Patent Publication Number: US-2016228652-A1

Title: Needle retraction mechanism for autoinjector

Description:
BACKGROUND OF THE INVENTION 
     The present invention, in some embodiments thereof, relates to a needle point safeguarding mechanism and, more particularly, but not exclusively, to a retraction mechanism of an autoinjector. 
     U.S. Pat. No. 7,530,964 to Cabiri discloses a needle device having a needle retraction mechanism that retracts the needle upon removing the device from the skin surface (either intentionally or unintentionally). Once the needle is retracted, the device is rendered inoperative. The needle can be further made inoperative by bending it when one attempts to reuse the device. In another embodiment, a needle opening formed in the base of the housing can be covered to render the needle inoperative when one attempts to reuse the device. In another embodiment, the needle device instead has a needle shield that automatically covers the needle after use. 
     U.S. Pat. No. 8,348,898 to Cabiri, discloses a needle assembly adapted for fluid communication with a vial containing a substance to be delivered to a subject, the needle assembly including a needle held in a needle holder, the needle holder confined to move in a housing, and an activation mechanism for activating delivery of the substance through the needle, the activation mechanism including a safety latch that initially impedes movement of the needle holder, wherein when the safety latch is placed on the subject, the safety latch moves to a position that permits moving the needle holder to cause the needle to protrude outwards of the housing to pierce the subject to allow administration of the substance to the subject, characterized by a biasing device arranged to apply a biasing force on the needle to cause the needle to protrude outwards of the housing to pierce the subject, and needle release apparatus including a needle arrestor that initially blocks movement of the biasing device and which releases the biasing device when the safety latch moves to the position that permits moving the needle holder to cause the needle to protrude outwards of the housing. 
     U.S. Patent Application Publication No. 2009/093,792 to Gross and Cabiri discloses an apparatus for administering a substance to a subject. A vial contains the substance and a stopper is disposed within the vial and is slidably coupled to the vial. A first threaded element is (a) rotatable with respect to the vial and (b) substantially immobile proximally with respect to the vial during rotation of the first threaded element. A second threaded element is threadedly coupled to the first threaded element. At least a distal end of the second threaded element is substantially non-rotatable with respect to the vial, and the distal end of the second threaded element defines a coupling portion that couples the second threaded element to the stopper. The first threaded element, by rotating, linearly advances the stopper and at least the distal end of the second threaded element toward a distal end of the vial. Other embodiments are also described. 
     Additional background art includes International Patent Application Publication No. WO/2013/104414 to SANOFI-AVENTIS DEUTSCHLAND GMBH, U.S. Patent Application Publication No. 2011/0166509 to Gross and Cabiri, U.S. Patent Application Publication No. 2012/0130344 to Ebbett, U.S. Pat. No. 8,267,890 to Alchas and U.S. Patent Application Publication No. 2009/0012494 to Yeshurun. 
     SUMMARY OF THE INVENTION 
     According to an aspect of some embodiments of the present invention there is provided a drug injector having a needle safeguard mechanism including a housing with a shielded location; a point of the needle protruding from the housing; a retractor mechanically coupled to the needle, the retractor retracting the point to the shielded location; and a sensor operationally linked to the retractor, the sensor sensing a resistance to discharging of the drug through the needle; wherein the retractor is responsive to the sensor to retract the point to the shielded location in response to the resistance. 
     According to some embodiments of the invention, said retractor includes a support of the needle and the support reverts to a retracted state in response to the resistance. 
     According to some embodiments of the invention, the support includes an interference element, and the resistance overcomes the interference element. 
     According to some embodiments of the invention, the interference element includes an annular snap. 
     According to some embodiments of the invention, the support includes a telescoping assembly. 
     According to some embodiments of the invention, the telescoping assembly is held in an extended mode by an interference element. 
     According to some embodiments of the invention, the drug injector further includes a driver driving the discharging and the driver is supported by the support, and in response to the resistance the driver produces a stress on the support and the stress reverts the support to the retracted state. 
     According to some embodiments of the invention, the drug injector further includes a plunger and the driver drives the discharging by imparting a linear motion to the plunger and the resistance is to the linear motion of the plunger. 
     According to some embodiments of the invention, the drug injector further includes a lock mechanically coupled to the needle, the lock retaining the point in the protruding position; and wherein the retractor is operationally linked to the lock to release the lock in response to the resistance. 
     According to some embodiments of the invention, the sensor is further sensitive to a second condition, and the lock retains the point in the protruding position until the second condition is met. 
     According to some embodiments of the invention, the point is biased to the shielded position. 
     According to some embodiments of the invention, the lock includes at least one element selected from the group consisting of an interference element, an annular snap, a rib snap, a flange and a groove. 
     According to some embodiments of the invention, the second condition is a volume of the discharging passing a predetermined threshold. 
     According to some embodiments of the invention, the sensor senses a torque. 
     According to some embodiments of the invention, the retracting is in response to a change in the resistance. 
     According to some embodiments of the invention, the retracting is in response to an increase in the resistance. 
     According to some embodiments of the invention, the retracting is in response to a decrease in the resistance. 
     According to some embodiments of the invention, the retracting is in response to the resistance passing a threshold. 
     According to an aspect of some embodiments of the present invention there is provided a method of safeguarding a needle of an injector comprising: discharging a drug through the needle; sensing a resistance to the discharging, and safeguarding the needle in response to the resistance. 
     According to some embodiments of the invention, the safeguarding is in response to the resistance passing a predetermined threshold. 
     According to some embodiments of the invention, the safeguarding is in response to a change in the resistance. 
     According to some embodiments of the invention, the safeguarding is in response to an increase in the resistance. 
     According to some embodiments of the invention, the safeguarding is in response to a decrease in the resistance. 
     According to some embodiments of the invention, the method further includes locking the needle in an extended position during the discharging; and the safeguarding includes releasing the locking. 
     According to some embodiments of the invention, the resistance occurs upon at least one event selected from the group consisting of a completion of the discharging, a fluid leak, jamming of a mechanical component, and disconnection of a mechanical component and obstruction of a fluid flowpath. 
     According to some embodiments of the invention, the method further includes inhibiting the safeguarding until a second condition is met. 
     According to some embodiments of the invention, the second condition includes the discharging passing a predetermined volume. 
     According to some embodiments of the invention, the volume of discharging is measured by counting motor rotations. 
     According to some embodiments of the invention, the needle is a component of a pre filled syringe inside autoinjector and the method further includes: placing the autoinjector on a patient; extending the needle to an extended position subsequent to the placing and prior to the discharging, and the safeguarding includes retracting the needle to a retracted position. 
     According to some embodiments of the invention, the method further includes indicating that it is safe to remove the autoinjector after the retracting. 
     Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some embodiments of the invention are herein described, by way of example only, with reference to the accompanying drawings. With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of embodiments of the invention. In this regard, the description taken with the drawings makes apparent to those skilled in the art how embodiments of the invention may be practiced. 
