Retest date vs expiry date: what a COA should show

Two definitions, two consequences

The glossary of ICH Q7 keeps the two ideas apart. The expiry date marks the end of the period in which the API is expected to stay within its established shelf-life specifications if stored as defined, after which it should not be used. The retest date is simply the date when the material should be re-examined to confirm it is still suitable.

The practical difference is what happens when the date passes. After an expiry date the material is out of its assured period and should not be used. After a retest date the material may still be perfectly good, but that can no longer be assumed: a representative sample should be taken and the relevant tests repeated before the batch is used (11.63).

Which one APIs usually carry

ICH Q7 11.61 says that an API expiry or retest date should be based on an evaluation of stability data, and that common practice is to use a retest date rather than an expiration date. Section 11.60 adds that when an intermediate leaves the manufacturer's control with such a date assigned, supporting stability information should be available.

Preliminary dates may be based on pilot-scale batches, provided the pilot process simulates the commercial process and the quality of the material represents what will be made at scale (11.62).

What the certificate should show

Section 11.41 is specific: for intermediates or APIs with an expiry date, the expiry date should be on the label and the certificate of analysis; for those with a retest date, the retest date should be on the label and/or the certificate.

For a reviewer, three checks follow. First, one of the two dates is present. Second, it is labelled unambiguously, since "valid until" or "best before" can be read either way. Third, it is consistent with the manufacturing date and with any shelf-life statement elsewhere on the document: a retest date earlier than the manufacturing date, or a date that implies an implausible shelf life, is a finding in its own right.

When the date has passed on a certificate you are reviewing

A certificate is often reviewed long after it was issued, for example when material is being considered for purchase from stock or when a batch record is audited. If the stated retest date has passed, the certificate's results describe the batch as it was at testing, not as it is now; use should wait for a retest on a representative sample. If the stated expiry date has passed, the material is outside its assured period.

Either way the certificate itself is not wrong; it is the decision to use the material that needs more evidence. That is why a date that has passed should be surfaced as a hold point rather than folded into a general score.

Définitions

Expiry date (expiration date)

ICH Q7 glossary: the date placed on the container or labels of an API designating the time during which the API is expected to remain within established shelf-life specifications if stored under defined conditions, and after which it should not be used.

Retest date

ICH Q7 glossary: the date when a material should be re-examined to ensure that it is still suitable for use.

Sources

1. ICH Q7, Good Manufacturing Practice Guide for Active Pharmaceutical Ingredients (Step 4, 10 November 2000), International Council for Harmonisation (section 11.41, sections 11.60 to 11.63, and the glossary entries for Expiry Date and Retest Date)

Les sources primaires sont citées de préférence aux résumés. Lorsqu'une source est sous licence (par exemple une monographie de pharmacopée), la référence est donnée et le texte n'est pas reproduit.

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