Injection device

Abstract

An injection device for injecting a drug into a patient is disclosed. The injection device comprises a housing, a first substance chamber configured to receive a first precursor of the drug, and a second substance chamber configured to receive a second precursor of the drug. The injection device also includes a user activatable mechanism configured to open a first fluid path between the first and second substance chambers and permit mixing of the first and second precursor substances to form the drug when activated, and a needle connectable in fluid communication with the drug through a second fluid path. The user activatable mechanism is further configured to open the second fluid path when activated and thereby permit injection of the drug through the needle.

Description

[0001] INJECTION DEVICE

[0002] Field

[0003] The present disclosure relates to medical injection devices, and more particularly to an injection device for administering a drug that comprises a mixture of two substances.

[0004] Background

[0005] For some treatment processes, it is necessary to inject a drug into body tissue at one or more particular locations. The injections are typically administered by a medical professional, or by a clinician under the guidance of a medical professional.

[0006] For example, some cosmetic treatment processes require injection of a neuromodulator, which may include botulinum toxin, at defined body locations, for example to treat glabellar lines, lateral canthal lines (crow’s feet) and horizontal forehead lines.

[0007] It is also known that a neuromodulator, such as botulinum toxin, can be used to treat primary axillary hyperhidrosis (PAH) by injection into multiple defined sites in the hyperhidrotic area of each axilla.

[0008] It is also known that a neuromodulator, such as botulinum toxin, can be used to treat migraine by paralysing specific muscles of the head and neck to thereby prevent spasms that might cause a migraine to develop.

[0009] Cosmetic treatments involving injection of substances below the skin have become increasingly popular. These treatments can be used to reduce the appearance of wrinkles, add volume to certain facial features, or provide other aesthetic enhancements. Traditionally, such treatments have been administered by trained medical professionals in clinical settings due to the potential risks involved with injecting substances into the body.

[0010] Additionally, some injectable substances used in cosmetic treatments, such as botulinum toxin formulations, can have serious adverse effects if not administered correctly, and the preparation of certain injectable formulations also often involves precise measurements and processes to ensure the proper concentration, sterility and efficacy of the active ingredients.

[0011] Such existing arrangements are cumbersome, prone to error that may include inconsistency of dosage and the risk of sterility issues.

[0012] Summary

[0013] According to an aspect of the present disclosure, an injection device for injecting a drug into a patient comprises: a housing; a first substance chamber configured to receive a first precursor of the drug; a second substance chamber configured to receive a second precursor of the drug; a user activatable mechanism configured to open a first fluid path between the first and second substance chambers and permit mixing of the first and second precursor substances to form the drug when activated; and a needle connectable in fluid communication with the drug through a second fluid path; wherein the user activatable mechanism is further configured to open the second fluid path when activated and thereby permit injection of the drug through the needle.

[0014] In an embodiment, the first drug precursor comprises a lyophilized powder.

[0015] In an embodiment, the second drug precursor comprises saline.

[0016] In an embodiment, the user activatable mechanism comprises a valve rotatable between a first position wherein the first and second chambers are not in fluid communication and the first and second drug precursors are not able to mix, and a second position wherein the first and second chambers are in fluid communication and the first and second drug precursors are able to mix.

[0017] In an embodiment, the valve is rotatable by a quarter-turn.

[0018] In an embodiment, the housing defines a cavity having a minor cross-sectional dimension and a major cross-sectional dimension, the major cross-sectional dimension being larger than the minor cross-sectional dimension.

[0019] In an embodiment, the cavity has an elliptical cross-sectional shape. In an embodiment, the housing comprises a flexible wall, whereby application of a compression force to the flexible wall causes the valve to move from the first position to the second position.

[0020] In an embodiment, the injection device comprises a plunger slidably engaged with the housing.

[0021] In an embodiment, the plunger comprises a recess configured to slide over the valve when the valve is in the second position so that the plunger is able to move inwardly of the housing and cause ejection of the drug through the needle.

[0022] In an embodiment, the recess comprises a chamfered inlet.

[0023] In an embodiment, the injection device comprises a needle safety sleeve configured to retract the needle after injection.

[0024] In an embodiment, the needle is configured to enter a user's skin at an angle of less than 90 degrees relative to a surface of the housing.

[0025] In an embodiment, the needle is configured to enter the user's skin at an angle of less than 50 degrees relative to the surface of the housing.

[0026] In an embodiment, the first substance chamber is configured to hold the first drug precursor under vacuum or partial vacuum.

[0027] In an embodiment, the second drug precursor in the second substance chamber comprises a liquid, wherein the vacuum or partial vacuum in the first substance chamber causes the liquid to be drawn towards the first substance chamber when the first and second chambers are in fluid communication.

[0028] In an embodiment, the predetermined drug comprises a botulinum toxin formulation.

[0029] In an embodiment, the first substance chamber comprises a first collapsible chamber containing the first drug precursor, and the second substance chamber comprises a second collapsible chamber containing the second drug precursor.

[0030] In an embodiment, the injection device comprises a sliding gate movable between a first position wherein fluid communication between the first chamber and the second chamber is prevented, and a second position wherein fluid communication between the first chamber and the second chamber is allowed. In an embodiment, movement of the sliding gate from the first position to the second position is prevented by a removable member, whereby removal of the removable member enables movement of the sliding gate from the first position to the second position.

[0031] In an embodiment, the sliding gate is biased towards the second position such that removal of the removable member causes the sliding gate to move to the second position.

[0032] In an embodiment, the injection device comprises a spring configured to bias the sliding gate towards the second position.

[0033] In an embodiment, the injection device comprises a needle slider carrying a needle, the needle slider movable between a needle retracted position and a needle extended position.

[0034] In an embodiment, movement of the needle slider from the needle retracted position to the needle extended position is prevented by a removable member, whereby removal of the removable member enables movement of the needle slider from the needle retracted position to the needle extended position.

[0035] In an embodiment, the needle slider is configured to connect the needle in fluid communication with the drug when the needle slider is in the needle extended position.

[0036] In an embodiment, fluid communication between the first chamber and the second chamber is prevented when a removable member is attached to the injection device and fluid communication between the first chamber and the second chamber is enabled when the removable member is removed from the injection device.

[0037] In an embodiment, the first chamber includes a first plunger capable of fluid communication with the needle, wherein inward movement of the first plunger after mixing of the first substance and the second substances to form the drug causes ejection of the drug through the needle.

[0038] In an embodiment, the second chamber includes a second plunger slidably received in the second chamber, and the injection device comprises a biasing device arranged to bias the second plunger inwardly of the second chamber, wherein inward movement of the second plunger by the biasing device is prevented when the removable member is attached to the injection device, and inward the movement of the second plunger by the biasing device is enabled when the removable member is removed from the injection device, and wherein removal of the removable member causes the second substance in the second chamber to move to the first chamber and mix with the first substance.

[0039] In an embodiment, the biasing device comprises a spring.

