Description:RELATED ART

[0001] Embodiments of the present specification relate generally to a dispensing device, and more particularly to a dispensing device that is integrated with safety features that prevent a user from setting a wrong dose for delivery and further prevent the user from reusing the dispensing device once an associated cartridge is empty.
[0002] Generally, treating patients suffering from various diseases entails injecting medicament using syringes. One example of a simple syringe includes a transparent medicament barrel that includes graded scale markings marked on a cylindrical external surface of the medicament barrel. The graded scale markings allow a caregiver to set a desired dose to be injected into a patient’s body. A proximal end of the medicament barrel includes a plunger, and a stopper that is placed within the medicament barrel and is coupled to one end of the plunger. A distal end of the medicament barrel is designed and is shaped to couple to a needle that pierces patient’s skin for injecting a medicament by actuating the plunger.
[0003] The amount of medicament to be injected is set by piercing the needle through a rubber stopper of a container carrying the medicament and by pulling out the plunger towards the distal end. The plunger is pulled out towards the distal end until level of the medicament within the medicament barrel corresponds to a desired graded scale marking. Then, the syringe is primed to remove any air bubbles that may be formed while setting the dose and it is ensured that the syringe is carrying only the desired amount of medicament substance to be injected. Then, the set dose is injected by pushing the plunger towards the proximal end, during which time, the plunger along with the stopper moves within the transparent medicament barrel. Movement of the plunger and stopper within the transparent medicament barrel causes the enclosed medicament to pass out through the needle.
[0004] The same amount of certain medicaments may need to be injected once in a week, once in a day, or at designated intervals in the day. For such cases, injector pens have been developed that allow patients to set and deliver a dose themselves more accurately in a controlled manner. Such injector pens, in general, have a cartridge that contains a rubber stopper and a multi-dose quantity of the medicament. In addition, a driving member such as a plunger or a piston rod extends out from a proximal end of such typical injection pens and operably connects to dose delivery mechanisms at a distal end of the pen. The dose delivery mechanisms generally include complex mechanical assemblies such as gear arrangements and/or rack and pinion arrangements. While delivering a fixed dose, the dose delivery mechanisms control the movement of the driving member towards the distal end of the pen. Thus, the driving member, with its controlled movement, pushes the rubber stopper to dispense only a designated amount of medicament from the cartridge.
[0005] Generally, the injector pens are designed to prevent patients from re-using the injector pens once a final dose is delivered and the cartridge is empty. Mechanisms that prevent re-using of the injector pens are in-built into the injector pens to avoid risks associated with re-using of the injector pens such as microbial growth and contamination at the needle tip, experiencing pain when injecting the medicament, breaking of the needle, and formation of lumps on the skin. However, the existing injector pens that are capable of injecting the same amount of substance multiple times are costlier, use complex mechanisms and expensive components to set the dose, to deliver the set dose, and to prevent re-using of the pens after their end of life (EOL). Accordingly, there remains a need for an injector pen that has in-built mechanisms that execute all the functionalities of typical injector pens, but is still cost-effective, more efficient, has improved accuracy in setting and delivering the dose, and prevents re-using of the injector pen after its EOL.

BRIEF DESCRIPTION

[0006] According to an exemplary aspect of the present specification, a dispensing device is provided. The dispensing device includes a cam follower including a dose setting pawl and a dose delivering pawl that are disposed with respect to each other to form a locking groove, a cam drum, and a lead screw. The cam drum is coupled to the cam follower. The cam drum includes one or more linear cam profiles and one or more helical cam profiles. Each of the one or more linear cam profiles includes an end-of-life locking snap. The lead screw is coupled to the cam drum. The lead screw is adapted to move within the cam drum by a designated distance while delivering each dose of a material from the dispensing device and is further adapted to be positioned below the end-of-life locking snap after delivering a final dose of the material from the dispensing device. The lead screw, thus positioned below the end-of-life locking snap after the final dose is delivered from the dispensing device, elevates the end-of-life locking snap from a non-elevated position to an elevated position. The end-of-life locking snap positioned in the elevated position locks with the locking groove when the cam follower is pulled out in a direction of a proximal end of the dispensing device to prevent a reuse of the dispensing device.
[0007] The locking groove formed between the dose setting pawl and the dose delivering pawl corresponds to a V-shaped groove. The end-of-life locking snap includes a first cutout portion disposed at an associated top portion of the end-of-life locking snap and a second cutout portion disposed at an associated bottom portion of the end-of-life locking snap for enabling the end-of-life locking snap to move freely from the non-elevated position to the elevated position. The cam follower includes a first extension slot, a second extension slot, a flange, and a first spring support structure disposed at a proximal end of the cam follower. The cam follower is coupled to a thumb pad. The thumb pad includes a guide disposed at a distal end of the thumb pad. The guide moveably fits within the first extension slot of the cam follower. Further, the thumb pad includes a thumb pad snap disposed at the distal end of the thumb pad. The thumb pad snap moveably fits within the second extension slot of the cam follower. The thumb pad snap prevents the thumb pad from disengaging from the cam follower when the thumb pad is pulled out in the direction of the proximal end of the dispensing device. In addition, the thumb pad includes a second spring support structure disposed at a proximal end of the thumb pad.
[0008] The cam follower is coupled to the thumb pad such that the guide is positioned at a distal end of the first extension slot and the thumb pad snap is positioned at a distal end of the second extension slot before setting a dose of the material for delivery. The thumb pad moves linearly with respect to the cam follower and is designed to be positioned in a ready-to-pull position when the thumb pad is pulled out by a first distance in the direction of the proximal end of the dispensing device. The guide is positioned at a proximal end of the first extension slot and the thumb pad snap is positioned at a proximal end of the second extension slot when the thumb pad is positioned in the ready-to-pull position. The thumb pad in the ready-to-pull position pulls the cam follower and causes the cam follower to move linearly in the direction of the proximal end of the dispensing device when the thumb pad is further pulled out by a second distance from the ready-to-pull position. The linear movement of the cam follower in the direction of the proximal end causes the dose setting pawl to ride on a linear cam profile selected from the one or more linear cam profiles to set the dose of the material for delivery.
[0009] The thumb pad is pushed in a direction of a distal end of the dispensing device from the ready-to-pull position to a ready-to-push position after setting the dose of the material for delivery. The guide is positioned at the distal end of the first extension slot and the thumb pad snap is positioned at the distal end of the second extension slot when the thumb pad is positioned in the ready-to-push position. The thumb pad in the ready-to-push position pushes the cam follower and further causes the cam follower to move linearly in the direction of the distal end of the dispensing device when the thumb pad is further pushed from the ready-to-push position. The linear movement of the cam follower in the direction of the distal end causes the dose delivering pawl to ride on a helical cam profile selected from the one or more helical cam profiles to deliver the dose of the material set for delivery. The dispensing device includes an elastic member that is disposed between the first spring support structure of the cam follower and the second spring support structure of the thumb pad.
[0010] The dose setting pawl is locked with a one-way ratchet in a linear cam profile selected from the one or more linear cam profiles, and thereby prevents a linear motion of the cam follower in a direction of the distal end of the dispensing device when delivery of a dose is attempted without completely pulling out the thumb pad by the second distance from the ready-to-pull position. The elastic member disposed between the cam follower and the thumb pad undergoes compression from an extended state to a compressed state when delivery of the dose is attempted without completely pulling out the thumb pad by the second distance from the ready-to-pull position. Compression of the elastic member to the compressed state absorbs a force exerted by a user on the thumb pad and the one-way ratchet. The dispensing device corresponds to a fixed dose delivery device, an auto-injector device, a needle-based injection device, a fluid substance delivery device, a medical device, and a construction material delivery device.

BRIEF DESCRIPTION OF DRAWINGS

[0011] These and other features, aspects, and advantages of the claimed subject matter will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0012] FIG. 1 illustrates a top view of an exemplary dispensing device, in accordance with aspects of the present disclosure;
[0013] FIG. 2 illustrates an exploded view of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0014] FIG. 3 illustrates a side perspective view of a thumb pad of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0015] FIG. 4 illustrates a side perspective view of a cam follower of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0016] FIG. 5 illustrates a front perspective view of a cam drum of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0017] FIG. 6 illustrates a front view of the cam drum of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0018] FIG. 7A illustrates a top view of a portion of the cam follower illustrating an exemplary position of the cam follower with respect to the cam drum in an initial state before pulling out the thumb pad for setting a dose, in accordance with aspects of the present disclosure;
[0019] FIG. 7B illustrates a side perspective view of the thumb pad that is placed in a ready-to-push position with respect to the cam follower of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0020] FIG. 7C illustrates a side perspective view of the thumb pad that is placed in a ready-to-pull position with respect to the cam follower of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0021] FIG. 8 illustrates a top view of a portion of the cam follower illustrating an exemplary position of the cam follower with respect to the cam drum of the dispensing device of FIG. 1 when a dose is set only partially for delivery, in accordance with aspects of the present disclosure;
[0022] FIG. 9A illustrates a cross-sectional view illustrating an elastic member that is placed in a fully extended state between the thumb pad and the cam follower of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0023] FIG. 9B illustrates another cross-sectional view illustrating the elastic member that is placed in a compressed state between the thumb pad and the cam follower of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0024] FIG. 10 illustrates a top view of a portion of the cam follower illustrating one example of a position of the cam follower with respect to the cam drum of FIG. 6 at an end of a first dose setting stage, in accordance with aspects of the present disclosure;
[0025] FIG. 11 illustrates a left side view of the cam drum depicted in FIG. 6, in accordance with aspects of the present disclosure;
[0026] FIG. 12 illustrates an exploded view of a pen barrel of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0027] FIG. 13 illustrates a front perspective view of an exemplary embodiment of a pawl nut of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0028] FIG. 14 illustrates a top perspective view of a lead screw of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0029] FIG. 15 illustrates a rear perspective view of a push pad of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0030] FIG. 16 illustrates a front perspective view of a cartridge holder of the dispensing device of FIG. 1, in accordance with aspects of the present disclosure;
[0031] FIG. 17 illustrates a cross sectional view of the dispensing device of FIG. 1 depicting an initial state of the dispensing device before setting a first dose, in accordance with aspects of the present disclosure;
[0032] FIG. 18 illustrates a cross sectional view of the dispensing device of FIG. 1 after a user successfully sets the first dose for delivery, in accordance with aspects of the present disclosure;
[0033] FIG. 19 is another cross-sectional view of the dispensing device of FIG. 1 depicting the dispensing device at an end of the first dose delivery stage, in accordance with aspects of the present disclosure; and
[0034] FIGS. 20A-B illustrate another cross-sectional view of the dispensing device of FIG. 1 depicting the dispensing device at an associated end-of-life, in accordance with aspects of the present disclosure.

