Adjustabel injection length pen needle

BACKGROUND OF THE INVENTION

1. FIELD OF THE INVENTION

The present invention relates to a pen needle with adjustable injection length for use on a drug delivery pen having a cartridge assembly and a pen body assembly.

Second DESCRIPTION OF THE RELATED STATE

Hypodermic syringes are used to deliver selected dosages of a drug to patients. The conventional hypodermic syringe comprises a syringe barrel having opposite proximal and distal ends. A cylindrical chamber wall extends between the ends and defines a fluid receiving chamber. The proximal end of the conventional syringe container is substantially open and includes a piston in a sliding fluid sealed engagement. The distal end of the conventional syringe container includes a channel communicating with the chamber. A needle cannula is attached to the distal end of the conventional syringe container such that the lumen of the needle cannula communicates with the channel and chamber of the syringe container. Movement of the piston in a proximal direction draws fluid through the lumen of the needle cannula and into the chamber. Movement of the piston in a proximal-to-distal direction forces fluid out of the chamber and out through the lumen of the needle cannula.

A drug to be injected with the conventional hypodermic syringe is often stored in a vial having a pierceable elastomeric seal. A drug in the conventional vial is accessed by puncturing the elastomeric seal with the needle cannula. A selected dose of the drug is drawn into the chamber of the syringe container by moving the plunger to a selected distance in a proximal direction. The needle cannula is withdrawn from the vial and the drug is injected into a patient by moving the plunger in a distal direction.

Some medicines, such as insulin, are self-administered. The typical diabetes patient will need insulin injections several times throughout the day. The required dose of insulin will change from one patient to the next and may change for each patient throughout the day and from one day to another. Each diabetic patient will establish a treatment that is appropriate to his or her own medical condition and lifestyle. The treatment typically includes any combination of a slow or medium acting insulin and a faster acting insulin. Each of these treatments may require the diabetic patient to periodically deliver insulin to public places, such as at workplaces or restaurants. The required handling of the standard conventional hypodermic syringe and vial may be inconvenient and embarrassing in these public environments.

Drug delivery pens have been developed to facilitate self-treatment with the drug. A conventional drug delivery pen includes a cartridge holder in which a cartridge may be taken with insulin or other drug. The cartridge holder is an elongate generally tubular structure having proximal and distal ends. The distal end of the conventional cartridge holder includes attachment means for engagement with a double-ended needle cannula. The proximal end also includes attachment means for engagement with a driver and dose adjuster, as further discussed below. A disposable cartridge for use with the conventional cartridge holder includes a distal end having a pierceable elastomeric seal that can be pierced with one end of the double-ended needle cannula. The proximal end of the conventional cartridge includes a piston slidably disposed in fluid-tight engagement with the cylindrical wall of the cartridge. This conventional drug delivery pen is used by inserting the drug cartridge into the cartridge holder. A conventional pen body is then connected to the proximal end of the cartridge holder. The pen body includes a dose setting device for determining a dose of drug to be delivered from the pen and a driver for urging the piston of the cartridge distally a distance corresponding to the selected dose.

The user of the stylus mounts the double-ended needle cannula to the distal end of the cartridge holder such that the proximal tip of the needle cannula pierces the elastomeric seal on the cartridge. The patient then selects a dose and operates the stylus to push the plunger distally to deliver the selected dose. The dose selector returns to zero upon an injection of the selected dose. The patient then removes and discards the needle cannula and stows the conventional drug delivery pen at an appropriate location for the next required drug treatment. The medicine in the cartridge will go out after such multiple drug treatments. The patient then separates the cartridge holder from the pen body. The empty cartridge can then be removed and discarded. A new cartridge may be inserted into the cartridge holder, and the cartridge holder and pen body may be reassembled and used as discussed above.

The drug delivery pen described above is effective and much more convenient for self-treatment with a drug than the typical hypodermic syringe and separate drug vial. However, double-ended pen needles that are currently available are limited to specific injection lengths, ie 8 mm and 12.5 mm, which may not be the preferred lengths for all injections. In fact, many insulin pen users regularly change their site of injection from day to day or from place to place on their bodies. Therefore, there is a need for a pen needle that allows the insulin pen user to choose the injection length in accordance with the site of injection on his or her body. In addition, such a pen needle would also be useful for families having more than one insulin pen user, with each pen user having a different body size and / or injection technique.

According to US Pat. No. 3,605,744, there is provided an injection device usable for both pre-injection and completion of injection of anesthetic, and a method for pre-injection and completion of the injection. Preinjection is achieved at high pressure and then injection is completed at a lower pressure under manual control. Both injection stages use a needle. The apparatus also includes a spring loaded piston which is movable to inject an anesthetic through the needle at a high pressure and is also movable for manual injection of the anesthetic through the needle at a lower pressure. The needle is adjustable relative to the injection housing for penetration of deeper tissue during the lower pressure injection.

SUMMARY OF THE INVENTION

The present invention relates to a pen needle assembly in accordance with claim 1 and suitable for a drug delivery pen that overcomes the problems associated with current double-ended pen needles by providing a pen needle having an adjustable injection length.

The pen needle of the present invention includes a dilator (extender) rotatably mounted on a hub on the pen needle to set the pen needle to the desired injection length. The extender is rotated to a plurality of predefined positions using a separate shield removably mounted on the post needle. Each predefined position for the dilator corresponds to a predetermined injection length for the pen needle so that the dilator covers a portion of the pen needle that is not used for the injection. After the shield has been used to rotate the extender to one of the predefined positions, the shield is removed from the post needle to expose the distal tip of the post needle so that the injection can be performed.

These and other aspects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS

In the drawings show:

Fig. 1 is an exploded perspective view of a pen needle assembly in accordance with the present invention;

Fig. 2 is a perspective view of the pin needle hub in the pen needle assembly shown in Fig. 1;

Fig. 3 is a perspective view of the extender in the pen needle assembly shown in Fig. 1;

Fig. 4 is a perspective view of the shield in the pen needle assembly shown in Fig. 1;

Fig. 5 is a perspective view, partially in section, of the pen needle assembly shown in Fig. 1, assembled and adjusted to the longest injection length; and

Fig. 6 is a perspective view, partially in cross section, of the pen needle assembly shown in Fig. 1, assembled and adjusted to the shortest injection length.

DETAILED DESCRIPTION

A pen needle assembly in accordance with the present invention is designated generally by reference numeral 1 in FIG. 1 shows an exploded perspective view of a pen needle assembly 1 and the major components including an outer cover 10, a shield 20, an extender 30, and a needle hub 40 having a double ended cannula 50.

FIGS. 2-4 show perspective views of the needle hub 40, the extender 30, and the shield 20, respectively, in greater detail.

The outer cover 10 includes a sealed distal end 11 and an open proximal end 12 that removably receives the pin needle hub 40 to cover the cannula 50, shield 20, and extender 30 for shipping prior to use. Pin needle hub 40 includes an open proximal end 41 formed by a rim 54 having dimensions and means for attaching pin needle hub 40 to the distal end of a conventional drug delivery pen such as described above. As shown in Figs. 1 and 2, the pin needle hub 40 includes a distal surface 45 having a centrally located shaft 53 and a retaining ring 43 extending therefrom. The inner surface of the retaining ring 43 is designed to mate with a flange 25 on the proximal end 22 of the shield 20, which will be discussed further below. The retaining ring 43 is shown in two cross sections, separated at each end by a pair of apertures 56 used to identify a long-length injection setting and a short-length injection setting, which will be discussed further below. The long-length injection setting and the short-length injection setting are also designated by the character 55, that is, "L" and "S".

As shown in FIG. 2, the shaft 53 includes a pair of ribs 49 offset 180 degrees on the upper surface of the shaft 53 and a pair of spiral grooves 44 extending from the distal surface 45 to the distal end 42 of the shaft 53 extend. The grooves 44 form a helical profile of the rib 49 to prevent the extender 30 assembled on the shaft 53 from disengaging from the shaft 53 during adjustment of the injection length by the user as described below. Each groove 44 includes a slot 46 near the distal end 42 of the shaft 53 adjacent to one of the ribs 49 on the outer surface of the shaft 53. The shaft 53 also includes a bore 47 through the distal end 42 that receives the double ended cannula 50. The double-ended cannula 50 is potted or otherwise permanently attached thereto such that the distal tip 51 extends from the distal end 42 and a proximal tip (not shown) extends into and is surrounded by the rim 54.

The extender 30 has a generally cylindrical shape with an open distal end 31 and an open proximal end 32. A pair of protrusions 34 are imaged on the inner surface 36 of the extender 30 and a plurality of ridges 33 are formed on the outer surface 37 of the extender 30. Each projection 34 extends from the distal end 31 toward the proximal end 32 and includes a stop 35 at its proximal end. When the extender 30 is assembled in the shaft 53, the stop 35 is aligned with the grooves 44 on the shaft 53 and rides in the grooves 44 to the upper portion of each groove 44. Each stop 35 then snaps into a slot 46 at the end of the groove Groove 44 to prevent the extender 30 from moving forward and disengaging from the shaft 53 during adjustment of the injection length and removal of the shield 20, which will be discussed further below. In other words, the extender 30 is rotatably mounted on the shaft 53 so that each stop 35 within one of the grooves 44 moves from a retracted position shown in FIG. 5 where a long injection length is set to an advanced position. which is shown in Fig. 6, where a short injection length is set runs.

