`Knauer
`
`(54)
`
`SELF ADMINISTERED INJECTION PEN
`APPARATUS AND METHOD
`
`(75)
`
`73)
`
`Inventor: Peter M. Knauer, San Carlos, Calif.
`Assignee: Genentech, Inc., South San Francisco,
`Calif.
`
`21
`22
`51
`52
`
`(58)
`
`(56)
`
`Appl. No.: 195,307
`Feb. 14, 1994
`Filed:
`Int. Cl. ........................... A6M S/20
`U.S. Cl. .......................... 604/136; 604/187; 604/198;
`604/28
`Field of Search ............................ 604/131, 135-139,
`604/156, 187, 208, 211, 218, 220, 232
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`3,905,365
`4,394,863
`4,405,317
`4.413,760
`4,498,904
`4,585,439
`4,601,708
`4,642,099
`4,673,396
`4,701,165
`4,755,169
`4,832,690
`4,865,591
`4,874,383
`4,883,472
`4,931,043
`4,936,833
`4,966,585
`4,968,299
`4,969,874
`5,017,190
`5,019,053
`5,032,114
`5,042,977
`5,050,617
`5,085,641
`
`9,975 Colombo.
`7/1983 Bartner.
`9, 1983 Case.
`11F1983 Paton .
`2A1985 Turner et al.
`4f1986 Michel.
`7/1986 Jordan.
`2/1987 Phillips et al..
`6/1987 Urbaniak.
`10/1987 DeHaitre
`7/1988 Sarnoff et al. .
`5/1989 Kuu.
`9/1989 Sams.
`10/1989 McNaughton.
`f989 Michel.
`6/1990 Ray et al..
`6/1990 Sans.
`10/1990 Gangemi.
`11/1990 Ahlstrand et al. .
`11F1990 Michel et al. .
`5/1991 Simon et al. .
`5/1991 Hoffman et al. .
`7/1991. Oowson
`8/1991. Bechtoid et al. .
`9/1991 Columbus et al.
`2/1992 Sarnoff et al. .
`
`III III
`US005514097A
`11) Patent Number:
`45) Date of Patent:
`
`5,514,097
`May 7, 1996
`
`5,085,642 2/1992 Sarnoff et al..
`5,092,842 3/1992 Bechtold et al. .
`5,104,380 4/1992 Holman et al..
`5,112,317 5/1992 Michel.
`5,114,406 5/1992 Gabriel et al..
`5,176,657
`1/1993 Shields.
`5,226,895 7/1993 Harris.
`5,226,896 7/1993 Harris.
`5,232,459 8/1993 Hjertman.
`5,244,465 9/1993 Michel.
`5,273,544 12/1993 van der Wal.
`FOREIGN PATENT DOCUMENTS
`0268191A2 11/1987 European Pat. Off. .
`0327910A2 8/1989 European Pat. Off..
`0373321A1 10/1989 European Pat. Off..
`0496141 7/1992 European Pat. Off..
`0525525 2/1993 European Pat. Off. .
`0557559A1 9/1993 European Pat. Off. .
`8813905 12/1989 Germany.
`WO87/02895 5/1987 WIPO
`WO90/04423 5/1990 WIPO
`93.10838
`6/1993 WIPO.
`WO93/16740 9/1993 WIPO.
`Primary Examiner-C. Fred Rosenbaum
`Assistant Examiner-Perry E. Van Over
`Attorney, Agent, or Firm–Skjerven, Morrill, MacPherson,
`Franklin & Friel; Forrest E. Gunnison; Philip J. McKay
`(57)
`ABSTRACT
`A medicament injection apparatus for subcutaneous or intra
`muscular delivery of a medicament conceals the needle
`behind a needle shroud. On apparatus activation, the needle
`is trust forward, pushing the needle tip outside the needle
`shroud with enough force to puncture the skin. The needle
`is thus automatically introduced into the tissue at the proper
`needle\skin orientation. In the same action, the apparatus
`automatically dispenses an accurate pre-set dose. The dose
`can be set by a manual, variable dosing assembly or by an
`automatic dosing assembly. The automatic dosing assembly
`includes a safety mechanism preventing the pre-set dose
`from being changed except by a doctor or patient using a
`special wrench or tool.
`
`202
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`62 Claims, 16 Drawing Sheets
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`May 7, 1996
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`1.