[0040] In an embodiment, the first chamber includes a first chamber opening, the second chamber includes a second chamber opening, and the drug injection device includes a flexible membrane disposed over at least one of the first and second chamber openings, wherein the removable member engages with the flexible membrane and the first and / or second chamber opening to prevent fluid communication between the first and second chambers when the removable member is attached to the injection device.

[0041] In an embodiment, the removable member includes a protruding portion that urges the membrane towards the first and / or second chamber opening to thereby seal the first and / or second chamber opening when the removable member is attached to the injection device.

[0042] In an embodiment, the injection device comprises a resilient layer provided with a fluid communication path extending between the first chamber and the second chamber, and a compression member, wherein the removable member is arranged to urge the compression member against the resilient layer to close the fluid communication path when the removable member is engaged with the injection device, and wherein removal of the removable member from the injection device causes the fluid communication path to open. In an embodiment, the removable member comprises a clevis pin.

[0043] In an embodiment, the removable member is configured to engage with the second plunger to prevent movement of the second plunger inwardly of the second chamber. In an embodiment, the removable member comprises a clevis pin.

[0044] In an embodiment, the injection device comprises: a housing assembly having the housing, the first substance chamber, the second substance chamber and the user activatable mechanism; a cradle member comprising the needle, the cradle member configured to receive the housing assembly such that the housing assembly is movable towards and away from the cradle member; and a biasing arrangement arranged to bias the housing assembly away from the cradle member; wherein movement of the housing assembly towards the cradle member causes the needle to form a fluid communication path with the drug.

[0045] In an embodiment, the housing assembly is arranged to engage with the needle when the housing assembly has moved towards the cradle member so that retraction of the housing assembly away from the cradle member causes the needle to retract with the housing assembly.

[0046] According to an aspect of the present disclosure, a drug injection system comprises a support member and at least one injection device, the support member configured to engage with the at least one injection device, and each injection device comprising: a housing; a first substance chamber configured to receive a first precursor of the drug; a second substance chamber configured to receive a second precursor of the drug; a user activatable mechanism configured to open a first fluid path between the first and second substance chambers and permit mixing of the first and second precursor substances to form the drug when activated; and a needle connectable in fluid communication with the drug through a second fluid path; wherein the user activatable mechanism is further configured to open the second fluid path when activated and thereby permit injection of the drug through the needle.

[0047] In an embodiment, the support member is arranged to engage with the at least one injection device such that each injection device is pivotable between a first position wherein the needle does not protrude from the support member and a second position wherein the needle protrudes from the support member.

[0048] The foregoing general description of the illustrative embodiments and the following detailed description thereof are merely exemplary aspects of the teachings of this disclosure and are not restrictive.

[0049] Brief description of figures Non-limiting and non-exhaustive examples are described with reference to the following Figures, in which:

[0050] Figure 1 is a diagrammatic sectional view of a first embodiment of an injection device prior to use;

[0051] Figure 2 is a diagrammatic sectional view of the injection device shown in Figure 1 with a fluid communication path open between first and second chambers and a needle of the injection device shown exposed;

[0052] Figure 3 is a diagrammatic sectional view of the injection device shown in Figures 1 and 2 with a fluid communication path open to the needle;

[0053] Figure 4 is a diagrammatic sectional view of the injection device shown in Figures 1 to 3 after injection;

[0054] Figure 5 is a diagrammatic upper perspective view of a second embodiment of an injection device with a paddle of the device shown in a first position before use;

[0055] Figure 6 is a diagrammatic lower view of the injection device shown in Figure 5;

[0056] Figure 7 is a diagrammatic lower view of the injection device shown in Figure 5 with the paddle shown in a second position;

[0057] Figure 8 is a diagrammatic first perspective view of a third embodiment of an injection device before use;

[0058] Figure 9 is a diagrammatic second perspective view of the injection device shown in Figure 8;

[0059] Figure 10 is a diagrammatic sectional view of the injection device shown in Figures 8 and 9;

[0060] Figure 11 is a diagrammatic exploded view of the injection device shown in Figures 8 to 10;

[0061] Figures 12 to 17 are diagrammatic cross-sectional views of the injection device shown in Figures 8 to 11 that illustrate operation of the injection device during use;

[0062] Figure 18 is a diagrammatic sectional view of a fourth embodiment of an injection device before use; Figure 19 is a diagrammatic sectional view of the injection device shown in Figure 18 after removal of a packaging member;

[0063] Figure 20 is a diagrammatic sectional view of the injection device shown in Figures 18 and 19 after use;

[0064] Figure 21 is a diagrammatic rear perspective view of an example mask that includes at least one injection device according to a fifth embodiment;

[0065] Figure 22 is a diagrammatic rear perspective view of an example mask body of the mask shown in Figure 21 ;

[0066] Figure 23 is a diagrammatic perspective view of the injection device shown in Figure 21 ;

[0067] Figure 24 is a perspective partially transparent view of a portion of the injection device shown in Figure 23, with the injection device shown prior to use;

[0068] Figure 25 is an exploded view of the injection device shown in Figures 23 and 24;

[0069] Figure 26 is a perspective view of a needle component of the injection device shown in Figures 23 to 25;

[0070] Figure 27 is an upper perspective view of a housing of the injection device shown in Figures 23 to 25;

[0071] Figure 28 is a perspective view of a second plunger arrangement of the injection device shown in Figures 23 to 25;

[0072] Figure 29 is a lower perspective view of components of the injection device shown in Figures 23 to 25;

[0073] Figure 30 is a cross-sectional view of portions of the injection device shown in Figures 23 to 25;

[0074] Figure 31 is a perspective partially transparent view of a portion of the injection device shown in Figures 23 to 25, with the injection device shown before mixing of first and second precursor substances;

[0075] Figure 32 is a perspective partially transparent view of a portion of the injection device shown in Figures 23 to 25 after mixing of the first and second precursor substances; Figure 33 is a cross-sectional view of portions of the injection device shown in Figures 23 to 25 after mixing of the first and second substances;

[0076] Figure 34 is a lower perspective view of the injection device shown in Figures 23 to 25; and

[0077] Figures 35 and 39 are cross-sectional views of the mask shown in Figure 21 , showing steps of an injection process during use.

[0078] Detailed Description

[0079] It should be recognized that the following description is not intended as a limitation on the scope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein.

[0080] The present disclosure provides an injection device configured for the administration of a predetermined drug, for example for cosmetic treatment purposes. The device includes a housing that contains two separate substance chambers, each configured to hold a different precursor substance. One of these chambers may be configured to maintain a vacuum or partial vacuum.

[0081] The device is a user-activatable mechanism that can establish a fluid path between the two substance chambers. This allows the first and second precursor substances to mix and form the drug intended for injection. The device also includes a needle that is connected or connectable in fluid communication with the constituted drug, so that when the needle is projected from the housing, injection of the drug is enabled.