DETAILED DESCRIPTION

[0035] The following description presents an exemplary dispensing device that dispenses a fixed amount of a material upon every single actuation. Examples of the material deliverable using the dispensing device include a medicament, a chemical substance, an injectable fluid for use in therapy, an injectable fluid for use in building repair, and a composition of suitable substances. Examples of the medicament include vaccines, hormones such as parathyroid, teriparatide, gonadotropin and adrenaline, anti-venom, insulin used for treating diabetes, antibodies, proteins, chemotherapy agents, and immune-system suppressants.
[0036] The dispensing device includes various components that allow a user to set a dose of a material to be dispensed out and to deliver the set dose. In addition, the dispensing device prevents a user from setting a wrong dose for delivery, prevents damages that occur to the dispensing device when the user intentionally or unintentionally attempts to deliver the wrong dose that is set, and prevents the user from setting a subsequent dose after a final dose of the material is delivered from the dispensing device. The term “dose” used in the various embodiments described herein, broadly refers to an amount of material to be dispensed out. Certain exemplary configurations of the dispensing device that provide the various features and functions defined herein are described in greater detail with reference to FIGS. 1-20A-B.
[0037] Generally, some dispensing devices that exist in the market include an end-of-life feature that prevents patients from reusing the dispensing devices once the medicament in associated cartridges become empty. Preventing reuse of the dispensing devices after their end-of-life provides improved safety to the patients. Specifically, preventing reuse of the dispensing devices avoids risks such as microbial growth and contamination at the needle tip, experiencing pain when injecting the medicament, breaking of the needle, and formation of lumps on the skin of the patients. The end-of-life feature in such dispensing devices are usually implemented using a complex mechanism and a variety of components.
[0038] For example, the dispensing devices conventionally include a cam drum, an end-of-life adapter that is coupled to the cam drum, and a plurality of end-of-life locks that are mounted on the end-of-life adapter, which are all implemented as part of the end-of-life feature. The end-of-life locks are designed to avoid formation of locks with a thumb pad of the dispensing devices when the cartridges of the dispensing devices have medicaments. However, when the cartridges of the dispensing devices are completely empty, the end-of-life locks are designed to be locked with the thumb pad for preventing patients from reusing the dispensing devices after their end-of-life.
[0039] However, as noted previously, the dispensing devices use a variety of components such as the end-of-life adapter and multiple end-of-life locks for merely achieving one particular functionality of preventing the patients from reusing the dispending devices. As a result, the process of manufacturing the dispensing devices becomes complex due to an increased number of components to be manufactured and assembled. Consequently, manufacturing costs and market prices for which these dispensing devices are made available to the public are generally high.
[0040] In contrast, the dispensing device described in various embodiments of the present disclosure uses a custom designed cam drum for achieving an end-of-life functionality of the dispensing device without a need for additional set of components such as the end-of-life adapter and multiple end-of-life locks. Specifically, the cam drum includes one or more end-of-life locking snaps, which are custom designed for to be locked with a cam follower of the dispensing device once the medicament in an associated cartridge is empty to prevent reuse of the dispensing device by patients. Since the dispensing device achieves the end-of-life functionality without additional set of components such as the end-of-life adapter and locks, the dispensing device is easy to manufacture and assemble. Accordingly, the manufacturing cost and the market price of the dispensing device may be reduced substantially when the dispensing device is manufactured bulk in volumes.
[0041] In addition, certain existing dispensing devices include a component that is generally known as a thumb pad device to enable patients to set and deliver a dose. The thumb pad in those dispensing devices is generally designed to ride over one or more one-way ratchets in a cam drum when a patient sets a dose for delivery. Further, the thumb pad is designed to be engaged with the one-way ratchets when the patient inadvertently sets an incorrect dose such as a partial dose and attempts to deliver the partially set dose by exerting a force on the thumb pad. When the patient exerts an excessive amount of force inadvertently while attempting to deliver the partially set dose, the thumb pad transmits the force exerted by the patient to the one-way ratchets. As a result, the teeth in the one-way ratchets may break, which damages the dispensing devices and makes these expensive devices unusable before their end-of-life.
[0042] In order to address the aforementioned issues, the present disclosure provides a custom designed elastic member, for example, a spring that is disposed between a thumb pad and a cam follower. When a patient exerts an excessive amount of force on the thumb pad while attempting to deliver the partial set dose, the spring absorbs the force exerted by the force and substantially minimizes the force that is eventually acted on the teeth of one-way ratchets. As a result, the teeth of the one-way ratchets will not break and the dispensing device will not be damaged even when the patient exerts an excessive amount of force on the thumb pad.
[0043] FIG. 1 illustrates a top view (100) of an exemplary dispensing device (102). In one embodiment, the dispensing device (102) is a medicament-dispensing device having an appearance of a pen. The dispensing device (102) is a mechanical dispensing device and does not include any electrical and electronic components. In certain embodiments, the dispensing device (102) is a disposable device that is repeatedly operable by a user to deliver a fixed dose of the medicament. The term “fixed dose,” used herein and throughout various embodiments, broadly refers to substantially the same amount or volume of the medicament delivered through a needle on every single actuation of the dispensing device (102). The dispensing device (102) includes a proximal end (104) including an actuation mechanism and a distal end (106) for securing a needle that delivers the fixed dose of medicament to a patient. In one embodiment, the distal end (106) of the dispensing device (102) is disposed opposite to the proximal end (104) of the dispensing device (102). Various components of the dispensing device (102) are depicted and described in greater detail with reference to FIGS. 2 through 20A-B.
[0044] FIG. 2 is an exploded view of the dispensing device (102) of FIG. 1. The dispensing device (102) includes a thumb pad (202), a cam follower (204), an elastic member (206), a cam drum (208), a pen barrel (210), a pawl nut (212), a lead screw (214), and a push pad (216). The dispensing device (102) further includes a cartridge (218), a cartridge holder (220), a cap (222), and a needle (not shown in FIG. 2) having a needle hub for securing the needle to the cartridge holder (220). Each of these components of the dispensing device (102) is depicted and described in detail in subsequent figures and paragraphs.
[0045] FIG. 3 illustrates a side perspective view of the thumb pad (202) of FIG. 2. In one embodiment, the thumb pad (202) is a circular shaped body that is used for setting a dose and for delivering the set dose. For setting the dose, the thumb pad (202) is pulled out in a direction of the proximal end (104) (shown in FIG. 1) of the dispensing device (102). For delivering the set dose, the thumb pad (202) is pushed in a direction of the distal end (106) (shown in FIG. 1) of the dispensing device (102). In certain embodiments, the thumb pad (202) includes an identification groove (302) that is visible to a user when the thumb pad (202) is completely pulled out during setting of the dose to visually indicate to a user that the dose has been set. In one embodiment, instead of the identification groove (302), the thumb pad (202) can have other indication mechanisms, for example, a color indication to notify the user that the dose has been set.
[0046] In addition, the thumb pad (202) also includes a holding surface (304) that allows the user to hold the thumb pad (202) and to pull and push the thumb pad (202) for setting and delivering the dose, respectively. In one embodiment, the thumb pad (202) also includes a guide (306) and a thumb pad snap (308) disposed at a distal end (310) of the thumb pad (202). The guide (306) and the thumb pad snap (308) of the thumb pad (202) are operatively coupled and fit within extension slots (402 and 404) (shown in FIGS. 4 and 7B) in the cam follower (204) for enabling a user to set and deliver the dose, as described subsequently with reference to FIG. 4.
[0047] FIG. 4 illustrates a side perspective view of the cam follower (204) of FIG. 2. In one embodiment, the cam follower (204) is a rectangular shaped hollow elongated body that includes an interior space for accommodating the lead screw (214). Specifically, the cam follower (204) includes a first extension slot (402) (see FIG. 7B), and a second extension slot (404) that is disposed perpendicular to the first extension slot (402). When the thumb pad (202) and the cam follower (204) are assembled together, the guide (306) of the thumb pad (202) moveably fits within the first extension slot (402), and the thumb pad snap (308) of the thumb pad (202) moveably fits within the second extension slot (404), as depicted in FIG. 7B.
[0048] Referring back to FIG. 4, the cam follower (204) also includes a first extension arm (406), a second extension arm (408), and a set of flanges (410). It may be noted that only a flange (410) disposed on one side of the cam follower (204) from the set of flanges (410) is visible in FIG. 4 and the other flange (410) disposed on the other side of the cam follower (204) is not visible in FIG. 4. In certain embodiments, the cam follower (204) is designed to move linearly without exhibiting any rotational motions while setting and delivering the dose. To that end, the first and second extension arms (406 and 408) and the flanges (410) of the cam follower (204) are designed to fit within and linearly slide against extension-arm guides (1234A-B) (shown in FIG. 12) and flange guides (1244 and 1246) (shown in FIG. 12), respectively in the pen barrel (210).
[0049] In one embodiment, the first extension arm (406) of the cam follower (204) includes a first U-shaped cutout portion (412A) on an associated surface, and a first lever (414A) disposed between the first U-shaped cutout portion (412A). Further, the first lever (414A) includes a first dose setting pawl (416A) and a first dose delivering pawl (418A). Similarly, the second extension arm (408) of the cam follower (204) includes a second U-shaped cutout portion (412B) on an associated surface, and a second lever (414B) disposed between the second U-shaped cutout portion (412B). Further, the second lever (414B) includes a second dose setting pawl (416B) and a second dose delivering pawl (418B).
[0050] In certain embodiments, the first dose setting pawl (416A) in the first lever (414A) and the second dose setting pawl (416B) in the second lever (414B) ride on corresponding linear cam profiles (602A-D) (shown in FIG. 6) in the cam drum (208) when a user sets the dose by pulling out the thumb pad (202) in a direction of the proximal end (104) of the dispensing device (102). Similarly, the first dose delivering pawl (418A) in the first lever (414A) and the second dose delivering pawl (418B) in the second lever (414B) ride on corresponding helical cam profiles (604A-D) (shown in FIG. 6) in the cam drum (208) when the user dispenses the set dose by pushing the thumb pad (202) in a direction of the distal end (106) of the dispensing device (102).
[0051] In one embodiment, the first dose setting pawl (416A) and the first dose delivering pawl (418A) in the first lever (414A) are relatively positioned with respect to each other such that a first locking groove (420A) (shown in FIGS. 20A-B) is formed between the first dose setting pawl (416A) and the first dose delivering pawl (418A). Similarly, the second dose setting pawl (416B) and the second dose delivering pawl (418B) in the second lever (414B) are relatively positioned with respect to each other such that a second locking groove (420B) (see FIG. 4) is formed between the second dose setting pawl (416B) and the second dose delivering pawl (418B).
