WO2004073554A2

WO2004073554A2 - Needle-free injection system

Info

Publication number: WO2004073554A2
Application number: PCT/US2004/005176
Authority: WO
Inventors: Sergio Landau; John R. Marshall
Original assignee: Bioject, Inc.
Priority date: 2003-02-19
Filing date: 2004-02-19
Publication date: 2004-09-02
Also published as: US20040159364A1; WO2004073554A3; US6935384B2

Abstract

The present invention provides method and apparatus for providing high throughput injections. In one embodiment the invention provides a filling device adapted to deliver injectate from a common reservoir to a plurality of disposable fluid injection assemblies and a reusable propulsion assembly adapted to receive a filled disposable fluid injection assembly and deliver an injection to a patient.

Description

NEEDLE-FREE INJECTION SYSTEM

Background of the Invention

[0001] It is often desirable to deliver inoculations, medications, or other

injectable substances to a large number of recipients. For example, it has been

shown that vaccinations are an effective method for reducing and/or

eliminating the spread of communicable diseases. However, the delivery of

injections to large numbers of people presents several problems including

expense, difficulty of transportation, cross-contamination between recipients,

and the creation of hazardous biowaste. These problems can be compounded

in economically deprived areas where resources may be limited.

[0002] Current methods for delivering vaccinations to populations of

recipients typically use needled syringes. These methods typically require

filling of the syringes and disposal of the needle and syringe after each use.

Even in the hands of the most careful users, accidental needle sticks, and the

accompanying concerns about cross-contamination take place.

[0003] Needle- free injection systems allow a faster immunization

process than needled syringes and eliminate the possibility of accidental needle

sticks. However, because the nozzle of the needle-free injector (rather than a

disposable needle) makes contact with the patient during injection, the use of

current needle-free injection systems to inject multiple patients raise concerns

about contamination unless the equipment is properly sterilized between

injections. Therefore, it is important that equipment is properly sterilized between injections. However, this can increase costs and reduce the number of

injections that can be administered in a given time period, decreasing the

likelihood that everyone who needs or wants a vaccination will receive one.

Summary of the Invention

[0004] In one embodiment, the present invention provides a high

throughput needle free injection system including an injection assembly and a

filling assembly. The injection assembly may include a removable fluid

ejection assembly and a propulsion assembly. The removable injection

assembly may include a body terminating in a nozzle, a fluid reservoir housed

within the body, and a plunger disposed within the fluid reservoir. The

propulsion assembly may include a housing adapted to receive at least a portion

of the removable fluid ejection assembly and a propulsion system adapted to

apply sufficient force to the fluid ejection assembly to cause ejection of the

fluid injectate through the nozzle. The filling assembly may be adapted to

sterilely deliver a predetermined amount of injectate from a common reservoir

to a plurality of fluid ejection assemblies.

Brief Description of the Drawings

[0005] Fig. 1 is a block diagram of a high throughput needle-free

injection system according to the present invention.

[0006] Fig. 2 is an isometric view of an embodiment of a high

throughput needle-free injection system according to the present invention. [0007] Fig. 3 is sectional side elevation view of the filling station shown

in Fig. 2 showing the syringe installed but not pressurized.

[0008] Fig. 4 is an isometric view of the filler valve shown in Fig. 2.

[0009] Fig. 5 is an isometric close-up view of the portion of the filling

station shown in Fig. 2 that is adapted to receive the filler valve shown in Fig.

4.

[0010] Fig. 6 is a sectional side elevation view of the filling station

shown in Fig. 5 showing the syringe pressurized and the cartridge ready to be

filled.

[0011] Fig. 7 is an isometric view of the filling station shown in Fig. 2 in

a storage configuration.

[0012] Fig. 8 is an isometric view of the cartridge shown in Fig. 2.

[0013] Fig. 9 is a schematic bottom view of the rack structure shown in

Fig. 2.

[0014] Fig. 10 is a close up of the filler valve of Fig. 6 in a closed

position.

[0015] Fig. 11 is a close up of the filler valve of Fig. 6 in an open

position.

