Insulin Bioidentity and Biopotency – USP <121>
Pacific BioLabs has extensive experience in performing in vivo cGMP bioassays. For over 15 years, PBL has performed insulin bioassays including both biopotency and bioidentity tests according to USP <121>, Insulin Assays.
The in vivo bioidentity and the biopotency tests for insulin utilize the rabbit blood sugar method in which four rabbit test groups are injected with insulin and their blood glucose levels are measured over time. An insulin reference standard is used for this test and the sample being tested is measured against that reference standard. Between 0.25 and 0.5 mL of the reference standards and samples are injected subcutaneously into the rabbit and the amount of insulin injected into the rabbit should not be high enough to induce hypoglycemia.
At prescribed periods of time after the injection blood samples are taken from the animal and their blood glucose levels are analyzed on a validated Siemens Dimension Xpand Plus Integrated Chemistry System. The biopotency is a quantitative test and requires six animals to be tested per group and once the glucose levels of all six animals from the four test groups are determined the potency of the insulin product is calculated. The bioidentity test is a qualitative test which requires only two rabbits per test group. The blood glucose levels of the rabbits should indicate an insulin potency above a specific threshold (15 USP Units/mg) to qualitatively identify the product as insulin.
The in vivo insulin bioassay is typically used as a lot release assay.