[0082] The injection device is designed with considerations for safety and ease of use, potentially allowing individuals to self-administer cosmetic treatments without the need for medical supervision. The device may be configured to ensure proper dosage control and sterility, addressing challenges associated with administration of injectable treatments. In some instances, the device may be particularly useful for treatments involving substances such as botulinum toxin formulations, which require precise handling and administration.

[0083] A first embodiment of an injection device is shown in Figures 1 to 4.

[0084] Referring to Figure 1 , an exemplary injection device 10 is depicted. The device 10 comprises a housing 12 and a needle safety sleeve 14. The housing 12 may be constructed from any suitable material, such as plastic, metal, or a combination thereof, and may be designed to be robust and durable to withstand the forces exerted during operation of the device.

[0085] Within the housing 12, two distinct substance chambers are provided: a first substance chamber 16 and a second substance chamber 18. The first and second chambers hold different precursor substances that are used to form the predetermined drug intended for injection. In the present example, each of the first and second substance chambers 16, 18 has an annular cross-sectional shape and the annular cross-sections are concentric.

[0086] In some embodiments, the first substance chamber 16 is configured to receive a first drug precursor under vacuum or partial vacuum. This configuration may be particularly suitable for storing a lyophilized powder, which may be used as a drug precursor for a variety of treatments. The vacuum or partial vacuum within the first substance chamber 16 may help to preserve the stability and efficacy of the lyophilized powder over an extended period of time.

[0087] The second substance chamber 18 is configured to receive a second drug precursor, in this example a liquid. In some embodiments, the liquid may comprise a saline solution, which is commonly used as a diluent in various medical and cosmetic treatments. The second substance chamber 18 may be configured to maintain the sterility of the saline and to allow for its controlled release during operation of the device.

[0088] The injection device 10 further comprises a user-activatable mechanism, which may include a primary plunger 20 and a secondary plunger 22, in this example integrally formed with the primary plunger 20. The secondary plunger 22 is slidably disposed in the first substance chamber 16. The primary plunger 20 may be configured so as to be manually depressed by a user to activate the device, initiate mixing of the first and second precursor substances, and initiate delivery of the mixed substances.

[0089] In this example, the device 10 also includes a plunger lock member 24 that prevents relative movement between the plungers 20, 22 and the housing 12 until intended delivery of the mixed substances. In this example, the plunger lock member 24 is a removable packaging member that sits under a head 26 of the primary plunger 20 to prevent movement of the primary plunger 20 until the plunger lock member 24 is removed.

[0090] The injection device 10 also includes a needle 28 which is connected in fluid communication with a mixing chamber 30. The needle 28 projects from the housing 12 when the user-activatable mechanism is activated to allow for injection of the predetermined drug. The needle 28 may be constructed from a biocompatible material and may be of a size and shape suitable for the intended injection site.

[0091] The needle safety sleeve 14 is disposed around the needle 28 before injection, thereby preventing accidental needle sticks and enhancing the safety of the device. In the present example, the needle safety sleeve 14 is movable relative to the housing 12 and is biased away from the housing 12, for example using a sleeve spring (not shown) to cause the needle safety sleeve 14 to automatically cover the needle 28 when the user releases force from the primary plunger 20 after use.

[0092] Referring to Figure 2, the injection device 10 is shown after a first stage of the activation process. The device 10 is configured such that after disposal of the device adjacent a person's skin and application of an initial force to the primary plunger 20, the housing 12 is caused to move relative to the needle safety sleeve 14 against the biasing force of the sleeve spring (not shown), thereby exposing the needle 28 and causing the needle 28 to pierce the person's skin.

[0093] Movement of the housing 12 relative to the needle safety sleeve 14 also causes a shuttle valve 32 to move from a first position shown in Figure 1 wherein a first fluid path between the first and second substance chambers 18, 16 is blocked by the shuttle valve 32, to a second position shown in Figure 2 wherein the first fluid path between the first and second substance chambers 16, 18 is open.

[0094] When the first fluid path is open, the second substance in the second substance chamber 18, in this example a solution containing at least saline, is able to move to the mixing chamber 30, and this is promoted by virtue of the vacuum or partial vacuum in the first substance chamber 16. The vacuum or partial vacuum also causes a stopper 34 in the second substance chamber 18 to move through the second substance chamber 18 and push the shuttle valve 32 further away from the mixing chamber 30 to open an aperture 36 in the center of the shuttle valve 32, as shown in Figure 3. The aperture 36 causes a second fluid path to be defined from the mixing chamber 30 to the needle 28.

[0095] After removal of the plunger lock member 24, a force can be applied to the primary plunger 20 which causes the secondary plunger 22 to move inwardly of the first substance chamber 16, thereby causing the mixed substance in the mixing chamber 30 to move through the aperture 36 and the needle 28 and into the patient, as shown in Figure 4. After injection and removal of the force from the primary plunger 20, the action of the biasing arrangement associated with the needle safety sleeve 14 causes the housing 12 to move away from the needle safety sleeve 14 and the needle 28 to retract from the patient.

[0096] A second embodiment of an injection device 38 is shown in Figures 5 to 7.

[0097] Referring to Figure 5, the injection device 38 comprises a housing 40 that may be constructed from a variety of materials, such as plastic, metal, or a combination thereof, and may be designed to be robust and durable to withstand the forces exerted during the operation of the device.

[0098] The housing 40 defines a cavity that has a minor cross-sectional dimension and a major cross-sectional dimension that is larger than the minor cross-sectional dimension. For example, the housing 40 may define a cavity that has a generally elliptical cross- sectional shape.

[0099] Within the housing 40, two distinct substance chambers are defined: a first substance chamber 42 and a second substance chamber 44. The chambers hold different precursor substances that are used to form the drug intended for injection. In some embodiments, the first substance chamber 42 is configured to receive a first drug precursor that may include a lyophilized powder, which can be a drug precursor for a variety of treatments. A vacuum or partial vacuum in the first substance chamber 42 may be provided to help to preserve the stability and efficacy of the lyophilized powder over an extended period of time.

[0100] The second substance chamber 44 is configured to receive a second drug precursor comprising a liquid. In some embodiments, the liquid may be saline, which is commonly used as a diluent in various medical and cosmetic treatments. The second substance chamber 44 may be configured to maintain the sterility of the saline and to allow for its controlled release during the operation of the device.

[0101] A feature of the device 38 is a user-activatable mechanism that can establish a fluid path between the two substance chambers 42, 44. The mechanism includes a valve paddle 46 that extends across the housing 40 and is initially oriented across the minor axis of the housing 40. The valve paddle 46 is configured so as to be rotatable within the injector housing 40, in this example by a quarter-turn, between a first position wherein the valve paddle 46 extends across the minor dimension of the housing 40, and a second position wherein the valve paddle 46 extends across the major dimension of the housing 40. In the first position, the valve paddle 46 forms a seal between the first and second substance chambers 42, 44, and in the second position the valve paddle 46 does not form a seal and the substances in the first and second chambers 42, 44 are allowed to come together and mix. The valve paddle arrangement allows a user to effect mixing of the first and second substances by applying a compression force to the housing 40 which causes the valve paddle 46 to rotate.

