Device for the dosed administration of a fluid product, adapted for the replacement of a container

A device for administering a fluid product, said device comprising:

• a) a housing comprising a first casing part and a second casing part connected to the first casing part;
• b) a linear guide formed directly by the housing;
• c) a piston rod arranged in the housing and configured to be driven in an advancing direction;
• d) a drive member configured to cause the piston rod to be driven in a delivery movement, wherein the drive member is configured as a unitary sleeve and comprises a thread, wherein the linear guide is configured to cause the drive member to be linearly guided relative to the housing in and counter to the advancing direction;
• and
• e) a coupler comprising a coupler input member adapted to couple the drive member to the piston rod in a coupler engagement, wherein the coupler input member is adapted to transfer a drive force of the drive member onto the piston rod, wherein the coupler input member is sleeve-shaped and comprises a thread complementary to the thread of the drive member, and wherein the coupler input member is in a threaded engagement with the drive member such that a linear drive movement of the drive member causes a rotational movement of the coupler input member;
• f) wherein the coupler input member is coupled to the piston rod such that the rotational movement of the coupler input member causes the delivery movement of the piston rod;
• and
• g) a dosing member for setting a product dosage deliverable by operating or triggering the drive member, wherein during dose setting the dosing member is rotationally secured to the coupler input member such that the coupler input member rotates with the dosing member.