`SELF ADMINISTERED INJECTION PEN
`APPARATUS AND METHOD
`
`FIELD OF THE INVENTION
`This invention relates, generally, to medicament delivery
`apparatuses, and, more particularly, to self administered
`injection pen apparatuses.
`
`2
`axial movement in a direction toward needle assembly 13.
`The movement of plunger 15 towards end 12 controls the
`volume of medicament expelled through needle assembly
`13.
`Prior art injection pen device 11 has no mechanism for
`allowing the introduction of an accurate dose less than the
`entire content of medicament cartridge assembly 10. Several
`improvements have been made on this basic design which
`deliver portions of medicament 28 in medicament cartridge
`assembly 10 in pre-set doses. However, the improved ver
`sions require considerable patient interaction with some
`form of relatively complicated dosing mechanism to set the
`dose with each injection.
`Typically, prior art medicament injection devices require
`the patient to manually insert an exposed needle into his or
`her own tissue. For many patients this is a traumatic routine.
`Often injections are necessary on a daily basis which can
`result in considerable psychological damage to the patient
`and his or her attitude towards treatment. In many cases the
`patient simply stops giving himself or herself treatment;
`adopting the attitude that the cure is worse than the affliction.
`Patient non-compliance is a particularly poignant problem
`when the patient is a child and, unfortunately, children make
`up a considerable percentage of those patients taking part in
`treatment programs requiring self administered subcutane
`ous or intramuscular injections. For instance, at present, in
`the United States, growth hormone treatment is only
`approved for children. Additionally, many diabetics must
`begin insulin treatment at an early age.
`Further, when a patient manually inserts a needle there is
`a strong possibility that the patient will not place the needle
`in the proper orientation relative to the skin. The needle
`typically should enter the body perpendicular to the skin
`surface. If the patient is traumatized by the treatment rou
`tine, or is under time pressure, a sloppy and ineffective
`injection is likely to result from a non-perpendicular injec
`tion. When the needle enters the tissue at the wrong needle/
`skin orientation the injection may fail to properly introduce
`the medicament. Such improperly oriented injections, of
`course, are, at best, a waste of costly medicament and, at
`worst, may be dangerous.
`Yet another difficulty with prior art injection pens is that
`the dose-setting mechanisms are complicated and usually
`involve reading some form of digital or analog meter while
`setting the dose. These prior art injection pens do not allow
`the patient to accurately set the dose in the event that the
`patient is either disabled or in a state incapable of reading a
`dose meter or setting some relatively complicated analog
`device.
`Prior art dose-setting mechanisms using dose meter dis
`plays alone are a particular problem for diabetics who,
`because of their disease, are often blind. However, any
`patient who is either permanently or temporarily disabled, or
`is in an emergency situation, may find prior art dose mecha
`nisms inadequate or perhaps useless.
`Another problem is that two different unit systems for
`measuring the dose are commonly used; milliliters (ml) and
`international units (IU). In some cases, the patient can
`become confused as to which units the prior art dose meter
`is displaying. This situation can lead to improper dosage
`which, of course, is dangerous. Thus, while prior art injec
`tion pens are better than a syringe, such injection pens are
`not suitable for use in a wide variety of circumstances.
`SUMMARY OF THE INVENTION
`According to the principles of this invention, a medica
`ment injection apparatus automatically administers a prede
`
`10
`
`15
`
`25
`
`BACKGROUND OF THE INVENTION
`Self administered subcutaneous or intramuscular injec
`tions are well known in the medical arts and have long been
`considered standard treatment for those persons, such as
`diabetics, who require fixed or measured doses of medica
`ment on a regular and relatively frequent basis. Further,
`newer treatments, such as growth hormone injections, also
`require self administered injections on a regular basis.
`Self administered injections considerably decrease the
`cost of treatment and increase the quality of the patients life
`by decreasing or even eliminating the need for some visits
`to the doctor. Self administered injections also provide
`patients with the opportunity to privately administer their
`own treatment, without involving third parties, thus giving
`the patient a sense of independence and control.
`Typically, self administered injections were rendered
`using common syringes adapted to receive cartridges of
`pre-measured doses of medicament. However, such self
`administered injections suffered from several drawbacks and
`were particularly ill suited for use by children or patients
`30
`with disabilities because they required the patient to manu
`ally insert an exposed needle in the tissue.
