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Therapeutic products such as drugs, biologics, medical devices and dietary supplements are commonly packaged in plastic packaging systems. It has been shown that plastic packaging systems can be a source of extractable constituents which can leach into the therapeutic products they contain. As a result, United States Pharmacopeia (USP) General Chapter <661> entitled “Plastic Packaging Systems and their Materials of Construction” was created to provide standards for testing plastic articles such as bulk plastic resins, molded plastic packaging components (e.g., containers and caps) and entire plastic packaging systems (i.e., the assembled primary container).
Plastics are composed of a mixture of homologous polymers having a range of molecular weights. Plastics may contain other substances such as residues from the polymerization process (fragments of polymers) and additives such as plasticizers, stabilizers, antioxidants, pigments, and lubricants. These are the materials which can pose a health risk if they leach into therapeutic products from the plastic packaging systems which contain them.
The USP provides specific standards for testing Polyethylene Containers (High-Density and Low-Density), Polypropylene Containers, Polyethylene Terephthalate Bottles, and Polyethylene Terephthalate G Containers. Plastics not included in this list and combinations of plastics must also be tested, however the USP describes testing of a general nature rather than providing a specific standard for each.
In addition to USP <661> which is the current Standard, USP has also introduced <661.1> entitled “Plastic Materials of Construction” and <661.2> entitled “Plastic Packaging Systems For Pharmaceutical Use”, both of which may be implemented at any time as an option replacing <661>. These two ‘optional’ Standards are scheduled to take effect on December 1, 2025 but may be employed at any time prior to their December 2025 effective date.
Based upon the physical and chemical nature of each plastic and the particular application for which a packaging component made from that plastic will be used, USP <661> provides specific testing standards as follows:
| Test | Polyethylene (HDPE and LDPE) | Polypropylene | Polyethylene Terephthalate Bottles and Polyethylene Terephthalate G Containers | ‘Other’ Plastics or ‘Combinations of Plastics’ |
|---|---|---|---|---|
| Infrared Spectroscopy | X | X | X | |
| Differential Scanning Calorimetry (DSC) | X | X | X | |
| Heavy Metals | X | X | X | X |
| Nonvolatile Residue | X | X | ||
| Buffering Capacity | X (Only if in contact with ‘oral’ liquids.) | X (Only if in contact with ‘oral’ liquids.) | X | |
| Colorant Extraction | X | |||
| Total Terephthaloyl Moieties | X | |||
| Ethylene Glycol | X | |||
| Residue on Ignition | X | |||
| Biological Testing: Agar Diffusion Test Direct Contact Test Elution Test | X (Only if used for Inhalation, parenteral or ophthalmic products.) | X (Only if used for Inhalation, parenteral or ophthalmic products.) | X (Only if used for Inhalation, parenteral or ophthalmic products.) | X (Only if used for Inhalation, parenteral or ophthalmic products.) |
“X” indicates a required test; A ‘blank’ box indicates a test is not required for that plastic type.
Many significant changes from <661> are introduced in USP <661.1 and 661.2>. Cyclic Olefins, Polyamide 6, Poly(Ethylene-Vinyl Acetate), Polyvinyl Chloride and Polyvinyl Chloride – Plasticized have been added to the list of specified plastics. New testing is also introduced including UV Absorbance, Acidity/Alkalinity, Total Organic Carbon (TOC), Extractable Elements, Plastic Additives and Related Substances. Although some of the new tests do not apply to every plastic in every application, one might generally conclude that the level of testing is increased over what is required in <661>.
Although plastic container testing is specified in the USP and required by FDA, many therapeutic product manufacturers/distributors have still not conducted this testing on their plastic packaging systems. Yes, the testing requirements are confusing but this important testing must still be conducted. The CPT Team of experienced scientists and regulatory advisors are ready to assist you in determining which testing applies to your specific plastic packaging systems. Our state-of-the-art Analytical Chemistry Laboratory stands ready to conduct the chemical testing that is required for your plastic packaging systems. Why not give us a call today?
Please Note: CPT℠ only performs testing for companies. We do not perform product testing for the general public.