Janoshik result on a Wuxi survodutide lot lands 2.9 points above the supplier’s stated figure

A peptide content determination commissioned by the Journal on a 15 mg survodutide vial from MKM has returned 93% 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 97.1%. 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 97.1%, lowest 95.2%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 14 of them stated an integration threshold. The Journal has asked the laboratory to publish thresholds on all reports as a matter of routine.

Content by elemental nitrogen determination returned 93% of the labelled nominal mass, which on a 15 mg vial corresponds to roughly 6.38 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 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.

"Ask for the suitability summary before you argue about the percentage," said Dr Beatriz Sarmiento, clinical pharmacologist, Universidad de Navarra. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."

MKM’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.