Is glass permeable against gases and water vapour?
Glass has been in use for pharmaceutical packaging since decades. It was always first choice not least for its inertness, its transparency and its impermeability. Due to the dense structure of the glass gases and water vapour are not capable of migrating through the glass. There has been a study on ampoules with OPC that showed that even if there is a cut in the constriction of the ampoule not even helium gas (which is much smaller than oxygen and water vapour) can migrate inside the ampoule. This is important especially when it comes to biological products which often are oxygen and or water vapour sensitive and would be degraded.
Does glass contain any organic substances, like BSE or Pthalates?
Certain organic materials can interact with the drugs or alter the inner surface of the glass packaging. In some case e.g. the meniscus of the solution would appear more flat than without any organic materials. These particular containers are then rejected in the filling line due to improper filling even if they are properly filled. BSE bears the risk for the Creutzfeld-Jakob disease. These are only a few of the reasons why this information is requested by regulatories. For the production of glass temperatures of around 1600°C are needed. At this temperature all organic substances like BSE, Pthalates and others are decomposed. Also bacteria and other living organisms cannot survive these temperatures. When the tubing comes out of the melting tank it is absolutely pure and clean and free of any organic material.
(To feature in this column, email your queries to Dr Bettine Boltres, SCHOTT AG: bettine.boltres@schott.com)