Medical injection device for multiple injections

Abstract

A medical injection device comprises a medication container having a movable piston; a push rod having a plurality of spaced-apart position setting means disposed along the length and selectively displacing the movable piston to dispense a medicament from the medication container; a push rod sheath configured to engage with the position setting means on the push rod and moving the push rod toward to the distal end of the medical injection device; an upper cylinder configured to engage with the push rod sheath and moving the push rod sheath toward to the distal end of the medical injection device; and a resilient member configured to move the push rod sheath toward the proximal end of the medical injection device. The prefilled injection device is used to deliver multiple doses of medication.

Description

MEDICAL INJECTION DEVICE FOR MULTIPLE INJECTIONSBACKGROUND OF THE INVENTION

[0001] The present invention relates to a medical injection device for delivering medication in fluid dosage forms, such as solution dosage form, suspension dosage form, emulation dosage form or other forms in fluid state.

[0002] As injectable drugs increase in popularity, medical injection devices are expected to be widely used. Medical injection devices, such like the autoinjector, can ease medication preparation / administration and reduce needle injury, which results in improved patient convenience and compliance. Due to the advantages mentioned above, more patients and healthcare professionals prefer the user-friendly medical injection devices over the traditional manual syringes. Many devices of the above mentioned type allowing a patient to self-administer one or two doses of a medication are known. US Pat. No. 6,575,939 discloses an autoinjector device comprising a syringe housed in a casing formed by an inner part and an outer part capable of sliding in relation to each other. This device allows a single dose of medicament to be administered. EP Pat. No. 700307 discloses a two-dose medical injection device allowing the automatic delivering of a first dose of a medicament and the manual administration of a second dose. US Pat. No. 8,961 ,463 describes a medical injection device that allows the end-user to self administer first and second doses of a medicament. However, the actuation mechanism for delivering the first and second doses are quite different and the mechanism cannot be applied for delivering more than two doses. DE 19519147 A1 relates to an injection device allowing the injection of multiple doses through a pushing member having several tooth pitches disposed along its length. DE 19519147 A1 also discloses a pushing member displacing a syringe piston to dispense an amount of medicament contained in such syringe depending on the position of the tooth pitch engaging the pawls.However, the arming operation of the device disclosed in DE 19519147 A1 has to be done by manually pulling the device in order to re-arm the injection device. Similarly, WO 94 / 26331 A1 also fails to disclose an injection device with a re-arming mechanism without manual operation.

[0003] Another popular type of medical injection device is a pen injector. Such pen injector devices may contain a dose metering mechanism that administers a dose based on end-user selection. These devices are capable of delivering multiple doses. As for pen injectors, a lead screw or rotating plunger is provided which is mechanically coupled to a dose-setting knob or other actuator through a series of screw type of mechanical connections. The typical pen injector mechanism is fairly complex and consists of multiple cooperating parts. For the reasons of cost and simplicity of use, a minimum number of working parts is desired. Furthermore, the dosing amount using the pen injector can be modified by the user, which is not a good option when the fixed dose is required for each injection. Moreover, none of the pen injectors can be automatically re-armed for multiple injections.

[0004] It would be an improvement in the art, therefore, to provide a multiple use injection device with automatic re-arming operation for injecting a medicament multiple times for fixed doses with the same operation manner, which is also user- friendly and is easier to manufacture as compared to the existing devices. The fixed doses mean that each dose among the multiple injections cannot be changed by user.SUMMARY OF THE INVENTION

