Medutest result on a Shenzhen retatrutide lot lands 2.4 points below the supplier’s figure

Medutest has published a purity determination of 96.0% on a 10 mg vial of retatrutide supplied by Homopeptide, against a figure of 93.2% on the certificate that accompanied the vial. The sample was submitted by the Journal in February 2026 as part of a continuing programme of arm’s-length purchasing, and the vendor was told before the order was placed that any result would be published.

The Journal purchased 4900 vials from the same lot and had 24 of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

The Journal purchased 4900 vials from the same lot and had 24 of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

The wider context is that material sold for research use carries no regulatory release specification in any jurisdiction the Journal has examined. A certificate is a commercial document, not a compliance one, and its content is whatever the issuer chooses to put on it. That is the gap independent testing fills, and it fills it imperfectly.

Rowena Ashcombe, community pharmacist and diabetes educator, was more cautious. "One lot tells you about one lot. I would not draw a conclusion about a company from a single determination, and I would not let a company draw one either."

Homopeptide’s dossier has been updated with this determination and with the date of the request for comment. The dossier’s "what we could not verify" box records the questions still outstanding.