How would I detect oxidation in a tirzepatide vial without sending it to Janoshik?

The case in front of me: oxidation · tirzepatide · Janoshik.

I have done this once and I suspect I got away with it rather than got it right.

For context: I keep records of every batch, every lot number and every result, so an answer that requires me to track something is fine.

What does a defensible version of this look like in practice?

Specifically, this is a two-minute procedure that resolves a large fraction of the questions people ask afterwards.

After reconstitution, hold against a light and look for haze, floaters or a Tyndall effect. A clear solution that goes clear on contact is what a well-made preparation looks like.

Check the fill looks proportionate to the label claim. Ten milligrams of peptide is a small volume of powder, but it is not nothing, and a vial that looks empty is worth a photograph.

Visual inspection for particulate matter is a pharmacopoeial requirement for parenteral products and the standard technique uses both light and dark backgrounds.

Inspect before reconstitution. Afterwards you cannot tell whose particle it is.

The relevant principle is that anything you find before reconstitution is the supplier's, and anything you find after might be yours.

Look for fibres, glass fragments and dark particulate in the cake. Glass is the one that matters and is usually a crimping or handling artefact rather than a synthesis one.

Weigh the vial if you have a scale reading to a milligram. It will not give you content, but a vial several tens of milligrams lighter than its siblings is a fill problem.

A vial that passes inspection has passed a very weak test. It has not been verified.

Crimp, stopper, label, contents. Light background and dark background.

The short version: intact crimp, seated stopper, legible lot code, and a cake that looks like a cake.

Check the aluminium crimp is fully seated with no lift at the edge, the flip-off cap has not been previously removed, and the stopper sits flush without a visible gap or dimple.

Container closure integrity depends on the crimp and stopper seating, which is why those are the first things checked in any incoming-goods inspection.

Do not open a vial you intend to return or claim on; photograph it sealed first.

Photograph anything unexpected before touching it further.

The lot code on the vial, not on the box, is what ties your material to a certificate.

Confirm the lot code is physically on the vial and legible, and that it matches the certificate and the invoice. A code on the box only ties a certificate to a box.

The caveat is that inspection cannot detect identity, purity, content or endotoxin, which are the things most likely to be wrong.

Passing inspection is a weak result. It rules out the obvious and nothing else.