Medutest result on a Tianjin exenatide lot lands 2.1 points above the supplier’s stated figure

Medutest has published a purity determination of 96.5% on a 30 mg vial of exenatide supplied by SWB, against a figure of 93.2% on the certificate that accompanied the vial. The sample was submitted by the Journal in December 2025 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.

Content by elemental nitrogen determination returned 94% of the labelled nominal mass, which on a 30 mg vial corresponds to roughly 8.73 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.

Reported figures across the set were: highest 96.5%, lowest 93.2%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 20 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

Four independent services — Medutest, VendorInvestigate, and the two others operating in this market — carry the analytical burden for a trade that has no release-testing obligation of its own. Each is paid by whoever submits the sample, which is usually the vendor. The Journal’s position is that a submitter-pays model is workable but that its incentive structure has to be stated whenever a result is quoted as verification.

Dr Beatriz Sarmiento, clinical pharmacologist, Universidad de Navarra, wanted the wavelength printed. "A method reading at 280 nanometres cannot see a fragment that has lost its aromatic residue. That is not a failure of the laboratory, it is a fact about the question they were asked."

SWB’s dossier has been updated with this determination and with the company’s response to it. The dossier’s ordering box records the lead times, the minimum quantities and what a buyer should ask for at the point of order.