[0102] The injection device 38 is designed with safety and ease of use in mind, allowing individuals to administer cosmetic treatments without the need for medical supervision. The device's design ensures proper dosage control and sterility. The device may be particularly useful for treatments involving substances such as botulinum toxin formulations, which require precise handling and administration.

[0103] Slidably disposed in the housing 40 is a plunger 48 provided with a recess 50 shown more particularly in Figure 6. The recess 50 is shaped such that when the valve paddle 46 is disposed in the second position, the valve paddle 46 is receivable in the recess 50 to thereby enable the plunger 48 to move inwardly of the housing 40 in response to user force.

[0104] In the present example, at least one of the first and second chambers 42, 44 has a vacuum or partial vacuum, and as such, when the valve paddle 46 is aligned with the recess 50, the plunger 48 moves slightly inwardly of the housing 40. In some embodiments, the recess 50 may have a chamfered inlet to guide the valve paddle 46 into engagement with the recess 50.

[0105] In other embodiments, the recess 50 may have a different shape or configuration, depending on the specific design of the injection device 38 and in particular the cross- sectional shape of the valve paddle 46.

[0106] Figure 7 shows the valve paddle 46 in the second position. After disposing the device on a person's skin with the needle 52 piercing the person's skin, the user applies a force to the plunger 48 which causes the plunger 48 to move further inwardly of the housing 40 and the drug to be injected into the person through the needle 52.

[0107] The device shown in Figures 5 to 7 may also include a needle safety sleeve (not shown) disposed around the needle 52 before injection, thereby preventing accidental needle sticks and enhancing the safety of the device. The needle safety sleeve may be biased away from the housing 40, for example using a spring (not shown) to cause the needle safety sleeve to automatically cover the needle 52 when the user releases force from the primary plunger 48 after use.

[0108] A third embodiment of an injection device 54 is shown in Figures 8 to 17.

[0109] Referring to Figure 8, the device 54 comprises a housing 56 that contains several components. The housing 56 may be constructed from a variety of materials, such as plastic, metal, or a combination thereof, and may be designed to be robust and durable to withstand the forces exerted during the operation of the device.

[0110] The housing 56 is connected to two distinct collapsible reservoirs: a first collapsible chamber 58 and a second collapsible chamber 60. The chambers are designed to hold different precursor substances that are used to form the drug intended for injection. In some embodiments, the first collapsible chamber 58 is configured to contain a first drug precursor substance in the form of a lyophilized powder. The lyophilized powder may comprise a botulinum toxin formulation, which is commonly used in cosmetic treatments. The second collapsible chamber 60 is configured to contain a second drug precursor substance comprising a liquid. In some embodiments, the liquid may be saline, which is commonly used as a diluent in various medical and cosmetic treatments. The second collapsible chamber 60 may be configured to maintain the sterility of the saline and to allow for its controlled release during the operation of the device.

[0111] The injection device 54 provides a user-friendly solution for administration of a predetermined drug. The device 54 allows for the separate storage of two precursor substances in the first and second substance chambers 58 and 60, and provides a user- activatable mechanism for mixing the precursor substances and injecting the resulting drug. The design may be particularly advantageous for treatments involving substances that require precise handling and administration, such as botulinum toxin formulations.

[0112] The injection device 54 is designed with safety and ease of use in mind and the device's design ensures proper dosage control and sterility. The device may be particularly useful for treatments involving substances such as botulinum toxin formulations, which require precise handling and administration.

[0113] The device 54 includes a needle slider 62 configured to move relative to the housing 56 between a needle retracted position wherein a needle 64 is concealed in the housing 56 and a needle extended position wherein the needle 64 extends through an aperture 66 in the housing 56. The needle slider 62 may be configured to move diagonally relative to the housing 56. In this example, diagonal movement of the needle slider 62 is effected by providing the housing 56 with an elongate notch 68 and providing the needle slide 62 with an elongate aperture 70 that slidably receives the elongate notch 68, the elongate aperture 70 being longer than the elongate notch 68, as shown in Figure 10.

[0114] The needle slider 62 also includes a slider fluid path aperture 72 that serves to provide a fluid path between the first chamber 58 and the needle 64 when the needle slider is disposed in the needle extended position and the slider fluid path aperture 72 aligns with a housing needle fluid path aperture 74.

[0115] The device 54 further includes a removable packaging member 76 that engages with the needle slider 62 and prevents movement of the needle slider 62 to the needle extended position when the removable member 76 is engaged with the housing 56. The removable member 76 may be constructed from a variety of materials, such as plastic, and may be designed to be easily removed by the user when the device is ready for use.

[0116] As shown in the cross-sectional view in Figure 10, the device 54 also includes a sliding gate 78 movable between a first position wherein fluid communication between the first and second chambers 58 and 60 is prevented, and a second position wherein a first fluid path is defined and fluid communication between the first and second chambers 58 and 60 is allowed. The sliding gate 78 is biased towards the second position, for example using a spring 80, and is restrained from moving to the second position by the removable member 76 when the removable packaging is attached to the housing 56.

[0117] In order to facilitate communication between the first and second chambers 58, 60, the sliding gate 78 comprises a sliding gate aperture 82 that aligns with a mixing path 84 in the housing 56 to provide a first fluid path between the first and second chambers 58 and 60 when the sliding gate 78 is in the second position. The sliding gate aperture 82 does not align with the mixing path 84 when the sliding gate 78 is in the first position.

[0118] The sliding gate 78 is also movable to a third position, as shown in Figure 16, wherein the fluid path between the first and second chambers 58, 60 is prevented. The sliding gate 78 is prevented from moving to the third position by engagement between the needle slider 62 and the sliding gate 78 when the needle slider 62 is in the needle retracted position, as shown in Figure 14. When the needle slider 62 is in the needle extended position, the sliding gate 78 is able to move to the third position in response to the biasing force of the spring 80. In this example, the first chamber 58 comprises a vacuum or partial vacuum so that when the fluid communication path is created between the first and second chambers 58, 60, the second precursor substance in the second chamber 60 is drawn into the first chamber 58 and the second chamber 60 automatically collapses.

[0119] The needle 64 is connected by a second fluid path to the first substance chamber 58, which, after combination of the first and second precursor substances, contains the mixed predetermined drug.

[0120] As shown in Figure 10, the first reservoir 58 includes a pin 86 that engages with the needle slider 62 when the needle slider 62 is in the needle retracted position to prevent compression of the first chamber 58. The pin 86 does not engage with the needle slider 62 when the needle slider 62 is in the needle extended position and accordingly in this position the first chamber 58 is collapsible by application of a force by a user.

[0121] With the needle slider 62 in the needle retracted position, the drug in the first collapsible reservoir 58 is not in fluid communication with the needle 64 because the needle fluid path aperture 72 is not aligned with the housing needle fluid path 74. When the removable member 76 is removed and the needle slider 62 is moved to the needle extended position, the needle fluid path aperture 72 is aligned with the housing needle fluid path 74 and application of a compression force to the first collapsible reservoir 58 causes injection of the drug through the needle 64.

