VendorInvestigate result on a Hong Kong dulaglutide lot lands 3.1 points below the supplier’s figure

An independent purity determination on dulaglutide material sold by ERP has returned 95.4%, a figure 3.1 percentage points below the number printed on the accompanying certificate. The analysis was performed by VendorInvestigate on a vial the Journal bought as an ordinary retail customer in August 2024 and posted unopened.

Content by elemental nitrogen determination returned 93% of the labelled nominal mass, which on a 2 mg vial corresponds to roughly 14.19 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.

The Journal purchased 2200 vials from the same lot and had 10 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.

Sinéad Corrigan, patient advocate and former trial participant, was more cautious. "One lot tells you about one lot. I would not draw a conclusion about a company from a single determination, and I would not let a company draw one either."

ERP’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.