Would you re-test semaglutide after twelve weeks at minus 80 °C, or accept the original certificate?

Concretely: semaglutide · twelve weeks · minus 80 °C.

I want to decide this in advance so that I am not deciding it under pressure later.

Assume I will follow the plan I write down, so I would like it to be a good one.

What would you do, and what would make you change course?

Specifically, if a lot has visibly segregated — some vials showing different appearance — then sampling the top and bottom of the shipment is worth doing.

If the entire lot failed qualification, a retest on a different vial is sometimes done, but reporting a retest result under the same lot number is misleading.

In practice, the sample size determination requires choosing a confidence level and an acceptable error rate, and the smaller the error rate you want, the larger your sample must be.

Sampling plans for pharmaceutical manufacturing are defined in ISO 2859 and ANSI Z1.4, and they are based on statistical sampling theory.

The practical summary: a lot number without a sampling statement is a lot number without meaning.

edited 13 May 2026 by anders_vestby — added a caveat about sampling

The honest statement is that unless you have tested multiple vials or have segregation data, you are making an assumption about lot homogeneity that may not hold.

If the lot was manufactured in multiple batches, testing vials from each batch separately establishes whether batch-to-batch variation is acceptable.

The statistical foundation here is well-established, which is why sampling plans from decades ago are still valid.

Published data on lot homogeneity from manufacturers who sample multiple vials consistently find variation below the published specifications, suggesting the sampling plans work.

Assume segregation is possible, and design your sampling to catch it if it exists.

Put another way, the failure mode here is publishing a result that applies to the tested vial alone while implying it applies to the entire lot.

Under AQL sampling plans, testing two vials from a fifty-vial lot gives you an operating characteristic curve that tells you what risks you are accepting.

Worth noting that thermal excursions during shipping affect different vials differently, so the lot may not be homogeneous even if it left the factory that way.

If testing multiple vials, state how many you tested and why you chose those vials.