Patent Description:
Pen needles are used to attach to a medication pen and are especially useful for delivering self-administered injectable medications such as insulin. In one known commercial device, a needle-bearing hub is provided inside a funnel-shaped outer cover, sometimes referred to as the "outer shield," or simply as the "cover. " The cannula is affixed in an axial bore of the hub with one end protruding from the distal or "patient side" of the hub and the other end of the needle is recessed in a cavity on the proximal or "non-patient" side of the hub, adapted for attachment to the medication pen. A paper and foil "teardrop" label is heat sealed on the edge of the open end of the funnel shaped outer cover. In addition, the medication pen may have a cap received over the distal end of the medication pen, over the opening where the pen needle is installed. To install the pen needle on a medication pen, the user removes the medication pen cap. The user then removes the label on the pen needle outer cover and holds the outer cover to install the hub, typically threading the hub onto the pen. Once the hub is installed on the medication pen, the outer cover can be removed by pulling the outer cover distally off the hub. A separate inner needle shield sits over the needle, which the user must remove to administer an injection. The inner shield generally sits on the hub and simply helps the user locate the needle without forming a sterility barrier. After use, the user may use the outer cover to unthread the hub from the pen and dispose of the pen needle.

Medication pens and associated pen needles are disclosed in <CIT>, and <CIT> and <CIT>. A device for arranging a releasable pen needle on an injection pen and releasing the pen needle into a mating storage or disposal container is disclosed in <CIT>.

With the prior art described above, it is not always possible for the user to tell that the hub is properly seated on the medication pen. The pen does not provide a sensory feedback that the pen needle is seated on the pen (other than the tightening of the threaded connection itself). This can lead to over-tightening the pen needle on the pen, which would render the pen needle difficult to remove, or under-tightening the pen needle on the pen, which could cause the pen needle to leak. Likewise, when removing the needle, the outer cover does not always align properly over the hub and it may take two or more tries to unscrew the hub. Although passively shielded pens are known, including pen needles which shield the non-patient end of the needle automatically after use, many pen needles simply leave the non-patient end of the needle exposed after use, relying on the proximal end cavity to provide protection from accidental needle sticks after use.

While the prior devices are generally suitable for the intended use, there is a need in the industry for improvements to the pen needles.

<CIT> discloses a disposable double pointed injection needle having a needle hub to which a thin needle cannula is permanently fasten and which needle hub can be mounted on to a syringe comprising a dose setting and injection mechanism and a cartridge containing a liquid medicine to be injected subcutaneously into a human body. A safety shield is guided on the outside surface of the needle hub. The safety shield is urged in a direction away from the needle hub by a spring located between the needle hub and the safety shield.

<CIT> discloses a safety pen needle assembly which includes a hub and a needle fixed to the hub which extends distally from the hub so as to define an injection length. A shield is slidable relative to the hub from a shield covering state to a needle exposing state.

The subject matter of the invention is defined by independent claim <NUM>.

The invention is directed to a pen needle having a retractable needle shield where the needle shield can lock in an extended position to cover the end of the needle after use.

One feature of the invention is to provide sensory feedback when a pen needle is seated securely on a delivery device, such as a medication pen or delivery pen. Sensory feedback includes an audible and/or tactile sensation indicating correct attachment to the delivery device. A stop member is included to stop rotation of the pen needle after properly seated on the delivery pen. An advantage of the pen needle is to use less plastic material in the pen needle construction and to provide features to enhance ease of use.

The pen needle hub is able to attach to a delivery pen or other delivery device where the needle hub assembly includes a needle shield that can lock in place after use to cover the exposed end of the needle. The pen needle of the invention can include a needle shield that is in an extended position before use and can retract to expose a needle or cannula during use, and then can be deployed after use to cover the needle or cannula.

The pen needle includes a hub body supporting a needle. A cover can be fitted over the end of the hub body to cover the needle during storage until ready for use. The hub body supports a needle retainer that supports the needle. A movable needle shield is mounted to the hub body that can retract during use to expose the needle and can be deployed by moving or sliding outwardly after use to cover the end of the needle and prevent further use or accidental needle stick. A biasing member, such as a spring member is provided between the needle shield and the retainer to bias the needle shield outwardly.