[0122] As shown in Figure 10, in this example the injection device 54 further comprises an adhesive layer 88 disposed on surface of the housing 56 adjacent the needle 64. The adhesive layer 88 facilitates attachment of the device 54 to a user's skin during the injection process.

[0123] The adhesive layer 88 may be made of a biocompatible adhesive material that is capable of securely adhering the device 54 to the user's skin without causing irritation or discomfort. The adhesive layer 88 may be designed to provide a secure and stable attachment of the device 54 to the user's skin, ensuring that the device 54 remains in place during the injection process. This can be particularly important for ensuring accurate and consistent delivery of the predetermined drug to the desired injection site.

[0124] The adhesive layer 88 may be covered with a removable protective layer (not shown) prior to use. The protective layer can be peeled off by the user immediately before the device 54 is attached to the user's skin, thereby exposing the adhesive layer 88 and enabling it to adhere to the user's skin. The activation sequence of the injection device 54 is illustrated in Figures 12 to 17.

[0125] In Figure 12, the device 54 is shown in a pre-use configuration with the removable member 76 attached to the housing 56, the sliding gate 78 disposed in the first position and the needle slider 62 disposed in the needle retracted position. In this configuration, the fluid path between the first and second chambers 58, 60 is blocked, the fluid path between the first chamber 58 and the needle 64 is blocked, and the first and second chambers 58, 60 are not compressible.

[0126] As shown in Figures 13 and 14, after removal of the removable member 76, the biasing effect of the spring 80 causes the sliding gate 78 to move towards the needle slider 62 until the sliding gate 78 contacts the needle slider 62. At this location, the sliding gate aperture 82 aligns with the mixing path 84 to create a fluid path between the first and second chambers 58 and 60. Because of the vacuum or partial vacuum in the first chamber 58, the second drug precursor substance in the second chamber 60 is drawn into the first chamber 58 and mixes with the first drug precursor substance. This also causes the second chamber 60 to collapse. The fluid path between the first chamber 58 and the needle 196 remains closed.

[0127] The protective layer is then removed to expose the adhesive layer 88 and the device 54 is placed against a user's skin. As shown in Figure 15, the needle slider 62 is then moved towards the needle extended position by a user which causes the needle 64 to pierce the user's skin. Movement of the needle slider 62 to the needle extended position also causes a fluid communication path to open between the first chamber 58 and the needle 64, and the pin 86 to move out of engagement with the needle slider 62 to thereby enable compression of the first substance chamber 58 by the user.

[0128] In some embodiments, the needle 64 may be configured to enter a user's skin at an angle of less than 90 degrees relative to a skin contact surface of the housing 56. In other embodiments, the needle 64 may be configured to enter the user's skin at an angle of less than 50 degrees relative to the skin contact surface. This angled delivery of the needle 64 may provide greater control of the needle penetration depth into the user's skin.

[0129] Movement of the needle slider 62 towards the needle extended position also enables the sliding gate 78 to continue movement in response to the biasing effect of the spring 80, as shown in Figure 16. This additional movement of the sliding gate 78 causes the fluid path between the first and second chambers 58, 60 to close, thereby ensuring that during use the drug in the first substance chamber 58 is ejected through the needle 64 and does not flow back to the second substance chamber 60.

[0130] After movement of the needle slider 62 to the needle extended position, the user applies a compression force to the first substance chamber 58 which causes the drug in the first substance chamber 58 to be ejected through the needle 64.

[0131] A fourth embodiment of an injection device 90 is shown in Figures 18 to 20.

[0132] The device 90 comprises a housing 92 that may be constructed from a variety of materials, such as plastic, metal, or a combination thereof, and may be designed to be robust and durable to withstand the forces exerted during the operation of the device.

[0133] Within the housing 92, two distinct substance chambers are provided: a first substance chamber 94 and a second substance chamber 96. The chambers 94, 96 are designed to hold different precursor substances that are used to form the predetermined drug intended for injection. The first substance chamber 94 is configured to contain a first drug precursor substance 118, which in this example is a lyophilized powder. The second substance chamber 96 is configured to contain a second drug precursor substance 120, in this example a liquid, for example that contains saline, which is commonly used as a diluent in various medical and cosmetic treatments. The second substance chamber 96 may be configured to maintain the sterility of the saline and to allow for its controlled release during the operation of the device.

[0134] The first substance chamber 94 has a first chamber opening 98 and the second substance chamber 96 has a second chamber opening 100.

[0135] A first plunger 102 is slidably received in the first chamber 94 and includes a first plunger head 104 and a first plunger end 106. A needle 108 is mounted on and extends away from the first plunger end 106. A second plunger 110 is slidably received in the second chamber 96 and includes a second plunger head 112 and a second plunger end 114. The second plunger 110 is biased to move inwardly of the second chamber 96, in this example using a biasing device in the form of a coil spring 116.

[0136] The device 90 is arranged to prevent contact between the first and second substances 118, 120 in the first and second substance chambers 94, 96 until activation of the device 90 by a user. In the present example, activation of the device 90 is achieved by providing a removable member 122 that has a stop portion 124 disposed between the second plunger head 112 and the housing 92 to prevent movement of the second plunger 110 inwardly of the second chamber 96 under action of the coil spring 116. A flexible membrane 126 extends across the second chamber opening 100, and the removable member 122 includes an outlet seal portion 128 that acts towards the second chamber opening 100 against the flexible membrane 126 to seal the second chamber opening 100 and prevent egress of the second substance 120 from the second chamber 96 towards the first chamber 94. In this example, the outlet seal portion 128 is a nipple member that extends in the second chamber opening 100 and urges the flexible membrane 126 against the second chamber opening 100 when the removable member 122 is engaged with the housing 92.

[0137] When the removable member 122 is removed by a person, as shown in Figure 19, the outlet seal portion 128 moves away from the first chamber opening 98 to define an open fluid path 130 between the first chamber opening 98 and the second chamber opening 100. In addition, in the absence of the stop portion 124 between the housing 92 and the second plunger head 112, the second plunger 110 is caused to move inwardly of the second chamber 96 by the coil spring 116, which causes the second substance 120 to move from the second chamber 96 through the fluid path 130 into the first chamber 94, thereby mixing with the first substance 118.

[0138] In the present example, the first substance 118 is a mixture of botulinum toxin powder, sodium chloride and albumin and the second substance 120 is saline solution, although it will be understood that any suitable first and second substances are envisaged depending on the proposed treatment process.

[0139] In the present example, the injection device 90 is arranged to deliver about 0.1 mL of saline and about 0.07mg of botulinum toxin powder, sodium chloride and albumin mixture that may comprise 0.045mg of sodium chloride, 0.025mg of albumin and 0.25ng of botulinum toxin.

