Automatic injector with cartridge having separate sequentially injectable medicaments

An automatic injector comprising an elongated housing assembly having a forward end, a stressed spring assembly mounted within the rearward end of the housing assembly so as to be released in response to a predetermined manual actuation procedure, and a medicament injection cartridge assembly mounted within the forward end of the housing assembly in cooperating relation with the stressed spring assembly. The improvement of the present invention is in the medicament injection cartridge assembly which includes a medicament container, a hypodermic needle disposed forwardly of the container mounted in a sterile condition within the housing assembly adjacent the forward end thereof. A forward seal is provided for sealing the forward end of the container from the hypodermic needle. A rearward piston is mounted in the rearward end of the container for forward movement therein in slidably sealed relation thereto. A plurality of individual dosages of different relatively incompatible liquid medicaments is disposed within the container between the forward seal and the piston separated by a movable interior seal within the interior of the container between the piston and the forward seal. The improved arrangement is operable in response to the manual accomplishment of the manual actuating procedure and the resultant release of the stressed spring assembly to move the hypodermic needle forwardly and outwardly of the housing assembly into the muscle tissue of a patient and the piston forwardly into the container so that the plurality of individual dosages therein is moved forwardly out of sealed relation with respect to the forward and interior seal outwardly through the needle into the muscle tissue of the patient.

This invention relates to the injection of medicaments and more 
particularly to improvements in injection devices of the type in which the 
insertion of the hypodermic needle and injection of the medicament dosage 
through the inserted needle are both accomplished automatically by a 
spring force in response to a simple actuation procedure. 
It has long been recognized that there are many situations where an 
individual must self-inject a medicament dosage where it is not practical 
to provide the individual with the same syringe type of injection 
equipment normally utilized by professionals to inject others. It is well 
known that many individuals have great difficulty in performing the act of 
pushing a hypodermic needle into one's own flesh. To enable self injection 
to become a simpler, more viable procedure, so-called "automatic 
injectors" have been developed. Basically, injectors of the automatic type 
provide for the storage of a medicament dosage and hypodermic needle 
within a housing in operative relation with a cocked or stressed spring. 
The stressed spring is controlled by a releasing mechanism which, when 
actuated, serves to release the stressed spring, thereby releasing a force 
sufficient to move the hypodermic needle outwardly and the medicament 
dosage outwardly through the needle. A safety device is provided for 
preventing an unwanted actuation of the spring releasing mechanism, thus 
insuring that actuation will take place only after a deliberate actuating 
procedure has been accomplished including an appropriate interengagement 
of the device with the muscle tissue to be injected. 
Examples of automatic injectors which have been heretofore available for 
the injection of nerve gas antidotes and cardiac arrhythmia dosages under 
emergency conditions are U.S. Pat. Nos. 2,832,339; 3,712,301; and 
3,882,863. 
The present invention relates to the provision of automatic injectors which 
have the capability of injecting a plurality of individual medicament 
dosages. This capability has been dealt with in the prior patented 
literature. An early example is contained in U.S. Pat. No. 3,572,336. The 
patent contemplates the automatic injection of a plurality of drugs 
through a plurality of needles simultaneously or where the drugs are 
slightly incompatible, they can be mixed prior to injection into the 
patient through a single needle. In both instances, however, the plural 
capability is obtained by simply providing a plurality of parallel dosage 
receiving chambers and directing the dosages either to a common needle or 
separate needles. In both instances the discharge of the plural dosages is 
simultaneously accomplished by moving interconnected plungers through the 
chambers in a single dosage discharging stroke by a single spring. 
In commonly assigned U.S. Pat. No. 4,226,235, there is disclosed an 
improvement upon the simple plural arrangement of the earlier patent in 
which advantages are attributable to the use of plural injectors having 
the capability of insuring simultaneous or substantially simultaneous 
sequential actuation. The advantages obtained as a result of the 
improvements disclosed in the later patent accrue largely in situations 
where one of the plural dosages is of the type which is likely to be 
changed in the future. 
