USP <661> compared with USP <661.1> and USP <661.2>

USP <661> compared with USP <661.1> and USP <661.2>

A common question is: Which chapter should you perform testing to?

Work conducted to either <661> or <661.1> / <661.2> is valid now, but you should consider how you use the data, what you are testing (material or container), the benefits of each testing approach and when data is needed or used.

USP <661.1> and <USP 661.2> will become official on May 1, 2020. However, until May 20, 2020 you are still able to use USP <661> if you choose not to adopt <661.1> and <661.2>. If early adoption of USP <661.1> and USP <661.2> is chosen, then this is permitted and USP <661> need not be followed.

Whether to use USP <661.1> or <661.2> is a slightly different question and the answer will depend on whether you seek to secure and own regulatory approval of an entire packaging system or just an individual plastic material. Plastic materials are considered characterized and appropriate for use if they meet the requirements of USP <661.1> or are used in a packaging system that meets the requirements of USP <661.2>. In the latter case, the material is only considered to be characterized and appropriate for use for a specific packaging system and pharmaceutical product tested to USP <661.2>. Ultimately, if you wish to secure regulatory approval of a packaging system you need to fulfil the requirements of USP <661.2>.

What happens to USP <661> from May 1, 2020?

USP <661>, in its current form, will completely change. It is proposed that the USP <661> chapter remains and, although there are no test procedures, e.g. colour of solution, explicitly described in the chapter, the scope directs the reader to establishing the suitability of material through a series of stages including: Material screening, controlled extractables work (USP <1663>) and product assessment (leachables) (USP <1664>). Additionally, the reader is directed to the testing of materials and packaging systems under <661.1> and <661.2>.

Why have these changes happened?

There is no doubt that USP <661.1> and USP <661.2> provide more comprehensive data packages than USP <661> and they link closely with the philosophies of USP <1661>, <1663>, <1664> and <1664.1> and the discussions ongoing around USP <665> (Single Use Systems). USP <661.1> and USP <661.2> data packages provide a greater knowledge base to facilitate an appropriate evaluation for the correct selection of materials and ultimately facilitate a chemical risk assessment for pharmaceutical packaging.

 What are the differences?

The most obvious changes are the chapter titles; materials and packaging have been separated into two chapters:

  • USP <661> Plastic Packaging Systems and their Materials of Construction


  • USP <661.1> Plastic Materials of Construction
  • USP <661.2> Plastic Packaging Systems for Pharmaceutical Use.

USP <661.1> contains more specific testing, based on the resins formulation, using GC, HPLC, and TLC for additives, stabilizers, related substances, residual solvents, etc.; and is more detailed than USP <661>. USP <661.2> adds a specific requirement for chemical risk assessment, discussing extractables and leachables, that is not present in USP <661>. USP <661.2> states that extractables and leachables testing must be “…based on sound and justifiable scientific principles…” [USP 41 – NF36).

Other applicable USP Chapters

The following USP Chapter are closely linked with USP <661>, <661.1>, and <661.2> and are within the testing capabilities of Smithers:

  • USP <671> - Containers – Performance Testing
  • USP <381> - Elastomeric Closures for Injections
Find out more about the extractables and leachables testing services that Smithers offer.

Download our USP comparison chart below: