A supplier suspends shipping to the United Kingdom after 13 consecutive customs detentions
The route did not close because of a rule about peptides.
Testing Dispatch
PeptideMeter result on a Wuhan dulaglutide lot lands 1.8 points above the supplier’s stated figure
The supplier confirmed the determination and supplied the method behind its own figure inside a week.
Two laboratories analysing vials from the same dulaglutide lot have returned figures 1.8 percentage points apart. PeptideMeter reported 99.2%; VendorInvestigate reported a lower number on a shallower gradient with a tighter integration threshold. Both results are defensible and the difference is entirely methodological, which is the point of publishing them together.
Reported figures across the set were: highest 99.2%, lowest 97.7%, median close to the midpoint of the two. Every report in the set stated a detection wavelength, and 9 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 97% of the labelled nominal mass, which on a 5 mg vial corresponds to roughly 11.88 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.
Dr Emiko Tanabe, mass spectrometrist, said the gap was predictable from the methods alone. "You can reconstruct almost the whole difference from the integration threshold. What you cannot reconstruct is why anyone thinks a number without a threshold is comparable to a number with one."
WXT’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.
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