Detailed Description of a Preferred Embodiment of the Invention

[0016] In one embodiment the invention provides a high throughput

needle-free injection system. As shown, system 10 may include a filling device 12 and a needle-free injection assembly 14. Filling device 12 is adapted to

sterilely transfer a predetermined amount of injectate from a reservoir 16 to a

plurality of fluid ejection assemblies 18 via a fluid path 20. As shown, a carrier

22 may hold or otherwise join two or more of the fluid ejection assemblies 18

together. In some embodiments, all components of the filling device that come

into contact with the injectate, including the reservoir, fluid path, and fluid

ejection assemblies may be disposable. Some components, such as the

reservoir or fluid ejection assemblies may be single-use, such that once their

contents are depleted they are thrown away. Other components, such as the

fluid path, may be used for a given period of time, such as a day, or for a

certain number of uses, such as for 100 cartridge fillings, and then disposed of.

[0017] Needle-free injection assembly 14 includes a propulsion

assembly 24 and may removably engage a filled fluid ejection assembly 18.

Upon activation by a user, injection assembly 14 may eject the contents of the

fluid ejection assembly 18 with sufficient velocity to deliver the injectate to a

desired target, such as beneath the dermal layers of a recipient.

[0018] Typically, a new fluid ejection assembly 18 is inserted into

needle-free injection assembly 14 before each injection. As shown, the fluid

ejection assembly 18 may be seated within needle-free injection assembly 14.

Fluid ejection assembly 18 may include a first portion 18b that is inserted into

needle-free injection assembly 14 and a second portion 18c that is exposed.

Typically, this exposed portion is placed against the patient during an injection. Thus, fluid ejection assembly 18 may be designed such that only the

replaceable fluid ejection assembly 18 and no portion of needle- free injection

assembly 14 makes contact with the patient during an injection.

[0019] An exemplary high throughput needle-free injection system 110

is shown in Fig. 2. As shown, system 110 includes a filling station 112 and a

reusable needle-free injector 114. In system 110, filling station 112 is adapted

to sterilely transfer a predetermined amount of injectate from a fluid reservoir,

which in the embodiment shown takes the form of a syringe 116, to a plurality

of disposable cartridges 118. As shown, a cartridge rack 122 joins the

plurality of disposable cartridges together.

[0020] Fig. 3 is a cross-section of portable filling station 112 during the

set-up process. As shown, filling station 112 includes syringe 116, a filler

valve 120, a curved handle 126, tubular rods 128, sliding rods 130, and springs

132.

[0021] Syringe 116 includes a syringe reservoir 134 terminating in a

nozzle 136 through which fluid in the syringe may be expelled. Syringe 116

further includes a plunger 138 having a first end 138a that terminates in a

thumbpad 140 and a second end 138b that is received by syringe reservoir 134.

Syringe 116 may be a commercially available syringe, such as the BD™

syringe, available from Becton, Dickinson and Company or other syringes such

as those sold by Monoject, and Terumo. Typically, syringe 116 is able to store

enough injectate to fill a number of cartridges. It should be appreciated that the size and capacity of syringe 116 may depend on availability, the size of filling

station 112, the number of cartridges it is desired to fill, the shelf life of the

injectate, and other relevant factors. As a non-limiting example, syringe 116

may take the form of a 60cc syringe. However, it should be appreciated that

other sizes and other types of non-syringe fluid reservoirs may be used with the

present invention.

[0022] As previously stated, filler valve 120 provides a fluid path

between syringe 116 and each of the cartridges during the filling process. Fig.

4 shows an exemplary filler valve 120. As shown, valve 120 includes a body

120a including a fluid path defined by aperture 120b. Valve 120 further

includes an extended portion 120c including a spring 120d. Valve 120 also

includes a recess 120e and a handle 120f, which coordinate to facilitate the

positioning of the valve in station 112.

[0023] Fig. 5 is a close up of the portion of station 112 adapted to

receive filler valve 120. As shown, station 112 includes a valve seat 142.

Valve seat 142 includes a shelf 144 that provides access to an orifice 146.

Orifice 146 is adapted to receive extended portion 120c of filler valve 120.

Filler valve 120 slides into shelf 144 and may then be pushed downward, such

that orifice 146 receives extended portion 120c. Filler valve 120 may then be

locked into place by rotating handle 120f under ledge 148. Filler valve 120

may be removed and sterilized or disposed of and replaced as desired in order

to maintain the desired level of sterility during the filling procedure. Of course it should be appreciated that alternative shapes and arrangements for filling

valve 120 may be used.

[0024] It will be appreciated that in the embodiment described above, the

entire fluid path consists of syringe 116, filler valve 120, and cartridges 118.

Thus, any injectate introduced into the system makes contact only with syringe

116, filler valve 120, and cartridges 118. It should further be appreciated that

each of these components may be disposable. In some cases, syringe 116 and

each cartridge 118 may be "single use," i.e., used once and then thrown away.

Because a single-use filler valve may not be practical, it may be desirable to

use filler valve 120 for a given period of time, for example, several hours, half

a day, or a day before being disposed of. Alternatively filler valve 120 may be

used to fill a certain number of cartridges, for example, 50, 100, or 500 and

then disposed of.

[0025] Returning to Fig. 3, curved handle 126 is connected at either end

to a pair of tubular rods 128. Each tubular rod 128 includes a first end 128a

and a second end 128b, which is adapted to engage and be received by sliding

rod 130. Each sliding rod 130 includes a first end 130a and a second end 130b.

A handle 150 is situated on or near first end 130a of each sliding rod 130. Each

sliding rod 130 is adapted to engage and slide into a cavity 152. Thus, sliding

rods 130 move relative to tubular rods 128 and cavity 152 in a manner similar

to the movement of a trombone slide. [0026] A spring 132 is housed in each tubular rod 128. Spring 132

includes a first end 132a and a second end 132b. First end 132a of spring 132

is attached to first end 128a of tubular rods 128. Second end 132b of spring

132 is attached to second end 130b of sliding rods 130. When sliding rod 130

is in the "up" position, as depicted in Fig. 3, springs 132 may be relaxed, but

preferably will have some tension in them.

[0027] Syringe seat 156 is shaped to complement the external contour of

the lower end of syringe 116. When the syringe is properly positioned in

syringe seat 156, syringe nozzle 136 contacts aperture 120b of filling valve

120. In this position, plate 158 rests on thumbpad 140 of plunger 138.

[0028] Fig. 6 depicts a filling station 112 during the filling process. As

shown, handles 150 have been pushed downward, pushing sliding rods 130 into

cavity 152, extending springs 132. Typically, cavity 152 will include some

type of mechanism to retain second end 132b of spring 132. For example,

second end 132u of spring 132 may include a detent 160 that may be retained

by an orifice (not shown) located at the bottom of cavity 152. It should be

appreciated that the retention mechanism may not be applied to the spring, but

may instead be applied to second end 130b of sliding rods 130, to which

second end 132b of spring 132 is attached.

[0029] When extended, spring 132 is biased to pull first end 128a of

tubular rod 128 toward second end 130b of sliding rod 130. Because plate 158

is affixed to tubular rod 128, this bias essentially creates a downward force on plate 158. This downward force is applied by plate 158 on thumbpad 140 of

plunger 138. Thus, as the contents of syringe 116 are released into the

cartridges (i.e. as the cartridges are filled) the downward force on plunger 138

pushes plunger 138 further into syringe reservoir 134 until it meets resistance

from liquid injectate inside the syringe reservoir. Put briefly, the force created

by extended spring 132 is transmitted to syringe 116, so that the internal

contents of syringe 116 are placed under constant pressure.

[0030] Filling station 112 includes a series of cams 164 attached to a

rotating shaft 166. Each cam 164 is associated with a spring-loaded pin 168.

Center cam 170 controls central pin 172, which is responsible for positioning

and retaining cartridge 118 against the opening of filler valve 120. External

cams 174 and 176 control external pins 178 and 180, respectively, which are

affixed to block 182.

