n the process of making a glass syringe with a staked needle you need the inner outlet hole where the needle should be positioned to be precise.
This hole is formed when the glass is hot by putting a mandrel inside the hole while pressing on the outer side.
This mandrel should be heat stable. It has traditionally been made from tungsten. Recently, stability problems were discovered with some biologics, and after a long investigation period it was realized that tungsten ions from the formed process were the root cause.
Speaking about cartridges, this is not a problem as the outlet of the cartridge is free-formed and there are no strict demands on the dimensions.
Rubber stoppers give the same problems with stability and leaking into the drug. Therefore, a large number of rubber formulations are available from manufacturers to fit drug formulation. The drug stability program shall be performed in the primary packaging, including the rubber stopper that will be in use, in order to see if the stability of the drug is affected, and to see if specific drugs cause leaching from the rubber stopper. One cannot change without a second authority approval.
—By, Omar Sherief Mohammad, Novo Nordisk