The spring member is positioned within the hub body for biasing the needle shield outwardly to the extended position covering the distal end of the needle. The spring member also provides a torsional force or rotational force to the needle shield to rotate the needle shield to a locked position preventing re-use of the device.

In one embodiment, the cover and hub body are configured to provide a mechanism that provides an audible sound and/or a tactile feel to indicate to the user when the hub body is properly attached to the delivery pen. A rib or other detent can be provided on the inner surface of the cover that slides over a tab on the hub body to provide the audible sound. The tab can be formed on a flexible or resilient portion of the side wall of the hub body or can be a flexible tab. A stop member can be provided on the outer surface of the hub body and spaced from the tab to prevent further rotational movement of the cover relative to the hub body and provide a tactile and/or audible indication that the hub body is in the proper position on the delivery pen.

The features of the invention can be attained by providing a needle shield that can be retracted during use to expose the needle and can be deployed to cover the needle where the needle shield has a tab that slides in a track in the hub body. The needle shield and the tab slide and rotate to lock the needle shield in the extended position by rotating the tab to the locked position within the track. The needle shield is rotated by a spring member that biases the needle shield to the extended position. The spring member provides a biasing force to extend the shield over the needle and applies apply a torsional force to rotate the needle shield where the tab slides to a locked position in the track.

The needle shield includes one or more flexible tabs that project radially outward and engage an inner surface of the hub body. During use the needle shield can rotate when in the extended position where the tabs slide over a stop member thereby retaining the needle shield in a locked position and preventing further rotation. The tabs can engage a rib or recess on the inner surface of the hub body to prevent the needle shield from rotating back to the original position so that the needle shield cannot retract into the hub body. The needle shield can include one or more outwardly extending tabs that are able to slide in a track formed on the inner surface of the hub body to allow the needle shield to slide axially between the extended position and the retracted position and allow the needle shield to rotate to the locked position.

The features of the invention are attained by providing a spring to actuate the needle shield by applying a torsional force to rotate the needle shield and a biasing force to deploy the needle shield.

The features of the invention are attained by providing a pen needle comprising a hub body having a proximal end for attachment to a delivery device and a distal end. A needle is coupled to the hub body and having a distal end extending from said distal end of the hub body. A needle shield is mounted in the hub body for sliding between an extended position to cover the needle and a retracted position to expose the distal end of the needle. The needle shield is rotatable from a first angular position where the needle shield slides in the hub body to a second angular position where the needle shield is locked in the extended position.

The features of the invention are also attained by providing a pen needle where the needle shield includes at least one tab that slides within a track to allow the needle shield to slide between the extended position and the retracted position and to rotate from the first angular position to the second angular position.

The features of the invention are further attained by providing a pen needle where a track in the hub body includes a first longitudinal section that allows the needle shield to slide from a first extended position to the retracted position and a second longitudinal section that allows the needle shield to slide from the retracted position to a second extended position.

A pen needle includes a hub body having a proximal end for attachment to a delivery device and a distal end. A needle is coupled to the hub body and has a distal end extending from the distal end of the hub body. A needle shield is mounted in said hub body for sliding in the hub body. The needle shield has at least one radially extending tab that slides within a track formed on an inner surface of the hub body for sliding the needle shield between a first extended position to cover the needle, a retracted position to expose the distal end of the needle, and a second extended position to cover the distal end of the needle. The needle shield is rotatable from a first angular position where the needle shield slides in the track of the hub body from the first extended position to the retracted position to a second angular position where the needle shield slides to the second extended position where the needle shield is locked in the second extended position.

A method of using the pen needle, not according to the invention, such as for injecting a substance into a patient, is also provided. The method retracts the needle shield from a first extended position to a retracted position to expose the needle. The needle shield is then rotated from a first angular position to a second angular position by a biasing member such as a spring. The needle shield is then moved to a second extended position to cover the needle and rotated to an angular position with respect to the hub body to lock the needle shield in the extended position.