There are many other situations presented in which it is desirable to 
provide for the injection of plural dosages and yet which do not warrant 
the costs involved in pluralizing the automatic injector structure. For 
example, in nerve gas antidote injectors, a dosage of atropine and 
pralidoxime chloride, both of which are soluble in water, can be desirably 
coupled with a dosage of Valium which is not water soluble and requires a 
propylene glycol solution. Basically, the Valium is an adjuct in nerve gas 
therapy. Consequently, there exists a need for an automatic injector which 
can simply and economically accommodate an additional separate 
incompatible liquid medicament for effective injection together with the 
one already provided in accordance with usual manual procedure for 
effecting automatic operation. 
It is an object of the present invention to fulfill the aforesaid need. In 
accordance with the principles of the present invention this objective is 
obtained by providing an automatic injecting device which includes the 
usual three basic components of an elongated housing assembly having a 
forward end, a stressed spring assembly mounted within the rearward end of 
the housing assembly so as to be released in response to a predetermined 
manual actuation procedure, and a medicament injection cartridge assembly 
mounted within the forward end of the housing assembly in cooperating 
relation with the stressed spring assembly. The improvement of the present 
invention is in the medicament injection cartridge assembly. In accordance 
with the principles of the present invention the improved cartridge 
assembly includes a medicament container, a hypodermic needle disposed 
forwardly of the container mounted in a sterile condition within the 
housing assembly adjacent the forward end thereof. A forward seal is 
provided for sealing the forward end of the container from the hypodermic 
needle. A rearward piston is mounted in the rearward end of the container 
for forward movement therein in slidably sealed relation thereto. A 
plurality of individual dosages of different relatively incompatible 
liquid medicaments is disposed within the container between the forward 
seal and the piston separated by a movable interior seal within the 
interior of the container between the piston and the forward seal. 
Finally, means is provided which is operable in response to the manual 
accomplishment of the manual actuating procedure and the resultant release 
of the stressed spring assembly for moving the hypodermic needle forwardly 
and outwardly of the housing assembly into the muscle tissue of a patient 
and the piston forwardly into the container so that the plurality of 
individual dosages therein is moved forwardly out of sealed relation with 
respect to the forward and interior seal outwardly through the needle into 
the muscle tissue of the patient. 
In terms of the simplicity embodied in the present invention, reference is 
made to commonly assigned U.S. Pat. No. 4,031,893. This patent discloses 
an automatic injector which has been commercially manufactured under the 
trademark ComboPen.RTM. which provides an injection cartridge in which the 
amount of medicament contained within the cartridge is varied by the 
provision of a spacer member within the cartridge container rearwardly of 
the piston thereof. The present invention contemplates the utilization of 
the space taken up by the spacer within the cartridge to contain the 
second medicament. The other modifications to the structure required to 
obtain the present objectives can likewise be simply and economically 
effected. 
An important advantage of the present invention is that applicant has 
ascertained that the manual actuating procedure responsive means described 
above can take a form similar to the structures heretofore provided in 
manually actuated syringes for mixing two separate medicament ingredients, 
usually a powder and a soluent. Examples of prior art structures of this 
type are included in the following patents: U.S. Pat. Nos. 1,943,120; 
2,591,046; 3,326,215; 3,330,282; and 3,494,359. In all of these mixing 
devices of the prior art, the structure provided requires a preliminary 
manual manipulation through which the separately retained ingredients are 
communicated, a subsequent intermixing by manual shaking and, finally, a 
manual injection. As far as applicant is aware, structures of this type 
have never been utilized in automatic injectors where a spring force is 
utilized to effect injection, presumably because of the need for 
sequential manual procedures in the operation thereof. In its broadest 
aspects the present invention contemplates the utilization of any of the 
prior art mixing arrangements. However, in the preferred embodiment 
sequential injection of plural separately retained liquid medicaments is 
achieved by providing a by-pass bulge in the peripheral wall of the 
cartridge container. In order to insure sequential injection of a maximum 
amount of the liquid retained in the cartridge it is preferable to provide 
an intermediate piston having an axial groove in the periphery thereof 
which communicates with a forward peripheral groove in the piston. 
Another object of the present invention is the provision of an automatic 
injector with an improved cartridge having separate sequentially 
injectable medicaments which is simple in construction, effective in 
operation and economical to manufacture and maintain. 
These and other objects of the present invention will become more apparent 
during the course of the following detailed description and appended 
claims. 
The invention may best be understood with reference to the accompanying 
drawings, wherein an illustrative embodiment is shown.