       In the drawings: 
         FIG. 1  is a flowchart illustrating a method of safeguarding a needle of an autoinjector according to an embodiment of the present invention; 
         FIG. 2  is a illustrating a method of injecting a drug according to an embodiment of the present invention; 
         FIG. 3  is a state diagram of an autoinjector according to an embodiment of the present invention; 
         FIGS. 4A-D  are schematic illustrations of a needle safeguarding mechanism that is triggered by a linear force resulting from resistance to discharge of a drug according to an exemplary embodiment of the present invention; 
         FIGS. 5A-C  are schematic side view illustrations of an autoinjector with a needle safeguarding mechanism including concentric cylindrical telescoping elements according to an exemplary embodiment of the present invention; 
         FIGS. 6A-C  are schematic side view illustrations of a lock of a needle safeguarding mechanism triggered by a torque according to an embodiment of the present invention; 
         FIGS. 7A ,B illustrate a schematic side view and a top cross-sectional view respectively of a needle safeguarding mechanism triggered by a torque according to an embodiment of the present invention; 
         FIGS. 8A ,B illustrate a schematic side view and a top cross-sectional view respectively of a needle safeguarding mechanism triggered by a torque and a second condition according to an embodiment of the present invention; 
         FIG. 9A-F  are detailed schematic views illustrating states of an autoinjector according to an embodiment of the present invention; 
         FIGS. 10A-E  illustrate a needle safeguarding mechanism triggered by a torque and a linear force according to an embodiment of the present invention; 
         FIGS. 11A-C  illustrate a manual trigger for a needle protector of an autoinjector according to an embodiment of the present invention; 
         FIGS. 12A ,B illustrate an optional non-circular cross section for syringe according to an embodiment of the present invention; and 
         FIGS. 13A-D  illustrate an autoinjector with a motor switch located in the main body of the injector in accordance with some embodiments of the current invention. 
     
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION 
     The present invention, in some embodiments thereof, relates to a needle point safeguarding mechanism and, more particularly, but not exclusively, to a retraction mechanism of an autoinjector. 
     OVERVIEW 
     1 Needle Protection Mechanism 
     An aspect of some embodiments of the present invention relates to a needle safety mechanism for an autoinjector. Optionally, an unshielded needle may be safeguarded in response to resistance and/or a change of resistance to discharging of the injector payload. 
     In an exemplary embodiment, a lock may hold a needle in an unshielded position. The lock may optionally act as a support for a discharge driver. Increasing resistance to discharge may increase the stress on the driver. When the stress on the driver increases beyond a threshed and/or decreases beyond a threshold the lock may be released and/or the needle retracted to a safe location. For the sake of the current disclosure retraction of a needle may include pulling a needle point back into a shielded location without changing the length and/or shape of the shielding; and/or retracting may include extending the housing of the injector and/or a shield ahead of a needle point such that the needle is left in a shielded location. 
     In some embodiments, a support for a needle assembly may include a telescoping assembly. Optionally, the telescoping assembly may retract the needle (for example by contracting) in response to a stress from a driver. 
     In some embodiments, the safeguarding mechanism may include a sensor sensitive to a linear force from the driver. For example, a pushing force passes a threshold, a lock may be released moving the needle to the retracted configuration. 
     In some embodiments, the force to insert the needle to the skin of a patient may range for example between 0.1 to 0.5 N. Optionally, the force required to inject the drug (for example the force on a syringe plunger) may range for example between 5 to 20 N. 
     In some embodiments a needle protection mechanism may be triggered by a linear force greater than, for example, between 10 to 30 N. 
     For example, an autoinjector may be activated by manually pushing with enough force to insert the needle. The device may then apply an injection force to inject a drug. Once the entire drug is injected and/or when there is an obstruction and/or occlusion, the injection force may rise until it passes a threshold triggering safeguarding of the needle and/or ending injection. 
     For example in the event of an occlusion and/or at the end of delivery, the linear force generated by the device may increase to the level of up to 60 N. A needle safeguarding mechanism may include a sensor that is sensitive to the force. For example the sensor may include a snap that gives way at 40 N returning the needle to the retracted position. 
     In some embodiments, the stress to inject a medicine and/or to trigger safeguarding of a needle may include a torque. For example, injection of medicine may be driven by a plunger. The plunger may optionally be driven by a threaded assembly, for example a threaded screw and/or teeth and/or a telescoping assembly. Optionally the pitch of the teeth and/or an associated screw may range for example between 0.5 and 2 mm. The diameter of the screw may range for example between 3 and 12 mm. The torque to power injection may range for example between 0.2 and 1.0 N*cm. The trigger torque (the torque at which the needle safeguarding is triggered) may range for example between to 2-4 N*cm. 
     In some embodiments a safety mechanism may include linear movement of the ranging between 5 to 15 mm. For example movement of the safety mechanism may include extension of a needle during insertion and/or retraction of the needle and/or extensions of a safety shield and/or retraction of a safety shield. Optionally a needle insertion length (for example the length of needle inserted into a patient) may range for example between 5 to 10 mm. 
     During injection, the linear movement of a plunger may range for example between 10-50 mm. The length of movement of the plunger may vary for example with the volume of medicine to be injected that may range for example between 0.5 to 3 ml. 
     In some embodiments, a sensor of a safeguarding mechanism may be sensitive to a torque. For example, the needle may be retracted when the mechanism is exposed to a twisting moment. Optionally, discharge may be driven by a torque. For example the driver may apply torque to threaded element pushing a plunger. When the torque on the driver reaches a threshold value, the needle may be released and/or retracted and/or a needle shield may be deployed. 
     In some embodiments an interference element (for example a snap) may provide resistance to retraction. For example, an annular ring may impede contraction of a telescoping assembly. Alternatively or additionally a rib may impede twisting of a support structure. When stress from the driver passes a threshold, the stress may optionally overcome the interference element. Overcoming the interference element may for example revert the support to a retracted configuration. 
     In some embodiments, a stress resulting from resistance to discharge may trigger deployment of a needle shield. The needle shield may optionally move to shield the needle in reaction to the increased stress. 
     2 Manual Needle Safety Retraction Mechanism 
     An aspect of some embodiments of the present invention relates to a manual retraction mechanism for an autoinjector. The manual retraction mechanism may allow a user to retract the needle of the autoinjector to a safe position in case of for example a malfunction of the injector. For example the safety retraction mechanism may include a release switch. When activated by the user, the release switch may permanently retract the needle into the injector. Alternatively or additionally the release switch may trigger deployment of a needle shield. For example, the casing of the injector may be biased to an extended configuration covering the needle. When the autoinjector is activated the casing may locked in a contracted configuration unshielding the needle. When the user pushes a switch, the lock may be permanently released, covering the needle and preventing reuse and/or a needle stick hazard. 
     3 Flexible Cover to Peel Adhesive Protector 
     An aspect of some embodiments of the present invention relates to a mechanism to peel an adhesive protector when a safety cover is pulled off of an autoinjector. For example the safety cover may be flexible and/or a hinged and/or may be anchored to an edge of the adhesive cover. As the safety cover is pulled away the pulling force may be transferred to a peeling force at the edge of the adhesive protector. 
     4 Stabilized Manually Held Autoinjector 
     An aspect of some embodiments of the present invention relates to a manually held autoinjector with stabilization. For example, while in use the auto injector may be held to the skin of a patient by a user, for example the user may be a caretaker and/or the patient himself. In some cases, it may be difficult for a user to manually hold an autoinjector immobile enough and/or for long enough to complete injection. The auto injector may include an adhesive to increase stability of the injector. The adhesive may hold the activation zone of the injector and/or the injection zone and/or a needle aperture and/or a needle stable with respect to the skin of the patient. 