A method a attaching the pen needle to a delivery device is provided by threading the threaded end of the hub body to the end of a delivery device. An outer cover on the hub body is rotated until the hub body is seated on the delivery device. A rib on an inner surface of the cover slides over a tab on an outer surface of the hub body to provide an audible or tactile sensation to prevent over tightening of the hub body on the delivery device. The tab on the hub body can be formed on a flexible portion of the wall of the hub body or can a flexible tab or member that is able to cooperate with the rib on the cover.

These and other aspects and features of the invention will be apparent from the following detailed description of the invention and the drawings.

The following is a brief description of the drawings, in which:.

The figures are not to scale, and some features are omitted in certain views to better illustrate other features.

As used herein, the "distal" direction is in the direction of the injection site, and the "proximal direction" is the opposite direction. The "axial" direction is along the longitudinal axis of the injection device. The needle cannula is generally arranged axially in the device. "Radially" is a direction perpendicular to the axial direction. Thus, "radially inward" generally means closer to the needle. "Circumferentially" means arranged around the circumference, so that threads are arranged circumferentially on the end of a threaded fitting. The "top" view of a pen needle is looking at the pointed end of the needle. The different features of the embodiments can be used in combination with and used with other embodiments a long as the combined parts are not inconsistent with or interfere with the operation of the device and assembly.

Referring to the drawings, the pen needle <NUM> of the invention includes a needle hub assembly <NUM> and a cover <NUM> that fits over the needle hub assembly <NUM>. The cover <NUM> encloses the needle hub assembly <NUM> during storage and assists in attaching the needle hub assembly <NUM> to a delivery pen. A closure or peel tab is generally provided over the open end of the cover to maintain the needle hub assembly in a sterile condition until ready for use. The delivery pen <NUM> shown in <FIG>. It will be understood that the delivery pen can be a typical delivery pen or other medication delivery device as known in the art for dispensing and delivering a medication or pharmaceutical such as insulin. An example of a suitable delivery pen is disclosed in <CIT>.

In the embodiment shown in <FIG>, the pen needle <NUM> includes the hub body <NUM>, a needle shield <NUM>, a biasing member shown as a spring <NUM>, and a needle retainer <NUM> coupled to the hub body <NUM>. The hub body <NUM> includes an open bottom end <NUM> defining a proximal end and a top end <NUM> defining a distal end. The hub body <NUM> in the embodiment shown in <FIG> and <FIG> has a substantially conical shaped top portion that tapers toward the top end face <NUM>. The open bottom end <NUM> is provided with internal threads <NUM> shown in <FIG> for coupling to the delivery pen in a known manner. The top end <NUM> defines an opening <NUM> for the needle <NUM> or cannula and defines the skin contact surface during use. Needle <NUM> can be a hollow steel needle with a sharpened tip having a gauge and length for penetrating the skin to a desired depth.

The hub body <NUM> has a bottom end with a substantially cylindrical outer surface <NUM>. A tab <NUM> projects radially outward from the outer surface <NUM> at the open bottom end <NUM> as shown in <FIG>. The tab <NUM> has an inclined face <NUM> facing outward for cooperating with the cover <NUM> as discussed herein. As shown in <FIG> and <FIG>, the tab <NUM> is formed on a flexible member <NUM> that is formed with the hub body <NUM> so that the tab <NUM> and the flexible member <NUM> can deflect inwardly or downwardly when the cover engages the tab <NUM> during rotation of the cover on the hub body. The flexible member <NUM> is formed as a flexible portion or section of the wall and has a thinner thickness so as to allow the flexible section forming the flexible member <NUM> and the tab <NUM> to deflect inwardly when contacted by a rib <NUM> of the cover. In other embodiments, the flexible member <NUM> can be formed as flexible finger or tab that can deflect inwardly or upwardly when engaged with the cover.

A lug <NUM> is also formed on the outer surface <NUM> of the body <NUM> at the open bottom end <NUM> and spaced circumferentially from the tab <NUM>. The lug <NUM> in the embodiment shown in <FIG> and <FIG> has a flat leading face <NUM> oriented substantially perpendicular to the longitudinal axis of the hub body <NUM>. An inclined face <NUM> faces toward the top distal end of the hub body <NUM> as shown in <FIG> and <FIG>. In the embodiment shown, two tabs <NUM> and two lugs <NUM> are spaced around the perimeter of the open bottom end <NUM> on opposite side of the hub body as shown <FIG>.

As shown in <FIG>, the internal threads <NUM> are formed in a first inner portion <NUM> of the hub body <NUM> toward the bottom proximal end <NUM> for coupling with the delivery pen <NUM>. A second substantially cylindrical portion <NUM> is spaced axially from the internal threads <NUM> for receiving and supporting the retainer <NUM> as shown in <FIG>. The retainer <NUM> has a substantially cylindrical side wall <NUM>, a bottom end face <NUM>, and a top face <NUM>. In the embodiment shown, the side wall <NUM> is formed with threads <NUM> shown in <FIG> and <FIG> for mating with complementing threads <NUM> of the hub body <NUM> shown in <FIG> for securing the retainer <NUM> in the hub body <NUM>. The retainer <NUM> can also be secured in place by an adhesive or other attachment mechanism. In an alternative embodiment shown in <FIG>, the retainer <NUM> can have a smooth outer surface on the side wall to fit within the hub body by a snap fit, friction fit, interference fit, adhesive, or other suitable method of securing the retainer in place. The retainer <NUM> is maintained in a fixed position with respect to the hub body16 when installed to prevent rotation of the retainer <NUM> during use. The retainer <NUM> can be formed as two pieces bonded together or formed as a single one piece member. In the embodiment of <FIG>, the retainer <NUM> has a flat end face and can include internal lugs <NUM> for engaging the end of the spring.

As shown in <FIG>, the side wall <NUM> of the retainer <NUM> includes a slot <NUM> forming a notch for receiving one end of the biasing member shown as the spring <NUM>. The retainer <NUM> includes a center post <NUM> shown in <FIG> having an axial passage <NUM> forming an opening for receiving the needle <NUM>. In the embodiment shown, the needle <NUM> is fixed in the axial opening <NUM> with a distal end projecting from the open end of the hub body <NUM> and a proximal end projecting into the bottom end of the hub body <NUM> for connecting to a reservoir in the delivery pen <NUM>.

Referring to <FIG>, the side wall <NUM> of the retainer <NUM> defines an open top end for receiving the spring <NUM>. The axially extending post <NUM> projects in an upward axial direction for supporting and stabilizing the spring <NUM> and supporting the needle <NUM>. In the embodiment shown, the spring <NUM> is a coil spring having a first bottom end with a leg <NUM> for mating with the slot <NUM> formed in the side wall <NUM> and to resist rotation of the spring <NUM> relative to the retainer <NUM>. A second top end of the spring <NUM> includes a leg <NUM> for coupling to the needle shield <NUM> shown in <FIG>. In other embodiments, the biasing member can have other configurations and shapes that are able to bias he needle shield <NUM> outward from the distal end of the hub body <NUM> and rotate the needle shield <NUM> relative to the hub body <NUM>.

The needle shield <NUM> in the embodiment shown is configured to slide axially in the hub body <NUM> from an extended position shown in <FIG> to a retracted position shown in the sequential illustrations of <FIG>. The needle shield <NUM> has a body <NUM> with an end portion <NUM> extending axially from the body <NUM> as shown in <FIG>. The end portion <NUM> has a configuration to extend from and slide within the opening <NUM> in the open top end <NUM> of the hub body <NUM> during use. In the embodiment shown, the end portion <NUM> has flat side portions and rounded portions to slide within the hub body <NUM>. As shown in <FIG>, the axial face <NUM> of the end portion <NUM> has and opening and an axial passage <NUM> for sliding over the needle <NUM> during use.

