Activation mechanism for drug delivery device
A drug delivery device includes a housing, an injection assembly at least partially disposed in the housing, a shield, and a drive assembly at least partially disposed in the housing and coupled with the injection assembly and the shield. The shield has an extended position where at least a proximal end thereof extends a distance beyond a proximal end of the housing. The injection assembly includes a needle or cannula having an endpoint. Upon moving the shield axially towards the distal end of the housing a predetermined distance, a retraction profile commences whereby the drive assembly administers a medicament via the injection assembly. A peak resistance force is exerted within approximately the first 12 mm of axial movement of the shield.
1 . A drug delivery device comprising: a housing having a proximal end and a distal end and a longitudinal axis extending between the proximal end and the distal end thereof; an injection assembly at least partially disposed within the housing at the proximal end thereof, the injection assembly including a needle or a cannula having an endpoint; a shield slidably coupled with the housing, the shield having an extended position wherein at least a proximal end of the shield extends a distance beyond the proximal end of the housing; and a drive assembly at least partially disposed within the housing and operably coupled with the injection assembly and the shield, the drive assembly comprising: a nut; a trigger ring; a plunger rod guide operably coupled to a driving mechanism comprising a torque spring; and a plunger rod at least partially disposed within an opening of the plunger rod guide, wherein upon moving the shield axially towards the distal end of the housing a predetermined distance, a retraction profile commences whereby the drive assembly administers a medicament via the injection assembly, wherein a peak resistance force is exerted prior to the needle or cannula contacting a user's skin, and wherein the peak resistance force is generated by at least one of: a frictional force exerted between the plunger rod guide and the trigger ring generated by the driving mechanism; a frictional force exerted between the trigger ring and the nut generated by the driving mechanism; or a force generated by the nut and exerted between the trigger ring and the nut.
2 . The drug delivery device of claim 1 , wherein the peak resistance force is exerted within approximately the first 8 mm of axial movement of the shield or the first 3 mm of axial movement of the shield.
3 . The drug delivery device of claim 1 , wherein the drive assembly further comprises: a container disposed within the housing, the container having a first end and a second end, an inner volume of the container being adapted to contain the medicament to be administered to a user; the nut disposed within the housing and positioned adjacent to the first end of the container, the nut having a first engagement region and a second engagement region; the trigger ring disposed within the housing, the trigger ring having a first engagement region that slidably engages the first engagement region of the nut and a second engagement region, the trigger ring engaging a portion of the shield such that the trigger ring moves axially with the shield; and the plunger rod guide disposed within the housing, the plunger rod guide having a first engaging region and an opening, the first engagement region of the plunger rod guide slidably engaging the second engagement region of the trigger ring, wherein upon moving the shield axially towards the distal end of the housing, at least one of the first engagement region of the trigger ring disengages from the first engagement region of the nut or the second engagement region of the trigger ring disengages from the first engagement region of the plunger rod guide, thereby causing the driving mechanism to urge the plunger rod towards the proximal end of the housing.
4 . The drug delivery device of claim 3 , wherein the trigger ring is coupled to at least one of (a) and (b):
(a) the nut such that relative rotation between the trigger ring and the nut is restricted while the first engagement region of the trigger ring engages the first engagement region of the nut, or
(b) the plunger rod guide such that relative rotation between the trigger ring and the plunger rod guide is restricted while the second engagement region of the trigger ring engages the first engagement region of the plunger rod guide.
5 . The drug delivery device of claim 3 , wherein the nut further comprises at least one deflection finger that projects inwardly toward the longitudinal axis of the housing, thereby contacting an outer surface of the trigger ring, and wherein the at least one deflection finger imparts a frictional force on the nut that is sufficient to generate the peak resistance force prior to disengagement from the nut.
6 . The drug delivery device of claim 1 , wherein an injection process begins when the shield is initially moved axially and ends when the drive assembly completely administers the medicament, wherein the peak resistance force is exerted within approximately a first 15% of the duration of the injection process.
