Jet injector with hand piece

The present invention relates to a jet injector system with a hand piece. The present invention generally comprises a power unit, a medicine unit, an energy unit, a supply bottle, and a hand piece. The hand piece and power unit may be separate components connected to each other by a high pressure hose, which gives the user more flexibility. A valve assembly having a ball lock assembly and a needle assembly controls the release of medication from the high pressure hose into the hand piece and out a nozzle into the subject.

FIELD OF THE INVENTION

The present invention relates to needle-free injector systems, and more particularly to high work-load needle-free drug delivery devices for animal and human health applications.

BACKGROUND OF THE INVENTION

For many years, vaccination and administration of medicine has been accomplished by using syringes and needles. However, use of syringes and needles increases the risk of disease transmission among injection recipients. In addition, syringes and needles may cause tissue damage at the site of injection, thereby creating lesions and scar tissue. Particularly with the use of needle injection of animals, injection site lesions may result in losses of tens of millions of dollars each year to meat producers from reduced grade and carcass trim. Further, during injection needle tips may break causing residual needle fragments to remain in the subject. With animal use, this may further result in needle fragments entering into the food system. Disposable needles and syringes also create hazardous medical waste and waste disposal problems. A further drawback to disposable syringes and needles are the high costs when the units are provided for worldwide use. Many subjects, whether human or animal, have a strong aversion to needle injection. Accordingly, there exists a need for alternative methods of delivering medication to patients.

Alternative methods of delivering medication have been developed. One known method is to deliver medication using a needle-free injector. A needle-free injector delivers medication by providing a strong, high pressure blast of the medication through a small orifice, which causes a minute stream of the medication to exit the orifice at a high rate of speed, thereby allowing the medication to penetrate into the skin and subcutaneous tissues. A substantial amount of pressure is needed to create a high rate of speed of the medication. As a result, needle-free injectors are typically bulky and cumbersome to use. Further, accidental firing of the injector may cause misdosing of subjects and loss of medicine.

There is a need in the world health industry for a safe, economical, high work-load injection system to prevent and eradicate certain diseases in animals and humans.

SUMMARY OF THE INVENTION

The present invention is directed to a jet injector system with a separate hand piece. It generally comprises a power unit, a medicine unit, an energy unit, a supply bottle, and a hand piece. The hand piece and power unit may be separate components connected to each other by a high pressure hose, which gives the user more flexibility. A valve assembly having a ball lock assembly and a needle assembly controls the release of medication from the high pressure hose into the hand piece and out a nozzle into the subject. Separating the components allows for a smaller hand piece that is easier to control and handle.

DETAILED DESCRIPTION

FIG. 1depicts an injector10for injecting a human or an animal with a vaccine or other type of medication. The injector10has an energy unit12, a power unit14, a medicine unit16, a supply bottle18, and a hand piece20. Critical interfaces, where each of these components connect, are illustrated as “X.” A more detailed description of these interfaces is described below in reference toFIGS. 2 and 3.

FIG. 2depicts a schematic of the injector10. The energy unit12may include a gas cylinder22connected to a regulator24. In one embodiment, the gas cylinder22is a reusable carbon dioxide canister. In one embodiment, the regulator24regulates gas pressure from 50 to 120 psi. The energy unit12provides compressed regulated air or other gas to the power unit14. This may be accomplished by a compressor26(FIG. 3) or by a pre-filled cylinder. The compressor26may be portable or stationary. If a portable compressor26is used then batteries or an AC power connection will supply electrical power (not shown). Gas cylinders22of various sizes may be utilized to hold varying amounts of gas. In one embodiment, the gas cylinder22holds liquid carbon dioxide.

The energy unit12supplies energy to the power unit14. A hose28may be used to connect the energy unit12to the power unit14. In one embodiment the hose length between the energy unit12and power unit14is approximately 300 mm.

The power unit14comprises an amplifier30and an air distribution system32. The amplifier30converts pneumatic energy to hydraulic pressure to pressurize the medicine unit16for both filling the medicine from the supply bottle18to the medicine unit16and dispensing the medicine from the medicine unit16to the hand piece20. As depicted inFIG. 4, the amplifier30may include a power piston36connected to a refill spring38. The pressure created by the amplifier30may be varied to accommodate varying subject sizes by using a regulator34(FIG. 2). Higher operational pressures will deposit the medication more deeply and quickly. Lower pressures will inject the dose less deeply. The amplifier30ofFIG. 4may be used as a build able amplifier.FIG. 5depicts an alternate embodiment of the amplifier30of the present invention. The amplifier ofFIG. 5may be a disposable amplifier30designed for a predetermined service life.