An annular skirt <NUM> extends radially outward from the bottom proximal end of the body <NUM> of the shield <NUM> as shown in <FIG>. As shown in <FIG>, the skirt <NUM> has a side wall <NUM> extending around the peripheral edge of the skirt <NUM>. A lug <NUM> projects radially outward from the side wall <NUM> shown in <FIG>, <FIG> and <FIG> for mating with an inner surface of the hub body <NUM>. In the embodiment shown in <FIG>, two lugs <NUM> are formed on opposite sides of the side wall <NUM>. The skirt <NUM> has a dimension with a top edge oriented for mating with an inwardly extending ledge <NUM> at the top distal end of the hub body <NUM> shown in <FIG> to retain the needle shield within the cavity of the hub body.

The side wall <NUM> of the skirt <NUM> is formed with a flexible member <NUM> as shown in <FIG> having a curvature complementing the curvature of the side wall <NUM>. The flexible member <NUM> in the normal position is oriented to project outwardly from the side wall <NUM> toward the inner surface of the hub body. The flexible member <NUM> as shown in <FIG> and <FIG> has a substantially flat end face <NUM> for mating with an inner surface of the hub body <NUM>.

The needle shield <NUM> is configured for fitting within the axial cavity of the hub body <NUM> and sliding between an extended position shown in <FIG> and <FIG> and a retracted position shown in <FIG> and <FIG> through the opening in the top distal end of the hub body <NUM>. The needle shield <NUM> is positioned in the hub body <NUM> through the bottom end of the hub body <NUM> followed by the spring <NUM> and the retainer <NUM>. The retainer <NUM> is secured to the hub body <NUM> with the spring <NUM> and needle shield <NUM> captured within the hub body <NUM>. The lugs <NUM> project outwardly from the skirt <NUM> and slide within the hub body <NUM> as shown in <FIG>. In one embodiment, the lug <NUM> can slide in a longitudinally extending groove or recess <NUM> formed on the inner surface of the hub body <NUM> between ribs <NUM> shown in <FIG>. The recess can have a length to allow the needle shield <NUM> to slide axially within the hub body <NUM> and a radial width to allow limited rotational movement of the needle shield <NUM> in the hub body <NUM>.

As shown in <FIG>, the spring <NUM> extends between the bottom face of the skirt <NUM> and the top face of the retainer <NUM>. In one embodiment, the spring <NUM> is wound or twisted during assembly to provide a torsional or rotational force against the needle shield <NUM> for biasing and rotating the needle shield with respect to the hub body <NUM>. The bottom end of the spring <NUM> is coupled to the retainer <NUM> to prevent rotation of the bottom end of the spring <NUM> relative to the retainer <NUM> and the hub body <NUM>. The leg <NUM> at the top end of the spring <NUM> is coupled to the skirt <NUM> by a slot <NUM> that receives the leg <NUM> of the spring <NUM> so that the needle shield <NUM> is able to rotate relative to the retainer <NUM> and hub body <NUM>.

The top end of the body <NUM> of the needle shield <NUM> includes at least one and typically two outwardly extending tabs <NUM> for mating with a track <NUM> formed on an inner surface at the top end of the hub body <NUM>. The track <NUM> is configured for allowing the tabs <NUM> to slide axially within the track <NUM> so that the needle shield <NUM> can slide between the extended position where the end portion <NUM> of the needle shield <NUM> extends from the end of the hub body <NUM> to cover the needle <NUM> as shown in <FIG>. , and the retracted position shown in <FIG>. In the embodiment shown, a track <NUM> is provided for each of the tabs <NUM> to guide the tabs during the axial and rotational movement of the shield <NUM> with respect to the hub body <NUM>. The track <NUM> in the embodiment shown is a recess or slot on an inner surface of the hub body <NUM> for guiding the tabs <NUM>.

As best shown in <FIG> and <FIG>, the track <NUM> is a slot that includes a first longitudinal section <NUM> extending in an axial direction and having a top end <NUM> spaced from the top end of the hub body <NUM> so that the needle shield <NUM> can extend from the hub body <NUM> a distance where the needle shield <NUM> extends past the end of the needle <NUM>. As shown in <FIG>, the needle shield <NUM> can slide into the hub body <NUM> with the tabs <NUM> sliding in the first section <NUM> of the slot <NUM> to expose the needle <NUM> for injecting the patient.