     In some embodiments, a syringe may be held substantially perpendicular to a surface contacting the user&#39;s skin. For example, the syringe may be held at an angle ranging between 75° to 105° to the user&#39;s skin during injection. For example, holding the injector immobile may include holding a needle at an injection depth of between 5 to 10 mm. For example, holding the injector immobile may include not sliding the injector along the patient&#39;s skin and/or straining the needle enough to bend and/or occlude the needle. 
     In some embodiments the injector may be held substantially immobile with respect to the skin of a patient for a time ranging for example between 10 to 600 seconds and/or the injector may be held substantially immobile with respect to the skin of a patient for a time ranging for example between 30 to 180 seconds. For example the injector may inject of volume of drug ranging between 0.5 to 3 ml. 
     Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. 
     Exemplary Embodiments 
     1 Method of Safeguarding a Needle 
     Referring now to the drawings,  FIG. 1  illustrates a method of safeguarding a needle of an autoinjector according to an embodiment  100  of the present invention. In the exemplary method, when medicine is being discharged  104  from the autoinjector there may be a resistance to the discharging  104 . The resistance may be sensed  108 . When the resistance reaches a threshold level the needle may be safeguarded  110 . 
     In some embodiments of an autoinjector, the resistance to discharge may change at some point during the injection. For example, there may be an increase in resistance to movement of a plunger when it reaches the end of a syringe. For example, there may be an increase in resistance to movement of a plunger when a fluid path becomes obstructed. The change in resistance may be sensed  108  by, for example, a pressure sensitive trigger. Optionally increased pressure from the plunger may, trigger safeguarding  110  the needle. For example safeguarding  110  may include retracting the needle tip to a shielded location and/or movement of a shield to cover the needle tip. 
     2 Method of Injecting a Drug 
     Referring now to the drawings,  FIG. 2  illustrates a method of injecting a drug according to an embodiment  200  of the present invention. In the exemplary method, a needle is optionally retracted to a safeguarded position in response to a resistance to drug discharge. For example, the resistance may increase due to a malfunction such as an obstruction of a flow path and/or the injector completing injection of a full dose. 
     In exemplary embodiment  200  a user (for example a patient and/or a medical aid in home care) may be supplied  215  with an autoinjector ready to administer a medicine. The user may optionally remove  216  a safety cover from the injector. Removing  216  the cover may also automatically peel  218  an adhesive protector from an adhesive and/or remove a sterile cover from a needle. For example, the adhesive may be supplied to stabilize the injector on the skin of a patient during injection. The injector may optionally be placed  220  on a patient (who may be the user). In some embodiments a user may hold the injector to the skin of a patient, the adhesive may stabilize the injector for example from shifts and/or movements of the patient and/or the user. 
     In some embodiments, before injection, a needle may optionally be unshielded  202 . For example, while placing  220  the injector on the patient, the user may put pressure on an activation mechanism. The activation mechanism may react to pressure for example by unshielding  202  the needle, for example by extending the needle outward and/or inserting the needle into the patient. The needle may optionally be locked in the extended position. Optionally, the needle may be biased to a protected position (for example to retract into a housing of the injector). Alternatively or additionally, the needle may be biased to the unshielded position. Alternatively or additionally, the autoinjector may be supplied with the needle in an extended mode and/or protected by a cover. 
     At any point during the injection process, a manual safeguard  224  mechanism may be used to place the injector in a safeguarded mode. For example, if the user decides to abort  222   a - f  at any point in the process (for example if he detects some sort of malfunction and/or feels a negative reaction to the medicine) the user may manually safeguard  224  the needle. For example, a needle shield may be released to manually safeguard  224  the needle and/or the needle may be retracted. Optionally there may be an indicator to indicate  212  whether the needle was automatically safeguarded  210  and/or whether needle was manually safeguarded  224 . Alternatively or additionally there may be an indicator whether a full dose was administered and/or how much medicine was administered. 
     Once the needle is inserted into the patient, the injector may optionally begin discharging  204  medicine. For example the medicine may be injected through the needle into the patient. Optionally, discharge may continue until a full dose of the medicine is administered. 
     In some embodiments, after administration of a full dose of the medicine, there may be a change  206  in resistance to further discharging. For example in a syringe based injector, a plunger may reach the end of the syringe and cease to move increasing resistance. Alternatively or additionally, after discharging the entire dose a transmission may be disconnected (for example a threaded element may pass the end of its threading) reducing resistance. Alternatively or additionally, the change  206  in resistance may result from another cause for example increased resistance due to a full or partial occlusion of a fluid pathway and/or jamming of a mechanical component (for example cross threading of a screw). The change of resistance may optionally be sensed  208  triggering safeguarding  210  of the needle. 
     In some embodiments, the needle may be locked in an unshielded  202  state by a force sensitive lock. When the lock senses  208  the change  206  in resistance, it may release  209  the needle which may be safeguarded  210  by moving the tip to a shielded position (for example by retracting the needle tip to a shielded location). Alternatively or additionally, safeguarding  210  may include covering the needle tip with a needle shield. 
     In some embodiments, a flag may be supplied (for example a LED and/or a changing color indicator) to indicate  212  to the user that the needle has been safeguarded  210  and/or that the injector can safely be removed  214  from the patient. 
     3 States of an Autoinjector 
       FIG. 3  is a state diagram of an autoinjector according to an embodiment of the present invention. In general, may be supplied in an unattached  337  state. An unattached  337  autoinjector may have a secured  331  state. For example in the secured  331  state the injector may be safe to handle and/or transport. Optionally the injector may have an enabled  332  state. For example, in the enabled  332  state, the injector may be unstable and/or easily activated. For example, an injector may be switched from the secured  331  state to the enabled  332  state by removing a needle protector and/or an adhesive cover. 
     Once activated the injector may optionally be fastened to a patient. In the fastened  338  state the injected may optionally be activated. For example, while the injector is in the active  333  state, a needle may project from the injector. In some embodiments the injector may be hazardous to handle in the enabled  332  and/or active  333  state. 
     In some embodiments, after use (optionally whether or not administration of the full dose was successful) the user may want to remove and/or dispose of the autoinjector. In some embodiments, it may be difficult and/or dangerous to remove an injector in the enabled and/or active state. For example, when an injector is fastened to a patient by an adhesive, it may be difficult to remove the needle by pulling the injector away from the skin. Optionally, first a needle may be retracted from the skin into the injector. Subsequently the adhesive may be removal by peeling from the skin. In some embodiments, the injector may automatically be safeguarded  335  for example by retraction of a needle upon completion of injection. Alternatively or additionally, the user may have the option to manually secure the injector into a safeguarded  336  state. For example, the optionally of manually needle retraction may avoid the situation where a patient may not be able to properly remove the injector due to a malfunction that leaves the injector fastened to the skin with the needle inserted into the patient. During and/or after safeguarding  335 ,  336  the injector may be removed from the patient. 
