prevent rotation of the piston rod 206, and thus the pen upper body 201, relative to the brake tower 205. The brake tower core 220 is surrounded by a hollow piston rod 206. The hollow piston rod 206 includes a plurality of thread segments provided along substantially the entire length of the hollow piston rod 206. Each of the thread segments has a length substantially equal to a portion of the circumference of the open side 224 of the brake tower core 220. The thread segments extend inwardly into the inner bore of the hollow piston rod 206. The piston rod 206 is provided with respect to the brake tower core 220 such that its threads are aligned and protrude into the open side 224 of the brake tower core. In this position, pairs of longitudinally extending edges formed by the open side 224 abut the respective edges of the protruding thread segments, preventing the piston rod 206 from rotating relative to the brake tower core 220.

[0030] Similar to the above exemplary embodiment, a lead screw 204 is provided inside a hollow piston rod 206. A threaded portion 242 is provided at a distal end of the lead screw 204. The threaded portion 242 is configured to engage a threaded segment provided on the inside of the piston rod 206. The lead screw 204 is rotatably fixed to the setback member 209 such that rotation of the setback member 209 is transferred to the lead screw 204 during injection. Axial movement of the lead screw 204 relative to the brake tower core 220 is prevented in a proximal direction by the threads 242 of the lead screw 204 being larger than the diameter of the opening at the distal end of the brake tower core 220. Axial movement of the lead screw 204 relative to the brake tower core 220 is prevented in a distal direction by the flange 229 of the lead screw 204 engaging the enlarged portion 223 of the brake tower core 220. Thus, due to the threaded engagement between the threads 242 of the lead screw 204 and the threaded segments on the hollow piston rod 206, relative rotation of the lead screw 204 with respect to the piston rod 206 (which is rotatably fixed to the brake tower 205) tightens the piston rod 206 axially in a distal direction inside the cartridge 215, expelling the drug contained therein.

[0031] 1B, an improved and shortened injection pen 300 constructed according to an exemplary embodiment is shown, in which the rod 206, also referred to as the plunger rod, is constructed in two pieces extending from a single plunger rod 206. Comparing FIGS. 1A and 1B with each other, it is clear that the dimensions of the insulin cartridge assemblies 219 and 319 are the same in terms of circumference and length, but the pen upper bodies 201 and 301 have the same circumference, but their lengths differ from the length of the pen upper body 301 of the pen, which is advantageously shortened due to reduced forming elements, among other advantages. For example, the pen 200 in FIG. 1A and the pen 300 in FIG. 1B are both shown with their respective lower pen caps 212 and 312 removed, and with the needleless assembly assembled at the distal end of their respective insulin cartridge assemblies 219 and 319. However, the pen 200 in Figure 1A is 136.5 millimeters (mm) long, while the pen 300 in Figure 1B is only 108.0 millimeters (mm) long. It is understood that the housing 301 and its associated driver assembly may have different lengths than shown in Figure 1B.

[0032] As described below in connection with Figures 6-10, pen 300, according to an exemplary embodiment, includes a two-piece plunger rod having a dual-threaded telescoping screw train configuration (hereinafter referred to as the "dual-threaded" telescoping screw train embodiment or pen 300) to achieve coaxial movement of stopper 316, like stopper 216 moved by a single plunger rod 206 in pen 200, but without requiring extra length in housing 301 to accommodate the piston driver assembly. As described below in connection with Figures 11-14, pen 300, alternatively, according to another embodiment, includes a two-piece plunger rod having a dual-acting telescoping screw train configuration (hereinafter referred to as the "double-acting" telescoping screw train embodiment or pen 400) to achieve coaxial movement of stopper 316, like stopper 216 moved by a single plunger rod 206 in pen 200, but without requiring extra length in housing 301 to accommodate the piston driver assembly.