[0052] In certain embodiments, the first locking groove (420A) formed between the first dose setting and delivering pawls (416A and 418A) and the second locking groove (420B) formed between the second dose setting and delivering pawls (416B and 418B) are V-shaped grooves. However, it is to be understood that the first dose setting and delivering pawls (416A and 418A) and the second dose setting and delivering pawls (416B and 418B) may be relatively positioned with respect to each other to form the first locking groove (420A) and the second locking groove (420B) of any desired shapes such as U-shaped grooves or trapezoidal-shaped grooves. In one embodiment, the first and second locking grooves (420A-B) are custom designed to be locked with one or more end-of-life (EOL) locking snaps (612A-D) (shown in FIG. 6) in the cam drum (208) after a final dose of material is delivered from the cartridge (218) of the dispensing device (102) to prevent a reuse of the dispensing device (102) by a user. In one embodiment, the cam follower (204) further includes a first spring support structure (422) that is disposed at a proximal end (424) of the cam follower (204). The functionality of the first spring support structure (422) is described in detail with reference to FIGS. 8 and 9A-B.
[0053] FIG. 5 illustrates a front perspective view of the cam drum (208) of FIG. 2. It may be noted that, while setting the dose, the thumb pad (202) is to be fully pulled out in the direction of the proximal end (104). If the user sets a wrong dose by not fully pulling out the thumb pad (202) and tries to inject a medicament by mistake, the cam drum (208) is designed so as to ensure that the thumb pad (202) moves within the first and second extension slots (402 and 404) of the cam follower (204). Thus, the cam drum (208) prevents dispensing of the wrongly set dose from the dispensing device (102). Further, while delivering the dose, the cam drum (208) transfers a linear motion of the thumb pad (202) and the cam follower (204) in the direction of the distal end (106) into a circular motion of the lead screw (214) by its own rotation and using the pawl nut (212). At every dose delivery, the cam drum (208) is rotated by a designated angle for example, 90 degrees causing the lead screw (214) to move by a designated distance, which leads to delivery of the fixed dose every time.
[0054] To that end, the cam drum (208) is provided with a plurality of linear cam profiles (502) and a plurality of helical cam profiles (504). The linear cam profiles and the helical cam profiles are disposed on a surface of the cam drum (208). As used herein, the term “linear cam profiles,” and variations thereof, refer to linear paths through which the levers (414A-B) of the cam follower (204) ride while setting a dose. The term “helical cam profiles,” used herein, refers to helical paths through which the levers (414A-B) of the cam follower (204) ride while delivering a dose. In certain embodiments, the cam drum (208) includes four linear cam profiles and four helical cam profiles, as described with reference to FIG. 6. However, it is to be understood that the cam drum (208) can have any such number of linear cam profiles (502) and helical cam profiles (504).
[0055] FIG. 6 illustrates a front view of the cam drum (208) of FIG. 2. In one exemplary embodiment, the cam drum (208) may have four linear cam profiles including a first linear cam profile (602A), a second linear cam profile (602B), a third linear cam profile (602C) (shown in FIG. 17), and a fourth linear cam profile (602D). The cam drum (208) further includes four helical cam profiles including a first helical cam profile (604A), a second helical cam profile (604B) (shown in FIG. 19), a third helical cam profile (604C) (shown in FIG. 18), and a fourth helical cam profile (604D). Each of the linear cam profiles (602A) through (602D) include a start point (606A-D), an end point (608A-D), a one-way ratchet (610A-D) extending between the start point (606A-D) and the end point (608A-D), an EOL locking snap (612A-D), and cutout portions (614A-B) disposed in proximity to the EOL locking snap (612A-D).
[0056] For example, FIG. 6 depicts the first linear cam profile (602A) having a start point (606A), an end point (608A), a one-way ratchet (610A) extending between the start point (606A) and the end point (608A), an EOL locking snap (612A), and cutout portions (614A-B). Specifically, the cutout portions (614A-B) include a first cutout portion (614A) disposed at a top portion of the EOL locking snap (612A) and a second cutout portion (614B) disposed at a bottom portion of the EOL locking snap (612A). The cutout portions (614A-B) enable the EOL locking snap (612A) to move freely from a non-elevated position (1702) (shown in FIG. 17) to an elevated position (2002) (shown in FIGS. 20A-B) after a final dose is delivered from the dispensing device (102), as described further in detail with reference to FIGS. 20A-B. Though, it is not shown in FIG. 6, it is to be understood that, similarly, the second, third, and fourth linear cam profiles (602B) -(602D) have their own start points (606B-D), end points (608B-D), one-way ratchets (610B-D), EOL locking snap (612B-D), and cutout portions (614A-B).
[0057] In one exemplary embodiment, similar to the linear cam profiles (602A-D), each of the helical cam profiles (604A-D) has its own start point and end point. For example, FIG. 6 depicts a start point (616A) and an end point (618A) associated with the first helical cam profile (604A). Though it is not shown in FIG. 6, it is to be understood that, similarly, the second, third, and fourth helical cam profiles (604B) - (604D) have their own start points (616B-D) and end points (618B-D). In certain embodiments, the first helical cam profile (604A) connects the first linear cam profile (602A) with the second linear cam profile (602B), as shown in FIG. 6. Similarly, the second helical cam profile (604B) connects the second linear cam profile (602B) with the third linear cam profile (602C). The third helical cam profile (604C) connects the third linear cam profile (602C) with the fourth linear cam profile (602D). The fourth helical cam profile (604D) connects the fourth linear cam profile (602D) with the first linear cam profile (602A). It may be noted that start points of the helical cam profiles (604A-D) immediately follow end points of the linear cam profiles (602A-D), respectively. Similarly, start points of the linear cam profiles (602A-D) immediately follow end points of the helical cam profiles (604A-D), respectively.
[0058] In addition, each of these linear cam profiles (602A-D) and helical cam profiles (604A-D) includes a gradient path having a slope that gradually increases along its length from its start point to its end point. For example, the first linear cam profile (602A) has a gradient path having a slope that gradually increases along its length with a maximum slope towards its end point (608A). Similarly, the first helical cam profile (604A) has a gradient path having a maximum slope at its end point (618A). These gradient paths associated with the linear cam profiles (602A-D) and the helical cam profiles (604A-D) define paths to be followed by the levers (414A-B) of the cam follower (204) while setting and delivering a dose, as described in detail in with reference to FIGS. 17 through 20A-B.
[0059] FIG. 7A illustrates a graphical representation illustrating a position of the cam follower (204) with respect to the cam drum (208) of FIG. 2 in an initial state before pulling out the thumb pad (202) for setting a dose. In one exemplary embodiment, the first lever (414A) including the first dose setting pawl (416A) is placed in an engaged position with the start point (606A) of the first linear cam profile (602A) in the initial state. Although not depicted in FIG. 7A, it is to be understood that the second lever (414B) including the second dose setting pawl (416B) is placed in an engaged position with a start point (606C) of the third linear cam profile (602C).
[0060] Further, the cam follower (204) is operatively coupled to the thumb pad (202) such that thumb pad (202) is placed in a ready-to-push position (702) (depicted in FIG. 7B) in the initial state before setting the dose for delivery. In the ready-to-push position (702), the guide (306) of the thumb pad (202) is positioned at a distal end (704) of the first extension slot (402) of the cam follower (204), as depicted in FIG. 7B. In addition, the thumb pad snap (308) of the thumb pad (202) is positioned at a distal end (706) of the second extension slot (404) of the cam follower (204). For setting the dose, the user needs to pull out the thumb pad (202) in a direction (701) (indicated using an arrow mark in FIG. 7B) of the proximal end (104) of the dispensing device (102).
[0061] When the user pulls out the thumb pad (202) in the direction (701), the thumb pad (202) moves linearly from the ready-to-push position (702) (shown in FIG. 7B) to a ready-to-pull position (708) (shown in FIG. 7C). By the time the user completes pulling out the thumb pad (202) in the direction (701) by a first distance (710), the thumb pad (202) is designed to move and be placed in the ready-to-pull position (708). In one embodiment, as depicted in FIG. 7B, the first distance (710) corresponds to a distance by which the thumb pad snap (308) moves between the distal end (706) and a proximal end (712) of the second extension slot (404) during setting of the dose or delivery of the dose. In certain embodiments, when the thumb pad (202) is placed in the ready-to-pull position (708), the guide (306) of the thumb pad (202) is placed at the proximal end (714) of the first extension slot (402) and the thumb pad snap (308) of the thumb pad (202) is placed at the proximal end (712) of the second extension slot (404), as depicted in FIG. 7C.
[0062] After the thumb pad (202) is placed in the ready-to-pull position (708), the user needs to further pull out the thumb pad (202) by a second distance in the direction (701) to complete setting of the dose for delivery. When the user pulls out the thumb pad (202) further by the second distance in the direction (701), the thumb pad (202) starts to pull out the cam follower (204) and further causes the cam follower (204) to move linearly in the direction of the proximal end (104). This is because, the thumb pad snap (308) in the thumb pad (202) engages with the proximal end (712) of the second extension slot (404) when the thumb pad (202) is placed in the ready-to-pull position (708), as depicted in FIG. 7C. As a result, when the user pulls out the thumb pad (202) from the ready-to-pull position (708), the thumb pad snap (308) pulls out the cam follower (204) and further causes the cam follower (204) to move linearly in the direction of the proximal end (104) of the dispensing device (102).
[0063] In one embodiment, the linear movement of the cam follower (204) in the direction of the proximal end (104) causes the first dose setting pawl (416A) to move from the start point (606A) (depicted in FIG. 7A) of the first linear cam profile (602A) and to further ride over the EOL locking snap (612A) and the one-way ratchet (610A) in the first linear cam profile (602A). Similarly, the linear movement of the cam follower (204) causes the second dose setting pawl (416B) to move from the start point (606C) (shown in FIG. 17) of the third linear cam profile (602C) and to further ride over an EOL locking snap (612C) and a one-way ratchet (610C) in the third linear cam profile (602C). At an end of a first dose setting stage, the dose setting pawls (416A-B) are designed to complete their ride over the first and third linear cam profiles (602A and 602C), respectively. Further, at the end of the first dose setting stage, the dose delivering pawls (418A-B) are designed to be placed at start points (616A and 616C) of the first and third helical cam profiles (604A and 604C), respectively as depicted in FIG. 18.
[0064] In certain embodiments, if the user does not completely pull out the thumb pad (202) from the ready-to-pull position (708) while setting the dose, and attempts to inject a partially set dose of a medicament, the user is prevented from doing so, as depicted and described with reference to FIG. 8. Specifically, when the user sets a partial dose by pulling out the thumb pad (202) only partially without completely pulling out the thumb pad (202) by the second distance from the ready-to-pull position (708), the dose setting pawls (416A-B) of the cam follower (204) are designed to be secured with teeth of the one-way ratchets (610A and 610C), respectively. For example, FIG. 8 depicts an exemplary graphical representation illustrating a partial dose set condition in which the dose setting pawl (416A) is secured with one of the teeth in the one-way ratchet (610A). Though it is not depicted in FIG. 8, it is to be understood that the other dose setting pawl (416B) is similarly secured with one of the teeth in the one-way ratchet (610C) in the partial dose set condition. In one embodiment, the one-way ratchets (610A and 610C) allow the cam follower (204) to move only in the direction of the proximal end (104) of the dispensing device (102). Further, the one-way ratchets (610A and 610C) prevent the cam follower (204) from moving in the direction of the distal end (106) of the dispensing device (102).
[0065] As depicted in FIG. 9A, when the user attempts to deliver the partially set dose by exerting a force on the thumb pad (202) in a direction (900) of the distal end (106), the elastic member (206) disposed between the thumb pad (202) and the cam follower (204) undergoes compression from a fully extended state (902) (shown in FIG. 9A) to a compressed state (904) (shown in FIG. 9B). Examples of the elastic member (206) include a spring, a plastic material, a bellow, and a flexure. Specifically, the elastic member (206) is disposed between a second spring support structure (901) disposed at a proximal end (908) of the thumb pad (202) and the first spring support structure (422) disposed at the proximal end (424) of the cam follower (204). The compression of the elastic member (206) from the fully extended state (902) to the compressed state (904) causes the thumb pad (202) to move within the first and second extension slots (402 and 404) (shown in FIG. 7C) of the cam follower (204).
