Drug delivery devices with partial needle retraction
Methods, devices, and components are provided to reduce tissue resistive pressure during a subcutaneous drug delivery operation by increasing the size of the injection cavity by partially retracting the drug delivery member after inserting the drug delivery member to a subcutaneous position. The drug delivery devices described herein include a resilient member that interacts between stationary and moveable components of the drug delivery device. The drug delivery device include drives to move the stationary and moveable components relative to one another to insert a drug delivery member to a subcutaneous depth within a patient and to dispense a drug to the injection cavity in the patient. The resilient member is deformed during the operations or is pre-deformed and the stored energy of the resilient member in the deformed state then acts on the stationary and moveable components to partially retract the drug delivery member to relieve pressure in the injection region.
1. A drug delivery device comprising:
an outer casing including one or more sidewalls, a distal end wall, and a proximal end wall defining an interior, the distal end wall having an opening extending therethrough;
a primary container assembly at least partially received within the interior of the outer casing, the primary container assembly including a reservoir having a sidewall defining an interior containing a drug to be expelled, a plunger stopper disposed within the interior of the reservoir to expel the drug therefrom, and a drug delivery member operably connected to the reservoir and configured to be fluidly coupled to the interior thereof, at least the drug delivery member being movable between first and second positions with respect to the outer casing; and
a resilient member disposed between the primary container assembly and the outer casing, wherein upon moving the drug delivery member to the second position in which the delivery member is driven through the opening and prior to the plunger stopper expelling the drug from the interior of the reservoir, the resilient member is in a deformed state that biases the drug delivery member to move in a retraction direction toward the first position to partially retract the drug delivery member to a retracted position, whereby the plunger stopper expels the drug from the interior of the reservoir while the drug delivery member is in the retracted position.
2. The drug delivery device of claim 1 , wherein the primary container assembly includes a distal end, and the resilient member is disposed between the distal end of the primary container assembly and the distal end wall of the outer casing.
3. The drug delivery device of claim 2 , wherein the distal end of the primary container assembly comprises a distal end of the reservoir or the primary container assembly further includes a housing at least partially receiving the reservoir and drug delivery member therein and the distal end of the primary container assembly comprises a distal end of the housing.
4. The drug delivery device of claim 1 , wherein the primary container assembly includes an outwardly projecting flange at a proximal end thereof opposite the drug delivery member; the outer casing includes an inwardly projecting flange; and the resilient member is disposed between the outwardly and inwardly projecting flanges.
5. The drug delivery device of claim 4 , wherein the proximal end of the primary container assembly comprises a proximal end of the reservoir.
6. The drug delivery device of claim 4 , wherein the primary container assembly further includes a housing at least partially receiving the reservoir and drug delivery member therein; and the proximal end of the primary container assembly comprises a proximal end of the housing.
7. The drug delivery device of claim 1 , wherein the resilient member comprises a spring or an elastomeric bumper.
8. The drug delivery device of claim 1 , wherein the resilient member comprises one or more cantilevered tabs extending inwardly from the one or more sidewalls of the outer casing, the cantilevered tabs including inward end portions disposed within a path of the primary container assembly.
9. The drug delivery device of claim 1 , further comprising a drive mechanism configured to drive movement of the drug delivery member with respect to the outer casing in an insertion direction from the first position to the second position such that the drug delivery member extends through the opening in the distal end wall of the outer casing for a drug delivery member insertion operation.
10. The drug delivery device of claim 9 , wherein the drive mechanism further comprises a drive rod, the drive mechanism configured to drive the plunger rod to drive movement of the plunger stopper through the reservoir to expel a drug through the drug delivery member during a drug delivery operation; and the plunger stopper being driven through the reservoir causes the resilient member to deform and bias the primary container assembly to move in the second, opposite direction with respect to the outer casing to partially retract the drug delivery member after the drug delivery operation.
11. The drug delivery device of claim 1 , further comprising a release member engaging the primary container assembly or both the primary container assembly and the resilient member; and wherein the resilient member is held in the deformed state by the release member.
12. The drug delivery device of claim 1 , further comprising a locking mechanism including a lock member deflectable by the primary container assembly as the primary container assembly is moved in the retraction direction and a biasing mechanism configured to bias the lock member into a path of a portion of the primary container assembly in the insertion direction to restrict further movement of the primary container assembly.