[0005] The basic idea of the invention is to provide medication delivering mechanisms with features that are typically actuated through direct application of linear force. The present invention provides a multiple dosing injector with automatic re-arming mechanism. The medical injection device of the present invention includes a drive mechanism and a pre-filled medication container. The body of the medical injection device of the present invention includes proximal and distal portions, with the proximal portion housing the drive mechanism with an automatic re-arming mechanism and the distal portion housing the pre-filled medication container. The multiple injection of the present invention are achieved by providing a medical injection device including the driving mechanism having a push rod assembly with a plurality of spaced-apart position setting features along the length thereof. The position setting features are configured to allow the push rod to displace distallytoward a distal end of the body but not proximally toward a proximal end of the body. The injection operation of each time is the same, which is easy for user to remember. The drive mechanism is also capable of being automatically re-armed for multiple times of injection. The dosing amount is fixed for each time of the injection during the multiple uses. By this way, the dosing errors caused by user can be avoided.Additional and / or other aspects and advantages of the present invention will be set forth in part in the description that follows and, in part, will be apparent from the description, or may be learned by practice of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The figures are schematic and simplified for clarity, and they just show details, which are essential to the understanding of the invention, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts.

[0007] FIG. 1 is a perspective view of an exemplary medication injection device assembly according to the invention.

[0008] FIG. 2 shows a cross-sectional view of the exemplary medication injection device assembly according to the invention.

[0009] FIG. 3 shows another cross-sectional view of the exemplary medication injection device assembly according to the invention.

[0010] FIG. 4 shows operations of the first injection of the exemplary medication injection device assembly according to the invention.

[0011] FIG. 5 shows re-arming operation, after the first injection, of the exemplary medication injection device assembly according to the invention.

[0012] FIG. 6 shows a cross-sectional view of an alternative medication injection device assembly according to the invention.DETAILED DESCRIPTION THE DRAWINGS

[0013] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0014] The apparatus and methods presented herein can be used for delivering any of a variety suitable therapeutic agents or substances, such as a drug, into a patient. Initially it may be convenient to define that, the term "distal end" is meant to refer to the end of the medication injection device assembly inserted into the patient, whereas the term “proximal end” is meant to refer to the end opposite to the "distal end" along the longitudinal axis of the device body. The words "upward", "downward", "upper", "lower", “right” and “left” designate directions in the drawings to which reference is made. The words “inward” and “outward” refer to directions toward and away from, respectively,

[0015] FIGS. 1 -4 illustrate the construction and function mechanism of an exemplary medication injection device assembly 10 according to the invention. With reference to FIG. 1 , a push rod sheath 101 , placed at the proximal end of the device assembly 10, is part of the drive mechanism for injecting medication. The push rod sheath 101 is assembled together with an upper cylinder 102. The upper cylinder 102 is further assembled with a lower cylinder 103. With reference to FIG. 2, in this exemplary medication injection device assembly 10, a pre-filled cartridge 109 is used as medication container. A medication in liquid or suspension formulation is sealed by a movable piston 109a and stationary septum 109b. For the device assembly 10, there is a push rod assembly assembled together with the upper cylinder 102. The push rod assembly includes a push rod sheath 101 , a push rod 104, a stopping disk 107 and a spinner disk 108. On the push rod 104, there are multiple pairs of one-way inward bendable arms, 104a, 104b, 104c, 104d and 104e. At the distal end of the push rod 104, the spinner disk is attached to the push rod 104. The blocking feature 101 a is provided at the distal end of the push rod sheath 101 for applying pushing force on the push rod 104 and preventing the one-way bendable arms on the push rod 104 from moving proximally. There is an inner cylinder 106 placed inside theupper cylinder 102. The inner cylinder 106 is also assembled together with the lower cylinder 103 in a stationary position. With reference to FIGS. 2 and 3, a returning spring 105 is placed between the inner cylinder 106 and the push rod sheath 101 .

[0016] With reference to FIG. 2, before use, a double ended needle 1 10, for example, insulin pen needle, is assembled with the lower cylinder 103, and the double ended steel canula 110a penetrates the septum 109b on the pre-filled cartridge 109 to establish the fluid path for injection. With reference to FIG. 4, during the first injection, by manually pushing the upper cylinder 102 downward, the push rod sheath 101 is pushed downward. Because of the engagement between the blocking feature 101 a on the push rod sheath 101 and the one-way bendable arm 104b on the push rod 104, the push rod sheath 101 pushes the push rod 104 downward. The downward movement of the push rod 104, through the spinner disk 108, causes the downward movement of a movable piston 109a so that the first injection operation is enabled. Meantime, the first pair of one-way bendable arms 104a passes through the stopping disk 107 and the returning spring 105 is compressed.

