WO2000030704A1

WO2000030704A1 - Improved multi-dose non-needle jet injection device

Info

Publication number: WO2000030704A1
Application number: PCT/US1999/027856
Authority: WO
Inventors: Marc R. Pickrell; Jerry R. Pickrell
Original assignee: Pickrell Marc R; Pickrell Jerry R
Priority date: 1998-11-24
Filing date: 1999-11-23
Publication date: 2000-06-02
Also published as: AU1744200A

Abstract

This invention is an improved multi-dose non-needle jet injection device incorporating a reservoir which receives propellant under pressure which is delivered via a valve (21) to three interacting pistons (15A-15C), and cylinders. When the propellant is delivered to the pistons (15A-15C), the pistons (15A-15C) move to eject an injectable material from a reservoir contained within the device as a jet through a nozzle (1) located against the skin of the recipient into the hypoderma.

Description

IMPROVED MULTI-DOSE NON-NEEDLE JET INJECTION DEVICE

Background of the Invention

The present invention relates to an improved multi-dose device used to inject injectable material (nominally a liquid) into the hypoderma of animals or humans without the use of a hypodermic needle by a procedure known as "needleless hypodermic jet injection. " For the sake of conciseness, the term "injectable material" includes liquids, medicaments, inoculants, powders and substances which contain suspended solid particles. The term "animal" as used in this specification includes a mammal, a human, a bird and a reptile and the term "propellant" as used in this specification includes the term "gas, " "air" and all substances commonly associated therewith, and all combinations thereof, unless the context indicates otherwise. The term "skin" as used in this specification includes the term "hide. "

In modern times it has been the common practice to deposit injectable material into the hypoderma by the use of a device including a tubular needle connected to a reservoir of injectable material incorporating a piston. The needle is inserted through the epidermis into the hypoderma and the injectable material is discharged by moving the piston along the reservoir. Such devices have exhibited several shortcomings associated with their use, including pain, stress, operator injury and needle breakage, with the latter occurrence being especially prevalent in agricultural and veterinary use. Any penetration of the epidermis with a needle is a potential cause for skin injury, infection and cross-contamination. With respect to the meat production industry in particular, needle injury causes a substantial loss of product due to inflammation of muscle tissue.

Pneumatically-operated injection devices were created as an alternative to needle injection devices to ameliorate some of the shortcomings noted above. Typically, the pneumatically-operated device discharges injectable material from a reservoir through a port as a jet by a piston moved along the reservoir by subjecting it to a force created by the sudden release of a propellant under pressure. Propellant has been supplied to needleless injection devices to eject injectable material by various means, ranging from the use of small gas capsules which are punctured at the time of delivery to larger portable or stationary sources of compressed propellant for larger mass- dose models.

Needleless jet injection devices of the kind described are designed to provide a high velocity jet of injectable material, the jet typically having a diameter of from 0.001 to possibly 0.010 inches. Most, if not all, needleless jet injection devices produced to date have been manufactured for injecting injectable materials into humans and are generally unsuitable for animal applications, especially those typically associated with the food and dairy industries, zoos, equine interests and the like, due to the substantially greater dosages that are required to be administered and also due to the greater skin thickness usually presented.

There is disclosed herein an improved multi-dose jet injection device intended for connection to a propellant- dispensing device which regulates a compressed propellant supply derived from an external, separate source. A device in accordance with the invention referenced herein is intended to be particularly and uniquely well-suited for the single or mass-inoculation of animals. The device in accordance with the invention may be connected to any source of compressed propellant having a suitable fitting for connection, but it is primarily intended for attachment to any compressed propellant supply with a suitable outlet pressure regulator to supply the compressed propellant at a regulated, constant mass flow and at an acceptable pressure. This flow and pressure may be adjusted or changed by the external air pressure regulator between the times when an injection is being administered. The use of a nipple with a greater or lesser hole diameter will, in concert with the air pressure regulator, adjust the medicament outflow pressure upwards or downwards in relationship to the size of the hole, resulting in a greater or lesser skin penetration.

The propulsion force for the device in accordance with the invention, in lieu of or in combination with a pneumatic means, may also be an electromagnetic or mechanical means. Likewise, the control of propulsion forces existing within the device in accordance with the invention, in lieu of or in combination with a mechanical means, may also be a pneumatic or electromagnetic means.

