Coring, which is the name for when a piece of rubber is shaved off from the rubber stopper of a vial when the needle punctures it, is herein reported. We investigated whether or not coring could happen with insulin injections, and also whether or not such pieces of rubber could then actually pass through the needle. Vials for syringes and pen type injectors were used with 29, 30 and 31 gauge (G) needles, under cool and room temperature conditions, and at 60/90 degree puncturing angles. The shapes, sizes and number of pieces of rubber were measured at the 10th and 30 th puncturing times. For the passage test, the presence rubber pieces was measured during air venting, as well as in the insulin liquid actually ejected and in the liquid in the vial.
Coring often occurs in vials for syringes under cool conditions. Vials for pen type injectors also show coring under all the above conditions. The rubber pieces which passed through the needle could be found in both air venting and the insulin liquid. Coring was shown in thin hypodermic syringes, such as 29-31 G, and there was evidence that such rubber pieces may be dangerous if they enter the body. Rubber pieces can pass through the needle in a vial for pen type injectors, due to the design of the fixed needle in the injector. Based on our findings a safer injection system which prevents coring should thus be develepoed.
In addition Careful attention should also be paid to patients with rubber allergies.