[0140] As shown in Figure 20, after the first and second substances have mixed together to form an injectable drug, the drug is dispensed by application of a manual force to the first plunger 102, as indicated by arrow A. This action causes the first plunger 102 to move inwardly of the first chamber 94 and the drug to be injected into a person through the needle 108.

[0141] A fifth embodiment of an injection device 140 is shown in Figures 21 to 39. Operation of the injection device 140 is similar to operation of the injection device 90 according to the fourth embodiment shown in Figures 18 to 20. In this example, the injection device 140 is configured to be pivotably attached to a mask device 142 of the type used to define a predetermined drug injection pattern for a patient, as shown in Figure 21 . Figure 22 shows a mask body 144 of the mask device 142, the mask body 144 arranged to receive a support frame 146 that is movable between a disabled position prior to use and an enabled position wherein the or each injection device 140 mounted on the mask device 142 is activated and ready to be manually operated by a user to inject a drug into a patient.

[0142] In the present example, only 1 injection device 140 is shown mounted on the mask body 144, although it will be understood that any number of injection devices 140 are envisaged.

[0143] In this example, the mask body 144 includes an aperture 146 for receiving a tab 148 of the support frame 146, and removable activation devices, in this example first and second clevis pins 150, 152, are attached to the support frame 146, for example using rivets (not shown). The mask body 144 also includes a snap hook 154 that engages with the support frame 146 when a force is applied to the tab 148 by a user. Application of the force to the tab 148 causes the clevis pins 150, 152 attached to the support frame 146 to disengage from the injection device 140 and thereby activate the injection device 140 prior to use, as described in more detail below.

[0144] The mask body 144 also includes a pair of hinge recesses 156 that receive a spindle 158 of the injection device 140 and facilitate pivoting movement of the injection device 140 relative to the mask device 142 when the spindle 158 is received in the hinge recesses 156.

[0145] The injection device 140 is shown more particularly in Figures 23 to 34. The device 140 comprises a housing 160 that may be constructed from a variety of materials, such as plastic, metal, or a combination thereof, and may be designed to be robust and durable to withstand the forces exerted during the operation of the device.

[0146] Within the housing 160, two distinct substance chambers are provided: a first substance chamber 162 and a second substance chamber 164. The chambers 162, 164 are designed to hold different drug precursor substances that are used to form the predetermined drug intended for injection. As shown in Figure 31 , the first substance chamber 162 is configured to contain a first drug precursor substance 165, which in this example is a lyophilized powder. The second substance chamber 164 is configured to contain a second drug precursor substance 167, in this example a liquid, for example that contains saline, which is commonly used as a diluent in various medical and cosmetic treatments. The second substance chamber 164 may be configured to maintain the sterility of the saline and to allow for its controlled release during the operation of the device.

[0147] A first plunger assembly 166, shown more particularly in Figure 25, is slidably received in the first chamber 162 and includes a first plunger head 168 and a first plunger end 170 that forms a tight fit with the first chamber 162.

[0148] A second plunger assembly 174, shown more particularly in Figure 28, is slidably received in the second chamber 164 and includes a plunger cap 176 and a second plunger end 178 that forms a tight fit with the second chamber 164. The second plunger end 178 is integral with a shaft 180 that extends upwardly of the second plunger end 178 through a cap aperture in the plunger cap 176. A biasing device, in this example in the form of a spring 182, biases the second plunger end 178 away from the plunger cap 176. Movement of the plunger end 178 in response to the biasing force is prevented by the second clevis pin 152 that extends through a shaft aperture 184 provided in the shaft 180. The housing 160 and associated plunger assemblies together form a housing assembly 185, shown more particularly in Figure 31. Removal of the first and second clevis pins 150, 152 enables movement of the second plunger end 178 in response to the biasing force, as shown in Figure 32.

[0149] As shown in Figures 31 and 32, prior to removal of the clevis pins 150, 152, the shaft 180 of the second plunger assembly 174 extends through an aperture in the first plunger head 168. This provides a visual indicator to a user that the injection device 160 is not active.

[0150] In contrast, as shown in Figure 32, the clevis pins 150, 152 have been removed, the shaft 180 has moved inwardly of the second chamber 164, and the first plunger head 168 has moved upwardly. Accordingly, the shaft 180 is not visible above the first plunger head 168.

[0151] The injection device 140 also includes a cradle member 186 that includes a base 188 intended to be disposed adjacent a patient’s skin during use, and first and second upright members 190, 193. The cradle member 186 receives the housing assembly 185 such that the housing assembly 185 is reciprocably movable relative to the cradle member 186 towards and away from the cradle member 186. In this embodiment, the housing assembly 185 is biased away from the cradle member 186, for example using a spring 191.

[0152] The injection device 140 also includes a needle component 192 shown more particularly in Figure 26. The needle component 192 includes a needle body 194 and a needle 196 mounted in the needle body 194.

[0153] As shown more particularly in Figures 27 and 29, the housing 160 includes a housing body 200 that defines the first and second chambers 162, 164, and a housing upright member 202. The housing upright member 202 includes a clevis pin aperture 204 that receives the first clevis pin 150. The housing 160 also includes a resilient layer 206 that defines a fluid communication path 208 between the first and second chambers 162, 164. In this example, the resilient layer 206 is formed of silicone material, although it will be understood that other materials are envisaged.

[0154] The housing 160 also includes a housing cap member 207, for example shown in Figure 24, that engages with the housing body 200, the resilient layer 206 disposed between the cap member 207 and the housing body 200, and the housing cap member 207 including a cap aperture 205.

[0155] The needle body 194 rests in a needle aperture 197 provided in the base 188 of the cradle member 186, and the needle body 194 also includes a retaining notch 198 that cooperates with a corresponding retaining projection 199 provided on the housing cap member 207 to retract the needle component 192 towards the housing 160 after injection.

[0156] The housing 160 also includes a compression member 210 that is configured such that when the first clevis pin 150 is engaged with the clevis pin aperture 204, the compression member 210 is urged against and compresses the resilient layer 206 to thereby close the fluid communication path 208 between the first and second chambers 162, 164.

[0157] When the first clevis pin 150 is disengaged from the clevis pin aperture 204, the compression member 210 is able to move away from the resilient layer 206, which causes the fluid communication path 208 between the first and second chambers 162, 164 to open.

[0158] As shown more particularly in Figure 33, prior to ejection of the drug, the needle 196 of the needle component 192 is disposed adjacent to but not piercing the resilient layer 206. During the drug injection process, when the housing assembly 185 moves towards the cradle member 186, the needle 196 is caused to pierce the resilient later 206 and connect in fluid communication with the first chamber 162 so that the drug in the first chamber 162 may be injected into a patient.

[0159] A process of injection of a drug formed of the first and second precursor substances 165, 167 will now be described with reference to Figures 31 to 39.

[0160] As shown in Figure 31 , prior to activation of the injection device 140 and delivery of the drug, the first and second clevis pins 150, 152 are respectively engaged with the housing upright member 202 and the shaft 180 that extends from the second plunger end 178. With the first and second clevis pins 150, 152 in this position, the fluid communication path 208 between the first and second chambers 162, 164 is closed by the compression member 210, and the second plunger end 178 is restrained from moving inwardly of the second chamber 164.