It is intended that the device in accordance with the invention will be made substantially from some form of plastic or similar material in an injection molding process, although the device is amenable to construction in part from various other materials, such as stainless steel, aluminum, brass or ceramic, for example, where their use may be necessary or desirable to withstand more effectively greater operating pressures, repetitive movement or stress, or to eliminate possible chemical interactions with a particular injectable material.

Summary of the Invention In accordance with the present invention there is provided a device for multi-dose injection of injectable material into the body of an animal comprising a pneumatically and/or electro agnetically-operated needleless jet injector means for injecting injectable material through the skin of an animal into the hypoderma with a semiautomatic adjustable injection force and a control means for manually adjusting the injection dosage.

Brief Description of the Drawings It is to be understood that the drawings are designed for the purpose of providing a better understanding of the invention, and to show how the same may be carried into effect. The drawings are not intended as a definition of the limits of the invention. Reference will now be made, by way of example, to the accompanying drawings, in which:

FIG. 1 is an external view of the left side (from the operator's perspective) of the device in accordance with the invention, and

FIG. 2 is a cutaway longitudinal section view of the device in accordance with the invention depicted in FIG. 1 in the partially activated mode.

Detailed Description of the Operation of the Invention A presently preferred embodiment of the invention will now be described with reference to the accompanying drawings :

The jet injector illustrated in the drawings is in the general form of a pistol having a grip 42, a trigger 35 and a cylindrical body 7. The cylindrical body 7 is attached to the grip 4 by a mounting rail 24 which extends longitudinally of the body 7. The body 7 has a forward end 7a and a rear end 7b. A nose piece 5 is attached to the cylindrical body 7 at the forward end 7a and a cylindrical tube 2 is fitted in a quill which extends forward of the nose piece 5 and is clamped to the nose piece by tightening a clamping nut 4 onto the quill. The tube 2 is locked in one of four longitudinal positions relative to the nose piece 5 by an index pin 29 which projects from the nose piece 5 into a channel formed in the external peripheral surface of the tube 2. The channel has a longitudinal segment and four longitudinally-spaced circumferential segments. To change the position of the tube 2 relative to the nose piece 5, the operator loosens the clamping nut 4 and turns the tube 2 in order to align the longitudinal segment of the channel with the index pin 29.

The operator can then slide the tube 2 lengthwise of the body 7 to align a selected one of the four circumferential segments of the channel with the index pin. The operator then turns the tube 2 so that the index pin enters the selected circumferential segment and tightens the clamping nut 4.

A nozzle 1 is screwed onto the forward end of the tube 2. Between the nozzle and the forward end of the tube 2 there is a nozzle check valve composed of a ball 34 and a spring 38. The nozzle check valve allows fluid to pass out of the interior space of the tube 2 through the nozzle but does not permit reverse flow. A plunger 3 is fitted slidably in the tube 2. A medicament chamber is defined between the plunger 3 and the forward end of the tube 2. At its rear end, the plunger is attached to a hollow shaft 6 which is in turn attached at its rear end to a piston 15C. The piston 15C is fitted slidably in the cylindrical body 7. A compression spring 8 effective between the nose piece 5 and the piston 15C urges the piston rearwards .

The cylindrical body 7 is closed at its rear end by a power head 53. Between the piston 15C and the power head 53 are, in turn, a bulkhead 10, a piston 15B, a bulkhead 13 and a piston 15A. The bulkheads 10 and 13 are secured to the cylindrical body and are held against movement relative thereto by screws 58. The pistons 15B and 15A are fitted slidably in the cylindrical body 7 and are attached rigidly to a hollow shaft 11. In the condition shown in FIG. 3, the forward end of the shaft 11 is in contact with the piston 15C. The wall of the hollow shaft 11 is formed with openings which provide communication between the interior space of the hollow shaft and the chamber 12 between the piston 15B and the bulkhead 13. At its forward end, the hollow shaft 11 has notches which allow communication between the interior space of the hollow shaft and the chamber 9 between the piston 15C and the bulkhead 10.

