Abstract:
A medical injector is provided herein having a body and a reservoir disposed in the body, the reservoir including at least first and second mixable components. At least one stopper is associated with the reservoir where distal advancement of the stopper over a predetermined distance causes mixing of the mixable components. A plunger is disposed in the body, along with a knob stem and a knob fixed to the knob stem so as to be rotatable therewith. A sleeve is telescopingly disposed over the knob stem, wherein the knob stem and the sleeve have cooperating elements formed thereon which selectively permit rotation of the knob stem to be transmitted to the sleeve so that the knob stem and the sleeve may rotate together. A spring is also provided for urging the sleeve distally. A releasable retainer releasably retains the sleeve against force of the spring. Rotation of the knob releases the sleeve and allows the spring to displace the sleeve distally. Distal movement of the sleeve causes distal movement of the plunger which causes distal movement of the stopper thus causing mixing of the mixable components. Advantageously, with the subject invention, a medical injector may be provided where autoreconstitution can be achieved by the turning of a knob.

Description:
FIELD OF THE INVENTION 
     This invention relates to autoreconstitution devices and, more particularly, to autoreconstitution devices having dose-setting mechanisms. 
     BACKGROUND OF THE INVENTION 
     Certain drugs or medicaments (those terms being used interchangeably herein) are preferably provided in powder or dry form (such as a lyophilized form), and require reconstitution prior to administration. Lyophilized drugs, for example, typically are supplied in a freeze-dried form that needs to be mixed with a diluent to reconstitute the substance into a form that is suitable for injection. Medicaments may also be provided in other dry or powder form that require reconstitution. 
     In addition, drugs may be provided as multipart systems which require mixing prior to administration. For example, one or more liquid (e.g., flowable (slurry or liquid)) components, and/or dry (e.g., powdered or granular) components may be provided in a drug container or delivery device which require mixing prior to administration. The components can be mixed and used to form various administratable drugs, such as insulin. 
     Prior art devices have been developed that provide a wet component (e.g., liquid) and a dry component (e.g., powder) in separate chambers of a common container with the container being configured to permit the flow of the wet component to the dry component to cause mixing thereof in preparing an administratable solution for injection. U.S. Pat. No. 4,874,381 to Vetter is directed to an injector having a barrel configured for mixing, while U.S. Pat. No. 4,968,299 to Ahlstrand et al. is directed to a drug cartridge having a barrel configured for mixing. Both Vetter et al. and Ahlstrand et al. disclose typical configurations for mixing where a bypass channel is formed in the barrel of the device. As such, the device must be specifically configured for mixing. 
     Manual force may be applied to a reconstitution device to cause the mixing of the multiple components. In addition, autoreconstitution devices have been developed in the prior art which provide a trigger-activated automated reconstitution. U.S. Pat. No. 6,793,646 to Giambattista et al. is an example of an autoreconstitution device. U.S. Pat. No. 6,793,646 is incorporated by reference in its entirety herein. The Giambattista et al. injector includes telescoping upper and lower body portions. Autoreconstitution is achieved by telescopingly collapsing the body parts together, thus releasing a spring that forces the reconstitution. It has been found that the Giambattista et al. type device requires a fairly substantial amount of force to activate and is difficult for some. In addition, components occasionally get stuck, thus rendering the injector inoperable. 
     SUMMARY OF THE INVENTION 
     A medical injector is provided herein having a body with a proximal end and a distal end. A reservoir is disposed in the body, the reservoir including at least first and second mixable components. At least one stopper is associated with the reservoir where distal advancement of the stopper over a predetermined distance causes mixing of the mixable components. A plunger is disposed in the body, along with a knob stem and a knob fixed to the knob stem so as to be rotatable therewith. A sleeve is telescopingly disposed over the knob stem, wherein the knob stem and the sleeve have cooperating elements formed thereon which selectively permit rotation of the knob stem to be transmitted to the sleeve so that the knob stem and the sleeve may rotate together. A spring is also provided for urging the sleeve distally. A releasable retainer releasably retains the sleeve in a first position against force of the spring. The releasable retainer includes a detent formed on one of the body and the sleeve, and, a channel formed in the other of the body and sleeve. The channel has a first part disposed partially circumferentially about a longitudinal axis of the sleeve, and a second part extending from the first part and disposed generally parallel to the longitudinal axis. The channel is formed to receive the detent and to permit sliding movement of the detent therealong. The sleeve is retained in the first position with the tab being located in the first part of the channel. Rotation of the knob causes the detent to move into the second part of the channel thus allowing the spring to displace the sleeve distally. Distal movement of the sleeve causes distal movement of the plunger which causes distal movement of the stopper thus causing mixing of the mixable components. Advantageously, with the subject invention, a medical injector may be provided where autoreconstitution can be achieved by the turning of a knob. 
