Pre-filled syringe drug delivery system

A drug delivery system includes first drug (110) and second diluent (182) syringe assemblies which are respectively pre-filled with a drug concentrate and a liquid diluent. The diluent syringe assembly is positionable in operative association within a sterility maintenance sleeve (150) of the first syringe assembly so that the assemblies are joined in fluid communication. This fluid transfer connection permits the diluent to be transferred from the second syringe assembly into a sterile mixing chamber defined by a reciprocable stopper (134) in the first syringe assembly. Thereafter, the second syringe assembly can be moved with respect to the barrel of the first syringe assembly so that the resulting mixture can be delivered for patient administration.

TECHNICAL FIELD 
The present invention relates generally to medical devices for the 
preparation and administration of drugs and other therapeutic solutions, 
and more particularly to a drug delivery system which includes first and 
second syringe assemblies which are pre-filled with a drug and a liquid 
diluent, respectively. The syringe assemblies are positionable in a 
generally telescopic relationship with each other for mixing the drug with 
the diluent, and thereafter administering the resultant mixture to a 
patient. 
BACKGROUND OF THE INVENTION 
Modern healthcare facilities typically require the preparation and 
administration to patients of a very large number of pharmaceutical 
solutions such as intravenous drug solutions and other medicaments. In 
some instances, premixed solutions are provided to the healthcare 
facility, with subsequent administration to the patient in this ready to 
use form. 
However, some drug compositions are supplied in a concentrated form, which 
may be either liquid or particulate in nature. Preparation of the solution 
for administration to the patient may require mixing, either for dilution 
or reconstitution, with a sterile liquid, such as sterile water or saline. 
Efficient storage and handling of such concentrated compositions is 
facilitated since the drugs are not as bulky as they would be if supplied 
in the diluted concentration (i.e. premixed or ready to use). 
The drug delivery system of the present invention has been particularly 
configured to facilitate efficient and convenient preparation and 
administration of drug solutions and other wet or dry medicaments. 
Pre-filled syringe assemblies are provided which are conveniently operable 
to dilute a concentrated drug composition or to reconstitute a drug in dry 
form, and thereafter to administer the resultant solution. 
SUMMARY OF THE INVENTION 
The syringe drug delivery system of the present invention includes first 
and second pre-filled syringe assemblies which are positionable in a 
generally telescopic relationship with each other for effecting 
preparation of a drug-containing solution, and subsequent administration 
of the same. This is achieved by providing a first syringe assembly with a 
selected quantity of a concentrated drug or other medicament, which may be 
in dry, particulate form, or in the form of a liquid concentrate. The 
second syringe assembly can be pre-filled, or filled just prior to use, 
with a liquid diluent or the like, such as a sterile saline solution. The 
syringe assemblies are positioned in operative association with each other 
so that the liquid diluent can be mixed with the drug concentrate, and the 
resultant mixture thereafter administered from the assembled first and 
second syringes. The entire system is preferably configured for single 
use, so that the entire arrangement can thereafter be disposed of 
economically. 
In one embodiment of the invention, the drug delivery system includes a 
first syringe assembly including a first syringe barrel having an open end 
and an opposite, delivery end which defines a drug delivery passage. The 
first syringe assembly further includes a reciprocable stopper internally 
positioned within the first syringe barrel in slidably sealing engagement 
therewith. The reciprocable stopper defines an expandable, internal mixing 
chamber within the first syringe barrel. The mixing chamber is in fluid 
communication with the delivery passage. 
A sterility maintenance sleeve extends from the reciprocable stopper toward 
the open end of the barrel of the first syringe assembly. The sterility 
maintenance sleeve maintains the sterility of the inside surface of the 
first syringe barrel while accommodating movement of the reciprocable 
stopper outwardly and then inwardly within the first syringe barrel. 
The delivery system further includes a second syringe assembly including a 
second syringe barrel having a fluid discharge passage at one end thereof. 
A movable piston plunger is positionable within the second syringe barrel 
to define a fluid chamber therein. The fluid chamber is in fluid 
communication with the fluid discharge passage. The first syringe assembly 
is preferably pre-filled with a drug concentrate, which is sealed within 
the internal mixing chamber. The second syringe assembly can be pre-filled 
with a liquid diluent held in the fluid chamber. 
In order to mix the drug concentrate and the liquid diluent provided in the 
first and second syringe assemblies, the drug delivery system of the 
present invention includes a fluid transfer connector means or coupling 
means for joining the fluid chamber of the second syringe assembly in 
fluid communication with the internal mixing chamber of the first syringe 
assembly. Such fluid communication is achieved when the second syringe 
assembly is positioned, in a generally telescopic relationship with the 
first syringe assembly, so that the second syringe assembly is directly or 
indirectly connected with, or in engagement with, the reciprocable stopper 
of the first syringe assembly. 
In one form of the invention, the connector arrangement includes a cannula 
which is mounted on the second syringe assembly and which is insertable 
through the reciprocable stopper of the first syringe assembly as the 
first and second syringe assemblies are telescopically joined. Further, 
the reciprocable stopper of the first syringe assembly and the syringe 
barrel of the second syringe assembly respectively include threaded 
connecting means for threadably connecting the second syringe barrel to 
the reciprocable stopper. As the second syringe barrel and the 
reciprocable stopper are threadably connected, the cannula mounted on the 
second syringe assembly is being inserted through the reciprocable 
stopper. 
In another embodiment, the reciprocable stopper is elastomeric and hollow 
and includes a slit valve having flaps or lips normally biased closed. The 
reciprocable stopper has a receiving cavity for receiving the enlarged 
head of the sterility maintenance sleeve. The sterility maintenance sleeve 
is also connectable to the syringe barrel of the second syringe assembly. 
The sterility maintenance sleeve also has an outlet passage establishing 
fluid communication between the diluent in the second syringe assembly 
barrel and the slit valve of the reciprocable stopper. 
With either embodiment, once the first and second syringe assemblies are 
operatively connected, the liquid diluent within the fluid chamber of the 
second syringe assembly can be caused to flow into the internal mixing 
chamber of the first syringe assembly by movement of the piston plunger of 
the second syringe assembly within the syringe barrel of the second 
syringe assembly. During this action, hydraulic pressure expands the 
expandable internal mixing chamber of the first syringe assembly by moving 
the reciprocable stopper toward the open end of the first syringe barrel. 
The drug concentrate in the mixing chamber is thereby mixed with the 
diluent flowing from the second syringe assembly. 
After mixing is complete, the resultant mixture is caused to flow from the 
mixing chamber by movement of the second syringe assembly together with 
the reciprocable stopper and sterility maintenance sleeve inwardly in the 
first syringe barrel of the first syringe assembly. The resultant mixture 
flows out of the first syringe assembly through the delivery passage which 
is in fluid communication with the internal mixing chamber. The delivery 
passage can be connected to a suitable connector or tubing or the like for 
administration of the drug mixture to a patient. 
Other features and advantages of the present drug delivery system will 
become readily apparent from the following detailed description, the 
accompanying drawings, and the appended claims.

DETAILED DESCRIPTION 
While the present invention is susceptible of embodiment in various forms, 
there are shown in the drawings and there will hereinafter be described 
only some embodiments, with the understanding that the present disclosure 
is to be considered as an exemplification of the invention, and is not 
intended to limit the invention to the specific embodiments illustrated. 
With reference first to FIGS. 1-3, therein is illustrated a first 
embodiment of a drug delivery system 10 embodying the principles of the 
present invention. As will be further described, the present system 
includes a first syringe assembly, generally designated 12, which is 
pre-filled with a first constituent, such as a drug concentrate or other 
medicament, illustrated in particulate form and generally designated M 
(see FIG. 2). The present system further includes a second syringe 
assembly, generally designated 14, which is positionable generally 
telescopically within the first syringe assembly 12 for effecting mixture 
of a second constituent, such as a liquid diluent D (FIG. 3) provided in 
the second syringe assembly 14 with the medicament M in the first syringe 
assembly. 
With particular reference to FIG. 2, the first syringe assembly 12 includes 
a generally cylindrical first syringe barrel 16 having a cylindrical 
interior surface 17 and a transverse flange portion 18 at a generally open 
end of the barrel. The barrel 16 has a generally closed end at which a 
drug delivery passage 20 is defined. A removable cap or closure 22 is 
preferably provided to close and seal the drug delivery passage 20 prior 
to use of the present system. 
The first syringe assembly 12 further includes an internally reciprocable 
stopper 26, preferably elastomeric and slidably and sealingly positioned 
within the interior surface of the first syringe barrel 16. The 
reciprocable stopper 26 defines, with the interior surface of the first 
syringe barrel 16, an internal mixing chamber 24 within which a drug or 
other medicament M is provided in either dry or liquid concentrate form. 
The reciprocable stopper 26 may be alternatively described as a grommet, 
slidable seal, or slidable piston, and these terms may be used 
interchangeably. 
In the first embodiment illustrated in FIGS. 1-8, the reciprocable stopper 
26 is provided with a thread form or threaded sleeve portion 28 which 
facilitates connection of the reciprocable stopper 26 with the associated 
second syringe assembly 14, as will be further described. The reciprocable 
stopper 26 is movable or reciprocable within the first syringe barrel 16 
so that the internal mixing chamber 24 can expand to accommodate mixing of 
the liquid diluent D from the second syringe assembly with the medicament 
M in the first syringe assembly. A movable sleeve is therefore provided 
for maintaining the sterility of the interior surface 17 of the first 
syringe barrel 16. The sterility maintenance sleeve 30 is preferably 
connected to the reciprocable stopper 26, with the sterility maintenance 
sleeve 30 extending from the reciprocable stopper 26 generally toward the 
open end of the barrel 16. The sterility maintenance sleeve 30 further 
desirably acts to support and position the reciprocable stopper 26 within 
the barrel 16. A removable cap 32 is provided to close and seal the 
interior of the sterility maintenance sleeve 30, the threaded sleeve 
portion 28, and the exposed portion of reciprocable stopper 26 prior to 
use. 
The second syringe assembly 14 includes a second syringe barrel 36 having 
an outside diameter that is less than the inside diameter of the sterility 
maintenance sleeve 30 of the first syringe assembly 12 so that the entire 
second syringe assembly 14 can be inserted in telescopic fashion into the 
sterility maintenance sleeve 30 of the first syringe assembly 12. As best 
illustrated in FIG. 3, the second syringe assembly 14 is of a generally 
conventional configuration, including a barrel 36 and a movable piston 
plunger or plunger assembly 38 having a plunger stem 39 and an elastomeric 
piston portion 40. The piston portion 40 is slidably positionable and 
sealingly engages the interior surface of the second syringe barrel 36. 
The plunger stem 39 of the piston plunger 38 extends generally from an 
open end of the second syringe barrel 36. The opposite end of the second 
syringe barrel 36 is generally closed to define a fluid discharge passage 
42. The second syringe barrel 36 and the piston portion 40 of the movable 
piston plunger 38 together define an internal fluid chamber in the second 
syringe assembly 14. The fluid chamber is in fluid communication with the 
fluid passage 42. 
As noted, use of the present system includes mixing of a liquid diluent D 
from the internal fluid chamber of the second syringe assembly 14 with the 
drug concentrate M held in the internal mixing chamber 24 of the first 
syringe assembly 12. Accordingly, the chambers of the respective syringe 
assemblies must be joined in fluid communication, and to this end, the 
second syringe assembly 14 includes a cannula assembly 44 which is 
preferably mounted on the second syringe assembly 14 (see FIG. 4). The 
cannula assembly 44 includes a cannula 46 which is mounted on the 
substantially closed end of second syringe barrel 36 by a cannula mounting 
element 48 so that the cannula 46 is joined in fluid communication with 
discharge passage 42. A removable cover 51 can cover the cannula. 
In a preferred embodiment (with reference to FIGS. 5-7), a collapsible 
sheath 50 is provided for enclosing the cannula 46 prior to use of the 
present system. As will be further described, the collapsible sheath 50 
includes a penetrable end wall portion, which is penetrated by the cannula 
46 during use. Sheath 50 also includes a collapsible side wall portion 
depending from the end wall, which side wall portion collapses as the 
second syringe assembly 14 is operatively connected with the first syringe 
assembly 12, and the cannula 46 penetrates the end wall of the sheath 50. 
The end wall portion may also be partially or completely pre-slit to 
facilitate penetration by a modified cannula 46A, which can be provided as 
a blunt (i.e., non-sharpened) cannula. 
The reciprocable stopper 26 of the first syringe assembly 12 and the 
syringe barrel 36 of the second syringe assembly 14 are respectively 
provided with a threaded connector arrangement so that these components 
can be threadably connected attendant to disposition of the second syringe 
assembly 14 within the first syringe assembly 12. As noted, threaded 
sleeve portion 28 preferably extends from the reciprocable stopper 26. A 
threaded collar portion 52, having a thread form or threads configured for 
mating engagement with the threads of the threaded sleeve portion 28, is 
provided, either integrally or as an attached piece, on the outer end of 
the second syringe barrel 36 of the second syringe assembly 14. 
While the second syringe assembly 14 is, in many respects, generally 
conventional in configuration, the second syringe assembly 14 is 
preferably provided with an arrangement for locking the movable piston 
plunger 38 generally at its innermost disposition with respect to the 
second syringe barrel 36. In the illustrated embodiment, this locking 
arrangement comprises a locking recess 54 positioned generally at the open 
end of the second syringe barrel 36. The locking recess 54 is configured 
(such as with a snap-fit receiving groove) to receive and retain a 
cooperating locking flange 56 provided on the plunger stem 39 of the 
movable piston plunger 38. As will be further described, the provision of 
the locking recess 54 and locking flange 56 permits the forward movement 
of the movable piston plunger 38 in the second syringe barrel 36, and 
thereafter facilitates movement of the second syringe barrel 36 and piston 
plunger 38 (while locked or snapped together) in unison relative to the 
first syringe barrel 16 of first syringe assembly 12. 
With particular reference now to FIGS. 5 and 6, use of the present system 
will now be described. Prior to telescopic disposition of second syringe 
assembly 14 generally within first syringe assembly 12, the second syringe 
assembly is pre-filled with liquid diluent D. The end cap 32 of the first 
syringe assembly 12 is then removed. Thereafter, the second syringe 
assembly 14 is inserted into the first syringe assembly 12, and rotated so 
that the threaded collar portion 52 is threadably connected to threaded 
sleeve portion 28. As the collar portion 52 of the second syringe barrel 
36 is thus threadably joined to the threaded sleeve portion 28 of 
reciprocable stopper 26, collapsible sheath 50 surrounding cannula 46 is 
collapsed by engagement with reciprocable stopper 26. The cannula 46 thus 
penetrates the end wall of the collapsible sheath 50, and thereafter 
pierces the reciprocable stopper 26. During assembly of the first and 
second syringes, the reciprocable stopper 26 remains generally fixed with 
respect to the first syringe barrel 16, while the elastomeric piston 
portion 40 of the second syringe assembly remains generally fixed with 
respect to second syringe barrel 36. 
As the threaded collar portion 52 is rotated and threadably engaged with 
the threaded sleeve portion 28, the cannula 46 penetrates reciprocable 
stopper 26. As the cannula 46 is inserted through the reciprocable stopper 
26, the internal mixing chamber 24 of the first syringe assembly 12 is 
joined in fluid communication with the internal fluid chamber of the 
second syringe assembly 14. The assembled configuration of the components 
of the drug delivery system is illustrated in FIG. 6. The system is now 
ready for mixing of liquid diluent D with drug concentrate M by movement 
of the movable piston plunger 38 inwardly in the second syringe barrel 36. 
By comparison of FIGS. 6 and 7, the relative repositioning of the various 
components of the drug delivery system will be observed. As movable piston 
plunger 38 is moved into the second syringe barrel 36, the liquid diluent 
D flows through the fluid discharge passage 42, through the cannula 46, 
and into the expandable mixing chamber 24 defined by the reciprocable 
stopper 26 and the first syringe barrel 16 of the first syringe assembly 
12. As the diluent D and drug concentrate M are mixed, the resultant 
solution, designated as mixture MX in FIG. 7, is formed in the mixing 
chamber 24. As will be observed, flow of liquid from the second syringe 
assembly 14 into the mixing chamber 24 of the first syringe assembly 12 
acts to move the reciprocable stopper 26, the sterility maintenance sleeve 
30, and the second syringe assembly 14 outwardly (i.e. rearward or away 
from the drug delivery passage 20) in the first syringe barrel 16. The 
second syringe barrel 36 of the second syringe assembly 14 remains 
attached to, or fixed with respect to, the reciprocable stopper 26, as 
does the cannula 46 mounted on the second syringe assembly 14. 
After the piston plunger 38 has been fully inserted into the second syringe 
barrel 36 of the second syringe assembly 14, the cooperating locking 
recess 54 and locking flange 56 move into locking engagement, thereby 
fixing the movable piston plunger 38 against further movement relative to 
the second syringe barrel 36. The drug delivery system appears as 
illustrated in FIG. 7, and is now ready for administration of the mixture 
MX which has been formed. 
Use of the present system for solution administration is generally 
illustrated in FIG. 8. After removal of cap 22, the drug delivery passage 
20 of the first syringe barrel 16 of the first syringe assembly 12 is 
connected in fluid communication with a suitable connector or tubing T or 
other suitable administration means. The second syringe assembly 14 is 
then pushed or urged inwardly in the first syringe barrel 16 of the first 
syringe assembly 12. By this action, the second syringe assembly 14, the 
reciprocable stopper 26, and the sterility maintenance sleeve 30 move in 
unison inwardly (i.e. forward or toward the drug delivery passage 20 ) in 
the first syringe barrel 16, thereby causing the mixture MX to flow 
through the delivery passage 20. Administration of the mixture is thus 
complete, and the components of the system are ready for disposal. 
Another embodiment of the invention, in a presently preferred form, is 
illustrated in FIGS. 9-16. Like the above-described first embodiment, the 
preferred second embodiment is a syringe system for accommodating a 
concentrated liquid or dry drug, by storing the concentrated drug and a 
liquid diluent separately, combining the concentrated drug and diluent to 
reconstitute the drug in solution form, and administering the mixed 
solution. 
The system as seen in FIGS. 9 and 10 includes a first syringe assembly 
having a first syringe barrel 110. The first syringe barrel 110 includes a 
substantially closed end 112 which defines a delivery passage 114. The 
delivery passage preferably includes a male luer connection nozzle 102 
surrounded by an annular collar 104 having an interior, female thread 106. 
The delivery passage 114 is preferably closed with a removable closure 128 
which has an internal stem 129 for occluding the delivery passage 114. The 
removable closure 128 also preferably includes an exterior lug or flange 
108 for threadingly engaging the female thread 106 on the annular collar 
104 at the delivery end of the first syringe barrel 110. 
The first syringe barrel 110 has an open end 116 with a transverse flange 
117. The first syringe barrel 110 is preferably cylindrical and preferably 
has a cylindrical interior surface 118. 
When the removable closure 128 is properly secured to the first syringe 
barrel 110, the first syringe barrel 110 functions as a container defining 
an expandable mixing chamber 130 which can be filled with a predetermined 
quantity of a drug concentrate M which may be in a liquid or powder form. 
The concentrated drug M could be a lyophilized drug, for example. 
A reciprocable stopper 134 is disposed within the first syringe barrel 110 
at a first position to slidably seal and define the mixing chamber 130. 
The reciprocable stopper 134 may also be described as a grommet or 
slidable seal, and these terms may be used interchangeably. 
The reciprocable stopper 134 has an outer side 135 facing the open end 116 
of the first syringe barrel 110. The reciprocable stopper 134 also has an 
inner side 137 facing the delivery passage 114 of the first syringe barrel 
110. 
As best illustrated in FIG. 16, the reciprocable stopper 134 is resilient 
and has a generally hollow central portion. The reciprocable stopper 134 
has at least one longitudinal slit 141 through the body of the 
reciprocable stopper. The slit defines flaps or lips 142 which are biased 
to a normally closed position. When pressurized from the outer side 135 of 
the reciprocable stopper, the lips 142 can open at the inner side 137 of 
the reciprocable stopper toward the delivery passage 114 of the first 
syringe barrel. Preferably, the inner side 137 of the reciprocable stopper 
defines a generally conical surface when the slit 141 is closed. 
The reciprocable stopper 134 has an enlarged receiving cavity 143 defined 
in the hollow central portion adjacent the lips 142 of the reciprocable 
stopper The reciprocable stopper 134 also has a smaller entrance passage 
146 between the outer side 136 of the reciprocable stopper and the 
enlarged receiving cavity 143 so as to define a retention shoulder 148 
around the smaller entrance passage 146. 
With continued reference to FIG. 16, the reciprocable stopper 134 is 
adapted to be mounted to the end of a sterility maintenance sleeve 150. 
The sterility maintenance sleeve 150 has an outlet end having an enlarged 
head 152 which is force-fit into the enlarged receiving cavity 143 of the 
resilient reciprocable stopper 134. The sterility maintenance sleeve 150 
includes a reduced diameter neck 154 which is received in the smaller 
entrance passage 146 of the reciprocable stopper 134. A support flange 156 
projects radially outwardly from the top of the neck 154 of the sterility 
maintenance sleeve adjacent the outer side 135 of the reciprocable 
stopper. The support flange 156 functions as a support which keeps the 
reciprocable stopper 134 from collapsing or otherwise excessively 
deforming in a manner that would permit undesirable fluid leakage. 
As illustrated in FIGS. 10 and 16, the reciprocable stopper 134 preferably 
defines a clearance chamber or clearance space 157 between the lips 142 of 
the reciprocable stopper and the outlet end (bottom distal surface) of the 
enlarged head 152 of the sterility maintenance sleeve. This clearance 
space insures that the resilient lips 142 will always be able to close 
tightly against each other, even in the absence of a pressure differential 
sufficient to open them as described in detail hereinafter. 
The enlarged head 152 at the outlet end of the sterility maintenance sleeve 
150 has an outlet passage 158 from which fluid can flow into the clearance 
space 157 between the enlarged head 152 of the sterility maintenance 
sleeve and the inside surface of the lips 142 of the reciprocable stopper 
134. As illustrated in FIGS. 10 and 16, the upper end of the outlet 
passage 158 of the sterility maintenance sleeve communicates with the 
interior of a luer socket 160 which projects upwardly above the support 
flange 156 of the sterility maintenance sleeve. The luer socket 160 is 
adapted to receive a luer nozzle of a diluent syringe as explained in 
detail hereinafter. 
With continued reference to FIG. 10, the sterility maintenance sleeve 150 
has an enlarged diameter body portion 162 having an interior female thread 
164. As illustrated in FIG. 10, a removable plug 170 is provided for being 
initially inserted into the interior of the body portion 162 of the 
sterility maintenance sleeve 150. The plug 170 includes a nozzle-shaped 
distal end 172 for being received in the luer socket 160 of the sterility 
maintenance sleeve 150. The distal end 172 of the plug 170 is closed, 
however, so that there is no fluid passage from the plug 170 into the 
outlet passage 158 of the sterility maintenance sleeve. 
The plug 170 also includes a cylindrical body portion 174 which has, at its 
lower end, a lug or engaging member 176 for threadingly engaging the 
interior, female thread 164 on the body portion 162 of the sterility 
maintenance sleeve 150. The upper end of the plug 170 includes an exterior 
seal ring or seal portion 178 for sealing the offset portion 121 of the 
interior surface 118 of the first syringe barrel 110 as described in 
detail hereinafter. 
The plug 170 also includes a graspable portion 180. Preferably, the 
graspable portion 180 has an enlarged cross section and has an exterior 
surface which can be easily grasped to rotate the plug 170 to unthread it 
from the sterility maintenance sleeve 150 as described in detail 
hereinafter. 
The preferred embodiment of the syringe mixing system also includes a 
diluent syringe 182 as illustrated in FIG. 11. The diluent syringe 182 
includes a diluent syringe barrel 183 that holds a liquid diluent D. The 
lower portion of the diluent syringe barrel 183 has an exterior engaging 
member or lug 188 for engaging the interior thread 164 of the sterility 
maintenance sleeve as described in detail hereinafter. The diluent syringe 
barrel 183 has a discharge end 190 in the form of a luer nozzle defining a 
discharge passage 192. Preferably, a removable exterior closure 194 is 
provided for sealingly closing the discharge passage 192 of the diluent 
syringe. The removable closure 194 may employ a friction fit, or 
alternatively, a snap-fit or threaded connection may be employed. 
The diluent syringe 182 also includes a plunger assembly including a 
movable piston 184 and a plunger stem 185. The movable piston 184 is 
slidably and sealingly disposed in the diluent syringe barrel 183 and is 
used for expressing the liquid diluent D out of the syringe barrel 183 
through the discharge passage 192 in the well known manner. 
The preferred embodiment of the syringe system illustrated in FIG. 9 may be 
provided to the user as one package of two separate subassemblies. One 
subassembly is the prefilled and capped diluent syringe 182 as illustrated 
in FIG. 11, and the other subassembly includes the remaining components 
fitted together as illustrated in FIG. 10 with a drug M (which may be a 
lyophilized drug) in the first syringe barrel 110. 
Alternatively the drug subassembly illustrated in FIG. 10 can be provided 
to the user in a separate single package. The diluent syringe 182 
illustrated in FIG. 11 can also be supplied separately and stored for 
later use. At the time of use, the plug 170 is removed from the inside of 
the sterility maintenance sleeve 150 of the first syringe barrel 110 by 
rotating the plug in the clockwise or counterclockwise direction to 
unthread the plug 170 from the sterility maintenance sleeve 150. 
Preferably, the graspable portion 180 of the plug 170 has a knurled 
surface to accommodate the grasping of the plug between a person's thumb 
and fingers. 
Next, the diluent syringe 182 (FIG. 11) is prepared for insertion into the 
sterility maintenance sleeve 150 of the first syringe barrel 110. The 
diluent syringe 182 can be inverted and the cap 194 removed. The first 
syringe barrel 110 can also be inverted and aligned with the inverted 
diluent syringe barrel 183. Relative longitudinal movement can then be 
effected so as to telescopically insert the diluent syringe barrel 183 
into the sterility maintenance sleeve 150 in the first syringe barrel 110. 
The lug 188 on the diluent syringe barrel 183 is threadingly engaged with 
the female thread form 164 of the sterility maintenance sleeve as shown in 
FIG. 12. The diluent syringe barrel 183 is then threaded into the 
sterility maintenance sleeve 150 until the syringe barrel reaches the 
fully threaded position illustrated in FIG. 12. 
Referring now to FIG. 13, the liquid diluent D in the diluent syringe 
barrel 183 is expressed into the mixing chamber 130 of the first syringe 
barrel 110 by pushing on the plunger stem 185 of the diluent syringe. 
The slit 141 in the reciprocable stopper 134 opens under the increased 
pressure resulting from the movement of the movable piston 184. The liquid 
diluent D is thus forced into the first mixing chamber 130 of the first 
syringe barrel as shown in FIGS. 13 and 14. The liquid diluent D is 
thereby mixed or combined with the drug M. It the drug M is a dry powder 
such as a lyophilized drug, the liquid diluent D will reconstitute the 
drug in solution form. As the liquid diluent D fills the mixing chamber 
130 in the first syringe barrel 110, the volume of the mixing chamber 130 
increases, and the reciprocable stopper 134 is forced to slide outwardly 
in the first syringe barrel. As the reciprocable stopper 134 slides 
outwardly, the sterility maintenance sleeve 150 and the diluent syringe 
assembly 182 move outwardly with the reciprocable stopper 134. 