`FIG. 1 is a cross-sectional view of a typical prior art
`injection pen 11. Injection pen 11 had three major compo
`nents: (i) a pre-filled medicament cartridge assembly 10
`containing a medicament 28; (ii) a cartridge housing 16
`formed to receive pre-filled medicament cartridge assembly
`10, and having a double sided needle assembly 13 mounted
`on one end 20; and (iii) a dispensing assembly 2. Each of
`the three major components are described more completely
`below. For a more complete description of a particular
`injection pen 11, see commonly assigned U.S. patent appli
`cation Ser. No. 08/146,313 entitled "An Injection Pen Solu
`tion Transfer Apparatus and Method” of Peter Michel,
`Robert Freeman, James Oeswein filed on Nov. 2, 1993,
`which is incorporated herein by reference in its entirety.
`End 12 of pre-filled medicament cartridge assembly 10
`has a seal assembly 26 that is pierced and penetrated by
`needle 27 to dispense medicament 28. A second end 14 of
`pre-filled medicament cartridge assembly 10, that is oppo
`site to end 12, is sealed by a slidable plunger 15.
`Typically, cartridge housing 16 receives the pre-filled
`medicament cartridge assembly 10 through an open end 17.
`End 20 of cartridge housing 16, that is opposite open end 17,
`is generally removably mounted to double sided needle
`assembly 13 for subcutaneous or intramuscular injection of
`medicament 28. Removably mounted to end 17 is a dis
`pensing assembly 21 that is operably coupled to cartridge
`plunger 15.
`Specifically, a cartridge seat 22 of dispensing assembly 21
`is formed to mount directly to sleeve 16, via mating threads
`23. Upon mounting dispensing assembly 21 to cartridge
`housing 16, end 12 of medicament cartridge assembly 10 is
`forced into engagement with needle assembly 13. A pushrod
`24, having a pushrod piston head 18, which abuts a backside
`25 of plunger 15, is mounted to cartridge seat 22 to permit
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`termined dose of a medicament, sometimes called a pre-set
`dose, for either a subcutaneous or intramuscular injection
`when the patient activates a dose knob of the medicament
`injection apparatus. When activated, the medicament injec
`tion apparatus of this invention pushes a plurality of assem
`blies that include a needle, in one embodiment, forward with
`sufficient force that the needle penetrates the patient's skin
`and then the medicament injection apparatus dispenses a
`predetermined and pre-set dose of medicament into the
`patient's tissue. The patient is thereby spared the trauma of
`manually introducing an exposed needle into his or her own
`tissue. Further, the medicament injection apparatus of this
`invention includes an automatic dosing assembly which
`requires minimal patient manipulation to automatically set
`the predetermined dose. This feature allows the medicament
`injection apparatus to be used safely by disabled patients and
`patients in emergency situations.
`In one embodiment, the medicament injection apparatus
`of this invention includes a housing which encloses an
`interior volume. The housing has a first end and an second
`end opposite the first end. One end of a needle shroud is
`removably affixed to the first end of the housing. An
`opposite end of the needle shroud, removed from the hous
`ing, is open.
`A medicament injection assembly, that includes a plural
`ity of assemblies including, for example, a medicament
`cartridge assembly and a variable dosing assembly, is mov
`ably mounted within the housing so that upon engagement
`and activation of a motive force that is supplied by the
`medicament injection assembly, the plurality of assemblies
`move from a first position to a second position. This motion,
`which is supplied by a thrusting assembly, moves not only
`the entire plurality of assemblies but also subassemblies and
`parts within those plurality of assemblies to deliver the
`desired dose of medicament. In contrast, typically in prior
`systems, the only movement was of the parts required to
`deliver a dose and movement of entire assemblies was not
`provided because the user manually injected the needle into
`the skin.
`The medicament injection assembly can include a needle
`attached at an end closest to the needle shroud open end. In
`one embodiment, the needle is protected with a needle safety
`cap that encloses the needle.
`The plurality of assemblies are removably affixed to one
`another by threads or some other mechanism which allows
`the assemblies to be connected and disconnected from each
`other. For example, the medicament cartridge assembly is
`configured to contain a vial of medicament. When the
`medicament cartridge assembly is removably affixed to the
`variable dosing assembly, the vial is positioned within the
`medicament cartridge assembly by a cartridge seat which is
`part of a pushrod subassembly which, in turn, is part of the
`variable dosing assembly. Specifically, the cartridge seat has
`threads on an exterior surface that interface with threads on
`an interior surface of the medicament cartridge assembly.