[0066] Further, the compression of the elastic member (206) causes the distal end (906) of the elastic member (206) to exert a pressure on the cam follower (204) in the direction (900) of the distal end (106) of the dispensing device (102). However, the cam follower (204) does not move in the direction (900) of the distal end (106) despite the pressure being exerted on the cam follower (204) in the direction (900) of the distal end (106). This is because, the one-way ratchets (610A and 610C) (shown in FIGS. 8 and 18) in the linear cam profiles (602A and 602C) act as blocking structures for the cam follower (204).
[0067] Specifically, the one-way ratchets (610A and 610C) block the movement of the dose setting pawls (416A-B) in the direction (900) of the distal end (106) when compression of the elastic member (206) exerts the pressure on the cam follower (204). Blocking the movement of the dose setting pawls (416A-B) in the direction (900) of the distal end (106) also prevents the movement of the cam follower (204) in the direction (900) of the distal end (106). The prevention of the movement of the cam follower (204) towards the distal end (106), in turn, prevents delivery of the partially set dose that is intentionally or inadvertently set by the user.
[0068] In certain embodiments, the elastic member (206) disposed between the thumb pad (202) and the cam follower (204) is custom designed to prevent damages that occur to the dispensing device (102) when the user intentionally or unintentionally sets only a partial dose and attempts to deliver the partially set dose. However, conventional dispensing devices do not include any such elastic member disposed between the thumb pad and the cam follower. In fact, in certain conventional dispensing devices, both the thumb pad and the cam follower are combined and are molded as a one-piece component, which is generally known as a thumb pad device. Typically, the thumb pad device does not include any elastic member that prevents damages that may occur to the dispensing devices while users attempt to deliver partially set doses. Specifically, in those conventional dispensing devices, the thumb pad device is designed to be secured with one-way ratchets when a user inadvertently sets a partial dose for delivery. Thus, when the user attempts to deliver the partially set dose by exerting a force on the thumb pad towards a distal end of the conventional dispensing devices, the force exerted by the user directly transmits to the one-way ratchets. As a result, the teeth of the one-way ratchets may break when the user inadvertently exerts an excessive amount of force on the thumb pad device while attempting to deliver the partially set dose. When the teeth of the one-way ratchets are broken and/or damaged, the user may not be able to use the conventional dispensing devices subsequently.
[0069] In order to address the aforementioned issues, the present dispensing device (102) includes the elastic member (206) that is disposed between the thumb pad (202) and the cam follower (204), which are custom designed as two separate components. When the user attempts to deliver the partially set dose by exerting the excessive amount of force on the thumb pad (202), the elastic member (206) is designed to undergo compression to the compressed state (904) from the fully extended state (902), as depicted in FIG. 9B. The elastic member (206), thus moving from the fully extended state (902) to the compressed state (904), absorbs the force exerted by the user on the thumb pad (202). Further, the compression of the elastic member (206) prevents transmission of the entire force being exerted on the thumb pad (202) by the user, as is, to the dose setting pawls (416A-B) and to the one-way ratchets (610A and 610C) (shown in FIGS. 8 and 18). Hence, compression of the elastic member (206) effectively minimizes an impact of the force acting on the dose setting pawls (416A-B) and the one-way ratchets (610A and 610C). As a result, the one-way ratchets (610A and 610B) will not break and be damaged even when the user inadvertently exerts an excessive amount of force on the thumb pad (202) while attempting to deliver the partially set dose.
[0070] As noted previously, the first and second dose delivering pawls (418A-B) are designed to be placed at the start points (616A and 616C) of the first and third helical cam profiles (604A and 604C), respectively, after the user successfully sets a first dose for delivery, as depicted in FIGS. 10 and 18. Specifically, the dose delivery pawl (418A) that is placed at the start point (6161A) of the first helical cam profile (604A) is depicted in FIG. 10. The dose delivery pawl (418B) that is placed at the start point (418B) of the third helical cam profile (604C) is depicted in FIG. 18. For delivering the set first dose, the user needs to push the thumb pad (202) in the direction (900) of the distal end (106). When the user pushes the thumb pad (202) in the direction (900) of the distal end (106), the thumb pad (202) first linearly moves from the ready-to-pull position (708) (depicted in FIG. 7C) to the ready-to-push position (702) (depicted in FIG. 7B). When the user further pushes the thumb pad (202) from the ready-to-push position (702) in the direction (900) towards the distal end (106), the thumb pad (202) pushes and moves the cam follower (204) towards the distal end (106).
[0071] The movement of the cam follower (204) towards the distal end (106) of the dispensing device (102) causes the first and second dose delivering pawls (418A-B) to take gradients paths defined by the first and third helical cam profiles (604A and 604C) (depicted in FIGS. 10 and 18). In one embodiment, the cam drum (208) is designed to rotate in a designated direction, for example, in a clockwise direction whenever the dose delivering pawls (418A-B) ride over the helical cam profiles (604A and 604C). Further, when the dose delivering pawls (418A-B) complete taking the first and third helical paths (604A) and (604C), respectively, the cam drum (208) completes one rotation by a designated angle. An example of the designated angle is 90 degrees.
[0072] In one embodiment, one complete rotational movement of the cam drum (208) by the designated angle causes the lead screw (214) (shown in FIG. 2) to rotate and move a designated linear distance to deliver a fixed dose. To that end, a keyway (1102) (shown in FIG. 11) is provided at one end, for example, at a proximal end of the cam drum (208). The keyway (1102) is a slot made to engage the lead screw (214) with the cam drum (208). In one exemplary embodiment, the lead screw (214) is coupled to the keyway (1102) using a tongue and groove joint. As, the lead screw (214) is coupled to the cam drum (208) through the keyway (1102), rotation of the cam drum (208) by the designated angle causes rotation of the lead screw (214) too. The lead screw (214), therefore, moves forward by a designated distance in the direction of the distal end (106) to deliver the set first dose.
[0073] In certain embodiments, the dose delivering pawls (418A-B) complete paths defined by the first and third helical cam profiles (604A and 604C), respectively, at the end of the first dose delivery. In addition, the dose setting pawls (416A-B) are placed in a ready position at start points (606B and 606D) (shown in FIG. 19) of the second and fourth linear cam profiles (602B and 602D), respectively, at the end of the first dose delivery for a second cycle of dose setting. Similarly, at an end of a second dose setting stage, the dose delivering pawls (418A-B) are placed at start points (616B) and (616D) (not shown in FIGS. 1-20A-B) of the second and fourth helical cam profiles (604B and 604D), respectively. Upon pushing the thumb pad (202) for a second dose delivery, the dose delivering pawls (418A-B) take paths defined by the second and fourth helical cam profiles (604B and 604D) to deliver the fixed dose for the second time. The dose setting pawls (416A-B) are placed in a ready position at start points (606C and 606A) of the third and first linear cam profiles (602C and 602A), respectively at the end of the second dose delivery for a third cycle of dose setting.
[0074] Thus, the dose setting pawls (416A-B) ride on respective linear cam profiles (602A-D) while setting a dose for delivery and the dose delivering pawls (418A-B) are placed at start points of respective helical cam profiles (604A-D) adjacent to the respective linear cam profiles (602A-D) at the end of every dose set stage. Similarly, the dose delivering pawls (418A-B) ride on the respective helical cam profiles (604A-D) while delivering the set dose and the dose setting pawls (416A-B) are placed at start points of the respective linear cam profiles (602A-D) adjacent to the respective helical cam profiles (604A-D) at the end of every dose delivery stage.
[0075] FIG. 11 illustrates a left side view of the cam drum (208) of FIG. 2. The cam drum (208) is designed to rotate only in a selected direction while delivering the dose. In one embodiment, the selected direction is a clockwise direction. To that end, the cam drum (208) is provided with a one-way ratchet (1104) that mates with a pawl (1304) (shown in FIG. 13) associated with the pawl nut (212). In one embodiment, teeth of the one-way ratchet (1104) are designed in such a way that the one-way ratchet (1104) and the pawl (1304) arrangement allow the cam drum (208) to rotate only in a clockwise direction. When the cam drum (208) attempts to rotate in an anti-clockwise direction for any reason, the one-way ratchet (1104) is locked with the pawl (1304), and thus, the cam drum (208) is prevented from rotating in the anti-clockwise direction. Similarly, it is to be understood that, the cam drum (208) can also be made to rotate only in the anti-clockwise direction by designing the teeth of the one-way ratchet (1104) in such a way that the one-way ratchet (1104) and the pawl (1304) arrangement allow the cam drum (208) to rotate only in the anti-clockwise direction. In one embodiment, the cam drum (208) is housed within the pen barrel (210) when various components of the dispensing device (102) are assembled together. An exemplary embodiment of the pen barrel (210) of the dispensing device (102) is described in detail subsequently with reference to FIG. 12.
[0076] FIG. 12 illustrates an exploded view of the pen barrel (210) of FIG. 2. In certain embodiments, the pen barrel (210) corresponds to a structure including an upper half (1202) and a lower half (1204). Particularly, the pen barrel (210) acts as a casing that encloses and protects components of the dispensing device (102). In one embodiment, the upper half (1202) of the pen barrel (210) includes mating studs (1206). The bottom half (1204) of the pen barrel (210) includes mating slots (1208). The mating studs (1206) firmly fit within the mating slots (1208) to secure both upper and lower halves (1202 and 1204) of the pen barrel (210) together as a single non-separable unit.
[0077] In addition, the upper half (1202) of the pen barrel (210) includes a matching rib (1210). The bottom half (1204) of the pen barrel (210) includes a matching slot (1212). When the upper half (1202) and the bottom half (1204) of the pen barrel (210) are assembled together, the matching rib (1210) fits within the matching slot (1212) to secure both the upper and lower halves (1202 and 1204) together as the single non-separable unit. Further, the upper half (1202) of the pen barrel (210) includes a first cartridge holder slot (1214A) and the bottom half (1204) of the pen barrel (210) includes a second cartridge holder slot (1214B). When the cartridge holder (220) is coupled to the pen barrel (210) during assembly of various components of the dispensing device (102), a set of ribs (1602) (shown in FIG. 16) in the cartridge holder (220) fit within the cartridge holder slots (1214A-B) to form a tight seal between the cartridge holder (220) and the pen barrel (210). The tight seal, thus formed between the cartridge holder (220) and the pen barrel (210), prevents separation of the cartridge holder (220) from the pen barrel (210) when the dispensing device (102) is in use.
[0078] Further, both the upper and bottom halves (1202 and 1204) of the pen barrel (210) include corresponding stopper ribs (1216A and 1216B, respectively). The stopper ribs (1216A-B) prevent the movement of the cartridge holder (220) in the direction of the proximal end (104) when the user pierces the skin with a needle and self-injects a fixed dose of the material into his or her body. In one embodiment, the upper half (1202) of the pen barrel (210) includes a slot (1218A) disposed on an associated surface of the upper half (1202). Similarly, the lower half (1204) of the pen barrel (210) includes a slot (1218B) disposed on an associated surface of the bottom half (1204). Upon securing both halves (1202 and 1204) of the pen barrel (210) together, the slot (1218A) in the upper half (1202) aligns vertically with respect to the slot (1218B) in the bottom half (1204). The slots (1218A-B), thus disposed on the upper and bottom halves (1202 and 1204), accommodate rib portions (1302) (shown in FIG. 13) of the pawl nut (212) and prevent the pawl nut (212) from rotating during dose setting and dose delivery stages.
