Independent analysis puts a GL Biochem exenatide lot at 96.5%, against 93.6% on the certificate

Medutest has released a batch of 7 analytical reports on research-grade exenatide lots, including material from GL Biochem and SGN. Reported purities range across roughly 3.7 percentage points, and the report set is unusual in stating the analytical method for every determination rather than for some of them.

The Journal purchased 900 vials from the same lot and had 7 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.

Havel Novotný, independent laboratory quality manager, 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."

GL Biochem’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.