[0031] Rotation of shaft 166 after cartridge 118 is positioned against

filler valve 120 results in a slight downward movement of pins 178 and 180

and a corresponding slight downward movement of block 182. Downward

movement of block 182 compresses spring 120d on filling valve 120, opening

the valve.

[0032] Figs. 10 and 11 show a close up of the portion of filling station

112 housing valve 120 when the valve is in closed (Fig. 10) and open (Fig. 11)

positions. As shown in Figs 10 and 11, valve 120 further includes an o-ring

120g, which forms a seal between a middle portion 120h and a central plunger 120i, which terminates in a plug 120j. As shown, central plunger 120i defines

a fluid path or channel 120k, which terminates in side channels 1201. Middle

portion 120h is in a toothed engagement with upper external portion 120m and

lower external portion 120n. An o-ring 120o extends from the bottom of

middle portion 120h and in Fig. 10 creates a seal between middle portion 120h

and plug 120 . Plug 120j resides in a chamber 120p_, which is fluidly connected

to chamber 120q via channel 120r. An o-ring 120s extends from the bottom of

lower external portion 120n and is housed within opening 120c>.

[0033] In Fig. 10, no cartridge is seated beneath filler valve 120 and

valve 120 is closed. In this configuration, spring 120e is extended and a gap

183 exists between block 182 and upper external portion 120m. As shown,

plug 120j contacts o-ring 120o, preventing any liquid injectate in channel 120k

from escaping into chamber 12 Op.

[0034] In Fig. 11, a cartridge 118 is seated directly beneath filler valve

120 such that aperture 118d is in contact with o-ring 120s, creating a sealed

chamber 120t from opening 120q. As shown, block 182 has moved

downwards and is in contact with the upper surface of filler valve 120. This

movement compresses spring 120e and pushed plunger 120k downward,

releasing plug 120j from contact with o-ring 120o. Thus, liquid injectate in

channel 120k is released through side channels 1201 and into chamber 120p.

Once liquid injectate is in chamber 120p_, it can flow through channel 120r, past o-ring 120s εrid into chamber 120t and then into cartridge 118 via aperture

118d.

[0035] Thus, the opening of valve 120 allows fluid in syringe 116 to

flow into cartridge 118. As cartridge 118 fills with fluid, a plunger 118a within

cartridge 118 is pushed downwards to the bottom of the cartridge. When

cartridge 118 is full, plunger 118a meets end 184 of central pin 172. Once the

cartridge is filled, pin 186 acts as a cog, moving cartridge rack 122 through the

filling station until positioning pin 190 properly positions the next empty

cartridge in the filling station.

[0036] Typically, filling device 112 includes a power generator to

control operation of the device. It will be appreciated that the power generator

may be a user, motor, pump, or other mechanism.

[0037] For example, as described above, movement of pins 172, 178,

180, 186 and 190 is controlled and powered by rotation of shaft 166. Rotation

of shaft 166 may be electronic, motor-driven, hand-driven, or the like. If

rotation of shaft 166 is hand-driven, filling station 112 may include a hand

crank 194 (also shown in Fig. 2). In the depicted embodiment, movement of

hand crank 194 rotates belt 196, which engages and thus rotates shaft 166.

Thus, in this embodiment, the power generator includes a user operating a hand

crank.

[0038] Turning briefly to Fig. 7, filling device 12 may be configured to

adopt a compact storage configuration. Fig. 7 shows a storage configuration that may be adopted by filling station 112. As shown, syringe 116 has been

removed and tubular rods 128 and sliding rods 130 are pushed into cavity 152.

This storage configuration reduces the amount of space required when the

device is not in use and enables the device to be easily transported.

[0039] Fig. 8 is a close-up view of a single cartridge 118. It can be seen

that each cartridge 118 includes plunger 118a disposed within a shaft 118b.

