To prevent core formation in vials and ampules, how should the needle be inserted?

In sterile compounding, the technique used when inserting a needle into vials and ampules is crucial to prevent the formation of a "core," which is a piece of rubber or stopper that can break off and contaminate the solution. The correct method involves inserting the needle at the same point with both the tip and heel of the bevel in order to facilitate a smooth entry into the vial or ampule.

This approach allows for minimal disturbance to the rubber stopper or barrier, reducing the likelihood of creating a core. By ensuring that both parts of the bevel enter the vial simultaneously, the chances of pushing through the stopper and breaking off a piece are significantly decreased. Thus, this technique not only helps maintain the sterility of the compounding process but also ensures the integrity of the contents being prepared.

Other methods, such as inserting at an angle or perpendicular to the surface, may lead to uneven pressure on the stopper and increase the risk of breaking off a core. Inserting through the air space may not provide the stability and control necessary to minimize core formation, making the use of the bevel's tip and heel at the same insertion point the most effective technique.