[0033] Additional comparisons of reduced forming elements of the dual thread and double acting telescopic screw train embodiments are shown in Figures 2A, 2B, and 2C, and Figures 3A, 3B, and 3C. Figures 2A, 2B, and 2C show exterior side views of a standard length injection pen 200, an advantageously reduced forming element dual thread injection pen 300, and an advantageously reduced forming element telescrew injection pen 400, respectively, in a dose setting mode. Figures 3A, 3B, and 3C show cross-sectional views of a standard length injection pen 200, an advantageously reduced forming element dual thread injection pen 300, and an advantageously reduced forming element double acting injection pen 400, respectively, in a pre-dose setting mode.

[0034] Before describing the respective double screw and double action embodiments below, the dose setting and dosing (i.e., injecting) operations of the standard length injection pen 200 will be described with reference to FIG. 5. To set a dose, the user rotates the administration set knob 202 clockwise (CW) to the desired dose. The setback member 209 maintains its current angular position since its ratchet mechanism with the brake tower 205 only rotates counterclockwise (CCW). If the user rotates the administration set knob 202 CCW, the setback member 209 remains in the same angular position since there is no axial force locking the male detents in the setback member 209 into the corresponding female detents of the administration set knob 202. The double clicker 222 rattles the mechanism, preventing CW rotation relative to the setback member 209, as well as providing auditory feedback (e.g., a clicking sound) during the corresponding rotation of the administration set knob 202.

[0035] With continued reference to FIG. 5, to perform an administration, the user presses on the button 203. The administration set knob 202 begins to rotate CCW as its male thread screw tightens into the corresponding female thread in the body 201. The setback member 209 rotates CCW because the force generated by the user pressing the button 203 locks the male detents of the setback member 209 into the female detents of the administration set knob 202. The lead screw 204 rotates CCW because its head has two protrusions that engage longitudinal slots in the setback member 209. As the lead screw 204 rotates, it threads into the piston rod 206, advancing it, and ultimately the stopper 216, a selected axial distance to administer the desired amount of insulin. The tower core 220 is keyed into the brake tower 205 and the piston rod 206 to ensure that the piston rod 205 does not spin and ensures relative movement between the lead screw 204 and the piston rod 206.

[0036] According to the exemplary two-thread embodiment shown in Figures 6-10, the improved injection pen 300 achieves reduced form factor by using a two-piece plunger rod with a dual-thread telescopic screw train configuration. With reference to Figure 6, the pen 300 includes a body 301 having a dosing setting and dosing components, and a fluid cartridge assembly 319. Components 302, 303, 322, 316, and 319 may be similar to the respective components 202, 203, 222, 216, and 219 described above. The modified plunger rod is two pieces, a plunger rod 306 and a plunger rod inner member 307, each of which is shorter in length than the piston rod 206. Accordingly, the body 301, the lead screw 304, and the brake tower 305 in the pen 300 are also shorter in length than the corresponding components 201, 204, and 205 in the pen 200. However, the plunger rod 306 and the plunger rod inner member 307 are arranged to telescope and are screwed to extend so that when the piston rod 206 moves the stopper 216 in a cartridge assembly 219 having the same volumetric length dimension as the cartridge assembly 319, the piston rod 306 has a corresponding overall length and moves the stopper 316 the same overall length in the cartridge of the cartridge assembly 219.

[0037] For example, as shown in FIGS. 6-10, the plunger rod inner member 307 may provide internal threads 330 that engage the exterior of the lead screw 304 with threads 342. As shown in FIGS. 7A-7C, the external male threads 332 engage with female threads 344 provided on the plunger rod 306. Comparing pen 300 to pen 200, the threads 344 are repositioned compared to the threads in the piston rod 206. Additionally, the tower core 220 is eliminated. Instead, the exemplary embodiment employs a set of tongues 336 and grooves 338 on the plunger rod 306 and a brake tower 305 to stop the plunger rod 306 from rotating, as shown in FIG. 8A. A cap 340 is provided at the end of the plunger rod inner member 307 to facilitate threading of the pen body assembly in production and to provide a vertical surface to stop the plunger rod inner member from moving forward before the plunger rod 306 is unthreaded. This telescoping configuration allows the plunger rod inner members 306, 307 to nearly double in length (FIG. 7C) compared to the original nested position shown in FIG 7A. Because the plunger rod threads 334 move one at a time and have the same pitch as the threads in the piston rod 206, the plunger rod 306 moves in the pen 300 with the same increments as the piston rod 206 in the pen 200.