Shaft 118b terminates in a nozzle 118c. Typically, it is shaft 118b, or a portion

thereof, that is received or otherwise engaged by injector 114 in preparation for

an injection. Nozzle 118c may include one or more orifices (not shown)

through which injectate in the cartridge may be released. Typically, nozzle

118c is exposed when the injector engages shaft 118b so that the head of nozzle

118c may be placed against the patient during injection. In this manner, only

the removable cartridge, and not the injector, makes contact with the patient.

Thus, when the cartridge is removed and replaced between injections, the

injector may be reused without risk of contamination between patients.

[0040] It should be appreciated that it may be desirable for cartridge 118

to be a single use or disposable cartridge that, once spent, cannot be reused.

Consequently, it will be appreciated that some materials are more useful for

disposable cartridges. For example, plastics, which are lightweight and

inexpensive, tend to be suitable for disposable applications.

[0041] Returning to Fig. 2, it can be seen that multiple cartridges 118 are

joined by a rack structure 122, forming a rack assembly 188. In the embodiment shown, rack assembly 188 is fed through filling station 112 via

opening 198. As described above, during the filling process, reservoir 116 is

fluidly connected to each cartridge 118 via a filler valve 120. As shown, the

orientation of rack assembly 188, as it is fed through the filling station, is such

that the nozzle end 118c of each cartridge 118 is presented to filler valve 120.

However, it should be appreciated that alternative configurations may be used.

[0042] As shown in Fig. 9, rack structure 122 is formed of plastic and

each cartridge 118 is joined to the external frame 212 of the rack structure by

several sprues 214. Thus, the entire rack assembly 188 including the cartridges

may be extruded as a single piece. Alternatively, the cartridges can be formed

separately and then joined to the rack structure using any suitable means.

Cartridge 118 can be released from rack structure 122 by breaking the sprues

away from the cartridge. In system 110, filling station 112 is adapted to

receive and fill only cartridges that are part of a rack assembly. As such, once

a cartridge is broken away from the rack structure, it cannot be refilled. Of

course, it will be appreciated that a filling station could be adapted to receive

single cartridges or rack assemblies having different configurations from those

shown.

[0043] Returning to Fig. 2, in the embodiment shown, needle-free

injector 114 includes a generally gun-shaped body 200 having a barrel portion

202 and a handgrip portion 204. Barrel portion 202 houses the propulsion

assembly and terminates in a chuck 206, which is controlled by lever 208. As shown, lever 208 is designed to be within easy reach of a user holding injector

114 by handgrip portion 204. Handgrip portion 204 further includes trigger

210, which controls activation of the propulsion assembly. Of course it will be

appreciated that needle-free injector need not be gun-shaped. Many alternative

shapes are suitable for use in the present invention, including elongated tubular

shapes and the like.

[0044] Those of skill in the art will be familiar with various propulsion

assemblies useful for needle-free injectors. Suitable needle-free injectors

include those described in U.S. Patent Nos. 4,941,880, 5,064,413, 5,312,335,

5,383,851, 5,399,163, 5,520,639, 5,993,412, 6,096,002, 6,264,629, 6,383,168,

6,471,669, and co-pending U.S. Serial No. 10/164,920, each of which is hereby

incorporated by reference in its entirety for all purposes.

[0045] Generally, the propulsion assembly is adapted to engage cartridge

118 and directly or indirectly advance plunger 118a towards nozzle end 118c.

The movement of plunger 118a should expel liquid injectate in cartridge 118

from nozzle 118c with sufficient pressure to allow the fluid to penetrate the

target, such as the dermal layers of a patient's skin, to the desired degree. As

stated above, trigger 210 typically controls activation of the propulsion

assembly. However, it should be appreciated that other controllers could be

used, including user-activated buttons, touch pads, levers or the like.

[0046] Chuck 206 is adapted to removably engage a filled cartridge 118

such that a nozzle end 118c of the cartridge 118 is presented for placement against the patient. Pulling lever 200 towards grip 202 opens chuck 204 so that

the shaft 118u of filled cartridge 118 may be partially inserted into the barrel

portion 202. Lever 200 may then be pushed forward to lock the cartridge into

place. After an injection, lever 200 may once again be pulled backwards to

open chuck 202 and release the spent cartridge.

Conclusion

[0047] The present invention provides a system and apparatus for high

throughput needle-free injections. It is believed that the disclosure set forth

above encompasses multiple distinct inventions with independent utility. While

each of these inventions has been disclosed in its preferred form, the specific

embodiments thereof as disclosed and illustrated herein are not to be

considered in a limiting sense, as numerous variations are possible. The subject

matter of the inventions includes all novel and non-obvious combinations and

subcombinations of the various elements, features, functions and/or properties

disclosed herein. Similarly, where the claims recite "a" or "a first" element or

the equivalent thereof, such claims should be understood to include one or

more such elements, neither requiring nor excluding two or more such

elements.

[0048] It is believed that the following claims particularly point out certain

combinations and subcombinations that are directed to one of the disclosed

inventions and are novel and non-obvious. Inventions embodied in other

combinations and subcombinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or

presentation of new claims in this or a related application. Such amended or

new claims, whether they are directed to a different invention or directed to the

same invention, whether different, broader, narrower or equal in scope to the

original claims, are also regarded as included within the subject matter of the

inventions of the present disclosure.

Claims

What is claimed is:

1. A needle free injection system comprising:

an injection assembly comprising:

a single-use removable fluid ejection assembly comprising:

a body terminating in a nozzle;

a fluid reservoir housed within the body, the fluid

reservoir being adapted to receive a fluid injectate; and

a plunger disposed within the fluid reservoir;

a propulsion assembly comprising:

a housing adapted to receive at least a portion of the

removable fluid ejection assembly; and

a propulsion system adapted to apply sufficient force to

the fluid ejection assembly to cause ejection of the fluid injectate through the

nozzle; and

a filling device adapted to sterilely deliver a predetermined amount of

injectate from a common reservoir to a plurality of fluid ejection assemblies

2. The system of claim 1 wherein the filling device can be hand operated.

3. The system of claim 1 wherein the filling device is adapted to receive a

rack of fluid ejection assemblies.

4. The system of claim 3 wherein the filling device further comprises a

removable insert that defines the fluid path between the common reservoir and

each fluid ejection assembly.

5. A device for transferring a volume of liquid injectate into a plurality of

single-use cartridges, the device comprising:

a disposable fluid reservoir;

a disposable fluid path adapted to contact the fluid reservoir and deliver

fluid to the plurality of single-use cartridges;

a housing adapted to temporarily receive and retain the disposable fluid

reservoir and the disposable fluid path, the housing comprising:

a mechanism adapted to retain and position the plurality of

single-use cartridges such that each single-use cartridge is temporarily in fluid

contact with the disposable fluid path; and

a power generator adapted to provide power to the mechanism.

6. The device of claim 5 wherein the disposable fluid reservoir is a syringe.

7. The device of claim 5 wherein the disposable fluid path is a filler valve.

8. The device of claim 5 wherein the power generator includes a

handcrank.

9. The device of claim 5 wherein the housing is further adapted to adopt a

compact storage configuration.

10. The device of claim 9 wherein in the storage configuration the

disposable fluid reservoir is removed from the device.

11. A portable filling device comprising:

a body adapted to receive a carrier holding a plurality of single-use fluid

ejection assemblies;

a pressurized reservoir adapted to hold a volume of injectate;

a fluid transfer path adapted to provide a fluid connection from the

reservoir to the plurality of disposable fluid ejection assemblies;

a valve disposed along the fluid delivery path;

a first mechanism disposed within the body for moving the carrier;

a second mechanism disposed within the body for properly positioning

each fluid ejection assembly for filling;

a third mechanism disposed within the body for opening and closing the

valve.

12. The portable filling device of claim 11 wherein the first, second, and

third mechanisms are hand-powered.

13. The filling device of claim 11 wherein the reservoir is removable.

14. The filling device of claim 13 wherein the reservoir is a syringe.

15. The filling device of claim 14 wherein the syringe is disposable.

16. The filling device of claim 11 further comprising a pressure assembly

adapted to maintain constant pressure on the common reservoir.

