Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2001-02-09
2004-06-08
Casler, Brian L. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S198000, C604S206000, C604S202000
Reexamination Certificate
active
06746429
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a device for delivery of medicament, and in particular to a jet injector with a short needle to reduce the pressure at which the jet injector must eject the medicament for proper delivery.
BACKGROUND OF THE INVENTION
A wide variety of needleless injectors are known in the art. Examples of such injectors include those described in U.S. Pat. No. 5,599,302 issued to Lilley et al., U.S. Pat. No. 5,062,830 to Dunlap, and U.S. Pat. No. 4,790,824 to Morrow et al. In general, these and similar injectors administer medication as a fine, high velocity jet delivered under sufficient pressure to enable the jet to pass through the skin.
As the skin is a tissue composed of several layers and the injector is applied to the external surface of the outermost layer, the delivery pressure must be high enough to penetrate all layers of the skin. The layers of skin include the epidermis, the outermost layer of skin, the dermis, and the subcutaneous region. The required delivery pressure is typically greater than approximately 4000 p.s.i. (27,579 kPa) (measured as the force of the fluid stream divided by the cross-sectional area of the fluid stream).
Although this pressure is readily achievable with most injectors, there are some circumstances in which delivery of medicament to the subcutaneous region under a reduced pressure is desirable. For example, drugs that require a specific molecular structural arrangement, such as a linear protein configuration, may be rendered ineffective due to shear forces caused by the delivery of the drug at high pressures that alter the structural arrangement of the drug. As it is more difficult to deliver a large volume of fluid at a high pressure compared to a small volume, using a lower pressure facilitates delivery of a larger volume of fluid. Furthermore, the lower pressure could make manufacturing an injector device less expensive. The lower pressure would also reduce adverse stresses on the device and result in a corresponding increased useable device lifetime. Moreover, the lower pressure would make jet injection compatible with medicament stored and delivered in glass ampules, which typically cannot withstand the pressure typically reached by jet injectors.
One of the advantages associated with jet injectors is the absence of a hypodermic needle. Given the aversion to needles possessed by some, the absence of a needle provides a psychological benefit. Even devices that utilize conventional hypodermic needles have attempted to capitalize on this psychological benefit. For example, self-injectors or auto-injectors like the ones disclosed in U.S. Pat. Nos. 4,553,962, 4,378,015 and PCT International Publication No. WO 95/29720, WO 97/14455 have retractable needles which are hidden until activation. Upon activation, the needle extends from the bottom of the device and penetrates the user's skin to deliver medicament. As none of these devices involves delivery of the medicament using jet injection, the medicament delivery location is limited by the length of the needle. For example, if delivery in the subcutaneous region is desired, the needle must be long enough to reach the subcutaneous region. Furthermore, as auto-injectors operate like syringes, the injection time is several seconds or longer. In contrast, jet injectors typically inject in fractions of a second.
U.S. Pat. No. 5,304,128 to Haber et al. describes a jet injecting syringe that uses a short needle to assist injection. The syringe uses a gas powered driven plunger to force medication through the syringe and out of the needle. The needle is retracted until the syringe is activated and then is extended to puncture the skin of the person injected. However, the needle remains extended after the syringe is used. The extended needle could lead to potential biohazards and safety concerns, such as accidental injections and spreading of diseases. Also, the gas powered plunger is both complicated and expensive to manufacture.
PCT Publication No. WO 99/03521 of Novo Nordisk discloses an undefined concept of “jet” injection. However, this publication does not teach one the details of the driving mechanism necessary to practice the concept.
PCT Publication No. WO 99/22790 of Elan Corporation teaches a needle assisted injector having a retractable shield that conceals the needle both before and after use of the injector. The disclosed injector has a driving mechanism that operates on pressure created by a chemical reaction. Because of this chemically operated driving mechanism, the injecting time for the injector is at least three seconds and more likely greater than five seconds. This relatively long injection time may create discomfort in the patient receiving the injection. Also, the needle may move during the lengthy injection and add to the patients discomfort.
Even with minimally invasive medical procedures, it is advantageous to maintain the time for the procedures at a minimum. Thus, there exists a need for a needle assisted jet injector that operates at relatively low pressure and that is capable of quickly delivering medicament. There also exists a need for such an injector having a retractable or concealed needle to prevent the medical hazards associated with exposed needles.
SUMMARY OF THE INVENTION
The present invention relates to a needle assisted jet injector. In one embodiment, the injection device includes a housing; a retractable injection-assisting needle at a distal end of the injector; a nozzle assembly defining a fluid chamber having an opening for slidingly receiving at least a portion of the needle and being removably associated with the housing; a plunger movable in the fluid chamber; a trigger assembly; and a force generating source operatively associated with the trigger assembly so that movement of the trigger assembly activates the energy source to move the plunger in a first direction to expel a fluid from the fluid chamber. The retractable injection-assisting needle has a needle tip located at a distal end of the needle with at least a portion configured and dimensioned to slide through the nozzle assembly opening; a discharge channel within the needle tip and terminating in an orifice through which the fluid is expelled; a body portion to direct fluid towards the discharge channel; a plunger receptor configured and dimensioned to receive at least a portion of the plunger; and a retraction element operatively associated with the needle and disposed substantially within the nozzle assembly. The needle is located within the nozzle assembly in a retracted position prior to activation of the force generating source. Movement of the plunger in the first direction upon activation of the energy source results in at least a portion of the needle tip extending beyond the nozzle assembly opening to a needle insertion point and expelling the fluid through the needle tip and past the needle insertion point to a needle injection site. The needle insertion point is located at the needle tip, and the needle injection site is distal to the needle tip. The retraction element returns the needle tip to the retracted position after activation of the energy source.
The retraction element may be a resilient O-ring, a spring, or a flexible membrane which moves to allow extension of the needle tip beyond the nozzle assembly opening and then returns to its original position to return the needle tip to its retracted position. The needle body can have an exterior surface which includes a ridge or recess for accommodating the retraction element. A shoulder can be disposed between the needle tip and the needle body for accommodating the retraction element. Preferably, the needle tip, when extended, has a length of approximately 1-5 mm.
In a preferred embodiment, the jet injector includes a housing having distal and proximal ends; a fluid chamber having a seal at one end and located within the housing for holding at least about 0.02 ml to 3 ml of a medicament; an injection-assisting needle having an injecting end and a piercing end and coupled to
Berman Claude L.
DeBoer David M.
Holland Margaret L.
Lesch, Jr. Paul R.
Sadowski Peter L.
Antares Pharma, Inc.
Casler Brian L.
Thissell Jeremy
Winston & Strawn LLP
LandOfFree
Needle assisted jet injector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Needle assisted jet injector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Needle assisted jet injector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3364183