Clinical Biopotency of Insulin Analogues: Comparative Assessment in Different Species

Abstract

ObjectiveThe clinical potency of human insulin has classically been evaluated following the U.S. Pharmacopeia (USP) guideline for comparison to an international standard (IS) of activity (IU). However, since insulin analogues cannot be standardized against IS, there is a need for a bioassay to assess clinical specific activity (U). To this extent, we compared the biopotency (U) of different insulin products in different species and used human (recombinant) and pork (natural) insulin as reference standards.Methods: New Zealand White rabbits were fasted and injected subcutaneously (s.c.) at a dose level of 0.5 U/kg. Diabetic Yucatan miniature swine (Sus scrofa) were injected s.c. at dose level of 0.1 U/kg. Normal insulin suppression tests (nIST) were conducted in primates (Macaca fascicularis) receiving a bolus intravenous (i.v.) infusion of glucose. Insulin products were given at dose level of 0.05 U/kg. Glucose levels were recorded using handheld glucometer devices. The blood glucose kinetic (BGPK), the blood glucose area under the curve (BGAUC) and the slope of the blood glucose clearance rate (kG) were used to assess clinical biopotency.Results: The BGPK for short‐acting human and pork insulin were similar in the rabbit assay but their respective BGAUCs were different (ratio of 1.2). Accordingly pork insulin was more potent during nIST in the non‐human primate (slope of ‐0.012 vs. ‐0.010; pork and human, respectively).ConclusionOur data indicate that the clinical biopotency of insulin products can be assessed using BGAUC and kG, but that only the type 1 diabetic miniature swine can discriminate between differences in clinical biopotency for all aspects of BGPK.