[0038] 6-10, after setting the desired dose with the administration set knob 302, the user presses the button 303 to begin administration. As its male threads tighten with its female threads, the administration set knob 302 begins to rotate CCW. The force applied to the button locks the male detents of the setback member 309 into the female detents of the administration set knob 302, which in turn rotates CCW as well. The lead screw 304 also turns CCW as its head has two protrusions that engage with longitudinal slots in the setback member 309. The plunger rod of the rotating lead screw 304 threads into the inner member 307, which advances the plunger rod 306 and ultimately the stopper 316 to dispense the desired amount of fluid (e.g., insulin) from the cartridge.

[0039] The plunger rod inner member 307 is configured such that the plunger rod 306 is first moved and then bottomed out in the counterbore before becoming the plunger rod inner member 307. The lead screw 304 is positively temporarily coupled to the plunger rod inner member 307 for a desired time via the two detents 344a, 334b ​​as shown in FIG. 9. When the bottom surface of the cap 340 on the plunger rod inner member 307 bottoms out on the end of the plunger rod 306, the force of the threads creates enough rotational force to dislodge the two detents 344a, 334b. The four tongues 346a, 346b, 346c, and 346d on the plunger rod inner member 307 enter the proximal set of grooves 338 in the brake tower as shown in FIG. 10, thereby stopping the rotation of both plunger rod parts 306, 307 and applying an advancing force as the lead screw 304 rotates.

[0040] According to another exemplary embodiment, a double-acting telescopic screw train configuration will now be described with reference to pen 400, as shown in Figures 11-14. According to this embodiment, pen 400 has a modified plunger rod for an advantageously reduced form factor pen. For example, a plunger rod, such as plunger rod 206 in pen 200, is modified in pen 400 as plunger rod 406 and the double-acting telescopic screw train comprising plunger rod inner member 407 are each shorter in length than plunger rod 206. Accordingly, body 401, lead screw 404 and brake tower 405 in pen 300 are shorter in length than the corresponding components 201, 204 and 205 in pen 200. However, the plunger rod 406 and the plunger rod inner member 407 are arranged to telescope and are threadedly extended to an overall length equal to that of the piston rod 206, causing the piston rod 206 to move the stopper 216 into the cartridge of the cartridge assembly 219 having the same volumetric length dimension as the cartridge assembly 419, thereby causing the stopper 416 to move the same overall length into the cartridge of the cartridge assembly 419.

[0041] For example, as shown in Figures 12A-12C, the plunger rod inner member 407 may be provided with proximal male CCW threads 430 that mate with female CCW threads 434 in the brake tower 405 and distal male CW 432 that mate with female CW threads 436 in the plunger rod 406. This telescoping arrangement allows the plunger rod assembly 406, 407 to extend approximately twice as far when extended (12C) as compared to its initial nested position (Figure 12A). The plunger rod 406 and plunger rod inner member 407 have the same pitch as the threads in the piston rod 206, and so the plunger rod 406 and plunger rod inner member 407 move together because, for example, they have opposite thread directions, causing the plunger rod assembly 406, 407 to move twice as far per rotation of the lead screw 404 compared to the movement of the piston rod 206 by the lead screw 204 in the pen 200.

