The current revision of General Chapter "Plastic Materials of Construction" <661.1> should demonstrate when materials are considered as well-characterised. This includes among other things the following criteria:
Polyethylene (PE), polyolefin (PO), polypropylene (PP), poly(vinyl chloride) (PVC), polyethylene terephthalate, and polyethylene terephthalate G rank among the typical plastic materials.
Basically, new plastic materials of construction - which aren't expressly mentioned in this USP chapter - can be developed. However, extensive characterisation is required for such materials, as described in the chapter. Moreover, an agreement by the competent authority is necessary. The same procedure applies to the use of new additives.
The following additives are mentioned as typical additives for plastic packaging systems:
From a chemical perspective, packaging systems made of plastic should be such that the ingredients of the pharmaceutical product are neither adsorbed onto the surface of the packaging system nor absorbed into the body of the packaging system, and don't migrate through the packaging system. Furthermore, the packaging system shouldn't release any substances which can accumulate in the pharmaceutical product in quantities sufficient to affect its stability or to present a risk of toxicity.
More information can be found in the Pharmacopeial Forum.