The pistons 15A and 15B are moveable relative to the cylindrical body 7 between a rear end position in which the pistons engage the power head 53 and the bulkhead 13 respectively, and a forward end position in which the pistons engage the bulkheads 13 and 10 respectively. The piston 15C is moveable between a rear end position in which it engages the bulkhead 10 and a forward end position in which the plunger 3 engages the forward end of the medicament tube 2. FIG. 2 shows the pistons 15A, 15B and 15C intermediate their end positions. An on/off valve 21 is attached to the power head 53 by a valve support mount 22. The valve 21 has an air supply nipple which is connected through a flexible hose (not shown) to a source (not shown) of compressed propellant, such as air or carbon dioxide. The valve 21 has an outlet which is connected to the chamber 14 between the piston 15A and the power head 53 through a passage formed in the valve support mount 22 and a bore in the power head 53. The valve 21 has a spring-loaded control button 23 which projects forward of the valve body into a passage in the mounting rail 24. When the button is depressed against the force of its return spring, the valve opens and compressed propellant from the source pressurizes the chambers 14, 12 and 9, whereas when the button is released, the chambers 14, 12 and 9 are vented to atmosphere through spaces (not shown) around the periphery of the button 23.

A sensor assembly 18 includes a hollow actuator shaft 19 which is fitted in the passage of the mounting rail 24. The forward end of the control button 23 extends into a recess at the rear end of the actuator shaft 19. The sensor assembly also includes an extension rod 17 which fits in the bore of the actuator shaft at the forward end thereof and is attached to the actuator shaft 19 by a coupling pin fitted through a transverse hole in the shaft 19 and one of four longitudinally-spaced transverse holes in the extension rod

17. The extension rod 17 is provided at its forward end with a sensor ring 16 fitted around the tip of the nozzle 1.

When the trigger 35 is released, a trigger latch 20 (not shown in detail) engages the actuator shaft 19 and prevents movement of the shaft 19 towards the rear of the injector. When the operator pulls the trigger, the trigger latch 20 releases the actuator shaft 19 and allows the shaft to move rearwards against the spring-loaded control button 23.

A medicament tube 33 is fitted through a bore in the power head 53 and projects axially of the cylindrical body 7 through the hollow shaft 11 and the main shaft 6. The medicament tube 33 is connected by a flexible tube (not shown) to a source of injectable material. The plunger 3 accommodates a plunger check valve, including a ball 30, a retainer 37 and a spring 36, which permits flow of fluid from the medicament tube 33 into the medicament chamber, but prevents reverse flow. In use of the illustrated injector, let us assume that the injector is initially in the condition in which the pistons 15A, 15B and 15C are in the respective rear end positions and the medicament chamber is full of medicament to be injected. The operator holds the injector so that the sensor ring 16 is close to, but is not in contact with, the animal to be injected. The operator then pulls the trigger 35 and the trigger latch 20 releases the actuator shaft 19. The operator presses the sensor ring against the animal, thus urging the actuator shaft 19 rearward relative to the valve 21. Rearward movement of the actuator shaft is transmitted to the valve control button 23, which is thereby depressed against the force of its return spring. The valve 21 opens and the chamber 14 is thereby connected to the source of compressed propellant. The chamber 14 and the interior space of the shaft 11 are pressurized. The chamber 12 is pressurized through the apertures in the wall of the shaft 11, and the chamber 9 is pressurized through the notches at the forward end of the shaft 11. The chambers forward of the piston 15A, 15B and 15C are vented by holes 26 in the wall of the cylindrical body 7. All three pistons 15A, 15B and 15C are forced forwards, and the force applied to the pistons is transmitted to the plunger 3, which is driven forwards. A high pressure is thereby generated in the medicament chamber and medicament is expelled from the medicament chamber at high pressure through the nozzle 1.

The pistons 15A and 15B move only a short distance forwards before engaging the bulkheads 10 and 13. At this point, forward movement of the shaft 11 stops but the piston 15C continues to move forwards due to the pressure in the chamber 9. The piston 15C continues forward movement until the plunger 3 engages the wall at the forward end of the tube 2. Injection is then complete and the operator withdraws the injector from the animal and releases the trigger. The force of the return spring of the button pushes the shaft 19 forwards and the valve 21 closes, cutting off the supply of compressed propellant to the chamber 14 and allowing the chambers 9 , 12 and 14 to vent to atmosphere . The spring 8 pushes the piston 15C rearwards . Towards the end of the rearward travel of the piston 15C, the piston 15C engages the shaft 11, and the force of the spring 8 pushes the shaft 11 and the pistons 15A and 15B. Rearward movement of the piston 15C brings about rearward movement of the plunger 3 , creating a partial vacuum in the medicament chamber. The medicament chamber is refilled by medicament entering the chamber through the plunger check valve. In this manner, the jet injector is restored to its initial condition, in preparation for the next injection operation. The stroke of the plunger 3, and hence the quantity of medicament to be injected, can be varied in steps of 0.5 ml by adjusting the position of the medicament tube 2 relative to the nose piece 5 , in the manner described above . When the position of the tube 2 is changed, it is necessary to adjust the position of the rod 17 relative to the actuator shaft 19 by removing and reengaging the coupling pin so that the sensor ring 16 remains properly positioned around the nozzle 1.