[0042] According to another exemplary embodiment of the pen 400 with a double acting telescoping screw train configuration as shown in Figs. 11-14, the text or indicia on the administration set knob 402 is modified to reflect the doubling in the movement of the plunger rod assemblies 406, 407. Figs. 2A, 2B, and 2C show windows 213, 313, and 413 with indicia 250, 350, and 450 (e.g., 80 units maximum dose, 30 units maximum dose, and 60 units maximum dose), respectively. For example, in the window 413 of the pen 400 in Fig. 2C, each line, as shown at 450, now represents 2 units of insulin, as compared to, for example, 1 unit, as shown on the pen 200 in Fig. 2A. Thus, text or other indicia is added to every other line in Figs. 2A and 2B, whereas in Fig. 2C, the text or other indicia is added to each line in turn. The pen 400 may be implemented with a reduced font size for the indicia 450 to prevent different indicia from overlapping. A magnifying lens is used in the pen window 313 in FIG. 2B to aid in legibility of the dosage unit indicia 350 for the user.

[0043] 11-14, a stainless steel anti-rotation sleeve 428 has been provided in the pen 400. The anti-rotation sleeve 228 has a set of slots 440. Two sets of slots 442 and 444 are provided, respectively, on the plunger rod 406 and on the brake tower inside the set of slots 440 of the anti-rotation sleeve 428 to prevent rotation of the plunger rod 406, as shown in FIG.

[0044] 11-14, after setting the desired dose with the administration set knob 402, the user presses the button 403 to begin administration. When its male threads tighten the female threads of the body 401, the administration set knob 402 begins to rotate CCW. A force applied to the button 403 also rotates the setback member 409 CCW to lock the male detents of the setback member 309 into the female detents of the administration set knob 302. The lead screw 404 also rotates CCW because its head has two protrusions that engage with longitudinal slots in the setback member 409. The lead screw 404 is slidingly keyed into the plunger rod inner member 407, causing them to rotate together, as shown in FIGS. 14A and 14B. As the plunger rod inner member 407 rotates, it advances distally due to its threaded relationship with the brake tower 405. At the same time, the plunger rod 406 advances due to its threaded relationship with the distal male threads 432 on the plunger rod inner member 407. Advancement of the plunger rod 406 over the stopper 416 dispenses a desired amount of fluid (e.g., insulin) from the cartridge.

[0045] In accordance with exemplary embodiments of the present disclosure, injection pens (e.g., pens 300 and 400) can deliver a total of 300 units of insulin from cartridge 214 using a pen body (e.g., pens 301 and 401) that is 40% shorter than the body 201 of pen 200, which does not implement the technical solution of advancing a stopper (e.g., stopper 216) by means of, for example, a two-piece telescoping screw train as provided by the exemplary embodiments. Thus, a significant reduction in length of injection pens 300, 400 by approximately 20%, and a corresponding space saving, is achieved by the exemplary embodiments, enhancing user convenience.

[0046] Due to space limitations within many injection pens, the exemplary embodiment is shown with a two screw train arrangement. However, it should be understood that the exemplary embodiments of the present disclosure can be implemented using a three screw train arrangement. Additionally, the exemplary embodiments can be implemented with an administration set knob that is a two screw administration set knob, and the injection pen is further shortened.

[0047] The solution to the technical problem of reducing the drive train components for the plunger in the pen uses a screw drive mechanism and related principles such as lifting torque, efficiency, thread pitch, and friction (lifting torque is a function of the applied axial load (force or pressure), thread pitch, friction coefficient, and diameter). In some embodiments, the exemplary embodiments, the related mechanical equations may be further expanded to capture the full details of the thread geometry and other special parameters such as flank angle and lead angle. ACME threads can be used in general to fine-tune the balance of lifting torque, required force, efficiency, and other functional parameters such as ease of use and cost.

[0048] Exemplary embodiments are further advantageous for implementing an anti-rotation feature on the screw-like components of the plunger rod drive assembly (e.g., the use of tongues and grooves for the dual threaded telescoping screw train embodiment of FIGS. 6-10 and the use of an elongated anti-rotation sleeve for the double acting telescoping screw train embodiment of FIGS. 11-14).