The air distribution system32supplies and controls the air flow into and out of the amplifier30. As depicted inFIG. 6, gas travels through a supply line40from the regulator34(FIG. 2) into the air distribution system32, first entering a three way piloted valve42, which has two positions or a vent valve50. In position one, the piloted valve42exhausts the air from the amplifier30to the atmosphere via a muffler46. In position two, the piloted valve42releases air to an exit line44to the amplifier30. When the system is not pressurized, compressed air travels from the supply line40into a pilot chamber48through a narrow passage52that controls the refill rate. The gas in the pilot chamber48is controlled by the vent valve50. The vent valve50is mechanically actuated by the movement of the power piston36in the amplifier30.

When the injector10is pressurized, vent valve50is closed and air from regulator34travels to piloted valve42. The piloted valve42is in the second position when the injector10is pressurized and directs the air to the back side of power piston36in amplifier30. When power piston36reaches the end of its stroke after an injection, no pressure remains in piloted valve42, thereby causing piloted valve42to change to the first position allowing air from amplifier30to exhausts out of muffler46. The vent valve50then closes and the three way piloted valve42opens back to the second position, causing air to travel to the amplifier30.

The amplifier30then connects to the medicine unit16and may be integral with the medicine unit16as depicted inFIG. 1. The medicine unit16includes a piston rod76that controls the movement of medication within the medicine unit16. The medicine unit16is attached to or connected to the supply bottle18. The supply bottle18may be a conventional bulk medicine bottle18that is connected to the medicine unit16via an inlet tube80and a standard vent spike assembly (not shown). Alternatively, flexible medicine pouches (not shown) can be utilized in which only an un-vented spike assembly would be required. It is possible that the vent spike assembly be modified to provide proprietary connections for specific medications and to ensure that medications are not used with the wrong injector10.

As depicted inFIG. 7, the medicine unit16includes an inlet valve82to receive the medicine from the inlet tube80and an outlet valve84to control the flow of the medicine out of the medicine unit16and into a high pressure hose68to the hand piece20. A high pressure chamber86enclosed on one end by the piston rod76is located between the inlet valve82and the outlet valve84to store the medication after filling the medicine unit16and prior to injection. The size of the high pressure chamber86may be adjusted to accommodate various doses. In one embodiment, the diameter of high pressure chamber86is 8 mm and the diameter of the high pressure hose68is 2 mm. In one embodiment, the high pressure chamber86is sized to propel a 2 ml dose of medication to the subject.

In one embodiment, the piston rods76and36of the medicine unit16and the amplifier30, respectively, move as one unit in both directions (fill and expel). For example, when pressure is applied to the piston36of the amplifier30from the air distribution unit32, the piston76of the medicine unit16is also retracted within the high pressure chamber86causing the medication from the supply bottle18to be withdrawn into the high pressure chamber86and pressurized for injection. Upon activation of the injector10, the piston rod76and the piston36are released forcing the pressurized medication within the high pressure chamber86through the outlet valve84into high-pressure hose68to the hand piece20. In one embodiment, the high-pressure hose68has pressure capabilities of 10,000 psi or more. In yet another embodiment, the high-pressure hose68located between the medicine unit16and the hand piece20is 1300 mm +/−20 mm in length.FIGS. 8 and 9depict alternate embodiments of the medicine unit16of the present invention, wherein the inlet valve82and the outlet valve84are located in different configurations.

FIG. 10depicts one embodiment of the hand piece20of the present invention. The hand piece20includes a body88and a core90. The body88includes a housing94having an open end96and a closed end98. The core90, which rests at least partially within the housing94of the body88, connects to the medicine unit16through the high pressure hose68. In one embodiment, the hose68is made of stainless steel. The body88of the hand piece20may include a channel99which positions the hose68on the body88of the hand piece20to prevent rotation of the core90within the body88. The core90has a distal end100having a nozzle102held in place by a nozzle nut92and a proximal end106(FIG. 11). The entire core90may slide in the housing94so that the injector10will be actuated only when the nozzle102comes in contact with the subject being injected. In one embodiment, a bellows seal (not shown) may be utilized to prevent foreign material from entering the housing94.