17. The filling device of claim 11 further comprising a removable insert that

defines the fluid transfer path from the reservoir to each fluid ejection

assembly.

18. The filling device of claim 17 wherein the removable insert includes a

filler valve.

19. The filling device of claim 18 wherein the removable insert is designed

to be disposed of after use.

20. The filling device of claim 19 wherein the removable insert is made of

molded plastic resins.

21. A method for sterilely delivering needle free injections to multiple

recipients comprising:

sterilely filling a plurality of single-use ejection assemblies with

injectate by transferring fluid from a common reservoir to the single-use

ejection assemblies via a fluid path;

engaging a first single-use expulsion assembly including a first nozzle

with a reusable power assembly, wherein the reusable power assembly

comprises:

a housing adapted to engage a portion of the single-use fluid

ejection assembly while leaving the first nozzle exposed;

a propulsion system adapted to apply sufficient force to the

single-use fluid ejection assembly to cause ejection of the fluid injectate

through the nozzle;

contacting a first recipient with the first nozzle;

injecting the first recipient;

disengaging the first single-use ejection assembly from the power

assembly;

engaging a second single-use ejection assembly including a second

nozzle with the reusable power assembly;

contacting a second recipient with the second nozzle; and

injecting the second recipient.

22. The method of claim 21 wherein the common reservoir is disposable.

23. The method of claim 21 wherein the fluid path is disposable.

24. The method of claim 21 wherein the plurality of single-use ejection

assemblies are connected to each other with a carrier.

25. The method of claim 21 further comprising the step of removing the first

and second single-use ejection assemblies from the carrier before engaging

them with the reusable power assembly.

26. A method of delivering a predetermined amount of liquid injectate to a

plurality of fluid ejection assemblies comprising:

providing a fluid reservoir;

providing a filling nozzle;

providing a fluid path from the fluid reservoir to the filling nozzle;

providing first and second single-use fluid ejection assemblies joined

together by a rack, wherein each fluid ejection assembly is adapted to be used

in a needle-free injector;

engaging the rack with a filling device such that movement of the rack

will position each fluid ejection assembly so that it can be engaged by the

filling nozzle;

engaging the first fluid ejection assembly with the filling nozzle;

releasing a predetermined amount of liquid into the fluid path such that

the liquid flows through the filling nozzle into the first fluid ejection assembly;

disengaging the first fluid ejection assembly from the filling nozzle;

moving the rack;

engaging the second fluid ejection assembly with the filling nozzle;

releasing a predetermined amount of liquid into the fluid path such that

the liquid flows through the filling nozzle into the second fluid ejection

assembly;

disengaging the second fluid ejection assembly from the filling nozzle;

moving the rack.

27. The method of claim 26 wherein the fluid reservoir is disposable.

28. The method of claim 27 wherein the fluid reservoir is a syringe.

29. The method of claim 26 wherein the filling nozzle is part of a filler

valve.

30. The method of claim 29 wherein the filler valve is disposable.

31. A needle free injector comprising:

a single-use fluid ejection assembly comprising:

a body terminating in a nozzle;

a cavity defined by the body, the cavity being adapted to receive

a fluid injectate; and

a plunger housed within the cavity;

a propulsion assembly comprising:

a housing adapted to receive a portion of the removable fluid

ejection assembly and position the single-use fluid ejection assembly such that

the nozzle is exposed;

a first control mechanism for engaging and disengaging the

single-use fluid ejection assembly;

a propulsion system adapted to apply sufficient force to the

plunger to cause ejection of the fluid injectate through the nozzle; and

a second control mechanism for initiating the propulsion system;

wherein only the exposed nozzle of the single-use ejection assembly

makes contact with a patient during an injection.

32. The needle-free injector of claim 31 wherein the propulsion assembly is

isolated from the fluid injectate within the single-use fluid ejection assembly.

33. The needle-free injector of claim 31 wherein the first control mechanism

is a lever.

34. The needle-free injector of claim 31 wherein the second control

mechanism is a trigger.