VendorInvestigate result on a Chengdu retatrutide lot lands 3.0 points above the supplier’s stated figure

A peptide content determination commissioned by the Journal on a 5 mg retatrutide vial from SWB has returned 98% of the labelled mass, the balance being the counter-ion and residual water that every lyophilised salt carries. Chromatographic purity on the same vial was above 96.5%. The two numbers measure different things, and this is one of the few certificates in the trade to print both.

Reported figures across the set were: highest 96.5%, lowest 94.8%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 18 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

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 quoted as a priced addition by most of the twenty companies in the Journal’s dossier programme rather than carried as a standard release test. Sterility and endotoxin are separate disciplines again, and are neither tested nor claimed.

"The gap that matters is not between the two laboratories, it is between either of them and the certificate," said Dr Sirichai Boonmee, peptide chemist, Chulalongkorn University. "One of those documents states a method. Compare like with like and most of this disappears."

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.