Medutest result on a Shanghai mazdutide lot lands 1.2 points below the supplier’s figure

An independent purity determination on mazdutide material sold by SWB has returned 98.6%, a figure 1.2 percentage points below the number printed on the accompanying certificate. The analysis was performed by Medutest on a vial the Journal bought as an ordinary retail customer in August 2025 and posted unopened.

Content by elemental nitrogen determination returned 89% of the labelled nominal mass, which on a 10 mg vial corresponds to roughly 12.66 mg of peptide rather than the labelled figure. The remainder is accounted for by counter-ion, residual water and residual solvent, none of which is visible chromatographically.

Purity became this trade’s single figure of merit because it is the cheapest measurement to obtain and the easiest to compare. Peptide content, which determines how much drug is actually in a vial, costs several times as much and is not offered as a standard release test by any of the twenty companies in the Journal’s dossier programme. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.

Sinéad Corrigan, patient advocate and former trial participant, 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."

SWB’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.