     Optionally, the injector may have a final released state  339 , for example wherein the needle is retracted back into the injector and/or the needle tip is shielded and/or the injector has been unfastened from the patient. Optionally one or more indicators may be supplied to indicate the state of the injector and/or the quantity of medicine discharged. Once released, the injector may be in final  314  state (protected from hazards and/or ready for disposal, for example in a municipal waste). 
     4 Needle Safeguarding Triggered by a Linear Force 
       FIGS. 4A-D  are schematic illustrations of a needle safeguarding mechanism that is triggered by a linear resistance to discharge of a drug according to an exemplary embodiment  400  of the present invention. In exemplary embodiment  400 , a needle is biased to a retracted state for example by a spring  462 . During injection (for example as illustrated in  FIG. 4B ) the needle is optionally held in an unshielded state by a driver  444 . Driver  444  itself may be locked in place for example by an interference element  452   b . Additionally or alternatively driver  444  may push a plunger  448  to discharge a medicine. When a full dose has been administered (for example as illustrated in  FIG. 4C ), plunger  448  may optionally reach the end of its path and be stopped. For example plunger  448  may be stopped by the front end of a syringe  446 . Optionally syringe  446  may rest against a housing  440 . In some embodiments interference element  452   b  may serve as a sensor. For example, the force of the driver pushing a plunger rod  450 , plunger  448  and/or syringe  446  against housing  440  may optionally overcome interference element  452   b , unlocking driver  444  and/or syringe  446  and/or the needle (for example as illustrated by force  464   b  of  FIG. 4C ). Once unlocked, driver  444  may revert to a retracted state and/or the needle may optionally retract back into the housing (for example as illustrated in  FIG. 4D ). 
     In some embodiments, interference elements  452   a,b  and spring  462  may be elastic and/or deformable, allowing them to be deformed by a sufficient force (for example as illustrated by force  464   b  of  FIG. 4C ) to unshield the needle. 
       FIG. 4A  illustrates exemplary embodiment  400  in a deployed state prior to activation. For example, in the deployed state a needle tip  460  is shielded by an activation zone  442  of housing  440 . Needle tip  460  is safeguarded by a retraction assembly including for example a spring  462  biasing the needle into housing  440  and a lock  458  and a driver  444  which hold needle tip  460  and its supporting syringe  446  inside housing  440 . In exemplary embodiment  400 , lock  458  optionally includes a driver support  456  and a slot  454  and interference elements  452   a  and  452   b . In  FIG. 4A , driver  444 , syringe  446  and needle tip  460  are held in the retracted position by interference element  452   a  and/or spring  462 . 
       FIG. 4B  illustrates exemplary embodiment  400  in an activated state, for example right before and/or during discharge of a medication. For example, embodiment  400  is activated by placing activation zone  442  against the skin  466  of a patient and/or pushing driver  444  with a sufficient force  464   a . Pushing driver  444  optionally pushes needle tip  460 , syringe  446 , and/or driver support  456  from the retracted position (illustrated in  FIG. 4A ) to the extended position (illustrated in  FIG. 4B ). As support  456  moves from the retracted to the extended position, it slides along slot  454 . Sliding along slot  454 , support  456  overcomes biasing spring  462  and/or interference elements  452   a,b . Optionally support  456 , syringe  446  and/or driver  444  are locked into the unshielded position by interference element  452   b . Once activated, driver  444  may apply a force  464   b  (see  FIG. 4C ) on plunger rod  450  and/or plunger  448  to discharge medicine. 
       FIG. 4C  illustrates exemplary embodiment  400  at the end of discharge of a medicament. Plunger  448  has optionally reached the end of its path and is encounters resistance from further movement. For example, further movement may be resisted by the front end of syringe  446  which is resting against housing  440 . Optionally the resistance force  464   b  may be sensed by driver  444  as a strong counter force pushing driver  444  and driver support  456  distally away from plunger  448 . The counterforce may optionally become large enough to overcome interference element  452   b . Overcoming interference element  452   b  may optionally trigger safeguarding needle tip  460 . For example, biasing spring  462  and/or momentum may optionally overcome interference element  452   a  returning support  456 , driver  444 , syringe  446  and/or needle tip  460  to the retracted safeguarded position (as illustrated for example in  FIG. 4D ). 
     5 Needle Safeguarding by a Telescoping Element 
       FIGS. 5A-C  are schematic side view illustrations of an autoinjector with a needle safeguarding mechanism including concentric cylindrical telescoping elements according to an exemplary embodiment  500  of the present invention. The safeguard mechanism of exemplary embodiment  500  includes a cylindrical driver  544  mounted concentrically in a cylindrical sleeve  568 . When driver  544  telescopes out from sleeve  568  a needle tip  560  is unshielded. When driver  544  retracts into sleeve  568 , needle tip  560  is safeguarded. As used herein the word cylindrical may include a cylinder with a circular and/or a non-circular cross section. 
       FIG. 5A  illustrates the injector of exemplary embodiment  500  in an activated state before discharge of a medicine payload. Optionally, in the activated state, driver  544  is telescoped out of sleeve  568 . Driver  544  pushes, for example, against a housing  540 . Sleeve  568  optionally pushes a syringe  546  and/or needle point  560  extending needle point  560  out of housing  540  and/or unshielding needle point  560 . 
       FIG. 51  illustrates exemplary embodiment  500  at the end of medicine discharge. Driver  544  has optionally pushed a plunger rod  550  and/or plunger  548  into syringe  546  discharging the payload of the injector. In the example, further pushing by driver  544  will, for example, create a high stress between driver  544  and plunger rod  550 . The stress may optionally cause driver  544  to retract into sleeve  568 . 
       FIG. 5C  illustrates that in exemplary embodiment  500 , when driver  544  retracted into sleeve  568  needle point  560  is optionally retracted back into a protected position. In the protected position, needle tip  560  may optionally be shielded by housing  540  safeguarding needle tip  560 . 
     6 Needle Safeguarding Triggered by a Torque 
       FIGS. 6A-C  are schematic side view illustrations of a lock  658  of a needle safeguarding mechanism triggered by a torque according to an embodiment  600  of the present invention. For example, in embodiment  600  lock  658  holds a needle (not shown) in an unshielded and/or extended state. Optionally a torque overcoming an interference element releases lock  658 . For example in embodiment  600 , when lock  658  is released, a driver  544  slides into a sleeve  568  retracting the needle to a safeguarded location. 
     The needle safeguarding mechanism of embodiment  600  may optionally include concentric cylindrical telescoping elements similar for example to embodiment  500 . Embodiment  600  is illustrated in  FIGS. 6A-C  in states respectively similar to the states illustrated for embodiment  500  in  FIGS. 5A-C . Embodiment  600  may for example be used to hold a needle in an unshielded and/or safeguarded state in a manner similar to embodiment  500 . 
       FIG. 6A  illustrates the safeguarding mechanism of exemplary embodiment  600  in an exemplary activated state before discharge of a medicine payload. Optionally, in the activated state, driver  544  is telescoped out of sleeve  568 . Driver  544  may optionally be connected to a support  656 . Support  656  may for example move along a doglegged slot having two tracks, for example track  654   a  and track  654   b . In the extended state of  FIG. 6A  support  656  is blocked by a shoulder  655  of track  654   a  optionally preventing driver  544  from sliding into sleeve  568 . Optionally, support  656  is blocked from moving to track  654   b  by an interference element  652 . Optionally interference element  652  may be made of an elastic material that may be overcome by a sufficient stress. 
