| 摘要 |
A needleless injection device comprising a cylinder for medicament having an injection nozzle at a forward end thereof and an opening at its rearward end; a piston sliding in the cylinder through said open end, in use, to drive the medicament through the nozzle; a ram to drive the piston into the cylinder and having a longitudinal axis; and an energy accumulator to drive the ram when discharged and disposed between the ram and a discharge assembly, a rear end of the ram extending into said discharge assembly; wherein the discharge assembly comprises a retention member fixed in the assembly, said retention member having a plurality of retention elements spaced around and adapted to locate on the ram when in a charged position of the ram, and a release ring surrounding said retention elements to prevent radial outward displacement thereof and discharge of the ram; and wherein axial displacement of said release ring releases said retention elements and causes discharge of the ram by said accumulator; characterised in that said axial displacement is provided by means of a resistance-sensitive trigger comprising an axially-moveable shroud forming at least part of the outer surface of said device, the trigger being activated by application of forward axial force to the shroud which is resisted by the skin of the patient at an injection site. |
