Title:  Auto-injection device

United States Patent:  6,203,530

Assignee:  Pos-T-Vac, Inc. (Dodge City, KS)

Filed:  January 28, 1997

An auto-injection device is provided for mounting a standard medical syringe which enables the user to automatically inject the contents of the syringe to a desired penetration depth. The auto-injection device includes a barrel sized for receiving the syringe therein, a driver shiftably received in the barrel for moving the syringe and causing injection of its contents, and a trigger accessible from outside the syringe, the trigger requiring movement across the exterior surface of the barrel prior to depression for releasing the plunger as a safety against inadvertent needle exposure and discharge. The barrel may include a window for enabling the user to ascertain whether the device is cocked or not. The barrel may be provided in two separate sections with one of the sections receivable into the other to permit cocking. The barrel also may include a slot for receiving a button to permit exposure of the needle to remove a protective cap when the device is cocked and the syringe is withdrawn into the barrel.

SUMMARY OF THE INVENTION

These needs are largely met by the auto-injection device of the present invention which is adapted to receive a conventional syringe with the needle cap in place both during loading and up until administration. The device hereof is easy to use and includes a unique trigger which requires displacement along two axes in order to actuate the injection sequence.

The invention hereof broadly includes a body or barrel presenting an internal cavity for receiving a syringe therein. The barrel cavity presents a longitudinal axis adapted for receiving a syringe therein. The barrel presents an open front end for positioning against a patient's body and through which the needle of the syringe may project, and a rear end. A driver is positioned within the barrel for longitudinal shifting within the cavity, the driver being configured to carry a conventional syringe. The driver includes a catch at the rearward end thereof adapted to engage a release mounted on the barrel. The release includes a resilient member for biasing the release to a position engaged with the catch on the driver. The release is configured and mounted on the barrel to require movement of the release along the surface of the barrel as well as depression into the cavity in order to disengage from the catch and release the driver for injecting the contents of the syringe.

Advantageously, the auto-injection device hereof has a barrel separable into two separate sections. The driver is also provided in two components, including a syringe receiver mounted in the forward section of the barrel and a pusher positioned in the normally rearward section of the barrel. The two sections of the barrel are complementally configured to permit an elongated neck on the forward section to enter the cavity of the rearward section to thereby urge the pusher rearwardly until the catch on the pusher engages the release. The syringe receiver is provided with a plurality of inwardly directed fingers which hold the syringe in a central, longitudinally aligned position, but permit insertion and withdrawal of the syringe with the syringe cap retained thereon. The syringe receiver is also provided with a button which projects into a slot in the barrel to permit manual shifting of the syringe to remove or replace the cap on the syringe. The slot includes a recess which holds the button and thus the syringe in a retracted position within the cavity of the barrel.

A spring is provided to push the driver forwardly when released after cocking. A second spring, of a lesser spring force, is provided to urge the syringe receiver rearwardly into a position normally placing the tip of the syringe needle rearwardly of the front end of the barrel when the device is uncocked.

The release is preferably provided with a trigger which extends radially outwardly of the exterior surface of the barrel. The trigger is preferably integral with a resilient arm which biases the trigger outwardly, and also includes a resilient stem for biasing the trigger to a position opposite the exterior surface of the barrel and out of alignment with a trigger access. The release further includes a notch in which the catch of the driver is received when the device is cocked. In order to actuate the device and move the syringe forwardly within the cavity, the user must push the trigger along the surface of the barrel and then through the trigger access to overcome the resilient arm and move the notch to release the catch. Preferably, indicia is provided on the driver which is visible through a window defined in the barrel, whereby the user can identify when the device is cocked.

As so configured, the auto-injection device hereof is particularly easy to use. By separating the threaded connectors on the two barrel sections, a conventional syringe may be inserted into the syringe receiver with its needle or cannula pointing forwardly and its plunger extending rearwardly. The neck of the forward section is then inserted into the cavity of the rearward section and the pusher of the driver urged rearwardly until the catch is held in the notch of the release. The forward section is then threaded on the rearward section and may be stored until use is desired. In order to inject the medication in the syringe, the user pushes the button forwardly along the slot, which extends the needle and cap into a position whereby the user may manually remove the cap. The second spring then moves the needle back within the cavity.

Administering the injection is accomplished after the front end is placed on the desired injection site. The user is inhibited from inadvertently triggering the device by the two-direction movement of the trigger necessary to release the driver. Once the trigger is moved along the exterior surface of the barrel until it is over the access opening, it may be depressed to move the notch and release the catch on the pusher. The pusher then moves forwardly against the thumbutton of the syringe plunger, moving the syringe forwardly and pushing the cannula under the skin of the patient until the syringe is stopped from further movement within the cavity. After syringe movement is stopped, the pusher continues its forward movement, overcoming the resistance of the liquid medication in the syringe to express the medication from the cannula. Once the medication is injected into the patient, the needle is withdrawn and the cap replaced on the needle with the syringe receiver shifted rearwardly and the button thereon held in the recess.

It may be readily appreciated that the device hereof permits a simplified injection procedure with safeguards against undesired actuation of the mechanism in a simple, inexpensive device using conventional syringes. Thus, the device hereof presents significant advantages over more complicated auto-injection devices requiring specialized cartridges, additional tools, or which risk premature needle exposure.

Claim 1 of 20 Claims

What is claimed is:

1. An auto-injection device comprising:

a barrel having a wall with an external surface and defining therein an internal cavity having a longitudinal axis, said barrel having a front end for placement against a patient's skin and a rear end, said wall having a trigger access therethrough;

a driver shiftably received in said cavity for movement between a forward, uncocked position and a rearward, cocked position and adapted to engage a syringe for longitudinally shiftable movement of the drive and syringe within said barrel, said driver including a catch positioned more proximate said rear end than said front end of said barrel;

a release carried by said barrel, said release including a resilient member positioned within said cavity and a trigger projecting through said trigger access and biased by said resilient member to a first position on the exterior surface of the barrel adjacent said trigger access, said release being located within said cavity for retaining said catch when said driver is shifted into said cocked position, said trigger including a projection extending axially therefrom and opposing said exterior surface of said barrel and requiring shifting across said exterior surface about said axis and against said resilient member prior to depression of said trigger toward said axis and into said trigger access to shift the release out of engagement with the catch and permit movement of the driver forwardly to the uncocked position.

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