[0049] Exemplary embodiments of the present disclosure may address at least the above problems and / or other disadvantages not described above, although exemplary embodiments need not address all of the above-mentioned disadvantages and may not address any of the above problems.

[0050] Exemplary embodiments of the present disclosure provide system elements that facilitate reducing the overall size or footprint of a medication delivery device, such as a medication injection pen, through the configuration of a container, cartridge, vial, reservoir, or barrel for a medium or fluid having features or drive components for advancing a plunger to dispense a medium or fluid from the container, cartridge, vial, reservoir, or barrel (the features or drive members may be positioned such that the overall length of the drive member may be reduced as compared to conventional designs).

[0051] Matters of the exemplary embodiments that will be apparent to those skilled in the art that include the exemplary embodiments will not be described in detail herein. Furthermore, the various features of the exemplary embodiments may be implemented individually or in any combination, as would be understood by those skilled in the art of drug delivery devices.

[0052] Those skilled in the art will understand that the terms used herein, such as "fluid," "medication," "vehicle," "stopper," "plunger," "thread," "syringe," "driver," "screw," "gear," "piston," "top," "side," "bottom," "upper," "lower," "proximal," "distal," "container," "reservoir," "chamber," and other descriptions, are intended to facilitate the description of specific embodiments of the invention and are not intended to limit any of the components that may be used individually or in combination to implement various implementations of the embodiments of the present disclosure.

[0053] Those skilled in the art will appreciate that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth above or illustrated in the drawings. The embodiments herein may be implemented in other embodiments and may be practiced or carried out in various ways. The phrases and terminology used herein are for descriptive purposes only and should not be considered as limiting. The terms "comprise", "include", or "have" and variations thereof herein are intended to include the terms listed below, as well as additional terms, and their equivalents. Unless otherwise limited, the terms "connected", "coupled", "attached" and variations thereof herein are used broadly and include direct and indirect connections, couplings, and attachments. Furthermore, the terms "connected" and "coupled" and variations thereof are not limited to physical or mechanical connections or couplings. Additionally, the terms "upper", "lower", "bottom" and "top" are relative terms and are intended to aid in illustration and not to be limiting.

[0054] The above description and drawings are presented by way of example only and are not intended to limit the exemplary embodiments in any manner, except as set forth in the following claims. In particular, those skilled in the art will understand that various technical implementations of the various elements of the various exemplary embodiments described above can be readily combined in various alternative ways, all of which are considered to be within the scope of the claims of the present invention.

Claims

1. 1. A medication injection pen comprising: a chamber for holding a fluid, the chamber including an outlet for releasing the fluid therefrom, and a stopper configured to advance within the chamber to force the fluid out of the chamber through the outlet and to a patient; a housing including a plunger rod assembly component connected to the chamber and configured for controlled axial movement to move a stopper a selected amount within the chamber to expel a selected dose of fluid; A medication injection pen, wherein the plunger rod assembly part comprises at least two nested plunger rod members having a first plunger rod member slidably mounted within a second plunger rod member and is controllably operated to move the first plunger rod member relative to the second plunger rod member to axially extend the plunger rod assembly part and push a stopper through the distal end of one of the nested plunger rod members.

2. The housing further comprises: an administration set knob that rotates relative to the housing during administration; and a driver selectively engaging the administration set knob and threadably engaging the plunger rod assembly component; 10. The medication injection pen of claim 1, wherein the driver moves axially with the administration set knob during administration set and rotates with the administration set knob during injection to effect axial movement of at least one of the nested plunger rod members.

3. 2. The medication injection pen of claim 1, wherein the chamber is a fluid cartridge having a stopper and a subchamber for holding fluid, and the length of the plunger rod assembly components is less than the length of the subchamber when in an initial nested position and is at least as long as the subchamber when extended from the nested position.

