Determination of purity and identification of animal sources of insulin in various insulin preparations.

Prolonged administration of insulin leads to the formation of insulin-binding antibodies due to contaminant peptides and the animal source of the insulin. It follows that quantitation and identification of these factors are of significant importance in pharmaceutical insulin preparations. The assay and test procedures stipulated in the current pharmacopoeia of various countries, nevertheless, cannot determine either of these effects. In the present study, the content of impurities in insulin preparations was measured by polyacrylamide gel disc electrophoresis and the animal source of insulin identified by amino acid analysis. Assays of 17 commercial insulin preparations by these techniques revealed diversity in purity and animal sources of insulin. The present results suggest potential usefulness of these assay methods and advisability of their adoption not only by the manufacturers but also by the official pharmacopoeia as well.