Independent analysis puts a MKM dulaglutide lot at 98.2%, against 96.7% on the certificate

Two laboratories analysing vials from the same dulaglutide lot have returned figures 1.7 percentage points apart. PeptideMeter reported 98.2%; 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.

The Journal purchased 3100 vials from the same lot and had 12 of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

The Journal purchased 3100 vials from the same lot and had 12 of them analysed separately, in order to distinguish vial-to-vial variation from method variation. Vial-to-vial agreement was within 0.4 percentage points. Method-to-method disagreement was an order of magnitude larger.

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.

"Content is the number that matters if you are doing arithmetic with a vial, and content is the number nobody sells," said Lorcan Feeney, analytical services director at an independent laboratory. "Purity is what you can afford. Content is what you need."

MKM’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.