     These and other features of the invention will be better understood through a study of the following detailed description and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a medical injector formed in accordance with the subject invention; 
         FIG. 2  is a cross-sectional view taken along line  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a schematic view of a releasable retainer useable with the subject invention; 
         FIG. 4  is a partial cross-sectional view taken along line  4 - 4  of  FIG. 2 ; 
         FIG. 5  is a cross-sectional view showing the medical injector in a state after reconstitution; 
         FIG. 6  is a schematic view of a plunger and dose setting component useable with the subject invention; and, 
         FIG. 7  is a schematic view of a portion of an injector body and a dose setting component useable with the subject invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the figures, a medical injector  10  is shown having a body  12  with a distal end  14  and a proximal end  16 . The distal end  14  is intended to be directed towards a patient during use while the proximal end  16  is intended to be directed away from a patient during use. The medical injector  10  includes features  18  to which a needle assembly may be mounted in any known manner, such as threads. 
     A reservoir  20  is disposed in the body  12  for accommodating first and second mixable components  22 ,  24 . At least one stopper  26  is associated with the reservoir  20  configured such that distal advancement of the stopper  26  over a predetermined distance shall cause mixing of the first and second mixable components  22 ,  24 . Any known arrangement for allowing such mixing may be utilized. By way of non-limiting example, the first and second mixable components  22 ,  24  may be separated by a secondary stopper  28 . The secondary stopper  28  divides the reservoir  20  into first and second chambers  30 ,  32 , respectively, accommodating the first and second mixable components  22 ,  24 . A septum  34  seals off the distal end of the first chamber  30 , while the stopper  26  is positioned to seal off the proximal end of the second chamber  32 . Preferably, if a dry component is used as one of the mixable components, the dry mixable component is located in the first chamber  30 . 
     One or more by-pass channels  36  are formed in the wall of the reservoir  20 . In an initial state, as shown in  FIG. 2 , the secondary stopper  28  is located at least partially proximally of the by-pass channels  36  so as to define a seal between the first and second chambers  30 ,  32  and to define a seal between the second chamber  32  and the by-pass channels  36 . With distal advancement of the stopper  26 , and with the second mixable component  24  being wet and generally incompressible, force of movement of the stopper  26  is transmitted to the secondary stopper  28  through the second mixable component  24 . With sufficient distal movement of the secondary stopper  28 , the second chamber  32  comes into communication with the by-pass channels  36 , thus allowing the second mixable component  24  to be urged into the first chamber  30  with further distal movement of the stopper  26 . With reference to  FIG. 5 , with sufficient distal advancement of the stopper  26 , the second chamber  32  is collapsed with none or substantially none of the second mixable component  24  remaining therein. In addition, the secondary stopper  28  is located so as to define a seal between the first chamber  30  and the by-pass channels  36 . The first and second mixable components  22 ,  24  are mixed within the first chamber  32 , such as through agitation of the medical injector  10 , so as to produce an injectable solution  29 , ready for injection. 
     The reservoir  20  is defined in a barrel  38 . The barrel  38  may be the barrel of a separate drug cartridge ( FIG. 2 ) or a portion of the medical injector  10 . 
     As will be recognized by those skilled in the art, other arrangements for permitting reconstitution may be utilized. In addition, more than two-part systems, such as three-part and so forth, systems may be utilized. Active medical ingredients may be included in one or both of the first and second mixable components  22 ,  24 . The first mixable component  22  may be dry (e.g., a powder or granular substance) and/or a liquid (e.g., flowable (slurry or liquid)). As mentioned above, the second mixable component  24  is preferably only a wet flowable component such as a liquid or slurry. 
     A tubular plunger  40  is positioned and configured to engage the stopper  26 . A knob stem  42  is provided which, preferably, extends into at least a portion of the plunger  40 . A sleeve  44  is telescopingly disposed over the knob stem  42  and configured to engage the plunger  40 . A knob  46  is fixed to the knob stem  42  so as to be rotatable therewith. The knob  46  is located exteriorly of the body  12  and proximate to the proximal end  16 . 
     The knob stem  42  and the sleeve  44  have cooperating elements formed thereon which selectively permit rotation of the knob stem  42  to be transmitted to the sleeve  44  so that the knob stem  42  and the sleeve  44  may rotate together. In a preferred arrangement, a protrusion  48  extends from the knob stem  42  which is received in a slot  50  formed in the sleeve  44 . The interengagement of the protrusion  48  and the slot  50  causes the sleeve  44  to rotate with the knob stem  42 . As shown in  FIG. 5 , and discussed below, with distal displacement of the sleeve  44 , the protrusion  48  is configured to be removed from the slot  50  so as to permit rotation of the knob stem  42  separate from the sleeve  44 . As will be appreciated by those skilled in the art, the protrusion  48  may be formed on the sleeve  44  and the slot  50  may be formed on the knob stem  42  as an alternative. 
     A spring  52  is provided to distally urge the sleeve  44 . It is preferred that the spring  52  be located about the sleeve  44  to act between sleeve shoulder  54  and rear face  56 . The spring  52  may be a coil or compression spring. Alternatively, as recognized by those skilled in the art, various biasing elements may be utilized as the spring. 
       FIG. 2  shows the sleeve  44  being retained in a first position against force of movement generated by the spring  52 . A releaseable retainer  58  is provided which retains the spring  52  in the first state. With reference to  FIGS. 3 and 4 , the releaseable retainer  58  includes a detent  60  located on the sleeve  44 , preferably adjacent to the sleeve shoulder  54 , and a channel  62  formed in the body  12 . The channel  62  includes a first part  64  which partially extends about a longitudinal axis  66  of the sleeve  44 . The channel  62  also includes a second part  68  which extends from the first part  64  and is generally parallel to the longitudinal axis  66 . The channel  62  may have a general L-shape. The channel  62  is formed to receive the detent  60  and to permit sliding movement of the detent  60  therealong. The arrangement of the detent  60  and the channel  62  may be reversed with the detent  60  located on the body  12  and the channel  62  located on the sleeve  44 . 
     With reference to  FIGS. 3 and 4 , the detent  60  is shown to be nested in the first part  64  of the channel  62 . In this state, the sleeve  44  is retained in the first position. With rotation of the knob  46 , the knob stem  42  is caused to rotate, and, in turn, the sleeve  44  is caused to rotate. Such rotation causes the detent  60  to move into the second part  68  of the channel  62  thus allowing the spring  52  to distally advance the sleeve  44 . As shown in  FIG. 5 , the sleeve  44  is advanced distally causing the plunger  42  to advance distally, and, in turn, causing the stopper  26  to advance distally thus causing mixing of the first and second mixable components  22 ,  24 . Distal movement of the sleeve  44  under force of the spring  52  may be limited due to interengagement of the sleeve shoulder  54  with a stop surface  70  formed on the body  12  and/or engagement with the barrel  38 . 
     It is preferred that the mixing of the components be conducted without a needle mounted to the medical injector  10 . As such, the reservoir  20  is not vented during the mixing. With a needle being mounted to the medical injector  10  after the mixing, any residual gases trapped in the reservoir  20  are purged through the needle. It may be preferred to not provide a physical stop to the distal advancement of the plunger  40 . In this manner, the mixed components may be maximally compressed under force of the spring  52 . With mounting of a needle onto the medical injector  10 , the reservoir  20  is vented thus permitting further distal advancement of the plunger  40 . This secondary distal advancement may assist in priming a needle for use. 
     Once mixed, the size of a dose to be administered by the medical injector  10  may be adjusted. With reference to  FIG. 6 , the knob stem  42  is provided with a plurality of axially and radially spaced-apart abutment surfaces  72 . The abutment surfaces  72  correspond to different administrable dosage amounts. An engagement surface  74  is defined on the plunger  40 . Rotation of the knob stem  42  causes radial displacement of the abutment surfaces  72 . The abutment surfaces  72  are axially alignable with the engagement surface  74  such that with sufficient distal displacement of the knob stem  42  at least one of the abutment surfaces  72  will be caused to engage the engagement surface  74  and transmit force of movement to the plunger  40 . In this manner, distal displacement of the knob stem  42  may be transmitted to the plunger  40 . Moreover, stroke length corresponding to the movement of the plunger  40  may be adjusted depending on the abutment surface  72  which is in engagement with the engagement surface  74 . The greater the initial distance of the abutment surfaces  72  from the engagement surface  74 , the corresponding smaller dose that will be caused to be administered. Regardless of the selected dose amount, it is preferred that the knob stem  42  having a fixed length of stroke for distal displacement during administration of an injection. The further abutment surfaces  72  have greater lost motion with distal movement of the knob stem  42  and, thus, less distance engaging the engagement surface  74 . The extent of movement of the plunger  40  dictates the extent of movement of the stopper  26  and, thus, dictates the amount of the injectable solution  29  to be driven from the reservoir  20  in an injected dose. 
     The dose is selected by rotating the dose knob  46 . Indicia may be provided on the body  12  and/or the dose knob  46  in facilitating dose setting. To prevent the dose knob from being inadvertently turned prior to mixing of the mixable components  22 ,  24 , the knob stem  42  may be coupled to the sleeve  44  so as to prevent relative rotation therebetween, as described above. With reconstitution, the sleeve  44  may decouple from the knob stem  42  so as to permit relative rotation therebetween. In addition, with reference to  FIG. 6 , a groove  76  may be formed in the knob stem  42  corresponding to a rib  78  formed on the plunger  40 . In an initial state, as shown in  FIG. 2 , the rib  78  nests within the groove  76  so as to prevent relative rotation between the plunger  40  and the knob stem  42 . With reconstitution being completed, the plunger  40  may be advanced so as to have the rib  78  removed from the groove  76 . The knob stem  42  is then free to rotate in setting a dose. Alternatively, the rib  78  may still be partially nested in the groove  76  even in a post-reconstituted state. With this configuration, the knob stem  42  is proximally displaced to have the rib  78  removed from the groove  76  thus permitting subsequent dose setting. The dose is administered by causing distal advancement of the knob  46  once the dose has been properly set. 
     It is noted that the engagement surface  74  may be located at a proximal end  80  of the rib  76 . 
     It is preferred that the knob  46  be releasably retained in positions corresponding to the various dose settings. In this manner, it is preferred that once a dose has been set, there is no rotation of the knob  46  during distal displacement thereof, thus avoiding that an improper of the abutment surfaces  72  engage the engagement surface  74 . Such an arrangement is disclosed in U.S. Pat. No. 6,793,646. As shown in U.S. Pat. No. 6,793,646, with reference to  FIG. 7 , one or more tabs  82  may be formed on the knob  46  which are selectively engageable with positioning channels  84  formed on a portion of the body  12 . Positioning channels  84  are circumferentially separated by dividers  86  and positioned to correspond to the abutment surfaces  72 . The tabs  82  nest in the positioning channels  84  at given radial positions of the knob  46  corresponding to different dose sizes. With turning of the knob  46 , the tabs  82  are caused to by-pass the dividers  86  and move into a corresponding of the positioning channels  84 . The positioning channels  84  maintain the radial position of the knob  46 . 
     In addition, it is preferred that the knob  46  be maintained in an axial position so as to permit a fixed stroke length of distal advancement for dose administration. One or more retaining ribs  88  may be located along the positioning channels  84  so as to limit axial movement of the tabs  82 . With a dose having been selected, the knob  46  may be distally advanced with the tabs  82  by-passing the retaining ribs  88 . It is preferred that the tabs  82  and the retaining ribs  88  be configured so as to provide a locking affect so as to prevent rearward retraction of the knob  46  and re-use of the medical injector  10 . 
     As will be understood by those skilled in the art, the body  12  may be formed of one or more components with the features described herein being formed on any of those one or more components.