Glass syringe barrel with increased flange breaking resistance

A glass syringe barrel, comprising:

• a bottom end through which a liquid can be ejected;
• a top end into which a plunger stopper can be pushed;
• and
• a longitudinal axis defined through the bottom and top ends;
• wherein the glass syringe barrel, in a direction from the bottom end to the top end, includes:
• a cone region having a first end that corresponds to the bottom end and a second end;
• a shoulder region having a third end adjacent to the second end and a fourth end;
• a body region with a first outer diameter (d1) having a fifth end that is adjacent to the fourth end and a sixth end;
• and
• a flange region having, at least in parts, a circular shape, the flange region having a seventh end that is adjacent to the sixth end and an eighth end that corresponds to the top end, wherein the flange region has a second outer diameter (d2), the second outer diameter (d2) being larger than the first outer diameter (d1),
• wherein the flange region has a first outer contour at the seventh end and a second outer contour at the eighth end;
• wherein for any cut surface that includes the longitudinal axis and is obtainable by cutting the glass syringe barrel in a plane at which a shape of the flange region is circular:
• fo is a straight line that runs perpendicular to the longitudinal axis and touches the first outer contour at a deepest point (P1),
• f′o is a straight line that runs perpendicular to the longitudinal axis and touches the second outer contour at a highest point (P2),
• f(x) defines an absolute value of a vertical distance between any point of the first outer contour and the straight line fo at a position x, with f(x)=0 at point P1, wherein x is a horizontal distance between any given point on the straight line fo and point P0 at which the straight line fo crosses a line L1 that runs parallel to the longitudinal axis and that touches an outer surface of the body region, and a maximum value for the term f(x) in a range from x=P0 to x=P1 is f(x)max determined at position xmax;
• wherein f′(x) defines an absolute value of the vertical distance between any point of the second outer contour and the straight line f′o at a position x, with f′(x)=0 at point P2, and
• wherein the following condition is fulfilled:
• f′(xmax)/f(x)max>1.