`When the motive force of the medicament injection
`assembly moves the plurality of assemblies forward from
`the first position to the second position within the housing,
`one end of the needle extends a predetermined distance
`outside the open end of the needle shroud. The needle is
`thrust forward with sufficient force to penetrate the skin and
`extend into the tissue. The distance the needle extends
`outside the needle shroud can be adjusted by exchanging
`needle shrouds.
`In one embodiment, the needle shroud is removably
`affixed to the housing by a simple friction mounting. Thus,
`
`4
`in this embodiment, the needle shroud can be simply pulled
`off and another shroud attached in its place. This feature
`allows the same medicament injection apparatus to be used
`for different types of injections, i.e., intramuscular versus
`subcutaneous, and allows a single medicament injection
`apparatus to adapt to a growing child.
`The needle shroud conceals the injection needle from the
`patient until the medicament injection assembly is activated.
`Thus, the patient is spared the trauma of handling an
`exposed needle prior to and during injection and, in contrast
`to prior art systems, the patient is not forced to manually
`introduce the needle into his or her own tissue or even see
`an exposed needle prior to and during injection.
`Further, once the needle has been extended, the medica
`ment injection assembly dispenses a predetermined and
`pre-set amount of medicament into the tissue. The amount of
`medicament dispensed can be manually pre-set or, in one
`embodiment, an automatic dose can be selected by a simple
`manipulation of a dose knob. This novel feature allows the
`patient to administer an accurate pre-set dose without having
`to read a dose meter or make complicated adjustments as
`was required by prior art dosing mechanisms. Thus, the
`medicament injection apparatus of this invention is ideal for
`disabled persons such as the blind and for use in emergency
`situations where time is critical.
`Additionally, in one embodiment, the maximum auto
`matic dose can be set by a doctor or patient with a special
`tool. Once the automatic dose is set it cannot be changed
`without this tool. The automatic dose is a pre-set maximum
`dose and therefore provides protection from accidental over
`dose. Even when the dose is set manually it cannot exceed
`the automatic dose.
`Due to the simplicity of its operation and its safety
`features, the medicament injection apparatus of this inven
`tion is well suited for use by a wide range of patients
`including children and those with permanent or temporary
`disabilities. To use one embodiment of the medicament
`injection apparatus of this invention, the patient simply (i)
`energizes the motive force subassembly by cocking the
`medicament injection apparatus, (ii) removes the needle
`safety cap, (iii) turns the dose knob as far as it will turn in
`one direction, (iv) places the open end of the needle shroud
`over the injection site, and (v) depresses the dose knob. The
`result of these five simple steps is that the needle automati
`cally enters the skin at the proper, substantially perpendicu
`lar, orientation and an accurate pre-set dose is delivered
`without the patient ever having seen the needle. Thus, the
`medicament injection apparatus of this invention is simpler
`to use and safer than prior art systems.
`In one embodiment, the medicament injection assembly
`includes, in addition to the plurality of assemblies, an
`automatic dosing assembly mounted in the interior volume
`of the housing. Upon engagement and actuation of the
`medicament injection assembly, the automatic dosing
`assembly applies the motive force to the plurality of assem
`blies thereby moving the plurality of assemblies from the
`first position to the second position.
`The automatic dosing assembly includes a thrusting
`assembly, and a dose knob stop assembly. The thrusting
`assembly includes a motive force subassembly that is selec
`tively engaged and actuated by a user. Upon engagement and
`actuation of the motive force subassembly, the thrusting
`assembly moves the plurality of assemblies of the medica
`ment injection assembly from the first position to the second
`position.
`The thrusting assembly also includes a tubular dose knob
`that is selectively engaged with the variable dosing assembly
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`of the medicament injection assembly. The tubular dose
`knob has a first open end and a second end opposite to the
`first open end. Upon engagement of the tubular dose knob
`with the variable dosing assembly and movement of the
`tubular dose knob in a selected direction, the user adjusts the
`amount of medicament dispensed from the medicament
`injection apparatus. Those skilled in the art will appreciate
`that the dose knob can be utilized independently of the other
`parts and assemblies in the automatic dosing assembly and
`that the tubular nature of the dose knob is illustrative of only
`one embodiment of the dose knob and is not intended to
`limit the invention to only the tubular configuration.