Preferably, the source of compressed propellant is regulated, so that compressed propellant is not supplied to the control valve unless the pressure is sufficient for satisfactory injection. The regulator may also limit the maximum pressure of the compressed propellant that can be supplied to the control valve. As indicated above, the pistons 15A and 15B are limited to a very short stroke and the forward piston 15C has a full stroke. The purpose of this arrangement is to apply the combined force of all three pistons 15A, 15B and 15C to generate an initial high pressure of injectable material to penetrate effectively the skin with a small quantity of injectable material. When pistons 15A and 15B have reached the end of their stroke, piston 15C then continues on throughout the remainder of its stroke to discharge the remainder of the injectable material under the skin at a lower pressure to reduce the risk of breaching the intramuscular tissue.

In order to ensure that the medicament penetrates the epidermis but does not breach the intramuscular tissue, it is considered desirable that the medicament be expelled from the nozzle as a rapidly spreading spray rather than as a narrow jet. It has been observed in tests of the pattern in which liquid is expelled from the nozzle into the ambient air towards a target that is spaced from the nozzle that the liquid is in fact expelled as a rapidly spreading spray rather than as a narrow jet. It is believed that this desirable characteristic is caused or aided by the fact that the medicament must flow past the ball 34 and spring 38, which impart turbulence to the flow of medicament and ensure that the flow of medicament is non-laminar.

It will be appreciated that the invention is not restricted to the particular embodiment that has been described, and that variations may be made therein without departing from the scope of the invention as defined in the appended claims and equivalents thereof. For example, the invention is not limited to use of a pneumatic device for generating pressure in the medicament chamber and an electrical or electromagnetic device may be used instead.

Claims

1. Apparatus for injection of material into the body of an animal, comprising: a cylinder having first and second opposite ends, an inlet for supplying injectable material to the cylinder, a nozzle at the first end of the cylinder for allowing injectable material to leave the cylinder, a plunger fitted in the cylinder and movable within the cylinder in a forward direction from the second end of the cylinder towards the first end thereof for forcing injectable material from the cylinder by way of the nozzle, and a mechanism for applying force to the plunger for moving the plunger in said forward direction, said mechanism applying force that varies automatically as a function of position of the plunger.

2. Apparatus according to claim 1, wherein the mechanism applies force to the plunger at a high level during an initial phase of movement of the plunger in said forward direction and at a low level subsequent to said initial phase of movement.

3. Apparatus according to claim 1, wherein the mechanism includes a second cylinder aligned with the cylinder containing the plunger, first piston which is connected to the plunger and is fitted in the second cylinder and moveable within the second cylinder in phase with movement of the plunger, a second piston fitted in the second cylinder, and a means for partially coupling the second piston to the first piston over a limited range of positions of the first piston.

4. Apparatus according to claim 1, wherein the cylinder is fitted in a body that limits movement of the plunger in a rearward direction, opposite the forward direction.

5. Apparatus according to claim 4, wherein the cylinder is selectively adjustable in position relative to the body, whereby travel of the plunger in the forward direction is selectively adjustable for adjusting the quantity of injectable material expelled from the cylinder.

6. Apparatus according to claim 1, wherein said mechanism includes a pneumatic cylinder and a valve for controlling supply of compressed propellant to the pneumatic cylinder.

7. Apparatus according to claim 6, comprising a first control element for controlling the valve and a second control element for controlling the first control element.

8. Apparatus according to claim 1, comprising a sensor for detecting when the nozzle is pressed against a firm surface and for activating said mechanism.

9. Apparatus according to claim 8, wherein said mechanism includes a pneumatic cylinder and a valve for controlling supply of compressed propellant to the pneumatic cylinder, the valve includes an activation element, and the sensor includes a ring fitted about the nozzle and a member coupling the ring to the activation element.