Referring now more particularly to the drawings, there is shown therein an 
automatic injector, generally indicated at 10, which embodies the 
improvements of the present invention. The injector consists essentially 
of three basic assemblies: one, a housing assembly, generally indicated at 
12; two, a power pack or stressed spring assembly, generally indicated at 
14, mounted within the rearward end portion of the housing assembly 12 and 
operable in response to a predetermined manual actuating procedure to be 
released so as to operate the third assembly, which is a medicament 
injection cartridge assembly, generally indicated at 16, embodying the 
improvements of the present invention. While the housing assembly 12 and 
stressed spring assembly 14 can assume any known configuration, the 
preferred embodiment as shown is constructed in accordance with the 
teachings contained in U.S. Pat. Nos. 3,712,301 and 3,882,863, which 
disclosures are hereby incorporated by reference into the present 
specification. 
As best shown in FIGS. 1 and 2, the housing assembly 12 includes an outer 
tubular member 18 having a radially inwardly turned flange 20 on the 
forward end thereof and an interior annular groove 22 in the rearward end 
thereof. The housing assembly 12 also includes an inner tubular member 24 
having a forward end portion of reduced diameter defining an exterior 
forwardly facing shoulder 26 which is adapted to engage the forward flange 
20 of the outer tubular member 18 when the inner tubular member is 
disposed therein in operative position. The inner tubular member 24 
includes a forward end having a needle opening 28 therein and the interior 
of the inner tubular member is configured to receive the cartridge 
assembly 16. 
The stressed spring assembly 14 as preassembled includes an outer tubular 
member 30 having an annular ridge 32 formed on the exterior periphery 
thereof adjacent the rearward end portion which serves to engage within 
the annular groove 22 of the outer tubular member 18 when the injector is 
assembled in operative position, as shown in FIG. 1. The outer tubular 
member 30 includes a rearward end wall 34 having a central opening therein 
defined by a frustoconical surface 36 which diverges inwardly. The 
stressed spring assembly includes a safety cap 38 which detachably fits 
over the portion of the outer member 30 extending rearwardly from the 
outer tubular member 18. The safety cap 38 includes a central inwardly 
extending safety pin 40 which in its normal preassembly position extends 
through and inwardly of the frustoconical surface 36. 
The safety pin 40 is adapted to cooperate with a plurality of spring 
fingers 42 extending from the rear end of a plunger 44 having an annular 
flange 46 extending rearwardly outwardly from the forward end thereof. The 
rearward surface of the flange 46 is adapted to engage one end of a 
stressed coil spring 48, the other end of which engages an apertured rear 
wall 50 of a tubular member 52 slidably mounted within the tubular member 
30. The apertured end wall 50 has formed therein an apertured catch plate 
or disc 54. The central opening of the catch plate 54 is of a size to 
engage inclined surfaces 56 formed on the outer rearward portions of the 
spring fingers 42 so as to deflect the fingers radially inwardly as the 
rearward ends of the fingers pass rearwardly therethrough. Each spring 
finger 42 has formed therein an exterior catch receiving notch 58 which is 
adapted to receive the catch plate 54 when the spring fingers have been 
moved rearwardly through the catch plate into the normal spring stressed 
preassembly position, as shown in FIG. 1. In this regard it will be noted 
that safety pin 40 engages within the inner surfaces of the spring fingers 
42 and hence prevents their radially inward movement so that the tubular 
members 30 and 52, plunger 44 and safety cap 38 can be preassembled and 
mounted in operative position within the outer tubular member 18 as a 
unit. In the operative position, the members 30 and 52 of the power pack 
assembly 14 may be regarded as part of the housing assembly 12. 
Preferably, members 30 and 52, as well as members 18 and 24, are made of a 
suitable plastic material, as is indicated in the aforesaid patents. 
The cartridge assembly 16 which is constructed in accordance with the 
principles of the present invention includes a medicament container 60 
which, as shown, is preferably made of glass and is essentially in the 
form of a necked bottomless bottle having a substantially cylindrical 
peripheral wall. The cartridge assembly also includes a hypodermic needle 
62 which is disposed forwardly of the container 60 and has its rearward 
end connected with the necked end of the container 60 by a connecting 
assembly, generally indicated at 64. The connecting assembly 64 is 
preferably constructed in accordance with the teachings contained in 
commonly assigned U.S. Pat. No. 3,380,449 (see also U.S. Pat. Nos. 