[0161] As shown in Figure 35, the injection device 140 is engaged with the support frame 146 of the mask body 144 by engaging the spindle 158 with the hinge recesses 156. The engagement is such that the injection device 140 is able to pivot relative to the support frame 146. The injection device 140 is pivotable in response to application of a force to the first plunger head 168 between a first pivot position as shown in Figure 35, wherein the needle 196 does not extend from the mask body 144 and therefore does not pierce a patient’s skin during use, and a second pivot position as shown in Figure 36, wherein the needle 196 extends from the mask body 144 and therefore pierces the patient’s skin.

[0162] In the present example, the first and second clevis pins 150, 152 are disengaged after the injection device 140 is engaged with the support frame 146 by application of a force to the tab 148 of the support frame 146.

[0163] Removal of the first and second clevis pins 150, 152 causes activation of the injection device 140, wherein the compression member 210 is allowed to move away from the resilient layer 206, thereby opening the fluid communication path 208, and the second plunger end 178 is allowed to move inwardly of the second chamber 164 in response to the basing force provided by the spring 182. With the fluid communication path 208 open, movement of the second plunger end 178 inwardly of the second chamber 164 causes the second drug precursor substance 167 to move into the first chamber 162 and mix with the first drug precursor substance 165 to form the drug to be injected.

[0164] Continued application of a force to the first plunger head 168 causes movement of the housing assembly 185 towards the cradle member 186, which causes the needle 196 to pierce the resilient layer 206 and form a communication path with the first chamber 162, as shown in Figure 37.

[0165] Further application of a force to the first plunger head 168 causes the first plunger 166 to move inwardly of the first chamber 162, as shown in Figure 38, and the first plunger end 170 to cause the drug in the first chamber to be injected into the patient through the needle 196.

[0166] As shown in Figure 39, removal of the force from the first plunger head 168 causes the housing assembly 185 to move away from the cradle member 186 in response to the biasing force provided by the spring 191. A retaining projection 199 integral with the housing cap member 207, shown in Figure 34, engages with the needle notch 198 to cause the needle component 192 to retract with the housing assembly 185.

[0167] The cradle member 186 may also include an engagement mechanism (not shown) that causes the cradle member 186 to engage with and retain the injection device 140 relative to the mask body 144 when the injection device 140 is moved to the second pivot position shown in Figure 36. The engagement mechanism may include a snap lock device.

[0168] In some embodiments, the predetermined drug used in the injection devices 10, 38, 54 and 90 may comprise a botulinum toxin formulation. Botulinum toxin is a neurotoxic protein produced by the bacterium Clostridium botulinum and related species. While it is poisonous, when used in small, controlled doses, botulinum toxin can be used to treat a variety of medical conditions, as well as for cosmetic purposes.

[0169] For example, the botulinum toxin formulation may be used for cosmetic treatments, such as the reduction of facial wrinkles. Botulinum toxin works by blocking nerve signals in the muscles where it is injected. This causes a temporary reduction in muscle activity, which can reduce the appearance of facial wrinkles.

[0170] The botulinum toxin formulation may be provided in the form of a lyophilized powder, which is stored in the first substance chamber 16, 42, 58, 94 or 162 of the injection devices 10, 38, 54, 90 and 140. The lyophilized powder may be prepared by freeze- drying a solution of the botulinum toxin, resulting in a stable, long-lasting form of the toxin that can be stored under vacuum or partial vacuum conditions.

[0171] In some cases, the lyophilized botulinum toxin powder may be mixed with a liquid, such as saline, to form the predetermined drug for injection. The saline may be stored in the second substance chamber 18, 44, 60, 96 or 164 of the injection devices 10, 38, 54, 90 and 140. The saline serves as a diluent, reconstituting the lyophilized botulinum toxin powder into a liquid form that can be easily injected.

[0172] The mixing of the botulinum toxin powder and the saline is controlled by the user- activatable mechanism of the injection devices 10, 38, 54, 90 and 140. This mechanism allows the user to control the preparation of the predetermined drug, ensuring that the correct dosage is prepared for each injection.

[0173] Safety considerations are important when using botulinum toxin for injection. Incorrect dosages can lead to serious adverse outcomes, including permanent paralysis. Therefore, the injection devices 10, 38, 54, 90 and 140 are designed to ensure that the correct dosage of the botulinum toxin formulation is prepared and administered. The devices may include features such as a vacuum or partial vacuum in the first substance chamber to preserve the stability of the lyophilized botulinum toxin powder, a user- activatable mechanism to control the mixing of the botulinum toxin powder and the saline, and a needle safety sleeve to prevent accidental needle sticks. These features, among others, contribute to the safe and effective use of the injection devices for administering botulinum toxin formulations.

[0174] It will be understood that a requirement for medium and long term storage of some pharmaceutical substances, including lyophilized drugs such as botulinum toxin, is that all components that have contact with the substance must be made from inert material, and in the present examples such components are made from as cyclic olefin copolymer (COC) or cyclic olefin polymer (COP) material.

[0175] In addition, it will be understood that components of the injection devices may be coated with any suitable material in order to enhance or provide the components with desired properties. For example, particular components may be coated with Ethylene T etrafluoroethylene (ETFE) or any other suitable substance that provides the component with improved chemical resistance, increased durability, reduced friction and / or improved biocompatibility. In the present examples, any components of the injection devices that are formed of silicone, such as the plungers of the injection devices, are coated with ETFE.

[0176] For example, as shown in the fifth embodiment 140, a layer 209 of ETFE may be applied between the resilient layer 206 and the housing cap member 207, as shown in Figure 23; a coating 169 of ETFE may be applied to inwardly facing surfaces of the first and second substance chambers 162, 164, as shown in Figure 27; and a coating 179 of ETFE may be applied to the plungers, for example as shown in Figure 28.

[0177] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure.

Claims

Claims1. An injection device for injecting a drug into a patient, the injection device comprising: a housing; a first substance chamber configured to receive a first precursor of the drug; a second substance chamber configured to receive a second precursor of the drug; a user activatable mechanism configured to open a first fluid path between the first and second substance chambers and permit mixing of the first and second precursor substances to form the drug when activated; and a needle connectable in fluid communication with the drug through a second fluid path; wherein the user activatable mechanism is further configured to open the second fluid path when activated and thereby permit injection of the drug through the needle.

2. The injection device as claimed in claim 1 , wherein the first drug precursor comprises a lyophilized powder.

3. The injection device as claimed in claim 1 or claim 2, wherein the second drug precursor comprises saline.

4. The injection device as claimed in any one of claims 1 to 3, wherein the user activatable mechanism comprises a valve rotatable between a first position wherein the first and second chambers are not in fluid communication and the first and second drug precursors are not able to mix, and a second position wherein the first and second chambers are in fluid communication and the first and second drug precursors are able to mix.