When the extender 30 is in the retracted position shown in FIG. 5, each stop 35 is located at a proximal end 48 of the groove 44 such that an open distal end 31 is aligned with the distal end 42 of the shaft 53. When the dilator 30 is in the retracted position, the full length of the cannula 50 is available from the point at which the cannula 50 is attached to the distal end 42 of the shaft 53 to the distal tip 51 for injection. However, when the extender 30 is in the advanced position shown in FIG. 6 2, each stop 35 is received and retained in the slot 46 at the distal end of each groove 44 so that the open distal end 31 of the extender 30 extends beyond the distal end 42 of the shaft 53. When the extender 30 is in the advanced position, the usable length of the cannula 50 is reduced to the length extending from the distal end 31 of the extender 30 to the distal tip 51 of the cannula 50. Of course, multiple slots 46 could be positioned along each groove 44 to provide two or more predefined injection lengths, e.g. As a pin needle with a long length of 12.7 mm, an average length of 8 mm and a short length of 5 mm. It is intended that such an embodiment also be within the scope of the present invention.

The last major component of the needle pin assembly 1 is the shield 20. Shields are normally only used to protect the user from inadvertent needle sticks. However, the shield 20 according to the present invention is constructed for a second purpose. In the present invention, the shield 20 is used to transfer a radial torque to the extender 30 and to rotate the extender 30 of predefined injection length and to other predefined injection lengths. The shield 20 includes a closed distal end 21 and an open proximal end 22, and is divided into two sections: a smaller diameter distal section 26 closed by a distal end 21 and a larger diameter proximal section 28 that cooperates with the distal portion 26 is connected by a protruding edge 27. The open proximal end 22 leads to the proximal portion 28 and is surrounded by a flange 25 having a notch 24 which is selectively aligned with one of the apertures 56 to define whether the extender 30 is in the advanced position (labeled "S ") or in the retracted position (labeled" L "). The flange 25 is also used to attach the shield 20 to the needle hub 40 by contacting it with the inner surface of the retaining ring 43 discussed above. When the flange 25 on the shield 20 comes out on the distal surface 45 of the needle hub 40, the flange 25 snaps into the retaining ring 43 to hold the shield 20 in place during the injection length adjustment process, and before injection away. The proximal portion 28 also includes a plurality of ridges 23 on an inner surface 29 that mate with ridges 33 on the extender 3fl to cause the extender 30 to rotate on the shaft 53 and the extender 30 to retract it Move position to its advanced position or from its advanced position back to its retracted position.

To use the pen needle assembly 1 of the present invention, the user will first remove a sterility barrier (not shown) from the pen needle assembly 1 and use the outer cover 10 as a radial torque transfer tool on the stylus hub 40 to drive the pen needle assembly. Assembly 1 on a conventional drug delivery pen assemble. Thereafter, the outer cover 10 is removed from the pin needle hub 40. The user then chooses the length of needle he needs for his injection, e.g. B., long or short. In the present embodiment, an injection length of the pen needle assembly 1 is preset to the long injection length ("L") shown in FIG. Therefore, if the user desires a long injection length, there would be no need to change the length. It would only be necessary to remove the shield 20 and perform the injection. However, if the user desires a needle with a short injection length, the user would rotate the shield 20 and the desired injection length by rotating the shield 20 until the notch 24 contacts the flange 25 with the "S" on the distal surface 45 of the pin needle hub 40 (the position shown in Fig. 6). If the user then rethinks and desires a long injection length needle, the user would rotate the shield 20 in the other direction back to the "L" mark as shown in FIG.

Currently usable injection lengths for pen needles are 12.7 mm, 8 mm and 5 mm. Therefore, in a double-position pen needle assembly 1 such as that shown in Figs. 1-6, the injection length could have the following combinations:

LONG INJECTION SIZE (mm) / SHORT INJECTION SIZE (mm)

12,7 8

8 5

12,7 5

While the invention has been described in terms of a preferred embodiment, it will be understood that various changes may be made. For example, various other long and short injection lengths could be used and more than two selectable settings could be used in a pen needle in accordance with the present invention.