3,391,695 and 3,424,155), the disclosures of all of which are hereby 
incorporated by reference into the present specification. As shown, the 
assembly 64 includes a resilient stopper 66 engaged within the necked end 
of the container 60, the stopper providing a central passage 68 which 
leads to an exterior integral resilient diaphragm seal 70. Disposed in 
exterior engagement with the stopper 66 is a fitting 72. A rearward sleeve 
portion 74 of the fitting 72 is engaged over the forward marginal and 
outer periphery of the stopper 76 and the neck portion of the container 60 
and has its rearward end turned down to effectively secure the components 
of the assembly in operative position. A reduced forward end portion 76 of 
the fitting 72 fixedly receives a portion of the hypodermic needle 62 
spaced slightly from the rearward end thereof. As shown, the rearward end 
of the hypodermic needle is sharpened, as indicated at 77, and positioned 
in forwardly spaced relation from the seal 70. 
In accordance with the principles set forth in U.S. Pat. No. 3,882,863, the 
remaining forwardly extending portion of the hypodermic needle 62 is 
encased within a rubber sheath 78 which serves the dual function of 
maintaining the needle in a sterile condition when the injector 10 is in 
its storage condition and to provide a shock absorbing effect during the 
injection procedure, all in accordance with the teachings set forth in the 
aforesaid patent. 
In accordance with the principles of the present invention, the peripheral 
wall of the container 16 which is otherwise cylindrical includes an 
axially extending radially outward bulge 80. While it is within the 
contemplation of the present invention to simply provide a cylindrical 
interior surface within the interior tubular member 24 to longitudinally 
slidably receive the container 60 therein, as shown the interior periphery 
has formed therein an axial groove 80 of a shape to accommodate the bulge 
80. Mounted within the central portion of the container 60 in a position 
rearwardly of the bulge 80 is an interior seal in the form of an 
intermediate piston 84. As best shown in FIG. 4, the intermediate piston 
84 is preferably made of soft rubber and has formed in the exterior 
periphery thereof a pair of axially spaced forward and rearward annular 
grooves 86. Extending between the forward annular groove 86 and the 
forward face of the intermediate piston 84 is an axial groove 88 which is 
provided for a purpose hereinafter to be more fully described. 
The cartridge assembly 16 also includes a first liquid medicament 90 within 
the container 60 between the forward seal provided by the diaphragm 70 and 
the interior seal provided by the intermediate piston 84. As previously 
stated, an exemplary medicament is a mixture of atropine and pam in a 
water solvent which is used as an anti-nerve gas antidote. 
Mounted within the rear open end of the container 60 is a rearward piston 
92. This piston is similar in construction to the piston 84 except that it 
has a hollow interior configured to receive a central projection 94 
extending forwardly from the plunger 44 so as to provide an 
interconnection between the same. Finally, the cartridge assembly 16 
includes a second relatively incompatible liquid medicament 96 disposed 
within the container 60 between the interior seal provided by the 
intermediate piston 84 and the rear seal provided by the rearward piston 
92. An exemplary medicament 96 is Valium contained within a propylene 
glycol solvent. 
OPERATION 
FIG. 1 illustrates the assembled storage position of the automatic injector 
10 and it will be noted that the stressed spring assembly 14 includes the 
assembled safety cap 38 which serves to prevent the spring fingers from 
moving radially inward to release the stressed spring. The cartridge 
assembly 16 is mounted forwardly within the housing assembly 12 in 
cooperating relation with the stressed spring assembly 14. As previously 
indicated, the forward and rearward liquid medicaments are sealed within 
the container 60 in the manner previously indicated. When it is desired to 
inject the medicaments, the safety cap 38 is initially removed, thus 
displacing the safety pin 40 from its storage position within the spring 
fingers and hence permitting the same to move radially inwardly. 
