Drug delivery with an improved piston rod
An improved drug delivery device is provided having a piston rod that incorporates on its proximal end at least one guidepost that is configured for transmitting axial and rotational forces from a drive mechanism. The device comprises a drug delivery device housing and a medicament contained in the drug delivery device housing.
1. A piston rod for a device, especially a pen-type injector, comprising an elongated member having a distal end and a proximal end where the proximal end has at least two sets of guideposts, where at least one set has at least two guideposts that are in axial alignment with each other and are configured for transmitting axial and rotational forces from a drive member having at least one internal groove with a pitch P, wherein each guidepost is configured as a post, peg, or pin having a single longitudinal axis projecting radially outward from the proximal end and the at least two sets of guideposts are located on opposing sides of the proximal end of the piston rod.
2. The piston rod of claim 1 where the guideposts have circular or oblong shapes.
3. The piston rod of claim 1 where the guideposts are separated by a distance equal to pitch P.
4. The piston rod of claim 1 further characterized in that each set of guideposts has three guideposts that are separated by a distance equal to pitch P.
5. A piston rod for a pen device, especially a pen-type injector, comprising an elongated member having a distal end and a proximal end where the proximal end has at least two sets of two or more guideposts, where the guideposts are in axial alignment with each other and are configured for transmitting axial and rotational forces from a drive member having at least one internal groove with a pitch P, wherein each guidepost is configured as a post, peg, or pin having a single longitudinal axis projecting radially outward from the proximal end and the at least two sets of guideposts are located on opposing sides of the proximal end of the piston rod.
6. A drug delivery device, said device comprising:
a drug delivery device housing;
a retaining means for a medicament contained in said drug delivery device housing;
a drive mechanism; and
a piston rod in communication with at least one groove in the drive mechanism comprising an elongated member having a distal end and a proximal end, where the proximal end has at least two sets of two or more guideposts extending outwardly from the elongated member and is configured to engage a corresponding groove in a drive member and for transmitting axial or rotational forces from the drive member, wherein at least one of the at least two sets of two or more guideposts have guideposts configured as a post, peg, or pin having a single longitudinal axis projecting radially outward from the proximal end and the at least two sets of guideposts are located on opposing sides of the proximal end of the piston rod.
7. A pen type drug delivery device, said device comprising:
a drug delivery device housing, said housing having a distal end for mounting a needle assembly and a proximal end comprising a dose dial grip;
a cartridge contained in said housing, said cartridge containing a medication;
a drive mechanism; and
a piston rod in communication with at least one groove in the drive mechanism comprising an elongated member having a distal end and a proximal end, where the proximal end has at least two sets of two or more guideposts extending outwardly from the elongated member and is configured to engage a corresponding groove in a drive member and for transmitting axial or rotational forces from the drive member, wherein each guidepost is configured as a post, peg, or pin having a single longitudinal axis projecting radially outward from the proximal end and the at least two sets of guideposts are located on opposing sides of the proximal end of the piston rod.