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The practice of assigning retest dates is the recommended procedure in the US Food and Drug Administration’s Guidance for Industry document to the pharmaceutical industry: Q7A Good Manufacturing Practice Guidance for Active Pharmaceutical Ingredients (API’s) and is standard pharmaceutical industry practice for reference standards.

Per the Q7A:

“An API expiry or retest date should be based on an evaluation of data derived from stability studies. Common practice is to use a retest date, not an expiration date.”

“Retest Date: The date when a material should be re-examined to ensure that it is still suitable for use.”

“Expiry Date (or Expiration Date): The date placed on the container/labels of an API designating the time during which the product is expected to remain within established shelf life specifications if stored under defined conditions and after which it should not be used.”


Consistent with our accreditation to ISO Guide 34, expiration dates are assigned to Cerilliant products based on stability studies:

ISO Guide 34, Section 5.9.4, defines Expiration Dates as “An assessment of the stability of the assigned property values of the reference material performed at periodic intervals after characterization to confirm that all values are maintained from production until its expiry date. Wherever appropriate, the reference material producer shall provide an expiry date for the useable life to the reference materials produced, based on initial and on-going stability studies in compliance with ISO Guide 35.”

ISO 17025 does not specifically speak to the assignment of expiration dates or retest dates. It does speak to the calibration of equipment and the use of certified reference standards as follows:

  • Section 5.58 – “Whenever practicable, all equipment under the control of the laboratory and requiring Calibration shall be labeled, coded, or otherwise identified to indicate the status of calibration, including the date when last calibrated and the date or expiration criteria when recalibration is due.”

  • Section 5.6.2.1.2 – “There are certain calibrations that currently cannot be strictly made in SI units. In these cases calibration shall provide confidence in measurements by establishing traceability to appropriate measurement standards such as: - the use of certified reference materials provided by a competent supplier to give a reliable physical or chemical characterization of a material…”

  • Section 5.10.4.3 - “A calibration certificate (or calibration label) shall not contain any recommendation on the calibration interval except where this has been agreed with the customer. This requirement may be superseded by legal requirements.”


Return to Expiration/Retest Dates

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