Patent ID: 7771400
Filing Date: 2010-08-10
Classification: A61M

Abstract:
1. A drug delivery device comprising: a housing, a piston rod having a proximal thread and a distal thread, a nut member which is not axially displaceable in the housing and which has an inner thread mating the distal thread of the piston rod such that the piston rod is screwed in a distal direction when rotated relatively to the nut member, a drive sleeve which has an inner thread mating the proximal thread of the piston rod such that the piston rod is rotated when the drive sleeve is axially moved relatively to the piston rod wherein a releasable coupling operational between a first position and a second position is provided between the piston rod and the drive sleeve, wherein the coupling in the first position prevents rotation of the piston rod while allowing rotation of the drive sleeve and in the second position prevents rotation of the drive sleeve whilst allowing rotation of the piston rod.