Stoppers Used in Pre-filled Syringes

A syringe comprising:

• (a) a cylindrical barrel including a proximal end, a distal end, and a sidewall having a first internal diameter extending between the proximal and distal end, said distal end terminating in an outlet opening having a second internal diameter which is less than said first internal diameter, said cylindrical barrel including a second sloped surface extending between the outlet opening and the barrel sidewall;
• (b) a plunger rod extendable into said barrel through an opening in the proximal end of the barrel, said plunger rod including a front forward attachment portion;
• and
• (c) a stopper having a main body having an open rearward end, a closed front end, and a sidewall portion extending between said open rearward end and said closed front end, said open rearward end adapted to receive said front forward end attachment portion of such plunger rod, a core member integrally formed with said main body adjacent said closed end, said core member including a nose portion having a conical tip configured for entering the outlet opening of the syringe barrel, said closed front end including a first sloped surface extending from said conical tip to said stopper sidewall portion,
• wherein said first sloped surface of said stopper is steeper than the second sloped surface of the cylindrical barrel such that an application of a forward force to said plunger rod causes the conical tip of the stopper to enter into the outlet opening to result in essentially zero reflux and wherein the first and second slopes cooperate together to reduce dead space within the barrel.

A stopper adapted for attachment with a plunger rod for use within a syringe barrel, said stopper comprising:

• (a) a main body defining an open rearward end and a closed front end, said open rearward end adapted to receive a front forward end attachment portion of such plunger rod;
• (b) a core member integrally formed with said main body adjacent said closed front end, said core member including a nose portion, said nose portion having a profile adapted to create a positive seal with an outlet opening of such syringe barrel;
• (c) at least one rib extending radially outward around a perimeter of said main body for forming an active seal with such syringe barrel;
• and
• (d) an inward shoulder portion on an inner surface of said main body, said inward shoulder portion adapted for contact with a taper on the forward end of the plunger rod,
• wherein contact of said inward shoulder portion with said taper causes the stopper to apply a radial force to said at least one rib and the syringe barrel upon the application of a forward force to the plunger rod, and
• wherein said inward shoulder portion includes a first cylindrical wall portion extending from the closed front end of said main body, said first wall portion having a substantially flat surface profile, said inward shoulder portion further including a second cylindrical wall portion extending toward the open rearward end of said main body, and a sloped portion extending between the first wall and the second wall.

A plunger rod and stopper assembly adapted for use with a syringe barrel, said assembly comprising:

• (a) a plunger rod having a front attachment end and a back end and extending along a longitudinal axis, said front attachment end including a taper and a front flange extending therefrom;
• (b) a stopper having a main body defining an open rearward end, a closed front end, and a core member integrally formed with said main body adjacent said closed front end, said open rearward end defined by an inside wall surface, said open end adapted for receiving said front attachment end of said plunger rod and locking said plunger rod within said stopper;
• (c) at least one rib extending radially outward around a perimeter of said main body for forming an active seal with the syringe barrel;
• (d) a taper formed on an inner surface of said main body, said taper having a sloped portion adapted for contact with said taper on such forward end of such plunger rod, said contacting tapers forming an active seal surface for cooperating together causing said stopper to apply a radial force to said at least one rib and the syringe barrel upon the application of a forward force to the plunger rod;
• and
• (e) an open space defined by the inner surface of the main body, a portion of said core member, and said taper on the inner surface of said main body,
• wherein said front flange extending from said front attachment end of said plunger rod extends into said open space.