`The dose knob stop subassembly is coupled to the tubular
`dose knob so that the dose knob stop assembly limits
`movement of the tubular dose knob in the selected direction
`which in turn limits the amount of the medicament to be
`dispensed from the medicament injection apparatus to a
`predetermined and pre-set limit. The dose knob stop assem
`bly includes two structures that are coupled to the tubular
`dose knob. Each of the two structures has a surface. The two
`structures can be, for example, either angled cylinders or
`stepped angled cylinders.
`The two structures are mounted so that the surfaces
`interact and interface with one another such that a combined
`length of the two structures is variable depending on a
`relative position of the two surfaces. The variable combined
`length determines the predetermined and pre-set limit.
`A dose-limiting sleeve is coupled to at least one of the two
`structures. The dose limiting sleeve can be selectively
`engaged by the user, e.g., engaged by the user via use of a
`special tool, to adjust the relative position of the surfaces of
`the two structures to set the predetermined and pre-set limit.
`In one embodiment, the dose limiting sleeve is a tubular
`structure having a first open end and a second end opposite
`the first open end. One of the two structures is positioned
`within the first open end of tubular structure. This structure
`includes a set of grooves and the dose limiting sleeve tubular
`structure includes a set of rails. The sets of grooves and rails
`rotationally couple the one of the two structures and the dose
`limiting sleeve tubular structure so that the one of the two
`structures and the dose limiting sleeve tubular structure
`rotate together. The set of grooves and the set of rails are
`illustrative of a first rotational interlocking structure and a
`second rotational interlocking structure, respectively,
`wherein the interaction of the first and second rotational
`interlocking structures rotationally couples the two parts
`containing the first and second rotational interlocking struc
`tureS.
`As mentioned above, one of the plurality of assemblies of
`the medicament injection assembly is a variable dosing
`assembly movably coupled to the automatic dosing assem
`bly, and having a first end. The variable dosing assembly is
`selectively engaged by the user to dispense a predetermined
`and adjustable amount of a medicament from the medica
`ment injection apparatus upon engagement and actuation of
`the medicament injection assembly.
`Another one of the plurality of assemblies of the medi
`cament injection assembly is a medicament cartridge assem
`bly that is removably affixed to the first end of the variable
`dosing assembly, as described above. The medicament car
`tridge assembly has a first end and a second end opposite the
`first end. The second end is fashioned to accept a medica
`ment cartridge having a first sealed end and a second end
`opposite the first sealed end which contains a movable
`plunger.
`A needle subassembly is removably affixed to the first end
`of the medicament cartridge assembly, in one embodiment.
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`When the needle subassembly is in the first position, the
`needle is contained within the needle shroud, as explained
`above. Similarly, when the needle subassembly is in the
`second position, the needle has an end extending through the
`open end of the needle shroud. The needle safety cap is
`removably affixed to the medicament cartridge assembly so
`that the needle safety cap encloses the needle. Specifically,
`in one embodiment, a groove in an inner surface of the
`needle safety cap snaps over a radial lip of the medicament
`cartridge assembly.
`As mentioned previously, the variable dosing assembly
`includes a pushrod subassembly and a dosing sleeve subas
`sembly. The pushrod subassembly includes a pushrod that is
`used to engage the plunger and to moves the plunger in the
`first direction inside the medicament cartridge. The dosing
`sleeve subassembly is movably mounted on the pushrod.
`The dosing sleeve subassembly position on the pushrod
`determines how far the pushrod can move in the first
`direction, which in turn determines the dose injected by the
`medicament injection apparatus of this invention.
`In addition to the various assemblies and Subassemblies
`described above, the medicament injection assembly
`includes a runner having a first tubular portion and a second
`tubular portion. The first tubular portion has a first open end
`and a second open end opposite the first open end. The
`second open end of the first tubular portion is coupled to a
`first open end of the second tubular portion and the second
`tubular portion has a second open end opposite the first end.
`The dosing sleeve subassembly of the variable dosing
`assembly is partially positioned within the first open end of
`the first tubular portion of the runner such that the dosing
`sleeve subassembly can move back and forth in both the first
`direction and the second direction within the first tubular
`portion of the runner. The second tubular portion of the
`runner has a smaller cross-section than a cross-section of the
`first open end of the tubular dose knob so that at least part
`of the second tubular portion of the runner is positioned
`inside the first open end of the tubular dose knob and the
`second tubular portion can move back and forth in both the
`first direction and the second direction within the tubular
`dose knob.
