DEVICE FOR AUTOMATIC INJECTION OF DRUG DOSES

摘要

A device for the automatic injection of doses of a drug compound is described. The device has a sliding sheath which, when depressed with its front end against the injection site, interacts with cam means to activate triggering of a plunger, thus controlling delivery of a drug dose. Plunger guide means are provided for controlling the triggering sequence and means for arming the device in the dose delivery condition. Automatic needle re-sheathing and resetting of a lock-out condition after each dose is delivered are also provided.

主权项

1. An automatic drug injection device comprising:
an outer body extending along a longitudinal axis; a syringe group placed in said outer body and fixed thereto, said syringe group comprising a syringe containing a drug to be injected, a needle and plunger means axially slidable and pivotable relative to said outer body; means for arming said device from a stored position to a first armed position for injecting a first dose and at least a second armed position for injecting a second dose, said arming means being arranged at one end of the outer body; first elastic means arranged between said arming means and said plunger means, said first elastic means being in compressed condition when the device is in its stored position and decompressing to push forward said plunger means and delivery successively said first dose and said at least second dose; a sliding sheath arranged at the other end of said outer body and constrained to slide axially thereinto, as a result of a pressure exerted on its free end, in contrast with second elastic means arranged between said sliding sheath and said outer body, between a sliding lock-out position, in which said sliding sheath projects from said outer body covering the needle of the syringe, and a device trigger position, in which said sliding sheath is retracted in said outer body leaving the needle of the syringe exposed, said second elastic means being suitable to bring said sliding sheath back to said lock-out position when said pressure action ceases; cam drive means operatively connected to said sliding sheath and axially pivotable in said outer body; trigger cam means pivotable integrally with said cam drive means and connected operatively with said plunger means to angularly displace said plunger means to said device trigger positions of the first dose and the at least second dose, and stepped guide means integral to said outer body and operatively connected with said plunger means to control an extent of the axial sliding of said plunger means and therefore limit a volume of drug delivered for each dose, said trigger cam means and said drive cam means being formed on a same support pivotally arranged between said outer body and said plunger means.