       FIG. 6B  illustrates exemplary embodiment  600  at the end of medicine discharge. Driver  544  has optionally pushed a plunger rod  550  to the end of a syringe. Pushing of rod  550  may be for example by a telescoping screw. In the example of embodiment  600 , further pushing by driver  544  may, for example, create a high torque stress between driver  544  and plunger rod  550  and/or between driver  544  and sleeve  568 . The torque may for example overcome interference element  652  and slide support  656  onto track  654   b.    
       FIG. 6C  illustrates that in exemplary embodiment  600 , after support  656  has been forced by torque onto track  654   b . Support  656  may slide along track  654   b  and/or driver  544  may slide into sleeve  568 . Sliding driver  544  into sleeve  568  may optionally revert driver  544  and/or sleeve  568  and/or the needle to a retracted state and/or retract needle point  560  back into a protected position for example as illustrated in  FIG. 5C . 
     In some embodiments there may be biasing element, for example a spring, biasing the needle to a safeguarded state. Optionally, embodiments  500  and/or  600  may contain a biasing element, for example similar to spring  462 . 
     7 An Extended Area Rotational Interference Element 
       FIGS. 7A ,B illustrate a schematic side view and a top cross-sectional view respectively of a needle safeguarding mechanism triggered by a torque according to an embodiment  700  of the present invention. Embodiment  700  includes elongated interference elements  752   a,b  resisting rotation of driver  544  with respect to sleeve  568 . The elongated interference elements  752   a,b  spread the resistance to rotation over a large area. The large interference elements  752   a,b  may in some embodiments produce a consistent resistance even if there are small flaws during formation of part elements  752   a,b.    
     Similar to embodiment  600 , embodiment  700  includes two concentric cylindrical telescoping elements, a driver  544  in a sleeve  568 . A lock  758  includes a driver support  656  that moves between two tracks  654   a,b . Lock  758  may optionally move from a locked state (holding the system in an extended mode) to a released state in response to a torque twisting driver  544  with respect to sleeve  568 . For example twisting may trigger retraction of a needle. For example twisting may be triggered by a plunger reaching the end of a syringe after administering a full dose of a drug. Alternatively or additionally retraction may be triggered by an obstruction in a fluid pathway providing resistance to movement. The resistance to movement of a screw thread plunger may optionally produce the torque to twist and/or unlock the retractor. 
     One difference between embodiment  600  and embodiment  700 , is the location and geometry of the resistance interference elements. In  700  the resistance interference elements  752   a,b  include two ribs, one rib (element  752   a ) located on an outer surface of driver  544  and another rib (element  752   b ) located on an inner surface of sleeve  568 . Resistance interference elements  752   a,b  resist rotation of a driver  544  within sleeve  568  and/or movement of support  656  from track  654   a  to  654   b . When support  656  is on track  654   a , driver  544  and/or the needle may remain in an extended position. When support  656  is on track  654   b , driver  544  and/or the needle may be retracted. Alternatively or additionally there may be more than two ribs serving as resistance elements. For example, multiple pairs of ribs may engage simultaneously to create a compound resistance at a single point of rotation. Alternatively or additionally, there may be more than two sections of tracks and or there may be multiple steps of resistance and/or extension and/or retraction. 
     8 Multi-Conditional Needle Safeguarding 
       FIGS. 8A ,B illustrate a schematic side view and a top cross-sectional view respectively of a needle safeguarding mechanism triggered by a torque and a second condition according to an embodiment  800  of the present invention. Embodiment  800  includes a logical sensor. For example a logic controlled interference element  852  resists rotation of driver  544  with respect to sleeve  568 . Interference element  852  may optionally be responsive to a controller  874 . In some embodiments even when there is a torque capable of overcoming interference elements  752   a,b  the needle will not retract until controller  874  opens interference element  852 . For example, controller  874  may open resistance element  852  when a predetermined portion (for example substantially all of) a payload of the injector has be administered. Optionally, the needle will be retracted when there is a resistance to discharge of the medicine and the entire payload has been administered. Optionally the needle may not retract in response to an obstruction to the fluid pathway when it occurs before the entire payload is administered. 
     Embodiment  800  may be similar in many aspects to embodiment  700 . Embodiment  800  differs from embodiment  700 , at least in that embodiment  800  includes an additional interference element  852 . Optionally, element  852  blocks retraction of a needle until a further condition is fulfilled (for example in embodiment  700  the needle may retract on any application of a sufficient torque to driver  544  whereas in embodiment  800  the needle may optionally be prevented from retracted until a sufficient torque is applied and the payload of the injector has been sufficiently administered). 
     In some embodiments logic controlled resistance element  852  may block movement of support  656  to track  654   b . When the sufficient portion of the payload of the injector has been administered, controller  874  may close a switch  872 . Closing switch  872  may optionally allow a current from a battery  870  to flow to element  852 , melting element  852  and/or allowing support  656  to move to path  654   b  and/or allowing driver  544  to slide into sleeve  568 . 
     9 Detailed Illustration of States of an Injector 
       FIGS. 9A-D  include detailed cross sectional side views illustrating four states of an autoinjector according to an embodiment of the present invention. In some embodiments, an injector  900  is an automated self injection device. For example the self injecting device may in some ways be similar to a pen injector. Optionally injector  900  may be loaded with a standard type syringe  946  and/or hypodermic needle  960 . For example, needle  960  may be rigidly connected and/or project from a distal end of syringe  946 . Needle  960  may be coaxial with syringe  946 . Alternatively or additionally the axis of needle  960  may be parallel to the primary longitudinal axis  977  of syringe  946  but offset therefrom. Syringe may be loaded into injector  900  with needle  960  in a sterile state and/or covered by a sterile cover. 
     In some embodiments, an injector may include for example an adhesive  978  base  942 . For example, adhesive  978  base  942  may assist a user to hold injector  900  steady on the skin of a patient for an extended period. For example, injector  900  may be used to give injections of volume ranging between 0.5 and 3.0 ml over a time period ranging between 30 sec to 180 sec. 
     Injector  900  includes for example an annular snap resistance element  952  paired to an annular driver support  956 . When a linear stress increases past a threshold, the annular snap gives way and a needle  960  may optionally be retracted to a protected location. 
       FIG. 9A  is a schematic cross sectional side view illustrating injector  900  in an enabled state (ready for activation). For example, in the enabled state an optional safety cover and/or a sterile cover may and/or an adhesive protector may have been removed from the injector. In the enabled state needle  960  is in a protected location, created by a shield  941  which extends the distal end of a housing  940  of the injector. Needle  960  and/or shield  941  may optionally be retained in position, for example by a snap and/or held in position by a biasing device, for example a spring. 
     In some embodiments, needle  960  may optionally be supported by a syringe  946 ; which is in turn supported for example by a cylindrical outer sleeve  968 . Outer sleeve  968  may optionally be supported by an annular support  956  resting on an annular snap resistance element  952 . For example annular snap resistance element  952  may extend radially outward from a cylindrical inner sleeve  967 . Optionally, inner sleeve  967  and/or outer sleeve  968  and/or a driver  944  may be operationally linked to a transmission  984  such that rotating transmission  984  rotates one or more of inner sleeve  967  and/or outer sleeve  968  and/or a driver  944 . 