[0079] In certain embodiments, each of the upper and bottom halves (1202 and 1204) of the pen barrel (210) includes a semi-circular rib (1220). When both the upper and bottom halves (1202 and 1204) of the pen barrel (210) are secured together, the semi-circular rib (1220) in each of the halves (1202 and 1204) aligns adjacent to each other to form a complete circular rib (1222). The circular rib (1222) includes a front wall surface (1224), a rear wall surface (1226), and a slot (1228) disposed between the front wall surface (1224) and the rear wall surface (1226). In one embodiment, the circular rib (1222) includes the slot (1228) into which a barrel-engaging surface (1106) (shown in FIG. 11) of the cam drum (208) is positioned and is secured. Thus, the circular rib (1222) acts as a lock feature for the cam drum (208) and prevents the cam drum (208) from moving linearly forward or rearward using the wall surfaces (1224 and 1226) while setting and delivering the dose.
[0080] In addition, the upper half (1202) of the pen barrel (210) includes a semi-circular protrusion (1230A) and the bottom half (1204) of the pen barrel (210) includes another semi-circular protrusion (1230B). When both the halves (1202 and 1204) of the pen barrel (210) are assembled together, the semi-circular protrusions (1230A-B) align adjacent to each other to form a complete circular protrusion (1232). When the user completely pulls out the thumb pad (202) and sets a fixed dose for delivery successfully, the flange (410) (shown in FIG. 4) of the cam follower (204) is designed to be seated in an engaged state at a distal end of the circular protrusion (1232). When the user attempts to further pull out the thumb pad (202) after successfully setting the fixed dose for delivery, the circular protrusion (1232) forms a lock with the flange (410) and further blocks the movement of the cam follower (204) in the direction of the proximal end (104) of the dispensing device (102). Blocking the movement of the cam follower (204) in the direction of the proximal end (104) ensures that the user cannot further pull out the thumb pad (202) in the direction of the proximal end (104) post successfully setting the fixed dose for delivery.
[0081] In one embodiment, the upper half (1202) of the pen barrel (210) includes a first extension-arm guide (1234A) disposed between a left inner sidewall (1236A) and a right inner sidewall (1238A) of the upper half (1202). Similarly, the bottom half (1204) of the pen barrel (210) includes a second extension-arm guide (1234B) disposed between a left inner sidewall (1236B) and a right inner sidewall (1238B) of the bottom half (1204). When various components of the dispensing device (102) are assembled together, the first extension arm (406) (shown in FIG. 4) of the cam follower (204) fits within the first extension-arm guide (1234A) between the left and right inner sidewalls (1236A and 1238A). Similarly, the second extension arm (408) (shown in FIG. 4) of the cam follower (204) fits within the second extension-arm guide (1234B) between the left and right inner sidewalls (1236B and 1238B). While setting and delivering the dose, the extension-arm guides (1234A-B) guide and allow the cam follower (204) to move only linearly without exhibiting any rotational motion. If any attempts are made to rotate the cam follower (204) by rotating the thumb pad (202), the cam follower (204) is prevented from rotating due to placement of the extension arm (406) between the left and right inner sidewalls (1236A and 1238A) and placement of the extension arm (408) between the left and right inner sidewalls (1236B and 1238B).
[0082] In addition, the upper half (1202) of the pen barrel (210) includes a right guide (1240A) and a left guide (1242A) disposed at right and left sides, respectively of the upper half (1202). Similarly, the bottom half (1204) of the pen barrel (210) includes a right guide (1240B) and a left guide (1242B) disposed at right and left sides, respectively of the bottom half (1204). When both the halves (1202 and 1204) of the pen barrel (210) are assembled together, the right guide (1240A) of the upper half (1202) and the left guide (1242B) of the bottom half (1204) align in proximity to each other to form a left flange guide (1244) of the pen barrel (210). Similarly, the left guide (1242A) of the upper half (1202) and the right guide (1240B) of the bottom half (1204) align in proximity to each other to form a right flange guide (1246) of the pen barrel (210). When various components of the dispensing device (102) are assembled together, the flanges (410) (shown in FIG. 4) of the cam follower (204) fit within these flange guides (1244 and 1246). While setting and delivering the dose, the flange guides (1244 and 1246) guide and allow the cam follower (204) to move only linearly without exhibiting any rotational motion. If any attempts are made to rotate the cam follower (204) by rotating the thumb pad (202), the cam follower (204) is prevented from rotating due to the placement of the flanges (410) within the flange guides (1244 and 1246).
[0083] In addition, each of the upper half (1202) and the lower half (1204) of the pen barrel (210) includes a corresponding depression (1248). The depression (1248) provides adequate space between an inner surface of the pen barrel (210) and the cam follower (204) to prevent interference of the pen barrel (210) with the dose setting and delivering pawls (416A-B and 418A-B) of the cam follower (204) during dose setting and delivery processes. Provision of adequate space also ensures smooth riding of the dose setting and delivering pawls (416A-B and 418A-B) on the linear cam profiles (602A-D) and the helical cam profiles (604A-D) without being impeded by the pen barrel (210) during dose setting and dose delivery processes, respectively.
[0084] In certain embodiments, while delivering the dose, the cam drum (208) is designed to rotate only in a clockwise direction and is prevented from rotating in an anti-clockwise direction. To that end, the pawl nut (212) is provided at a distal end of the cam drum (208). An exemplary structure and functioning of the pawl nut (212) are described in detail with reference to FIG. 13.
[0085] FIG. 13 illustrates a front perspective view of an exemplary embodiment of the pawl nut (212). The pawl nut (212) includes a plurality of ribs (1302), a one-way pawl (1304), and a slot having internal threads (1306) through which the lead screw (214) advances towards the distal end (106) while delivering the dose. In one embodiment, any two ribs selected from the ribs (1302) are secured to the slots (1218A-B) in the pen barrel (210) and be placed in a locked condition with respect to the pen barrel (210) to prevent rotation of the pawl nut (212) during dose delivery. For example, the ribs (1302) at the top and bottom sides of the pawl nut (212) may be secured to the slots (1218A-B), respectively, and may be placed in the locked condition with respect to the pen barrel (210). In another example, the ribs (1302) at the left and right sides of the pawl nut (212) may be secured to the slots (1218A-B), respectively, in lieu of the ribs (1302) at the top and bottom sides, and may be placed in the locked condition with respect to the pen barrel (210).
[0086] In certain embodiments, the one-way pawl (1304) in the pawl nut (212) is placed in an engaged position with respect to the one-way ratchet (1104) of the cam drum (208). The teeth of the one-way ratchet (1104) are designed in such a way that the one-way ratchet (1104) and the one-way pawl (1304) arrangement allow the cam drum (208) to rotate, for example, only in a clockwise direction. If any attempts are made to rotate the cam drum (208) in an anti-clockwise direction, the one-way ratchet (1104) becomes locked with the one-way pawl (1304), thus preventing the cam drum (208) from rotating in the anti-clockwise direction. In addition, when the cam drum (208) is rotated in the clockwise direction during dose delivery, the one-way pawl (1304) slides up and over the teeth of the one-way ratchet (1104) and provides audible feedback to a user. The one-way ratchet (1104) and the one-way pawl (1304) arrangement also ensures the lead screw (214) cannot be rotated in an undesired direction, for example, in the anti-clockwise direction because of the lead screw (214) being positively locked with the cam drum (208) that is designed to rotate only in the desired direction.
[0087] In one embodiment, the internal threads (1306) of the pawl nut (212) include a pitch that corresponds to a pitch of the lead screw (214). In certain embodiments, the internal threads (1306) associated with the pawl nut (212) are right-handed screw threads. Since the pitches of the internal threads (1306) and the lead screw (214) correspond to each other, the lead screw (214) advances and moves towards the distal end (106) by a designated distance when the cam drum (208) completes one rotation, for example, by 90 degrees during dose delivery. This forward movement of the lead screw (214) pushes a stopper in the cartridge (218) to deliver the fixed dose.
[0088] FIG. 14 illustrates a top perspective view of the lead screw (214) of FIG. 2. The lead screw (214) includes a flange (1402), a universal ball joint (1404), and internal threads (1406) that extend between the flange (1402) and the universal ball joint (1404). Once a final dose is delivered from the dispensing device (102) and the cartridge (218) is empty, the flange (1402) is designed to be positioned below the EOL locking snaps (612A-D) (shown in FIGS. 17 and 20A-B). In one embodiment, the positioning of the flange (1402) below the EOL locking snaps (612A-D) elevates the EOL locking snaps (612A-D) from a non-elevated position (1702) (shown in FIG. 17) to an elevated position (2002) (shown in FIGS. 20A-B), as described subsequently in greater detail with reference to FIGS. 17 through 20A-B. When the user attempts to set a new dose after the final dose is delivered from the dispensing device (102) by pulling out the thumb pad (202), the thumb pad (202) pulls out the cam follower (204) in the direction of the proximal end (104).
[0089] When the cam follower (204) moves towards the proximal end (104), one of the EOL locking snaps (612A-D), for example, the EOL locking snap (612A) in the elevated position (2002) (shown in FIGS. 20A-B) is custom designed to lock with the first locking groove (420A) that is disposed between the first dose setting pawl (416A) and the first dose delivering pawl (418A) of the cam follower (204). Similarly, another EOL locking snap, for example, the EOL locking snap (612C) in the elevated position (2002) (shown in FIGS. 20A-B) is custom designed to lock with the second locking groove (420B) that is disposed between the second dose setting pawl (416B) and the second dose delivering pawl (418B) of the cam follower (204) when the cam follower (204) moves towards the proximal end (104). The EOL locking snaps (612A and 612C), thus being locked with the first and second locking grooves (420A-B), respectively, ensure that the cam follower (204) and the thumb pad (202) cannot be further pulled out in the direction of the proximal end (104). As the cam follower (204) and thumb pad (202) cannot be further pulled out towards the proximal end (104), the user cannot set the new dose after the end-of-life of the dispensing device (102).
[0090] Referring back to FIG. 14, the internal threads (1406) of the lead screw (214) are right-handed screw threads. A distance by which the lead screw (214) is supposed to move, due to one complete rotation by 90 degrees of the cam drum (208), is adjusted based on a pitch associated with the lead screw (214). In one embodiment, the dispensing device (102) is designed to be used multiple times until the cartridge (218) becomes empty, and each time, the dispensing device (102) delivers the fixed dose. In this embodiment, the pitch of the lead screw (214) is selected such that the lead screw (214) advances and moves forward by a designated distance each time when the dose is delivered. Since, the lead screw (214) moves by the same linear distance each time, the lead screw (214) also pushes and moves a stopper within the cartridge (218) gradually by the same distance, to deliver the fixed dose multiple times.
[0091] In an alternative embodiment, the dispensing device (102) is designed to be used only one time. All the medicaments accommodated with the cartridge (218) are delivered by a single actuation of the thumb pad (202) towards the distal end (106) of the dispensing device (102). In this embodiment, the length or pitch of the lead screw (214) is selected such that one complete rotation of the cam drum (208), for example by 90 degrees, causes the lead screw (214) to move linearly by a designated distance and to push the stopper to an end of the cartridge (218). Thus, the dispensing device (102) can be designed to dispense all the medicaments by the single actuation of the thumb pad (202) by selecting a desired pitch of the lead screw (214). In certain embodiments, the lead screw (214) includes the universal ball joint (1404) that is adapted to be coupled to the push pad (216), as shown and described in detail with reference to FIG. 15.
[0092] FIG. 15 illustrates a rear perspective view of the push pad (216) of FIG. 2. The universal ball joint (1404) of the lead screw (214) snap fits into a slot (1502) of the push pad (216). The push pad (216), thus snap fitted with the lead screw (214), allows the lead screw (214) to rotate within the push pad (216) and advance forward along with the lead screw (214) to deliver the medicaments carried by the cartridge (218). In addition, the push pad (216) is designed in a way such that the push pad (216) is prevented from rotating when the lead screw (214) rotates within the push pad (216) in order to reduce a frictional load on the cam drum (208). In one embodiment, a front surface (1504) of the push pad (216) pushes a stopper (2004) (shown in FIGS. 20A-B) placed inside the cartridge (218) to dispense the dose when the lead screw (214) advances forward to deliver the dose.