4. 2. The medication injection pen of claim 1, wherein the first plunger rod member and the second plunger rod member are a plunger rod and a plunger rod inner member, respectively, and are at least partially concentrically disposed with respect to each other such that the plunger rod at least partially encases at least a portion of the plunger rod inner member, and the plunger rod and the plunger rod inner member are controlled and manipulated to move telescopically relative to each other.

5. the housing includes a lead screw driver that is operated to be controllably rotated when a dosage of fluid is to be delivered, the plunger rod inner member includes internal threads that engage and rotate with external threads on the lead screw driver as the lead screw driver rotates, the plunger rod inner member includes external threads that engage with internal threads in the plunger rod; 5. The medication injection pen of claim 4, wherein the internal and external threads of the plunger rod inner member, the internal threads in the plunger rod, and the external threads on the lead screw driver have the same pitch.

6. 5. The medication injection pen of claim 4, wherein the plunger rod inner member includes a distally disposed external thread that engages with an internal thread in the plunger rod, the external thread being one of a male thread and a female thread, and the internal thread being the other of the male thread and the female thread.

7. a plunger rod disposed within the housing and prevented from rotating within the housing and relative to the plunger rod inner member, the housing further comprising a lead screw driver that is operated to controllably rotate when a dosage of fluid is to be delivered; and the plunger rod includes a counterbore at its proximal end to prevent the distal end of the plunger rod inner member from dislodging from the plunger rod; The plunger rod inner member is a cap at its distal end; an internal thread that rotates in engagement with an external thread on the lead screw driver as the lead screw driver rotates; and 7. The medication injection pen of claim 6, further comprising a coupling mechanism configured to provide temporary engagement between the internal plunger rod member and the lead screw driver until rotation of the internal plunger rod member moves the plunger rod axially to a point where the cap abuts the counterbore of the plunger rod and exerts a force to disengage the internal plunger rod member from the lead screw driver and allow the internal plunger rod member to move axially.

8. 8. The medication injection pen of claim 7, wherein the coupling mechanisms on the plunger rod inner member include at least one detent on their proximal ends, the at least one detent being correspondingly shaped and configured to frictionally engage with a snap-fit ​​notch provided on a distal surface of the lead screw driver.

9. the housing includes a brake tower axially and rotatably secured thereto, the brake tower including a plurality of slots, the plunger rod including at least one tongue extending into one of the slots to engage the plunger rod with the brake tower; 8. The medication injection pen of claim 7, wherein the plunger rod inner member has at least one tongue on its proximal end that enters the nearest slot after the plunger rod inner member is removed from the lead screw driver, further stopping rotation of the plunger rod and the plunger rod inner member, and after the plunger rod inner member advances axially as the lead screw rotates.

10. the housing includes a brake tower axially and rotatably secured thereto, the proximal end of the plunger rod inner member and the brake tower having mutually engaging same-turn threads, the same-turn threads being one of clockwise threads and counterclockwise threads; 5. The medication injection pen of claim 4, wherein the distal end of the plunger rod inner member and the plunger rod have threads of the same rotation, one of a clockwise thread and a counterclockwise thread that engage with each other, such that when the lead screw driver engaged with the brake tower and the plunger rod inner member rotate, the plunger rod and the plunger rod inner member move simultaneously.

11. 11. The medication injection pen of claim 10, wherein the threads on the plunger rod inner member, the plunger rod, and the brake tower have the same pitch.

12. 11. The medication injection pen of claim 10, wherein the housing further comprises an anti-rotation sleeve disposed between the brake tower and the plunger rod, the anti-rotation sleeve comprising a slot, and the brake tower and the plunger rod each comprising a stop member received in the slot.

13. 11. The medication injection pen of claim 10, wherein an axial cross section of the lead screw driver has at least a portion thereof shaped to key into an inner portion of the plunger rod inner member.

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