Device for Injecting Apportioned Doses of Liquid Drug

Abstract

An injection device ( 1 ) for injecting apportioned doses of liquid drug. The injection device ( 1 ) includes a dose setting structure, an injection structure, a removable cap ( 15 ) and a cap receiving part ( 9 ) adapted to abut or engage with the cap ( 15 ) when the cap ( 15 ) is mounted on the injection device ( 1 ). The dose setting structure is operatively coupled to the cap receiving part ( 9 ) in such a manner that mounting and/or dismounting of the cap ( 15 ) on/from the injection device ( 1 ) causes the dose setting structure to set a dose. Thereby a correct dose of drug is automatically set during a cap on/cap off cycle. Since such a cycle is normally performed between subsequent injections, the number of steps required to be performed by the user is reduced.

1 . An injection device for administering apportioned doses of liquid drug, the injection device comprising:
 a housing,   a reservoir for holding the drug,   a piston adapted to move axially in the reservoir,   dose setting means operable to set a dose,   injection means operable to inject the set dose and comprising a piston rod for sequentially advancing the piston in the reservoir to expel a volume of the liquid drug,   a push button operatively coupled to the dose setting means and the injection means and axially moveable between a first position in which the dose is set and a second position in which the injection means has been activated to inject the set dose, and   retaining means for holding the push button in the second position when the injection means has been activated to inject the set dose,   
       wherein the retaining means is operatively coupled to the dose setting means in such a manner that when the dose setting means is operated to set a dose the retaining means is automatically disabled. 
     
     
         2 . An injection device as in  claim 1 , wherein when the dose setting means is operated to set a dose, the push button is automatically moved from the second position to the first position. 
     
     
         3 . An injection device as in  claim 2 , wherein the push button is moved from the second position to the first position by a force transmitting member activating the push button via a translational and/or rotational movement. 
     
     
         4 . An injection device as in  claim 1  further comprising energy means acting on the push button to bias the push button towards the first position. 
     
     
         5 . An injection device as in  claim 4 , wherein the energy means comprises a spring. 
     
     
         6 . An injection device as in  claim 1 , wherein the movement of the push button from the second position to the first position is purely translational. 
     
     
         7 . An injection device as in  claim 1 , wherein the movement of the push button from the first position to the second position is purely translational. 
     
     
         8 . An injection device as in  claim 1 , wherein the retaining means comprises a snap fit between the push button and the housing. 
     
     
         9 . An injection device as in  claim 8 , wherein the push button comprises a catch member adapted to engage with a protuberance on the housing. 
     
     
         10 . An injection device as in  claim 9 , wherein the snap fit is disabled by a force transmitting member having an abutment surface adapted to slideably abut with an abutment surface on the catch member to thereby move the catch member out of engagement with the protuberance. 
     
     
         11 . An injection device as in  claim 3 , wherein the retaining means comprises a friction fit between the push button and the housing. 
     
     
         12 . An injection device as in  claim 1 , further comprising a drive member adapted to undergo relative motion with respect to the piston rod during dose setting and to transmit a driving force to the piston rod during injection, the drive member comprising force transmitting means. 
     
     
         13 . An injection device as in  claim 12 , wherein the push button and the drive member are operatively coupled in such a manner that a rotational or spiralling movement of the drive member causes an axial movement of the push button, and vice versa. 
     
     
         14 . An injection device as in  claim 12  further comprising a coupling element adapted to engage with the drive member and the push button. 
     
     
         15 . An injection device as in  claim 14 , wherein the push button and the coupling element are coupled via a threaded interface. 
     
     
         16 . An injection device as in  claim 15 , wherein the push button comprises a helical track segment and the coupling element comprises a protuberance adapted to engage with and travel the helical track segment. 
     
     
         17 . An injection device as in  claim 16 , wherein the retaining means comprises the engagement between the push button and the coupling element. 
     
     
         18 . An injection device as in  claim 13 , wherein the piston rod comprises a structural element adapted to engage with the drive member to prevent the drive member from rotating when the remaining amount of drug in the reservoir is insufficient to provide another full dose, thereby also preventing the dose setting means from setting a dose. 
     
     
         19 . An injection device as in  claim 13 , wherein the piston rod comprises a structural element adapted to engage with the drive member to prevent the drive member from rotating when the remaining amount of drug in the reservoir is insufficient to provide another full dose, thereby also preventing movement of the push button from the second position to the first position. 
     
     
         20 . An injection device as in  claim 1 , further comprising:
 a removable cap, and   a cap receiving part adapted to abut or engage with the cap when the cap is mounted on the injection device,   
       wherein the cap receiving part is operatively coupled to the dose setting means in such a manner that mounting the cap on the injection device automatically disables the retaining means and moves the push button from the second position to the first position. 
     
     
         21 . An injection device for administering apportioned doses of liquid drug, the injection device comprising:
 a reservoir adapted to hold the drug,   a piston adapted to move axially in the reservoir,   dose setting means operable to set a dose,   injection means operable to inject the set dose and comprising a piston rod for sequentially advancing the piston in the reservoir to expel a volume of the liquid drug,   a removable cap,   a cap receiving part adapted to abut or engage with the cap when the cap is mounted on the injection device,   
       wherein the injection means is operatively coupled to the cap receiving part in such a manner that mounting the cap on the injection device disables the injection means, thereby preventing an ejection of drug from the reservoir. 
     
     
         22 . An injection device as in  claim 21 , wherein dismounting the cap from the injection device enables the injection means, thereby allowing an ejection of drug from the reservoir. 
     
     
         23 . An injection device as in  claim 21 , wherein the cap is mounted on and/or dismounted from the injection device in a substantially linear movement. 
     
     
         24 . An injection device as in  claim 21 , wherein the cap is mounted on and/or dismounted from the injection device in a rotational or spiralling movement. 
     
     
         25 . An injection device as in  claim 21 , wherein when the cap is mounted on the injection device the piston rod is prevented from axial movement. 
     
     
         26 . An injection device as in  claim 21 , further comprising a drive member adapted to transmit a driving force to the piston rod during injection, wherein when the cap is mounted on the injection device the drive member is capable of performing rotational motion, but prevented from performing translational motion, with respect to the cap. 
     
     
         27 . An injection device as in  claim 26 , wherein the drive member abuts the cap when the cap is mounted on the injection device. 
     
     
         28 . An injection device as in  claim 26 , further comprising means for holding the cap on the injection device against a translational force from the drive member. 
     
     
         29 . An injection device as in  claim 26 , further comprising an injection button operatively coupled to the dose setting means and the injection means and axially moveable between a first position corresponding to a position in which the dose is set and a second position corresponding to a position in which the injection means has been activated to inject the set dose, wherein when the cap is mounted on the injection device the injection button is able to move between the first position and the second position. 
     
     
         30 . An injection device as in  claim 29 , further comprising energy means operatively coupled to the dose setting means and the injection means and adapted to store and release energy for translational and rotational motion. 
     
     
         31 . An injection device as in  claim 29 , wherein applying a force to move the injection button from the first position to the second position when the cap is mounted on the injection device causes the drive member to rotate while the energy means stores energy for rotational motion. 
     
     
         32 . An injection device as in  claim 31 , wherein removing the force from the injection button when the cap is mounted on the injection device causes the drive member to rotate while the energy means releases energy for rotational motion. 
     
     
         33 . An injection device as in  claim 32 , wherein the injection button is automatically moved from the second position to the first position when the force is removed. 
     
     
         34 . An injection device as in  claim 21 , wherein the dose setting means is operatively coupled to the cap receiving part in such a manner that mounting the cap on the injection device causes the dose setting means to set a dose.