The bottom end of the first longitudinal section <NUM> of the track <NUM> has a lateral section <NUM> with a dimension to receive the tab <NUM> and allow the tab <NUM> and needle shield <NUM> to rotate within the hub body <NUM>. At the end of the lateral section <NUM> is a second longitudinal section <NUM> extending in the axial direction substantially parallel to the first longitudinal section <NUM>. In the embodiment shown in <FIG>, the wall portion between the first longitudinal section <NUM> and the second longitudinal section <NUM> terminate with inclined surfaces <NUM> to guide the tab <NUM>. As shown in <FIG>, the second longitudinal section <NUM> has an axial length to extend axially toward the distal end of the hub body <NUM>. In the embodiment shown, the longitudinal section <NUM> extends a distance greater than the axial length of the first section <NUM> and terminates at second lateral section <NUM> to enable the needle shield <NUM> to move distally from the hub body <NUM> a distance greater than when the tab <NUM> of the needle shield <NUM> travels in the first section <NUM>. As shown, the second lateral section <NUM> has an inclined guide surface <NUM> and extends in a direction away from the second longitudinal section <NUM> in a direction opposite the first lateral section <NUM>.

A longitudinally extending rib <NUM> is provided on the inner surface of the hub body <NUM> for cooperating with the flexible fingers <NUM> upon rotation of the needle shield with respect to the hub body <NUM> as the tabs <NUM> of the needle shield <NUM> slide through the lateral sections <NUM> and <NUM>. The rib <NUM> is oriented to allow the flexible fingers <NUM> to slide over the rib <NUM> during use. The rib <NUM> forms a stop member to prevent the needle shield from being manually rotated back to the original position to prevent re-use of the device. The rib <NUM> also provides an audible and/or tactile feel to the user as the needle shield <NUM> rotates relative to the hub body <NUM>. In other embodiments, the stop member is formed by a recess rather than a projecting rib.

In the initial position, the needle shield <NUM> is oriented in the position shown in <FIG> with the tab <NUM> received in the top end of the first section of the slot <NUM> with the needle shield <NUM> extending over the end of the needle <NUM>. The hub assembly <NUM> is connected to the delivery pen where the proximal end of the needle <NUM> connects with the delivery pen for delivering the substance to the patient. The cover is used to connect the needle hub body <NUM> to the delivery pen by rotating the cover and the hub body to screw the hub body onto a threaded end of the delivery pen. In one embodiment shown in <FIG>, the cover <NUM> includes an inwardly extending rib <NUM> that cooperates with the tab <NUM> and lug <NUM> forming a stop member.

As the cover is rotated and the hub assembly is screwed onto the delivery pen, the rib <NUM> slides over tab <NUM> when sufficient resistance is provided with the hub assembly properly tightened on the threaded end of the delivery pen forming an audible click or snap sound and/or a tactile feel that can be perceived by the user thereby indicating the hub assembly is properly tightened without over tightening. The rib <NUM> then rotates into the contact with lug <NUM> to provide sufficient resistance that can be perceived by the user after the audible click or resistance to provide an indication to the user that the hub assembly is correctly and properly coupled to the delivery pen.

The end of the hub assembly attached to the delivery pen is pressed against the skin of the patient so that the needle shield <NUM> retracts by sliding into the hub body <NUM> to expose the needle <NUM> where the needle <NUM> penetrates the skin of the patient as shown in <FIG>. In the position shown in <FIG>, the tab <NUM> slides along the first longitudinal section <NUM> of the track <NUM> to the bottom end where the first lateral section <NUM> is located. The spring <NUM> provides a torsional force to the needle shield <NUM> relative to the fixed retainer <NUM> and the hub body <NUM>. The spring <NUM> rotates the needle shield <NUM> in the counter clockwise direction as shown in <FIG> where the tab <NUM> slides along the first lateral section <NUM> toward the second longitudinal section <NUM> as shown in <FIG>. After the injection is completed, the hub assembly <NUM> and needle <NUM> are withdrawn from the patient. The spring <NUM> biases the needle shield <NUM> outwardly to the extended position as shown in <FIG>. The spring <NUM> is wound or twisted during assembly with the hub body <NUM> to provide the rotational force to needle shield <NUM> to move the tabs <NUM> through the lateral sections of the track.

The torsional force applied by the spring <NUM> rotates the needle shield <NUM> to the position shown in <FIG> where the tab <NUM> slides along the second lateral section <NUM>. At the same time, the rotation of the needle shield <NUM> allows the flexible member <NUM> to slide over the rib <NUM> in the hub body <NUM> to the position shown in <FIG> where the end face <NUM> of the flexible member <NUM> contacts the side edge of the rib <NUM> and prevents the needle shield <NUM> from being rotated back toward a position where the tab <NUM> is aligned with the second longitudinal section <NUM> of the track <NUM>, thereby preventing re-use of the hub assembly.

In one embodiment as shown, the top distal end of the first longitudinal section <NUM> is spaced a distance from the top end of the hub body <NUM> where the needle shield projects from the top end a first distance to cover the needle <NUM>. The second lateral section <NUM> is shown as being open at the top end of the hub body <NUM> so that the needle shield <NUM> projects from the top end of the hub body a second distance that is greater than the first distance when the tab of the needle shield is received in the first longitudinal section <NUM>. A visual indicator such as a colored band <NUM> is provided on an outer surface of the needle shield <NUM> and is positioned so that the indicator is not visible when the needle shield <NUM> is in the first extended position shown in <FIG> but is visible when the needle shield is in the second extended position shown in <FIG> thereby providing a visual indication to the user that the device has been used. The visual indicator <NUM> can be an annular recess, rib, colored ring or band or other feature that is able to provide a visual indication to the user that the device has be used and the needle shield is deployed to the extended locked position. The visual indicator <NUM> can be formed on the end portion <NUM> or the body portion <NUM>.

In each of the foregoing embodiments, the components of the hub and outer cover are typically injection molded plastic, such as acrylonitrile butadiene styrene (ABS), polypropylene, or the like while the cannula is surgical grade stainless steel. Other materials and methods of manufacture known to those of ordinary skill in the art of medication pen technology may be adapted for use herein without departing from the scope of the invention. To assemble the parts, the hub assembly may be constructed with the needle separately, with adhesive applied in the interface area to secure the cannula to the hub, and this sub-assembly may then be assembled with an inner shield (optionally, depending on the embodiment), and fit by interference into an outer cover.

Claim 1:
A pen needle (<NUM>), comprising
a hub body (<NUM>) having a proximal end for attachment to a delivery device and a distal end;
a needle (<NUM>) coupled to said hub body (<NUM>) and having a distal end extending from said distal end of said hub body (<NUM>);
a needle retainer (<NUM>) coupled to said hub body (<NUM>) and configured to support said needle (<NUM>), and
a needle shield (<NUM>) mounted in said hub body (<NUM>) and sliding between a first extended position to cover said needle (<NUM>) and a retracted position to expose said distal end of said needle (<NUM>), and where said needle shield (<NUM>) is rotatable in a first direction from a first angular position where said needle shield (<NUM>) slides in said hub body (<NUM>) between said extended position and said retracted position, and a second angular position where said needle shield (<NUM>) is locked in a second extended position,
characterized by
a spring (<NUM>) having a first end coupled to said needle retainer (<NUM>) and a second end coupled to said needle shield (<NUM>) to bias said needle shield (<NUM>) to said second extended position and apply a rotational force to said needle shield (<NUM>) to rotate said needle shield (<NUM>) to a locked position
wherein said needle shield (<NUM>) includes at least one tab (<NUM>) that slides within a track (<NUM>) in said hub body (<NUM>) to allow the needle shield (<NUM>) to slide between the first extended position and the retracted position and to rotate from the first angular position to the second angular position.