7 . The drug delivery device of claim 1 , wherein the shield has a maximum axial travel towards the distal end of the housing of approximately 10 mm, and wherein the peak resistance force occurs within approximately the first 8 mm of travel of the shield.
8 . The drug delivery device of claim 1 , wherein the peak resistance force is exerted when a distance between the endpoint of the needle or cannula and the proximal end of the shield is one of (a) less than or equal to approximately 12 mm, (b) less than approximately 12 mm and greater than approximately 3 mm, (c) less than or equal to approximately 3 mm, or (d) less than 0 mm.
9 . The drug delivery device of claim 1 , wherein the peak resistance force is a maximum force across the entire retraction profile.
10 . The drug delivery device of claim 1 , further comprising a dose lockout mechanism including a tab disposed within the housing, wherein the dose lockout mechanism halts movement of the plunger rod upon moving the shield towards the proximal end of the housing.
11 . A drug delivery device comprising: a housing defining a shell having a proximal end and a distal end and a longitudinal axis extending between the proximal end and the distal end thereof; an injection assembly at least partially disposed within the housing at the proximal end thereof, the injection assembly comprising a needle or a cannula; a shield slidably coupled to the housing, the shield extending a distance beyond the proximal end of the housing; and a drive assembly at least partially disposed within the housing and operably coupled to the injection assembly and the shield, the drive assembly comprising: a nut; a trigger ring; and a plunger rod guide operably coupled to a driving mechanism comprising a torque spring, wherein upon moving the shield axially towards the distal end of the housing, a retraction profile commences where the drive assembly administers a medicament via the injection assembly, wherein a peak resistance force is exerted prior to the needle or cannula contacting a user's skin, and wherein the peak resistance force is generated by at least one of: a frictional force exerted between the plunger rod guide and the trigger ring generated by the driving mechanism; a frictional force exerted between the trigger ring and the nut generated by the driving mechanism; or a force generated by the nut and exerted between the trigger ring and the nut.
12 . The drug delivery device of claim 11 , wherein the drive assembly further comprises: a container disposed within the shell, the container having a first end and a second end, an inner volume of the container being adapted to contain the medicament to be administered to a user; the nut disposed within the shell and positioned adjacent to the first end of the container, the nut having a first engagement region and a second engagement region; the trigger ring disposed within the shell, the trigger ring having a first engagement region that slidably engages the first engagement region of the nut and a second engagement region, the trigger ring engaging a portion of the shield such that the trigger ring moves axially with the shield; the plunger rod guide disposed within the shell, the plunger rod guide having a first engaging region and an opening, the first engagement region of the plunger rod guide slidably engaging the second engagement region of the trigger ring; and a plunger rod at least partially disposed within the opening of the plunger rod guide; wherein upon moving the shield axially towards the distal end of the housing, at least one of the first engagement region of the trigger ring disengages from the first engagement region of the nut or the second engagement region of the trigger ring disengages from the first engagement region of the plunger rod guide, thereby causing the driving mechanism to urge the plunger rod towards the proximal end of the housing.
13 . The drug delivery device of claim 12 , wherein the trigger ring is coupled to at least one of (a) and (b):
(a) the nut such that relative rotation between the trigger ring and the nut is restricted while the first engagement region of the trigger ring engages the first engagement region of the nut, or
(b) the plunger rod guide such that relative rotation between the trigger ring and the plunger rod guide is restricted while the second engagement region of the trigger ring engages the first engagement region of the plunger rod guide.
14 . The drug delivery device of claim 12 , wherein the nut further comprises at least one deflection finger that projects inwardly toward the longitudinal axis of the housing, thereby contacting an outer surface of the trigger ring, and wherein the at least one deflection finger imparts a frictional force on the nut that is sufficient to generate the peak resistance force prior to disengagement from the nut.
15 . The drug delivery device of claim 11 , wherein an injection process begins when the shield is initially moved axially and ends when the drive assembly completely administers the medicament, wherein the peak resistance force is exerted within approximately a first 15% of the duration of the injection process.
16 . The drug delivery device of claim 11 , wherein the shield has a maximum axial travel towards the distal end of the housing of approximately 10 mm, and wherein the peak resistance force occurs within approximately the first 8 mm of travel of the shield.