[0093] FIG. 16 illustrates a front perspective view of the cartridge holder (220) that accommodates the cartridge (218) storing the medicament to be delivered. In one embodiment, the cartridge holder (220) includes a set of ribs (1602) (only one rib is visible and the other rib is not visible in FIG. 16), a cutout window (1604), and distal thread features (1606). In certain embodiments, the ribs (1602) of the cartridge holder (220) are designed to be secured to the cartridge holder slots (1214A-B) (shown in FIG. 12) in the pen barrel (210) for securing the cartridge holder (220) along with the cartridge (218) to the pen barrel (210). The cutout window (1604) allows the user to see the medicament level within the cartridge (218). The distal thread features (1606) are provided for securing a needle to the cartridge holder (220). Exemplary mechanisms by which the dispensing device (102) allows the user to set the dose and to deliver the set dose and prevent the user from reusing the dispensing device (102) after the end-of-life of the dispensing device (102) are described subsequently with reference to FIGS. 17 through 20A-B.
[0094] Further, FIG. 17 illustrates a cross sectional view of the dispensing device (102) of FIG. 1 depicting an initial state of the dispensing device (102) before setting a first dose. As previously noted, in the initial state, the first lever (414A) including the first dose setting pawl (416A) is disposed at the start point (606A) of the first linear cam profile (602A). The second lever (414B) including the second dose setting pawl (416B) is disposed at the start point (606C) of the third linear cam profile (602C). In one embodiment, the flange (1402) of the lead screw (214) engages against the cam follower (204), and there is no gap between the lead screw (214) and the thumb pad (202) in the initial state.
[0095] For setting a fixed dose of material for delivery, the user needs to first pull out the thumb pad (202) by the first distance in the direction of the proximal end (104) of the dispensing device (102), as noted previously. Pulling out the thumb pad (202) by the first distance causes the thumb pad (202) to move linearly from the ready-to-push position (702) to the ready-to-pull position (708). When the user further pulls out the thumb pad (202) after being placed in the ready-to-pull position (708) by a second distance in the direction of the proximal end (104), the thumb pad (202) pulls out the cam follower (204) in the direction of the proximal end (104). Thus, the cam follower (204) starts to move linearly in the direction of the proximal end (104) by a user action of pulling out the thumb pad (202) by the second distance from the ready-to-pull position (708).
[0096] The movement of the cam follower (204) in the direction of the proximal end (104) causes the first dose setting pawl (416A) to ride over the first linear cam profile (602A) and the second dose setting pawl (416B) to ride over the third linear cam profile (602C). Specifically, the first and second dose setting pawls (416A) ride over the one-way ratchets (610A) (clearly visible in FIG. 6) and (610C) (clearly visible in FIG. 18) when the cam follower (204) moves in the direction of the proximal end (104). Further, the first and second dose setting pawls (416A) ride over the EOL locking snaps (612A and 612C) that are disposed in a non-elevated position (1702) in the first and third linear cam profiles (602A and 602C), respectively when the cam follower (204) moves in the direction of the proximal end (104). When the user successfully sets the dose for delivery by completely pulling out the thumb pad (202) by the second distance from the ready-to-pull position (708), the dose setting pawls (416A-B) are designed to ride along the gradient paths defined by the linear cam profiles (602A and 602C). Further, the dose delivering pawls (418A-B) are designed to be placed in start points (616A and 616C) of the respective helical cam profiles (604A and 604C) after the user successfully sets the dose for delivery, as described subsequently with reference to FIG. 18.
[0097] FIG. 18 illustrates a cross sectional view of the dispensing device (102) of FIG. 1 after the user successfully sets a first dose for delivery. As noted previously, the dose delivering pawls (418A-B) are placed at the start point (616A) (clearly visible in FIG. 6) and the start point (616C) (clearly visible in FIG. 18) of the helical cam profiles (604A and 604C), respectively after the user successfully completes setting of the first dose for delivery. Post successfully setting the dose for delivery, the user needs to push the thumb pad (202) towards the distal end (106) of the dispensing device (102). Pushing of the thumb pad (202) towards the distal end (106) causes the thumb pad (202) to move linearly back from the ready-to-pull position (708) to the ready-to-push position (702).
[0098] When the thumb pad (202) positioned in the ready-to-push position (702) is further pushed inwards in the direction (900) towards the distal end (106), the thumb pad (202), in turn, pushes the cam follower (204) in the direction of the distal end (106). Thus, the cam follower (204) starts moving towards the distal end (106) of the dispensing device (102). When the cam follower (204) moves towards the distal end (106), the dose delivering pawls (418A-B) ride on the paths defined by the helical cam profiles (604A and 604C), respectively, which leads to rotation of the cam drum (208) in the clockwise direction by a designated angle of 90 degrees.
[0099] Since the lead screw (214) is already secured with the cam drum (208) through the keyway (1102), the rotation of the cam drum (208) also rotates the lead screw (214) in the same direction. In one embodiment, the internal threads (1306) of the pawl nut (212) include a pitch that corresponds to a pitch of the lead screw (214). Hence, the pawl nut (212) translates the rotational movement of the lead screw (214) and enables forward movement of the lead screw (214) towards the distal end (106). In addition, the pitch of the lead screw (214) is previously selected such that one rotation of the cam drum (208) by the designated angle leads to movement of the lead screw (214) by a designated distance.
[00100] Furthermore, as the universal ball joint (1404) of the lead screw (214) is snap fitted with the push pad (216), the movement of the lead screw (214) towards the distal end (106) also causes the push pad (216) to move distally towards the distal end (106). The advancement of the lead screw (214) along with the push pad (216) causes the stopper (2004) (shown in FIGS. 20A-B) placed within the cartridge (218) to move forward by the designated distance, thus allowing only a designated amount of medicament to be released from the cartridge (218).
[00101] FIG. 19 is another cross-sectional view of the dispensing device (102) of FIG. 1 depicting the dispensing device (102) at an end of a first dose delivery stage. At the end of the first dose delivery stage, the first and second dose delivering pawls (418A-B) complete the respective paths defined by the first and third helical cam profiles (604A) and (604C). Further, the first and second dose setting pawls (416A-B) are placed in ready positions at start points (606B and 606D) of the second and fourth linear cam profiles (602B and 602D), respectively of the cam drum (208) at the end of the first dose delivery stage for enabling the user to set a second dose for delivery. It may be noted that there is a small gap (1902) formed between the flange (1402) of the lead screw (214) and the cam follower (204). The small gap (1902) corresponds to the designated distance by which the lead screw (214) moved due to rotation of the cam drum (208) during the first dose delivery.
[00102] FIGS. 20A-B illustrate another cross-sectional view of the dispensing device (102) of FIG. 1 depicting the dispensing device (102) at an associated end-of-life. In one embodiment, the lead screw (214) is designed to be moved by the designated distance during delivery of each dose of the material from the dispensing device (102). At the end-of-life of the dispensing device (102), the flange (1402) of the lead screw (214) is designed to be positioned below the EOL locking snaps, for example, below the EOL locking snaps (612A and 612C) of the cam drum (208), as depicted in FIGS. 20A-B. The flange (1402) of the lead screw (214), thus positioned below the EOL locking snaps (612A and 612C) elevates the EOL locking snaps (612A and 612C) from the non-elevated position (1702) to an elevated position (2002). In the elevated position (2002), the EOL locking snaps (612A and 612C) protrude out of the cam drum (208) and are placed in the gradient paths defined by the linear cam profiles (602A and 602C).
[00103] When the user attempts to set a subsequent dose for delivery after the cartridge (218) is empty by pulling out the thumb pad (202), the thumb pad (202) pulls out the cam follower (204) in the direction of the proximal end (104). When the cam follower (204) moves in the direction of the proximal end (104), the first EOL locking snap (612A) in the elevated position (2002) fits within the first locking groove (420A) formed between the first dose setting and delivering pawls (416A and 418A). Similarly, the third EOL locking snap (612C) in the elevated position (2002) fits within the second locking groove (420B) formed between the second dose setting and delivering pawls (416B and 418B).
[00104] When the user further pulls out the thumb pad (202), the cam follower (204) further moves in the direction of the proximal end (104) such that the first EOL locking snap (612A) becomes locked with the first locking groove (420A) and the third EOL locking snap (612C) becomes locked with the second locking groove (420B). The locks, thus formed between the EOL locking snaps (612A-B) and the locking grooves (420A-B), respectively, ensure that the user cannot further pull out the thumb pad (202) and the cam follower (204) in the direction of the proximal end (104). This also ensures that the user would not be able to set the dose after the final dose is delivered from the cartridge (218), and thus, the user is prevented from re-using the dispensing device (102) after the associated end-of-life.
[00105] Unlike typical dispensing devices in which a user needs to keep turning a rotatable head for setting a dose, the dispensing device (102) allows the user to set a dose of a material to be dispensed by simply pulling out the thumb pad (202) towards the proximal end (104) of the dispensing device (102). The dispensing device (102) prevents the user from setting and delivering a wrong dose. Specifically, the one-way ratchets (610A-D) of the dispensing device (102) allow the cam follower (204) to move only towards the proximal end (104) of the dispensing device (102). When the user attempts to deliver a dose without setting the dose completely, the cam follower (204) is locked with the one-way ratchets (610A-D) to avoid delivery of the wrong dose.
[00106] Further, when the user attempts to set and deliver the wrong dose, such as a partial dose, by forcibly depressing the thumb pad (202), the elastic member (206) prevents transmission of the entire force being applied on the thumb pad (202) by the user to the one-way ratchets (610A-D) of the dispensing device (102). As a result, the one-way ratchets (610A-D) do not break or become damaged. The elastic member (206), thus, prevents damages that could potentially occur to the dispensing device (102) due to misuse of the dispensing device (102) by the user.
[00107] Further, the EOL locking snaps (612A-D) in the cam drum (208) are positioned in the non-elevated position (1702) by default. After the final dose of the material is dispensed from the dispensing device (102), the flange (1402) portion of the lead screw (214) positions itself below the EOL locking snaps (612A-D) and elevates the EOL locking snaps (612A-D) from the non-elevated position (1702) to the elevated position (2002). When the user attempts to set a subsequent dose after the final dose is delivered from the cartridge (218) by pulling out the thumb pad (202), one or more of the EOL locking snaps (612A-D) in the elevated position (2002) lock with the locking grooves (420A-B), which prevents the user from re-using the dispensing device (102) after its end-of-life. The cam drum (208) includes a linear cam profile (602A-D) that provides a path for setting a dose and a helical cam profile (604A-D) that provides an alternative path for delivering the dose to prevent any dose delivery when setting the dose. The dispensing device (102) can be designed to be used multiple times to dispense a fixed dose on every dose delivery operation or can be designed to be used once as a disposable pen.
[00108] Although specific features of various embodiments of the present systems and methods may be shown in and/or described with respect to some drawings and not in others, this is for convenience only. It is to be understood that the described features, structures, and/or characteristics may be combined and/or used interchangeably in any suitable manner in the various embodiments shown in the different figures.
[00109] While only certain features of the present systems and methods have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes.