5. The injection device as claimed in claim 4, wherein the valve is rotatable by a quarter-turn.

6. The injection device as claimed in claim 4 or claim 5, wherein the housing defines a cavity having a minor cross-sectional dimension and a major cross-sectional dimension, the major cross-sectional dimension being larger than the minor cross- sectional dimension.

7. The injection device as claimed in claim 6, wherein the cavity has an elliptical cross-sectional shape.

8. The injection device as claimed in claim 6 or claim 7, wherein the housing comprises a flexible wall, whereby application of a compression force to the flexible wall causes the valve to move from the first position to the second position.

9. The injection device as claimed in any one of claims 4 to 8, further comprising a plunger slidably engaged with the housing.

10. The injection device as claimed in claim 9, wherein the plunger comprises a recess configured to slide over the valve when the valve is in the second position so that the plunger is able to move inwardly of the housing and cause ejection of the drug through the needle.

11. The injection device as claimed in claim 10, wherein the recess comprises a chamfered inlet.

12. The injection device as claimed in any one of the preceding claims, further comprising a needle safety sleeve configured to retract the needle after injection.

13. The injection device as claimed in any one of the preceding claims, wherein the needle is configured to enter a user's skin at an angle of less than 90 degrees relative to a surface of the housing.

14. The injection device as claimed in claim 13, wherein the needle is configured to enter the user's skin at an angle of less than 50 degrees relative to the surface of the housing.

15. The injection device as claimed in any one of the preceding claims, wherein the first substance chamber is configured to hold the first drug precursor under vacuum or partial vacuum.

16. The injection device as claimed in claim 15, wherein the second drug precursor in the second substance chamber comprises a liquid, wherein the vacuum or partial vacuum in the first substance chamber causes the liquid to be drawn towards the first substance chamber when the first and second chambers are in fluid communication.

17. The injection device as claimed in any one of the preceding claims, wherein the predetermined drug comprises a botulinum toxin formulation.

18. The injection device as claimed in any one of claims 1 to 3, wherein:the first substance chamber comprises a first collapsible chamber containing the first drug precursor; and the second substance chamber comprises a second collapsible chamber containing the second drug precursor.

19. The injection device as claimed in any one of claims 1 to 3, comprising a sliding gate movable between a first position wherein fluid communication between the first chamber and the second chamber is prevented, and a second position wherein fluid communication between the first chamber and the second chamber is allowed.

20. The injection device as claimed in claim 19, wherein movement of the sliding gate from the first position to the second position is prevented by a removable member, whereby removal of the removable member enables movement of the sliding gate from the first position to the second position.

21. The injection device as claimed in claim 20, wherein the sliding gate is biased towards the second position such that removal of the removable member causes the sliding gate to move to the second position.

22. The injection device as claimed in claim 21 , comprising a spring configured to bias the sliding gate towards the second position.

23. The injection device as claimed in any one of claims 1 to 3, comprising a needle slider carrying a needle, the needle slider movable between a needle retracted position and a needle extended position.

24. The injection device as claimed in claim 23, wherein movement of the needle slider from the needle retracted position to the needle extended position is prevented by a removable member, whereby removal of the removable member enables movement of the needle slider from the needle retracted position to the needle extended position.

25. The injection device as claimed in claim 24, wherein the needle slider is configured to connect the needle in fluid communication with the drug when the needle slider is in the needle extended position.

26. The injection device as claimed in any one of claims 1 to 3, wherein fluid communication between the first chamber and the second chamber is prevented when a removable member is attached to the injection device and fluid communicationbetween the first chamber and the second chamber is enabled when the removable member is removed from the injection device.

27. The injection device as claimed in claim 26, wherein the first chamber includes a first plunger capable of fluid communication with the needle, wherein inward movement of the first plunger after mixing of the first substance and the second substances to form the drug causes ejection of the drug through the needle.

28. The injection device as claimed in claim 27: wherein the second chamber includes a second plunger slidably received in the second chamber, and the injection device comprises a biasing device arranged to bias the second plunger inwardly of the second chamber, wherein inward movement of the second plunger by the biasing device is prevented when the removable member is attached to the injection device, and inward the movement of the second plunger by the biasing device is enabled when the removable member is removed from the injection device; and wherein removal of the removable member causes the second substance in the second chamber to move to the first chamber and mix with the first substance.

29. The injection device as claimed in claim 28, wherein the biasing device comprises a spring.

30. The injection device as claimed in any one of claims 26 to 29, wherein the first chamber includes a first chamber opening, the second chamber includes a second chamber opening, and the drug injection device includes a flexible membrane disposed over at least one of the first and second chamber openings, wherein the removable member engages with the flexible membrane and the first and / or second chamber opening to prevent fluid communication between the first and second chambers when the removable member is attached to the injection device.

31. The injection device as claimed in claim 30, wherein the removable member includes a protruding portion that urges the membrane towards the first and / or second chamber opening to thereby seal the first and / or second chamber opening when the removable member is attached to the injection device.

32. The injection device as claimed in any one of claim 26 to 31 , comprising a resilient layer provided with a fluid communication path extending between the first chamber and the second chamber, and a compression member, wherein theremovable member is arranged to urge the compression member against the resilient layer to close the fluid communication path when the removable member is engaged with the injection device, and wherein removal of the removable member from the injection device causes the fluid communication path to open.

33. The injection device as claimed in claim 32, wherein the removable member comprises a clevis pin.

34. The injection device as claimed in any one of claims 28 to 33, wherein the removable member is configured to engage with the second plunger to prevent movement of the second plunger inwardly of the second chamber.

35. The injection device as claimed in claim 34, wherein the removable member comprises a clevis pin.

36. The injection device as claimed in any one of claims 1 to 3, comprising: a housing assembly having the housing, the first substance chamber, the second substance chamber and the user activatable mechanism; a cradle member comprising the needle, the cradle member configured to receive the housing assembly such that the housing assembly is movable towards and away from the cradle member; and a biasing arrangement arranged to bias the housing assembly away from the cradle member; wherein movement of the housing assembly towards the cradle member causes the needle to form a fluid communication path with the drug.

37. The injection device as claimed in claim 36, wherein the housing assembly is arranged to engage with the needle when the housing assembly has moved towards the cradle member so that retraction of the housing assembly away from the cradle member causes the needle to retract with the housing assembly.

38. The injection device as claimed in any one of the preceding claims, wherein at least one component of the injection device comprises cyclic olefin copolymer (COC) and / or cyclic olefin polymer (COP) material.

39. The injection device as claimed in any one of the preceding claims, wherein at least one component of the injection device is coated with EthyleneTetrafluoroethylene (ETFE) material.

40. A drug injection system comprising a support member and at least one injection device as claimed in any one of the preceding claims, the support member configured to engage with the at least one injection device.

41. The drug injection system as claimed in claim 40, wherein the support member is arranged to engage with the at least one injection device such that each injection device is pivotable between a first position wherein the needle does not protrude from the support member and a second position wherein the needle protrudes from the support member.

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