[0017] FIG. 5 shows the automatic re-arming or re-setting of the device assembly 10. After the first injection, the manual pushing force on the upper cylinder 102 is removed. During the automatic re-arming, the push rod sheath 101 and upper cylinder 102 is pushed proximally by the compressed returning spring 105, in absence of the manual pushing force on the upper cylinder. Because of the engagement between the stopping disk 107 and the one-way bendable arms 104a, the proximal movement of the push rod 207 is restrained. Consequently, the push rod 104 is pulled and extended out from the push rod sheath 101 . The third pairs of the one-way bendable arm 104c pass through the blocking feature 101 a on the push rod sheath 101 . At this point, the injection device 10 is re-armed and ready for the second injection. Before the second injection, the used pen double ended needle is removed and a new double ended needle is assembled with the device assembly 10. During the second injection, by manually pushing the upper cylinder 102 downward, the push sheath 101 is pushed downward. This time, the downward movement of the push rod sheath 101 applies pushing force on the third pair of the one-way bendable arm 104c on the push rod 104, through the engagement between the blockingfeature 101 a on the push rod sheath 101 and the one-way bendable arm 104c on the push rod 104, causing the push rod 104 to move downward. The downward movement of the push rod 104, through the spinner disk 108, causes the further downward movement of the movable piston 109a. Consequently, the second injection operation is delivered. Meantime, the second pair of one-way bendable arms 104b pass through the stopping disk 108 for the next injection. With the same pattern, the third and fourth injections can be accomplished with the automatic rearming mechanism.

[0018] FIG. 6 shows a cross-sectional view of an alternative medication injection device assembly 20 according to the invention. In the alternative medication injection device assembly 20, a push rod assembly includes a push rod 204. On the push rod 204, there are multiple pairs of one-way ratchet teeth, 204a, 204b, 204c, 204d and 204e. There is a push rod sheath 201 . At the distal end of the push rod sheath 201 , there is a pair of outward bendable arms 201 a to engage with the oneway ratchet teeth on the push rod 204 for applying push force on the push rod 204 and preventing the push rod 204 from moving proximally. There is also a pair of outward bendable arms 207a on the stopping disk 207 to engage with the one-way ratchet teeth on the push rod 204 to prevent the push rod 204 from moving proximally.

[0019] All the features in the above embodiments and design concepts herein can be interchanged and combined to generate new device designs. Those of skill in the art will understand that modifications (additions and / or removals) of various components of the apparatuses, methods and / or systems and embodiments described herein may be made without departing from the full scope and spirit of the present invention, which encompass such modifications and any and all equivalents thereof.

Claims

CLAIMS1 . A medical injection device having a distal end and a proximal end, comprising: a medication container having a movable piston; a push rod displaceably disposed in the medical injection device, the push rod having a plurality of spaced-apart position setting means disposed along the length thereof, the push rod selectively displacing the movable piston to dispense a medicament from the medication container; a push rod sheath configured to engage with the position setting means on the push rod and moving the push rod toward to the distal end of the medical injection device; an upper cylinder configured to engage with the push rod sheath and moving the push rod sheath toward to the distal end of the medical injection device; and a resilient member configured to move the push rod sheath toward the proximal end of the medical injection device.

2. A medical injection device as in claim 1 further comprising a stopping disk restraining the push rod from moving toward the proximal end of the medical injection device.

3. A medication injection device as in claim 1 , wherein the position setting means comprising a one-way bendable arm disposed along the length of the push rod.

4. A medication injection device as in claim 1 , wherein the position setting means comprising a one-way ratchet tooth disposed along the length of the push rod.

5. A medication injection device as in claim 1 , wherein the medication container is a pre-filled cartridge.

6. A medication injection device as in claim 5 further comprising a double ended needle.

7. A medication injection device as in claim 1 further comprising a lower cylinder to host the medication container.

8. A medication injection device as in claim 7 further comprising an inner cylinder assembled with the lower cylinder.

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