The nozzle102may be located distal to the nozzle nut92and has an orifice104that releases the medication into the subject. The velocity of medication to be injected may be controlled by varying the diameter of orifice104or by varying the pressure in the high pressure chamber86. In one embodiment, the orifice104has a diameter of 0.2–0.36 mm. In another embodiment, the nozzle102includes a ruby orifice104.

The front face of the nozzle102may have a textured surface. For example, in one embodiment depicted inFIG. 10, the nozzle102has a scalloped surface. The scalloped nozzle may be designed to ensure that there is no relative movement between the nozzle102and the subject. This is particularly important when attempting to vaccinate or give injections to moving subjects. In one embodiment, a protective cap (not shown) covers the nozzle102to prevent debris or blood from the subject from entering through the orifice104into the hand piece20.

As depicted inFIGS. 11 through 13, the core90further includes a valve assembly110located within the core90to control the release of medicine from the medicine unit16to the hand piece20and out to the subject. The valve assembly110includes a front seal plug138, a needle assembly118(FIG. 13), a ball lock assembly120(FIG. 12), and a rear housing plug140. As depicted inFIG. 12, the ball lock assembly120includes a button116at the proximal end106of the core90, a front separator128, a first ball lock130, a central core pin131, a second ball lock132, a main spring134, and a plurality of biasing springs144. The ball lock assembly120attaches to the core90via a ball lock frame129. The main spring134is located between the front separator128and the ball lock frame129.

The needle assembly118is located between the nozzle nut92and the front separator128(FIG. 11). Lateral movement of the needle assembly118within the core90controls the release of medicine from the hand piece20. The needle assembly118, depicted in further detail inFIG. 13, includes a front portion122and a back portion124housed in an insert sleeve126of the core90. The back portion124rests against the front separator128. The front portion rests against a saddle142of the front seal plug138when the injector10is not activated. The needle assembly118may further include pressurizing chambers146and148that must be pressurized in order to open the needle assembly118. The front seal plug138provides an exit for the medication from the high-pressure hose68to the orifice104when the needle assembly118opens.

The needle assembly118is designed so that it senses pressure within the high pressure chamber86. If the high pressure chamber86is not adequately pressurized (i.e. when the high pressure chamber86is not fully dosed), then the pressurizing chambers146and148are not pressurized and the needle assembly118blocks passage of the medicine from the high pressure hose68to the core90and will not open to release the medicine. When the needle assembly118senses an adequate level of pressure within the high pressure chamber86, the needle assembly118provides a passage for the medication from the high pressure hose68through the hand piece20and out the nozzle102.

When pressurizing chambers146and148are pressurized by the hydraulic pressure supplied from the high-pressure hose68, movement of ball lock assembly120controls the opening and closing of the needle assembly118. When the nozzle102is pressed against a subject, the core90moves toward the closed end98of the housing94causing the button116of the ball lock assembly120to contact a rear housing plug140, thereby causing the button116to depress. The button116contacts the rear housing plug140by a push or pull button core concept. In the embodiment depicted inFIGS. 11–13, the core90pushes the button116into the rear housing plug140. Depression of the button116against the rear housing plug140causes the central core pin131to move forward toward the distal end100, allowing the front ball lock130to release into the ball lock frame129. Release of the front ball lock130allows the front separator128to move toward the proximal end106of the core90due to the hydraulic pressure pushing on the back portion124of the needle assembly1118. When the pin131reaches the end of the stroke toward the distal end100, biasing springs144force the central pin131to move back toward the proximal end16, thereby releasing second ball lock132and allowing the button116, front separator128, and central pin to move independently from each. Movement of the back portion124toward the proximal end106of the core90causes the front portion122of the needle assembly118to move away from the saddle142toward the proximal end106. When the front portion122moves away from the saddle142, the medication can flow through the seal plug138and exit the orifice104.

As long as the central pin131, front separator128, and the button116move independently, the injector10cannot be actuated again. The flow of medication continues to exit the needle valve118until pressure in the pressurizing chambers146and148drops below a critical level (approximately 2000 psi). When the pressure reaches this level, the main spring134pushes the front separator128into the back portion124of the needle assembly118toward the distal end until the front portion122reaches the seal plug138, thereby closing the path for to the orifice104. Once the front portion122of the needle assembly118reseats against the saddle142, the first ball lock130reengages to its initial position. When the hand piece20is released from the patient being injected, the biasing springs144in the ball lock assembly120are released and the second ball lock132returns to the locked position. The first ball lock130cannot reopen until the button116is released again.