     In some embodiments, a motor switch  982  may be located in shield  941 . In the enabled state (before activation), switch  982  is optionally switched off. 
     In injector  900 , syringe  946  is held to outer housing  940  by a socket  961 . Socket  961  allows syringe  946  to slide axially with respect to housing  940  but not to move laterally. In injector  900 , transmission  984  is held rotatably fixed to housing  940  by bearing  959  in a hub  965 . 
       FIG. 9B  is a schematic cross sectional side view illustrating injector  900  immediately after activation. For example, to activate the injector, a user may place the distal end of the injector (including for example an adhesive  978  and/or an activation zone on base  942 ) against the skin  966  of a patient and/or push  964  on the proximal end of the injector until shield  941  collapses into housing  940  in a direction parallel to the longitudinal axis of needle  960 . Collapse of shield  941  may optionally unshield needle  960  tip which may for example be pushed into the skin  966  of the patient. For example, in operation, needle  960  may protrude from injector  900  into a patient. Optionally, in operation, needle  960  may be in fluid communication with syringe  946  and/or the patient. For example needle  960  may supply a fluid pathway for discharging medicine directly from syringe  946  through needle  960  into the patient. 
     In some embodiments, collapse of shield  941  may activate switch  982 . For example in injector  900  switch  982  is depressed by being pushed against syringe  946 . Depressing switch  982  may activate a motor  976  to start discharging a drug. For example, in injector  900  motor  976  turns a transmission  984 . Transmission  984  may include for example a gear. Transmission  984  may optionally rotate inner sleeve  967  and/or driver  944 . In exemplary injector  900 , driver  944  includes teeth and/or threads which engage a screw thread  953  on a plunger rod  950 . Rotating driver  944  may optionally drive plunger rod  950  and/or plunger  948  in the distal direction, discharging the medicine. Optionally, plunger  948  continues to move distally until it is stopped by for example a blockage in the fluid path (preventing further discharge) and/or until plunger  948  reaches the distal end of syringe  946 . Optionally, when needle  960  is in the extended position, a flange  947  of syringe  946  seats against a bracket  973 , which holds syringe  946  and/or prevents further longitudinal movement. 
       FIG. 9C  is a schematic cross sectional side view illustrating injector  900  at the end of discharge of the payload. For example plunger  948  has discharged all of the medicine out of syringe  946  and/or has reached the distal end of syringe  946 . Optionally, further rotation of driver  944  increases the stress pushing driver  944  proximally. Interference element  952  may serve as stress sensor. For example, motor  976  may supply enough torque to create a force which overcomes interference element  952 . 
     In some embodiments, once interference element  952  is overcome a course inner threading  955  in sleeve  967  rotates with respect to a course outer thread  951  of driver  944  drawing driver  944  and/or plunger  948  and/or syringe  946  and/or needle  960  proximally into a retracted state. For example, the course thread  951  has an opposite threading from the threading  953  between driver  944  and plunger rod  950 . The same direction of rotation that drives plunger  948  distally before overcoming interference element  952  also draws back plunger  948  and/or syringe  946  and/or needle  960  proximally after overcoming interference element  952 . Optionally needle  960  is retracted into a protected location inside housing  940  for example as illustrated in  FIG. 9D . Alternatively or additionally, course thread  951  may have an the same direction of threading as threading  953  between driver  944  and plunger rod  950  and optionally rotation may be reversed to retract needle  960 . 
       FIG. 9D  is a schematic cross sectional side view illustrating injector  900  in a safe state after finishing injection. Needle  960  point has optionally been retracted into a protected location within housing  940 . Syringe  946  has optionally been retracted. In exemplary injector  900 , when syringe  946  is retracted, it no longer depresses switch  982 . Switch  982  may be biased off and/or raising syringe  946  may shut off motor  976 . 
     In some embodiments one or more windows may be supplied. A user may be able to determine a status of the device by viewing for the windows. For example in  FIG. 9D , injector  900  has been supplied with two windows  990   a,b . For example window  990   a  is located such that during injection, the user views inner sleeve  967  through window  990   a . When outer sleeve  968  has been retracted, it may optionally slide over inner sleeve  967 . After outer sleeve  968  has been retracted, the user views outer sleeve  968  through window  990   a . Optionally window  990   a  may serve as an indicator whether it is safe to remove the injector. For example, outer sleeve  968  may be colored green and/or driver  944  and/or inner sleeve  967  may be colored red. For example, as long as the user sees red in window  990   a  needle  960  tip has not been retracted and/or it is unsafe to remove the injector from the patient&#39;s skin; and/or when the user views green through window  990   a  needle  960  has been retracted and/or discharge has ceased and/or it is safe to remove the injector from the skin of the patient. Optionally, window  990   b  may be used to indicate whether an entire payload of medicine has been administered. For example, syringe  946  may be made of a transparent material. For example, during injection, the user can see the medicine through window  990   b ; after syringe  946  is retracted if the payload has been fully discharged then the user will view plunger  948  through window  990   b . Optionally, if the user sees plunger  948  through both window  990   b  and outer sleeve  968  through window  990   a  then the user can ascertain that it is safe to remove the injector and/or that the drug was fully discharged. 
     In injector  900 , for example, after retraction of the needle the device may be twisted such that one side of the adhesive is lifted and/or peeled (as illustrated by arrow  983  in  FIG. 9D ) from the skin while the far edge of the base of the injector remains in contact with the skin and serves as a fulcrum. 
       FIGS. 9E and 6F  illustrate an external view and cut away view respectively of a needle retractor according to exemplary injector  900  of the current invention. Injector  900  may optionally be designed such that, under sufficient linear stress, support  956  of external sleeve  968  deforms and/or opens to pass over resistance element  952 . Optionally, transmission  984  and/or inner sleeve  967  may be formed of one or more pieces of molded plastic. Optionally outer sleeve  968  and/or driver  944  may be formed of one or more pieces of molded plastic. 
       FIG. 9F , illustrates details of a rotary needle retractor according to an embodiment of the current invention.  FIG. 9F  illustrates driver  944  before needle retraction (for example in a secured state, an enabled state and/or an active state). In the exemplary embodiment, driver  944  is engaged by a set of fine screw threads  953  to rod  950 . In the exemplary embodiment, driver  944  is engaged by a set of course screw threads  951 ,  955  to inner sleeve  967 . Optionally, course screw threads  951 ,  955  are threaded in an opposite sense from fine screw threads  953 . 
     In the exemplary embodiment, prior to needle retraction, sleeve  967 ,  968  and driver  944  are prevented from sliding longitudinally with respect one another. While sleeves  967 ,  968  and driver  944  are prevented from relative longitudinal movement, threads  951  and  955  prevent inner sleeve  967  and driver  944  from rotating with respect to one another. 
     In some embodiments, motor  976  drives transmission  984  to rotate inner sleeve  967 . Optionally, before needle retraction, rotating inner sleeve  967  rotates driver  944 . The sense of screw threads  953  and the rotating direction of motor  976  are optionally chosen such that rotating driver  944  relative to rod  950  pushes rod  950  and/or plunger  948  distally, optionally discharging a drug. 
     When plunger  948  has reached the distal end of syringe  946 , rod  950  is prevent from further distal movement. Torque applied to driver  944  produces a strong proximal stress on driver  944  and/or outer sleeve  968 . The strong proximal stress overcomes and/or releases interference element  952 . Once interference element  952 , is released outer sleeve  968  and/or driver  944  can move longitudinally with respect to inner sleeve  967 . Further rotation of inner sleeve  967  rotates sleeve  967  with respect to driver  944 . The sense of screw threads  955  and  951  and the rotating direction of motor  976  are optionally chosen such rotating driver  944  relative to sleeve  967  draws driver  944  and/or rod  950  and/or plunger  948  and/or syringe  946  and/or needle  960  proximally, optionally retracting needle  960 . Optionally the pitch of screw threads  951 ,  953  and/or  955  can be tuned to achieve a desired rate of medicine discharge and/or needle retraction for a given rotation rate of the motor. In some embodiments, as rod  950  and/or plunger  948  are drawn proximally, friction between plunger  948  and syringe  946  draws syringe  946  and/or needle  960  proximally. Alternatively or additionally, outer sleeve  968  may be attached to syringe  946 . Drawing hack on driver  944  may draw outer sleeve  968  and syringe  946  back with it. In some embodiments additional threaded elements may be added to produce a multi-part telescoping assembly for extending plunger  948  to discharge medicine and/or for retracting needle  960 . In some embodiments some or all of rod  950 , inner sleeve  967 , and/or outer sleeve  968  and/or transmission  984  may be formed of molded plastic and or other materials. 
     10 Stabilized Pen Injector 
       FIGS. 10A-H  illustrate a stabilized injector  1000  according to some embodiments of the present invention. Exemplary injector  1000  is an automated injection device in some ways similar to a pen injector. Optionally injector  1000  may be loaded with a standard type syringe  946  and/or hypodermic needle  960 . Optionally syringe  946  may be supplied loaded with medicine and/or covered with a sterile needle cover  1091 . Syringe  946  may be loaded into injector  1000  with in a sterile state with needle cover  1091  in place. Injector  1000  may include for example an adhesive  978  base  942 . In some embodiments, adhesive  978  base  942  may assist a user to hold injector  1000  steady on the skin of a patient for an extended period. For example, injector  1000  may be used to give injections of volume ranging between 0.5 and 3.0 ml over a time period ranging between 30 sec to 180 sec. 
       FIG. 10A  illustrates an exploded view of injector  1000 . Some components of the exemplary embodiment of injector  1000  which are similar to corresponding parts of the exemplary embodiment of injector  900  are marked with the same number as the corresponding parts of the exemplary embodiment of injector  900 . 
     In the exemplary embodiment of injector  1000  a power supply (for example batteries  1070 ) may optionally supply power to gear motor  976 .  FIGS. 10A ,B illustrate flange  947  of syringe  946 . Optionally flange  947  has at least one non-rounded edge which may be held inside an autoinjector (for example autoinjectors  400 ,  900  and/or  1000 ) preventing rotation of syringe  946 . Outer housing  1040  and/or shield  1041  of injector  1000  are similar to outer housing  940  and/or shield  941  of injector  900 . 
     Some embodiments of a stabilized autoinjector (for example as illustrated in injector  1000  but optionally included in injectors  900  and/or embodiments  400  and/or  200  and/or  100 ) may include a safety cover and/or an adhesive protector and/or a handle. 
       FIG. 10B  illustrates exemplary retraction mechanism  1058 . Retraction mechanism  1058  is optionally activated by a combination of torque and linear stress. For example retraction mechanism  1058  is optionally activated may when plunger  948  is blocked for example when it reaches the end of injection (for example as described in regards to  FIGS. 9A-D  and/or due to an occlusion of needle  960 ). 
     In some embodiments, during drug discharge a motor (for example motor  976 ) rotates transmission  984  in the direction of arrow  1083 . Transmission  984  may optionally be rigidly connected to and/or integrally molded with inner sleeve  1068 . Rotating transmission  984  may also rotate inner sleeve  1068 . A pin  1056  protrudes from driver  1044  into a nearly lateral slot  1054   a  in sleeve  1068 . While pin  1056  is in slot  1054   a , driver  1044  is prevented from moving longitudinally with respect to inner sleeve  1068 . In some embodiments syringe  946  is supported (from moving proximally) by driver  1044 . 
     In some embodiments, when there is a strong linear force on driver  1044  in the proximal direction and/or there is a strong torque on sleeve  1068  in the direction of arrow  1083 , arm  1057  is deflected upward and pin  1056  slides past an interference element  1052  into a longitudinal slot  1054   b . In slot  1054   b  pin  1056  may slide longitudinally (in the proximal direction). A geometry of pin  1056  and/or interference element  1052  may be chosen to achieve a desired resistance to movement. For example, pin  1056  and/or interference element  1052  may have a squared side, a flat side, a rounded side etc. 
     In some embodiments, a spring (for example spring  1062 ) biases syringe  946  in the proximal direction. For example spring  1062  may apply a proximal force to flange  947 . Optionally another biasing element may be used in place of spring  1062 . For example, a biasing element may include a stretched element (for example a rubber band and/or a twisted elements and/or a deflected plastic element). 
     Optionally when pin  1056  enters longitudinal slot  1054   b , spring  1062  pushes syringe  946  and/or outer sleeve  1067  and/or needle  960  and/or driver  1044  and/or pin  1056  proximally, retracting needle  960 . Optionally, needle  960  may be held in the retracted position by spring  1062 . Alternatively or additionally a locking mechanism may be included to lock needle  960  in the retracted position, for example, a one way catch and/or an interference element may lock against syringe  946  as it is retracted and/or against pin  1056  in slot  1054   b . Optionally, in injector  1000  driver  1044  includes two molded plastic telescoping pieces. One piece is optionally integrally molded with outer sleeve  1067 . Optionally, sleeve  1067  and/or driver  1044  may be made as a single piece and/or multiple parts. They may be formed of plastic and/or another material and/or they may be molded and/or formed by another process. 
       FIG. 10C  illustrates exemplary embodiment  1000  assembled and/or in an enabled state before insertion of needle  960  into a patient.  FIG. 10C  illustrates various optional details and/or supporting structures for syringe  946  and/or plunger. 
     In injector  1000 , syringe  946  is held to outer housing  1040  by a socket  1061 . Socket  1061  allows syringe  946  to slide axially with respect to housing  1040  but not to move laterally. In injector  1000 , transmission  984  is held rotatably fixed to housing  1040  by bearing  1059  in a hub  1065 . 
       FIG. 10D  illustrates exemplary injector  1000  in an active state. For example when the injector is in the enabled state, a user may place adhesive against the skin of a patient and push downward (distally) on housing  1040 . Housing  1040  and its contents (for example syringe  946 , transmission  984 , locking assembly of retraction mechanism  1058  etc.) along with needle  960  are all pushed distally along the axis of needle  960 . As needle  960  moves distally, the needle tip passes through a hole in shield  1041 . For example, in operation, needle  960  may protrude from injector  900  into a patient. Optionally, in operation, needle  960  may be in fluid communication with syringe  946  and/or the patient. For example needle  960  may supply a fluid pathway for discharging medicine directly from syringe  946  through needle  960  into the patient. 