The sterility maintenance sleeve 150 maintains the sterility of the 
interior surface 118 of the first syringe barrel 110 before and during the 
outward movement of the reciprocable stopper 134. Thus when the diluent is 
discharged from the second syringe barrel 183 into the mixing chamber 130 
of the first syringe barrel, the expanding portion of the mixing chamber 
130 has not been exposed to touch contamination. Thus the drug M and the 
diluent D are mixing in a sterile mixing chamber. 
When all of the liquid diluent D has been expressed from the diluent 
syringe 182, the movable piston plunger 184 bottoms out in the diluent 
syringe barrel 183. Preferably, the upper, distal end of the plunger stem 
185 has a radial flange 196, and the upper, distal end of the diluent 
syringe barrel 183 has a snap-fit type groove 198 for receiving and 
holding the radial flange 196 in a snap-fit engagement. The snap fit of 
the flange 196 and groove 198 retains the movable piston 184, the plunger 
stem 185 and the second syringe barrel 183 in a snapped-together 
condition. The snap fit prevents the movable piston 184 from being drawn 
outwardly from the diluent syringe barrel 183. 
The snapped-together diluent syringe 182 together with the sterility 
maintenance sleeve 150 and the reciprocable stopper 134 can now function 
as the plunger and piston, respectively, of the primary administration 
syringe. In order to dispense the reconstituted drug solution MX, the 
assembled system shown in FIG. 14 can first be shaken to insure good 
mixing and then inverted. 
The closure 128 is then removed from the inverted assembly. The snapped 
together and assembled plunger stem 185 and diluent syringe barrel 183 in 
conjunction with the reciprocable stopper 134 are then pushed to remove 
air from (i.e. prime ) the first syringe barrel 110 through the nozzle 
102. The nozzle 102 may then be connected to an appropriate connector of 
an administration set or other conduit. Then the snapped together diluent 
syringe assembly 182 and the reciprocable stopper 134 are pushed further 
inwardly to express the drug solution MX out of the first syringe barrel 
110 (FIG. 15). The hydraulic pressure of the drug solution in the first 
syringe barrel 110 forces the slit 141 in the reciprocable stopper to 
close (if it has not already closed) and to remain closed. The support 
flange 156 on the sterility maintenance sleeve 150 prevents undue 
deformation of the reciprocable stopper 134. The flange thus prevents 
leakage around the reciprocable stopper 134 between the reciprocable 
stopper 134 and the interior surface 118 of the first syringe barrel 110. 
Furthermore, the clearance space 157 between the enlarged head 152 at the 
lower end of the sterility maintenance sleeve 150 and the inside surface 
of the lips 142 of the reciprocable stopper permits the lips 142 on each 
side of the slit 141 to fully close. 
In an alternative operation of the drug delivery system of the present 
invention, it will be appreciated that in all of the illustrated 
embodiments, the diluent D from the second syringe assembly 182 can be 
caused to flow into the first syringe barrel 110 from the second syringe 
barrel by pulling the two barrels (i.e. first barrel 110 and second barrel 
183 in FIG. 13 for example) outwardly relative to each other. This will 
create a pressure differential as the mixing chamber 130 expands, which 
will move (i.e. pull or draw ) the diluent D in the second syringe barrel 
into the mixing chamber 130 of the first syringe barrel. 
From the foregoing, it will be observed that numerous modifications and 
variations can be effected without departing from the true spirit and 
scope of the novel concept of the present invention. It is to be 
understood that no limitation with respect to the specific embodiments of 
the present disclosure herein is intended or should be inferred. The 
disclosure is intended to cover, by the appended claims, all such 
modifications as fall within the scope of the claims.