The ball lock assembly120, as disclosed above, operates by pushing the button116with the sliding core90. Alternately, the ball lock assembly118may be designed to operate by pulling a pin (pull core). In the pull core, the entire core90does not move. Instead, the core90may include a sliding ring at the front of the injector10connected to a pin extending from the core assembly with bails or push rods (not shown).

The injector10may be designed to operate only if the hand piece20is held properly. The injector10may be designed so that in order to give the injection to a subject, the hand piece20must be pushed against the subject. The correct amount of force may cause the injector10to fire the medication into the subject. For example, as depicted inFIGS. 11 through 13, the sliding core90serves as at least one level of safety to prevent injection of the medication when the hand piece20is not held against a subject. In another embodiment, at least one other level of safety is included wherein the injector10may require the operator to hold a safety136(FIG. 10) down to allow the injector10to work, so that if the user drops the hand piece20, the injector10will not fire. For example, as depicted inFIG. 11, a safety136extends from the exterior of the housing94of the body88into the interior of the housing94to impede movement of the button116when the injector10is not in use. When the operator is ready to use the injector10, the operator releases the safety136to permit sliding movement of the button116. In yet another embodiment, an ON/OFF safety may be included on the hand piece20.

The hand piece20may take any shape suitable for injection into a subject. The design of the hand piece20is not intended to be limited to the embodiments depicted in the figures. In one embodiment, the hand piece20has an ergonomic design to minimize repetitive hand motion and fatigue and adapted to left- or right-handed operation. An ergonomic hand piece20is designed to fit in the hand of the operator for ease of use. In one embodiment, the hand piece20may include a counter (not shown) to count each injection cycle. The counter may be resettable or non-resettable.

In one embodiment, depicted inFIG. 14, the injector10is assembled and stored in an adjustable vest150, adaptable for both right- and left-handed users. The vest150may be designed to assure comfortable fit and weight distribution for users of all sizes and statures. The vest150may include two chest straps152attached to a back portion154and a waist portion156. Belts158may further secure the chest straps152and the waist portion156to the operator. The vest150may further include pockets160to accommodate the amplifier30, the gas cylinder22, supply bottles18of any size, markers, gloves, and other materials. A skilled artisan would recognize that any number of pockets160could be utilized with the present invention to accommodate the individual components. Further, these pockets160may be placed at any location on the vest150. In one embodiment, one pocket160is located on each chest strap152to hold the supply bottles18and two pockets160are located on the waist portion156to hold the amplifier30and the gas cylinder22. The vest150may also include a clip162that holds the hand piece20. Any configuration of the vest150is foreseen including but not limited to a one-piece vest150, resembling a clothing article that may be fastened by any type of fastener (button, zipper, ties, etc.) or a vest150as described above but with only one chest strap152.

In operation, the injector10of the present invention is capable of performing multiple actuations. First, the operator attaches a supply bottle18to the medicine unit16. Once the supply bottle18is connected, the power unit14automatically primes to the operational system pressure. The pilot valve42of the air distribution system32supplies pressure to the power piston36in the amplifier30, thereby pressurizing the high pressure chamber86of the medicine unit16. Once the high pressure chamber86is pressurized above 500 psi, the operator can approach the subject. The operator places the hand piece20in his hand to release the safety136and presses the hand piece20against the subject with a predetermined minimum force. In one embodiment, the predetermined minimum force is 2 psi. The predetermined minimum force, however, may be adjustable. When the pressure in the high pressure chamber86is at operational pressure and the nozzle102is pressed into the subject by the operator, core90applies pressure to the button116and causes the central pin131to move and disengage the first ball lock130. The force holding the front portion122of the needle assembly118against the saddle142is relieved and the needle assembly118opens. When the needle assembly118opens, the medicine in the high-pressure chamber86is able to flow through the outlet valve84of the medicine unit16, through the high pressure hose68, through the needle assembly118and out the orifice104.