LIST OF NUMERAL REFERENCES:

100 Top view of dispensing device
102 Dispensing device
104 Device proximal end
106 Device distal end
202 Thumb pad
204 Cam follower
206 Elastic member
208 Cam drum
210 Pen barrel
212 Pawl nut
214 Lead screw
216 Push pad
218 Cartridge
220 Cartridge holder
222 Cap
302 Identification groove
304 Holding surface
306 Guide
308 Thumb pad snap
310 Thumb pad distal end
402, 404 Extension slots
406, 408 Extension arms
410 Flanges
412A-B U-shaped cutout portions
414A-B Levers
1204 Pen barrel lower half
416A-B Dose setting pawls
418A-B Dose delivering pawls
420A-B Locking grooves
422, 901 Spring support structures
424 Cam follower proximal end
502, 602A-D Linear cam profiles
504, 604A-D Helical cam profiles
606A-D, 616A-D Start points
608A-D, 618A-D End points
610A-D One-way ratchets
612A-D EOL locking snaps
614A-B Cutout portions
702 Ready-to-push position
704, 706 Distal end of extension slots
708 Ready-to-pull position
710 First distance
712, 714 Proximal end of extension slots
902 Elastic member in extended state
904 Elastic member in compressed state
906 Elastic member distal end
908 Thumb pad proximal end
1102 Keyway
1104 One-way ratchet
1106 Barrel-engaging surface
1202 Pen barrel upper half
1404 Universal ball joint
1206 Mating studs
1208 Mating slots
1210 Matching rib
1212 Matching slot
1214A-B Cartridge holder slots
1216A-B Stopper ribs
1218A-B Slots
1220 Semi-circular rib
1222 Circular rib
1224 Front wall surface
1226 Rear wall surface
1228 Slot
1230A-B Semi-circular protrusions
1232 Circular protrusion
1234A-B Extension-arm guides
1236A-B, 1238A-B Inner sidewalls
1240A-B Right guides
1242A-B Left guides
1244 Left flange guide
1246 Right flange guide
1248 Depression
1302 Ribs
1304 One-way pawl
1306 Internal threads
1402 Flange
1406 Internal threads
1502 Push pad slot
1504 Front surface of push pad
1602 Ribs
1604 Cutout window
1606 Distal thread features
1702 Non-elevated position
1902 Gap
2002 Elevated position
2004 Stopper
701, 900 Direction of thumb pad movements , Claims:We claim:

1. A dispensing device (102), comprising:
a cam follower (204) comprising a dose setting pawl (416A) and a dose delivering pawl (418A) that are disposed with respect to each other to form a locking groove (420A);
a cam drum (208) that is coupled to the cam follower (204), wherein the cam drum (208) comprises one or more linear cam profiles (602A-D) and one or more helical cam profiles (604A-D), wherein each of the one or more linear cam profiles (602A-D) comprises an end-of-life locking snap (612A-D); and
a lead screw (214) that is coupled to the cam drum (208), wherein the lead screw (214) is adapted to move within the cam drum (208) by a designated distance while delivering each dose of a material from the dispensing device (102) and is further adapted to be positioned below the end-of-life locking snap (612A) after delivering a final dose of the material from the dispensing device (102), and
wherein the lead screw (214), thus positioned below the end-of-life locking snap (612A) after the final dose is delivered from the dispensing device (102), elevates the end-of-life locking snap (612A) from a non-elevated position (1702) to an elevated position (2002), and wherein the end-of-life locking snap (612A) positioned in the elevated position (2002) locks with the locking groove (420A) when the cam follower (204) is pulled out in a direction (701) of a proximal end (104) of the dispensing device (102) to prevent a reuse of the dispensing device (102).

2. The dispensing device (102) as claimed in claim 1, wherein the locking groove (420A) formed between the dose setting pawl (416A) and the dose delivering pawl (418A) corresponds to a V-shaped groove.

3. The dispensing device (102) as claimed in claim 1, wherein the end-of-life locking snap (612A) comprises a first cutout portion (614A) disposed at an associated top portion of the end-of-life locking snap (612A) and a second cutout portion (614B) disposed at an associated bottom portion of the end-of-life locking snap (612B) for enabling the end-of-life locking snap (612A) to move freely from the non-elevated position (1702) to the elevated position (2002).

4. The dispensing device (102) as claimed in claim 1, wherein the cam follower (204) comprises a first extension slot (402), a second extension slot (404), a flange (410), and a first spring support structure (422) disposed at a proximal end (424) of the cam follower (204).

5. The dispensing device (102) as claimed in claim 4, wherein the cam follower (204) is coupled to a thumb pad (202), wherein the thumb pad (202) comprises:
a guide (306) disposed at a distal end (310) of the thumb pad (202), wherein the guide (306) moveably fits within the first extension slot (402) of the cam follower (204);
a thumb pad snap (308) disposed at the distal end (310) of the thumb pad (202), wherein the thumb pad snap (308) moveably fits within the second extension slot (404) of the cam follower (204), wherein the thumb pad snap (308) prevents the thumb pad (202) from disengaging from the cam follower (204) when the thumb pad (202) is pulled out in the direction (701) of the proximal end (104) of the dispensing device (102);
a second spring support structure (901) disposed at a proximal end (908) of the thumb pad (202).

6. The dispensing device (102) as claimed in claim 5, wherein the cam follower (204) is coupled to the thumb pad (202) such that the guide (306) is positioned at a distal end (704) of the first extension slot (402) and the thumb pad snap (308) is positioned at a distal end (706) of the second extension slot (404) before setting a dose of the material for delivery.

7. The dispensing device (102) as claimed in claim 6, wherein the thumb pad (202) moves linearly with respect to the cam follower (204) and is designed to be positioned in a ready-to-pull position (708) when the thumb pad (202) is pulled out by a first distance (710) in the direction (701) of the proximal end (104) of the dispensing device (102), wherein the guide (306) is positioned at a proximal end (714) of the first extension slot (402) and the thumb pad snap (308) is positioned at a proximal end (712) of the second extension slot (404) when the thumb pad (202) is positioned in the ready-to-pull position (708).

8. The dispensing device (102) as claimed in claim 7, wherein the thumb pad (202) in the ready-to-pull position (708) pulls the cam follower (204) and causes the cam follower (204) to move linearly in the direction (701) of the proximal end (104) of the dispensing device (102) when the thumb pad (202) is further pulled out by a second distance from the ready-to-pull position (708), wherein the linear movement of the cam follower (204) in the direction (701) of the proximal end (104) causes the dose setting pawl (416A) to ride on a linear cam profile (602A) selected from the one or more linear cam profiles (602A-D) to set the dose of the material for delivery.

9. The dispensing device (102) as claimed in claim 8, wherein the thumb pad (202) is pushed in a direction (900) of a distal end (106) of the dispensing device (102) from the ready-to-pull position (708) to a ready-to-push position (702) after setting the dose of the material for delivery, wherein the guide (306) is positioned at the distal end (704) of the first extension slot (402) and the thumb pad snap (308) is positioned at the distal end (706) of the second extension slot (404) when the thumb pad (202) is positioned in the ready-to-push position (702).

10. The dispensing device (102) as claimed in claim 9, wherein the thumb pad (202) in the ready-to-push position (702) pushes the cam follower (204) and further causes the cam follower (204) to move linearly in the direction (900) of the distal end (106) of the dispensing device (102) when the thumb pad (202) is further pushed from the ready-to-push position (702), wherein the linear movement of the cam follower (204) in the direction (900) of the distal end (106) causes the dose delivering pawl (418A) to ride on a helical cam profile (604A) selected from the one or more helical cam profiles (604A-D) to deliver the dose of the material set for delivery.

11. The dispensing device (102) as claimed in claim 5, wherein the dispensing device (102) comprises an elastic member (206) that is disposed between the first spring support structure (422) of the cam follower (204) and the second spring support structure (901) of the thumb pad (202).

12. The dispensing device (102) as claimed in claim 11, wherein the dose setting pawl (416A) is locked with a one-way ratchet (610A) in a linear cam profile (602A) selected from the one or more linear cam profiles (602A-D), and thereby prevents a linear motion of the cam follower (204) in a direction (900) of the distal end (106) of the dispensing device (102) when delivery of a dose is attempted without completely pulling out the thumb pad (202) by the second distance from the ready-to-pull position (708).

13. The dispensing device (102) as claimed in claim 12, wherein the elastic member (206) disposed between the cam follower (204) and the thumb pad (202) undergoes compression from an extended state (902) to a compressed state (904) when delivery of the dose is attempted without completely pulling out the thumb pad (202) by the second distance from the ready-to-pull position (708), wherein compression of the elastic member (206) to the compressed state (904) absorbs a force exerted by a user on the thumb pad (202) and the one-way ratchet (610A).

14. The dispensing device (102) as claimed in claim 1, wherein the dispensing device (102) corresponds to a fixed dose delivery device, an auto-injector device, a needle-based injection device, a fluid substance delivery device, a medical device, and a construction material delivery device.