COMPARISON OF THE RABBIT, DIABETIC MINIATURE SWINE AND NON-HUMAN PRIMATE TO EVALUATE THE CLINICAL BIOPOTENCY OF INSULIN PRODUCTS

Scientific Poster
Comparison of the Rabbit, Diabetic Miniature Swine and Non-Human Primate to Evaluate the Clinical Biopotency of Insulin Products - SciPos107

Abstract

The potency of human insulin has classically been evaluated in rabbits following the U.S. Pharmacopeia (USP) guideline. However, since insulin analogues are intentionally different there is a need for a bioassay to assess clinical specific activity (U) in different species. To this extent, we compared the biopotency (U) of different insulin products in rabbits, in type 1 diabetic miniature swine and in normal non-human primates and used human and pork insulin as reference standards. New Zealand White rabbits were fasted and injected subcutaneously (s.c.) at a dose level of 0.5 U/kg. Yucatan miniature swine (Sus scrofa) were made diabetic by intravenous administration of alloxan and insulin products were injected s.c. at dose level of 0.1 U/kg in overnight fasted animals (no feed or insulin for 18 h). Normal insulin suppression tests (nIST) were conducted in fasted male cynomolgus primates (Macaca fascicularis) receiving a bolus intravenous (i.v.) infusion of glucose (ivGTT; 0.25 g/kg) and treated with somatostatin. 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) and the blood glucose area under the curve (BGAUC) were used to assess biopotency in the rabbit and in the diabetic miniature swine. The slope of the blood glucose clearance (kG) was used to assess biopotency during the nIST. Our data indicate that the 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 biopotency for all aspects of BGPK. In conclusion, 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).

Authors

Stricker-Krongrad A.1 and Bouchard G.F.1,2
1Sinclair Research Center, LLC and 2Sinclair Bio Resources, LLC, Auxvasse, MO, USA

Introduction

The major goals of Phase I and Phase III human clinical trials for new antidiabetic therapeutic entities (NCEs) are the evaluation of their potency, pharmacokinetic/pharmacodynamic and therapeutic efficacy. In addition, the major goal of bioequivalence human clinical trials for biological antidiabetic medicinal products is the demonstration of their similar nature (biosimilars).

In contrast, the major objective of animal models of diabetes is to be able to translate their clinical pharmacology and therapeutic efficacy to human in order to identify clinical trials candidates (drug development selection) or to model clinical trials to improve the prediction of study outcomes (comparative clinical trial modeling).

Therefore, the identification and characterization of animal models of diabetes having a high translational value has become more and more important at a time when the severe limitations of the rodent models have been fully recognized1.

For example, the potency of human insulin has classically been evaluated in rabbits following the U.S. Pharmacopeia (USP) guideline. However, since insulin analogues are intentionally different there is a need for a bioassay to assess clinical specific activity (U) in different species. To this extent, we compared the biopotency (U) of different insulin products in rabbits, in type 1 diabetic miniature swine and in normal non-human primates and used human and pork 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. The blood glucose kinetic (BGPK) and the blood glucose area under the curve (BGAUC) were used to assess biopotency in the NZW rabbit.

Yucatan miniature swine (Sus scrofa) were made diabetic with intravenous alloxan and regulated on insulin. Animals were considered diabetic if they became hyperglycemic (≥150 mg/dL) within 2-5 days following induction. All procedures were on overnight fasted animals (no feed or insulin for 18 hrs). Our diabetic miniswine average baseline BG of 429 ± 84.5 (SD) mg/dL (N=148 measurements) while nondiabetics average 58.7 ± 8.2 (SD) mg/dL (N=238 measurements). Prototypical and new insulin products were administered subcutaneously (s.c.) at mealtime, then blood glucose profiles recorded using handheld glucometer devices (One Touch Ultra®, Lifescan). The blood glucose kinetic (BGPK) and the blood glucose area under the curve (BGAUC) were used to assess biopotency in the diabetic miniature swine.

Normal insulin suppression tests (nIST) were conducted in fasted male cynomolgus primates (Macaca fascicularis) receiving a bolus intravenous (i.v.) infusion of glucose (ivGTT; 0.25 g/kg). All animal were pre-treated with somatostatin to suppress the endogenous release of insulin induced by the glucose load.

Insulin products were administered intravenously (i.v.) and glucose levels were recorded using handheld glucometer devices. The slope of the blood glucose clearance (kG) was used to assess biopotency during the nIST in the non-human primate. Insulin products (human: Humulin R and pork: Hypurin) were given at dose level of 0.5 U/kg in the NZW rabbit, 0.1 U/kg in diabetic miniature swine and 0.05 U/kg in non-human primate. Data are presented as mean +/- SEM.

Results

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