As the fluid in the high pressure chamber86escapes, the power piston36is driven by the air distribution system32which maintains the pressure in the high pressure chamber86during injection. The power piston36continues to move forward causing a predetermined amount of medication to be dispensed until the pressure in the high pressure chamber86drops below minimum pressure. This occurs as the power piston36reaches the end of the stroke and starts to retract being pushed back by the power spring38in the amplifier30. The valve assembly110will remain open until the pressure in the high pressure chamber86drops below the minimum pressure, typically 500 psi. In one embodiment, the needle assembly118remains open for approximately 100–200 milliseconds. Once the pressure in the high pressure chamber86and pressurizing chambers146and148drops below minimum, the force of main spring134against the needle assembly118overcomes the minimum pressure in chambers86,146, and148and closes regardless of whether the nozzle102is pressed against a subject. The hand piece20is then removed from the skin of the subject and the valve assembly110resets. As the power piston36returns to its initial position for the next injection, the predetermined amount of medication is drawn from the supply bottle18to the medicine unit16, the high pressure chamber86is repressurized, and the injector10is ready for the next injection. If the pressure in the high pressure chamber86is below minimum pressure, pressing the nozzle nut92against the subject will not cause the valve assembly110to open because the force of the main spring134continues to overcome the minimum pressure.

The following example illustrates the methods and devices of the present inventions, which should not be construed as limiting in any way.

The objective of the following study was to compare the serological responses induced by vaccination, the tissue reaction and general health-related safety between traditional injection by hypodermic needle and a needle-free injection device.

Materials and Methods

Two swine weaning groups were studied and designated Trial 1 and Trial 2. Pigs were bled, tagged, tattooed and randomly assigned to treatment groups (needle-free, needle, none/control) at 4–5 weeks of age. For the hypodermic needle injections, an 18 gauge×⅝ inch (first vaccination) or 1 inch (second and third vaccinations) needle was used to ensure intramuscular deposition of the vaccines. Needles were changed at least every 6 pigs. The injector described below in Table 1 was utilized for the needle-free injections.

The pigs were vaccinated with two doses of commercialMycoplasma hyopneumoniaevaccine (RespiSure®, Pfizer Animal Health) at 5–6 weeks of age and again 2 weeks later, and with a commercial pseudorabies virus vaccine (PrVac+®, Pfizer Animal Health) at 9–10 weeks of age. Blood samples were collected at 11–13 days after the second mycoplasma vaccination and 23–25 days after the PRV vaccination.

For safety evaluation, the pigs were weighed periodically, and injection sites were observed and palpated 2 days after each vaccination and at each bleeding. In addition, injection sites were thoroughly dissected at slaughter. Data was subjected to analysis of variance to determine statistical significance.

Serological data is presented in Table 2. All pigs were seronegative forM. hyo. and PRV prior to vaccination. The serological responses of vaccinated pigs, regardless of injection type, were significantly greater than the control pigs (P<0.05). There was no difference between the two injection types with regard to the serological responses induced by either vaccine.

Evaluation of the injection sites at slaughter indicated no injection site lesions in pigs from any of the three treatment groups. There was no difference in weight gain between the three treatments.

The pigs injected with the needle-free injector exhibited serological responses equivalent to those achieved with a needle injection. Further, injection with the needle-free injector did not result in more tissue damage when compared to conventional needle injection. Similar responses have been observed in trials with combination vaccines containing inactivatedM. hyo. and other viral and bacterial antigens.

Although the present invention is described by reference to a single and exemplary embodiment, and the best mode contemplated for carrying out the present invention has been shown and described, it is to be understood that modifications or variations in the structure and arrangements of this embodiment other than those specifically set forth may be achieved by those skilled in the art and that such modifications are to be considered as being within the overall scope of the present invention. It is to be further understood that the following pending patent applications owned by the assignee of the instant application are hereby incorporated by reference in their entirety as if fully set forth herein: U.S. Ser. No. 09/685,499; PCT/US00/41122; U.S. Ser. No. 09/685,633; PCT/US00/27991; U.S. Ser. No. 09/717,548; PCT/US00/32186; U.S. Ser. No. 09/717,559; PCT/US00/32187; U.S. Provisional Patent Application No. 60/329,082 filed on 12 Oct. 2001; and U.S. patent application Ser. No. 10/269,5848, entitled “Universal Protector Cap with Auto-Disable Feature for Needle-Free Injectors,” filed Oct. 11, 2002.