The actuation procedure consists in the patient manually gripping the 
exterior periphery of the outer tubular member 18 and then moving the 
injector forwardly into contact with the muscle tissue to be injected, as 
for example, a thigh. When the forward end of the inner member 18 engages 
the exterior of the thigh, continued forward movement exerted on the 
exterior periphery of the outer member results in a relative longitudinal 
movement between rear end walls 50 and 34, causing the frustoconical 
surface 36 to engage the spring finger surfaces 56 and thus move the same 
radially inwardly by a camming action so as to disengage the grooves 58 
from the catch plate, thus releasing the stressed spring 48. As the 
stressed spring 48 is released the entire cartridge assembly 16 is moved 
forwardly within the housing assembly 12 during which time the forward 
pointed end of the hypodermic needle 62 moves outwardly through the sheath 
78 and opening 28 and into the muscle tissue of the patient. Rubber sheath 
78 is compressed during this movement and this compression serves to 
retard the final forward movement of the cartridge with a shock absorbing 
effect. As the forward movement of the container 60 and needle 62 is 
retarded, the released stressed spring 48 continues to move the plunger 44 
forward which carries with it the rearward piston 92. The adjacent 
rearward liquid medicament 96 within the container 60 is placed under 
pressure in response to the initial movement of the rear piston 92. The 
pressurized liquid medicament 96 transmits the movement of the rearward 
piston 92 to the intermediate piston 84, thus pressurizing the forward 
liquid medicament 90, causing the diaphragm 70 sealing the forward end of 
the liquid medicament 90 to bulge forwardly. In the event that this 
bulging movement does not serve to burst the diaphragm 90 prior to the 
engagement with the sharpened rear end 77 of the hypodermic needle 62, the 
engagement with the sharpened rear end 77 insures that the diaphragm 70 
will burst, allowing the pressurized liquid medicament 90 in pressure 
communication therewith to pass into the forward portion 76 of the fitting 
72 and forwardly through the hypodermic needle 62 outwardly into the 
muscle tissue of the patient. 
Movement of the forward liquid medicament 90 outwardly through the 
hypodermic needle 62 will continue until the forward movement of the 
intermediate piston 84 is retarded by engagement of the forward surface 
thereof with the necked forward end of the container 60. It will be noted, 
however, that the axial extent of the bulge 80 is greater than the axial 
thickness of the intermediate piston 84 so that when the intermediate 
piston reaches the forward necked end of the container, the bulge 80 
provides a bypass for the flow of the rearward liquid medicament 96 
forwardly from a position rearwardly of the rear surface of the 
intermediate piston to a position forwardly of the forward surface 
thereof. The axial peripheral groove 88 in the piston 84 insures that 
there will always be a flow path from the bypassing rearward liquid 
medicament 96 to the stopper passage 68 and hypodermic needle 62 as the 
rearward piston 92 continues its forward movement under the bias of the 
released stressed spring 48. 
FIG. 2 illustrates the position of the parts just after forward movement of 
the intermediate piston 84 has been halted. During the remainder of the 
forward movement of the rearward piston 92, the rearward liquid medicament 
96 is forced outwardly through the bypass provided by the bulge 80 and 
piston groove 88 and outwardly through the hypodermic needle 62 into the 
muscle tissue of the patient. It will be noted that when the forward 
surface of the rearward piston engages the rearward surface of the 
intermediate piston, the rearward peripheral portion of the piston 92 has 
not yet reached the bulge 80. 
It will be understood that the above-described operation of the automatic 
injector 10 takes place quite rapidly so that insofar as the patient is 
concerned the operation occurs so rapidly after the actuating procedure 
has been performed as to require the operator simply to withdraw the 
needle after a few seconds have elapsed. It can thus be seen that by the 
improvements embodied in the cartridge assembly of the present invention 
it becomes possible to effectively independently store a plurality of 
relatively incompatible liquid medicaments within an automatic injector 
and to effectively sequentially inject the liquid medicaments in a 
conventional automatic fashion by an arrangement which is economical in 
the simplicity of the improvements provided when compared with an 
automatic injector having a conventional single dosage cartridge assembly. 
It thus will be seen that the objects of this invention have been fully and 
effectively accomplished. It will be realized, however, that the foregoing 
preferred specific embodiment has been shown and described for the purpose 
of illustrating the functional and structural principles of this invention 
and is subject to change without departure from such principles. 
Therefore, this invention includes all modifications encompassed within 
the spirit and scope of the following claims.