`In one embodiment, the second tubular portion of the
`runner includes a set of grooves and the tubular dose knob
`includes a set of rails. The set of grooves and rails rotation
`ally couple the runner and the tubular dose knob so that the
`runner and the tubular dose knob rotate together to move the
`dosing sleeve subassembly back and forth in both the first
`direction and the second direction within the first tubular
`portion of the runner. Thus, this action adjusts the amount of
`medicament dispensed from the medicament injection appa
`atuS.
`In this embodiment, the first open end of the second
`tubular portion of the runner contains one end of the pushrod
`along with the attached trust bearing. Thus, the pushrod
`effectively closes the first end of the second tubular portion.
`The second end of the tubular dose knob is also closed. The
`second tubular portion of the runner with the pushrod and
`the tubular dose knob form an enclosed cavity with a
`variable length which is smaller when the plurality of
`assemblies of the medicament injection assembly are in the
`first position and larger when the plurality of assemblies are
`in the second position.
`The pushrod and the runner are coupled so that when the
`plurality of assemblies are in the first position the pushrod
`and the runner are removably affixed and when the plurality
`of assemblies move from the first position to the second
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`position the pushrod and the runner remain removably
`affixed and move together a predetermined distance in the
`first direction. The pushrod is uncoupled from the runner
`once the pushrod and the runner have moved together the
`predetermined distance. Therefore, the pushrod can move
`forward, independently of the runner, past the predetermined
`distance in the first direction.
`The motive force subassembly is positioned inside the
`cavity such that the motive force subassembly exerts a force
`on the pushrod and, therefore the runner, in the first direction
`and the motive force subassembly exerts a force on the
`tubular dose knob in the second direction when the plurality
`of assemblies are in the first position.
`The thrusting assembly, described above, also includes a
`lock ring that selectively engages and holds the tubular dose
`knob against the force exerted in the second direction, and
`a needle thrust locking mechanism that selectively engages
`and holds the runner, and therefore the pushrod, against the
`force exerted in the first direction. The motive force subas
`sembly comprises a spring and a thrust bearing.
`The above embodiment is illustrative of only the prin
`ciples of this invention. Those skilled in the art will appre
`ciate that a variety of novel medicament injection appara
`tuses can be formed using various combinations of the novel
`assemblies and subassemblies of this invention. For
`example, if a maximum permissible dose is not of concern,
`only the thrusting assembly of the automatic dosing assem
`bly would be utilized. The resulting medicament injection
`apparatus provides manually adjustable doses by simply
`turning the dose knob, for example, three complete revolu
`tions would be one dose and four complete revolutions
`another dose. This simple dose adjustment combined with
`the motion provided by the thrusting assembly allows accu
`rate and reliable injections in a wide variety of situations
`including low light or use by a blind person.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 is an exploded, fragmentary, front elevation view,
`in partial cross-section, of a prior art injection pen device.
`FIG. 2 is an enlarged, front elevation view, in cross
`section, of a medicament injection apparatus constructed in
`accordance with the present invention.
`FIG. 3 is an enlarged, front elevation view, in cross
`section, of a medicament injection apparatus constructed in
`accordance with the present invention along with lines 5 and
`6 which divide the medicament injection apparatus into the
`three sections detailed in FIGS. SA-7.
`FIG. 4 is an angled cut away view of the medicament
`injection apparatus of FIG. 3.
`FIG. 5A is an enlarged, fragmentary, front elevation view,
`in cross section, of a portion of an medicament injection
`apparatus constructed in accordance with the present inven
`tion including the medicament cartridge assembly.
`FIG. 5B is an exploded top perspective view of the
`portion of the medicament injection apparatus of FIG. 5A.
`FIG. 6A is an enlarged, fragmentary, front elevation view,
`in cross section, of a portion of a medicament injection
`apparatus constructed in accordance with the present inven
`tion including the variable dosing assembly.
`FIG. 6B is an exploded top perspective view of the
`cartridge seat, pushrod locking mechanism, rachet sleeve,
`dose-setting sleeve, and runner of FIG. 6A.
`FIG. 6C is an enlarged, side view of the pushrod, with
`pushrod piston head, of FIG. 6A.
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`FIG. 6D is an enlarged, perspective view of a portion of
`the pushrod of FIG. 6C.
`FIG. 6E is an enlarged, top view of a portion of the
`pushrod o