LAL, kinetic chromogenic, recombinant factor C: three ways to the same figure
The limit for a parenteral product is calculable from the dose and the body weight in two lines. Almost nobody in this trade performs the calculation.
Testing Dispatch
VendorInvestigate result on a Hong Kong dulaglutide lot lands 3.1 points above the supplier’s stated figure
The Journal submitted the sample and paid for the analysis. The vendor was told in advance.
An independent purity determination on dulaglutide material sold by ERP has returned 95.4%, a figure 3.1 percentage points above the number printed on the accompanying certificate, which the supplier had reported against a shorter gradient and a tighter threshold. 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 96% 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 12 vials from the same lot at retail and had four 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 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 Emiko Tanabe, mass spectrometrist. "If the tailing factor and the replicate precision are outside limits, you are arguing about arithmetic performed on an unfit separation."ERP’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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