Pen-Type Injector

Abstract

The present invention relates to injectors, such as pen-type injectors, that provide for administration of medicinal products from a multidose cartridge and permit a user to set the delivery dose. The injector may include a housing, a cartridge containing medicinal product, the cartridge being retained within the housing, means for selecting a dose of medicinal product to be expelled, and means for expelling the selected dose of medicinal product. The housing may be a unitary housing within which the means for selecting a dose and the means for expelling the selected dose are moveably retained. Alternatively, the injector may include a housing, a piston rod, an insert located in the housing and through which the piston may rotate, ratchet means, a dose dial sleeve, a drive sleeve, a button located on the drive sleeve and rotatable with respect to the drive sleeve, and clutch means which upon depression of the button prevents rotation between the dose dial sleeve and the drive sleeve.

1 - 4 . (canceled) 
     
     
         5 . A pen-type injector comprising a housing a piston rod having a screw thread;
 an insert located in the housing and through which the piston rod may rotate;   a dose dial sleeve rotatable with respect to the housing and the insert; and   a drive sleeve which is axially displaceable with respect to the housing;   wherein a maximum angular displacement of the dose dial sleeve with respect to the housing is determined by abutment of a radially directed lug on the dose dial sleeve with a catch means on the insert.   
     
     
         6 . The pen-type injector according to  claim 5 ,
 wherein the radially directed lug extends parallel to a longitudinal axis of the dose dial sleeve.   
     
     
         7 . The pen-type injector according to  claim 5 ,
 wherein the catch means comprises a groove extending about a central land, the central land being wedge shaped such that a first edge extends radially less far than a second opposite edge to define a sloping surface between the first edge and the second edge.   
     
     
         8 . The injector according to any of  claim 5 ,
 wherein the insert and the dose dial sleeve comprise inter-engaging features to provide a helical thread between the insert and the dose dial sleeve.   
     
     
         9 . The injector according to any of  claim 5 ,
 wherein the injector further comprises a nut which is provided on a helical thread between the drive sleeve and the dose dial sleeve, with the nut being rotatable with respect to the drive sleeve and axially displaceable but not rotatable with respect to the dose dial sleeve.   
     
     
         10 . The injector according to  claim 9 ,
 wherein the injector further comprises a cartridge containing medicinal product, with the position of the nut along the helical thread corresponding to the amount of medicinal product remaining in the cartridge.   
     
     
         11 . The injector according to any of  claim 5 ,
 wherein a dose is set by rotating the dose dial sleeve with the piston rod and the drive sleeve not rotating, thus causing a relative rotation of the dose dial sleeve and the drive sleeve.   
     
     
         12 . The injector according to any of  claim 5 ,
 wherein a dose is delivered by rotating the dose dial sleeve together with the piston rod and the drive sleeve.   
     
     
         13 . A method for assembling a pen-type injector, the injector comprising an insert and a dose dial sleeve, the method comprising the step of threading the dose dial sleeve onto the insert,
 wherein that dose dial sleeve is provided with a radially directed lug and the insert is provided with a catch means comprising a groove extending about a central land, the central land being wedge shaped such that a first edge extends radially less far than a second opposite edge to define a sloping surface between the first edge and the second edge,   wherein by threading the dose dial sleeve onto the insert, the lug passes over the first edge and over the sloping surface.   
     
     
         14 . The method according to  claim 13 ,
 wherein once the lug is over the land, the second edge of the land acts as a stop to prevent removal of the dose dial sleeve from the insert.