17 . The drug delivery device of claim 11 , wherein the peak resistance force is exerted when a distance between an endpoint of the needle or cannula and the proximal end of the shield is one of (a) less than or equal to approximately 12 mm, (b) less than approximately 12 mm and greater than approximately 3 mm, (c) less than or equal to approximately 3 mm, or (d) less than 0 mm.
18 . The drug delivery device of claim 11 , wherein the peak resistance force is a maximum force across the entire retraction profile.
19 . A drug delivery device comprising: a housing having a proximal end, a distal end, and a longitudinal axis extending between the proximal end and the distal end thereof; an injection assembly at least partially disposed within the housing at the proximal end thereof, the injection assembly including a needle or a cannula having an endpoint; a shield slidably coupled with the housing, the shield having an extended position wherein at least a proximal end of the shield extends a distance beyond the proximal end of the housing; and a drive assembly at least partially disposed within the housing and operably coupled with the injection assembly and the shield, the drive assembly comprising: a nut; a trigger ring; a plunger rod guide operably coupled to a driving mechanism comprising a torque spring, wherein upon moving the shield axially towards the distal end of the housing a predetermined distance, a retraction profile commences whereby the drive assembly administers a medicament via the injection assembly, wherein a peak resistance force is exerted just prior to the needle or cannula contacting a user's skin, and wherein the peak resistance force is generated by at least one of: a frictional force exerted between the plunger rod guide and the trigger ring generated by the driving mechanism; or a frictional force exerted between the trigger ring and the nut generated by the driving mechanism.
20 . The drug delivery device of claim 19 , wherein the drive assembly further comprises: a container disposed within the housing, the container having a first end and a second end, an inner volume of the container being adapted to contain the medicament to be administered to a user; the nut disposed within the housing and positioned adjacent to the first end of the container, the nut having a first engagement region and a second engagement region; the trigger ring disposed within the housing, the trigger ring having a first engagement region that slidably engages the first engagement region of the nut and a second engagement region, the trigger ring engaging a portion of the shield such that the trigger ring moves axially with the shield; the plunger rod guide disposed within the housing, the plunger rod guide having a first engaging region and an opening, the first engagement region of the plunger rod guide slidably engaging the second engagement region of the trigger ring; and a plunger rod at least partially disposed within the opening of the plunger rod guide; wherein upon moving the shield axially towards the distal end of the housing, at least one of the first engagement region of the trigger ring disengages from the first engagement region of the nut or the second engagement region of the trigger ring disengages from the first engagement region of the plunger rod guide, thereby causing the driving mechanism to urge the plunger rod towards the proximal end of the housing.
21 . The drug delivery device of claim 20 , wherein
the trigger ring is coupled to at least one of (a) and (b):
(a) the nut such that relative rotation between the trigger ring and the nut is restricted while the first engagement region of the trigger ring engages the first engagement region of the nut, and
(b) the plunger rod guide such that relative rotation between the trigger ring and the plunger rod guide is restricted while the second engagement region of the trigger ring engages the first engagement region of the plunger rod guide.
22 . The drug delivery device of claim 19 , wherein an injection process begins when the shield is initially moved axially and ends when the drive assembly completely administers the medicament, wherein the peak resistance force is exerted within approximately a first 15% of the duration of the injection process.
23 . The drug delivery device of claim 19 , wherein the shield has a maximum axial travel towards the distal end of the housing of approximately 10 mm, and wherein the peak resistance force occurs within approximately the first 8 mm of travel of the shield.
24 . The drug delivery device of claim 19 , wherein the peak resistance force is exerted when a distance between the endpoint of the needle or cannula and the proximal end of the shield is one of (a) less than or equal to approximately 12 mm, (b) less than approximately 12 mm and greater than approximately 3 mm, (c) less than or equal to approximately 3 mm, or (d) less than 0 mm.
25 . The drug delivery device of claim 19 , wherein the peak resistance force is a maximum force across the entire retraction profile.