Independent analysis puts a SSA semaglutide lot at 98.0%, against 94.0% on the certificate

A peptide content determination commissioned by the Journal on a 15 mg semaglutide vial from SSA has returned 86% of the labelled mass. Chromatographic purity on the same vial was above 98.0%. The two numbers measure different things and only one of them was on the certificate.

Content by elemental nitrogen determination returned 86% of the labelled nominal mass, which on a 15 mg vial corresponds to roughly 10.91 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 300 vials from the same lot and had 16 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.

Batch variance rather than vendor quality is the recurring finding of this programme. Across the 16 determinations the Journal has commissioned to date, within-vendor spread has been wider than between-vendor spread for two thirds of the companies tracked, which is an argument against rating any supplier on a single number.

"The useful thing in that report is not the percentage, it is the system suitability data," said Havel Novotný, independent laboratory quality manager. "It is the only part that tells you whether the percentage means anything."

SSA’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.