     In some embodiments, when needle  960  is in the extended position, the front end of syringe  946  seats into a bracket  1073 . Bracket  1073  may optionally hold syringe  946  steady and/or prevents further longitudinal movement and/or prevent lateral movement with respect to housing  1040 . 
       FIG. 10E  illustrates injector  1000  after needle retraction. Optionally driver  944  includes a telescopic assembly, which is shown in an extended state in  FIG. 10E . Optionally, after retraction of needle  960 , the entire device may be twisted to peel adhesive  978  from the skin. 
     Various aspects or features illustrated herein with respect to a particular embodiment may be combined with other embodiments. For example, needle  460  and  560  of embodiment  400  and  500  are shown mounted at an angle to base and/or activation zone  442  or  542 . Alternatively or additionally they may be perpendicular to the base. For example, needles  960  of embodiments  900  and  1000  are shown perpendicular to base  942 . Alternatively or additionally they may be at an angle to the base. Needle covers and/or protective covers illustrated in one embodiment may be used with another embodiment. Retraction mechanisms illustrated in one embodiment may be used with another embodiment. A clip, an interference element, a catch and/or another locking mechanism may hold an injector in one or another state. For example an interference element may hold a needle in a retracted position and/or in the extended position. 
     11 Manual Needle Safeguard 
       FIGS. 11A-C  illustrate a manual trigger for a needle protector of an autoinjector according to an embodiment  1100  of the present invention. In some embodiments a user may want to abort administration of a drug by an autoinjector and/or safeguard a needle of the autoinjector (for example when the automatic safeguard mechanism fails). Embodiment  1100  supplies a manual system for triggering a needle shield at a user&#39;s discretion. 
       FIG. 11A  illustrates an autoinjector in an activated state. In the active state, a needle tip  1160  may be unshielded. For example, in  FIG. 11A  needle tip  1160  is shown extending out the proximal end of the injector. Optionally, a needle shield  1141  may be pushed distally into a housing  1140  of the injector unshielding needle tip  1160 . For example, in embodiment  1100  shield  1141  is held back in housing  1140  by a catch  1199  abutting against the distal side of a latch  1198 . 
       FIG. 11B  illustrates initiation of manual release of a needle shield according to an embodiment  1100 . For example, a user presses inward on a needle guard release  1186 . Optionally, pushing needle guard release  1186  disengages catch  1199  from latch  1198 . For example, needle shield  1141  may be biased to deploy outward (proximally) when catch  1199  is disengaged. The pressing needle guard release  1186  extends the needle guard and/or housing around the needle, retracting the needle point into a shielded location. 
       FIG. 11C  illustrates an exemplary result of manual extension of the housing and/or retraction of the needle in exemplary embodiment  1100  of the present invention. Needle shield  1141  is shown in an exemplary deployed state. For example catch  1199  may abut on the proximal side of latch  1186  locking shield  1141  in the deployed state. Optionally, needle tip  1160  is safeguarded in a protected space surrounded by deployed needle shield  1141 . 
     12 Rotation Resistance 
       FIGS. 12A ,B illustrate an optional non-circular cross section for syringe  946  according to an embodiment of the present invention. Optionally syringe  946  may be prevented from rotating for example by giving it a non-circular cross section. 
       FIG. 12A  is a side view of embodiment  900  showing a cutting plane for the cross sectional view of  FIG. 12B . 
       FIG. 12B  is a cross section view of embodiment  900  illustrating and optional non-circular cross section of syringe  946 . 
     13 Microswitch Activator for an Autoinjector 
       FIGS. 13A-D  is are cutaway illustrations of an exemplary embodiment of an autoinjector  1300  with a motor switch located in the main body of the injector in accordance with some embodiments of the current invention. Optionally the motor switch remains stationary with respect to the housing of the autoinjector, for example housing  940 , and/or with respect to and/or a motor and/or a power source, for example batteries  1370 . When an activator of the injector is triggered (for example by collapsing a shield  1341 ), movement of the activator may activate the switch. When the needle  960  is retracted and/or shielded (for example after injection), the switch is optionally returned to the inactivated state. Keeping a switch stationary with respect to a motor and/or power source may simplify assembly of the auto injector. 
       FIG. 13A  illustrates injector  1300 , prior to activation in accordance with an embodiment of the current invention. Optionally many structures are the same as other embodiments listed herein above or below, for example, injector  1300  may include the advancement and/or retraction mechanism of injector  900 . Optionally, prior to activation, switch  1382  is in a deactivated position. 
       FIG. 13B  illustrates injector  1300 , immediately after activation in accordance with an embodiment of the current invention. In some embodiments, an injector may be activated by collapsing a needle shield  1341 . Collapsing shield  1341  optionally exposes needle  960  and/or pushes an element  1352  against a side of a syringe and/or pushes an extension  1325  of shield  1341  into switch  1382  and/or activates switch  1382  and/or activates a motor (for example similar to motor  976  of injector  900 ). 
       FIG. 13C  illustrates injector  1300 , immediately at the end of injection in accordance with an embodiment of the current invention. Optionally for as long as shield  1341  remains in a collapsed state and/or needle  960  remains in an extended state (protruding from the injector), extension  1325  continues to hold switch  1382  in an activated state and/or a motor continues to drive plunger  948 . Optionally, when plunger  948  reaches the end of syringe  946  a retraction mechanism (for example lock  758 ) retracts syringe  946  and/or needle  960  to a retracted state (as illustrated for example in  FIG. 13D ). 
       FIG. 13D  illustrates injector  1300  in a retracted state in accordance with an embodiment of the current invention. Optionally, when needle  960  and/or syringe  946  is retracted, element  1352  is released and/or extension  1325  moves away from switch  1382  and/or switch  1382  moves into a deactivated state and/or the motor is switched off. 
     It is expected that during the life of a patent maturing from this application many relevant technologies will be developed and the scope of the terms are intended to include all such new technologies a priori. 
     As used herein the term “about” refers to ±5% 
     The terms “comprises”, “comprising”, “includes”, “including”, “having” and their conjugates mean “including but not limited to”. 
     The term “consisting of” means “including and limited to”. 
     The term “consisting essentially of” means that the composition, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure. 
     As used herein, the singular form “a”, “an” and “the” include plural references unless the context clearly dictates otherwise. For example, the term “a compound” or “at least one compound” may include a plurality of compounds, including mixtures thereof. 
     Throughout this application, various embodiments of this invention may be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numbers within that range, for example, 1, 2, 3, 4, 5, and 6. This applies regardless of the breadth of the range. 
     Whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range. The phrases “ranging/ranges between” a first indicate number and a second indicate number and “ranging/ranges from” a first indicate number “to” a second indicate number are used herein interchangeably and are meant to include the first and second indicated numbers and all the fractional and integral numerals therebetween. 
     It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination or as suitable in any other described embodiment of the invention. Certain features described in the context of various embodiments are not to be considered essential features of those embodiments, unless the embodiment is inoperative without those elements. 
     Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. 
     All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting.