John Allison Galloway

New Forms of Insulin

This paper reviews some recent developments in insulin purification and formulation. Neutral Regular insulin (unbuffered Regular insulin with pH adjusted to neutrality, designated NRI) maintained nearly full potency when stored at room temperature for twelve months, while the potency of acid Regular (“commercial”) insulin (ARI) had dropped 20 per cent. When NRI and ARI were administered in combination with NPH or Ultralente insulin, comparable time activity responses were elicited. In fasted normal subjects subcutaneous doses of NRI and ARI gave similar blood glucose responses. Thirty-seven patients with allergy to commercially available insulin were treated with one or both of two highly purified insulins (single peak and single component pork insulin). Improvement occurred in 78 per cent. Single component insulin was usually, but not always, superior to single peak insulin when both were tested in the same patient. Insulin was administered orally with an absorption promoter, Brij 98, to twenty normal and thirteen diabetic fasted subjects in crossover studies. Under optimum conditions, definite responses were observed in about 50 per cent of subjects. Serum insulin measurements in the normals and diabetics revealed that increased concentrations were not necessarily associated with falls in blood glucose concentrations in spite of delivery of the insulin by the portal route. Because of the amounts of insulin required, the limitations of test conditions, and a high incidence of nausea, this project has been discontinued.

Immunogenicity of Insulin

Highly purified bovine and porcine insulins (single component insulin) did not produce antibodies in rabbits, and the highly purified porcine insulin was less immunogenic in diabetic patients than USP porcine insulin. In rabbits one porcine high molecular weight fraction (peak A) and two bovine high molecular weight fractions (peak A and peak B) separated from USP insulin by Sephadex chromatography were immunogenic, producing increases in the amount of 125I-labeled single component insulin bound by the serum. Both peaks (A and B) derived from bovine insulin produced significantly greater insulin binding in rabbits than did the same peaks derived from porcine insulin. In diabetic patients single component porcine insulin produced less binding of insulin to the serum than did USP insulin.

Metabolism, Blood Levels and Rate of Excretion of Acetohexamide in Human Subjects

The metabolism of acetohexamide was studied in normal and diabetic subjects,utilizing acetohexamide-C-14 and hydroxyhexamide-C-14 in two types of experiments. In one, blood levels were determined by an isotopic dilution analysis (IDA). In the other, following the oral and intravenous administration of acetohexamide-C-14, radiocarbon levels in the blood and urine and the nature of the urinary metabolites were elucidated. IDA showed an average half-life for acetohexamide of 1.6 hrs. (range 0.8 to 2.4) and an average half-time for its principal metabolic product, hydroxyhexamide, of 5.3 hrs. (range 3.7 to 6.4). Half-time for total radiocarbon was 5.3 hrs. (range 3.5 to 11). Urinary recovery ofradioactivity after oral doses averaged 71.6 per cent in twenty-four hours. Of the urinary metabolites of acetohexamide (AH) recovered, about 65 per cent was L-hydroxyhexamide (HH) and the remainder consisted chiefly of 4-trans-hydroxyacetohexamide (HAH), 4-trans-hydroxyhydroxyhexamide (HHH), and unchanged acetohexamide with small quantities of other hydroxylated isomers. Fecal excretion was measured in one patient followingthe oral administration and found to be 15 per cent. The observation that, even followingintravenous injection, urinary recovery was only 85 per cent suggested that biliary excretion represents the secondary route of elimination of acetohexamide and/or its metabolites. The radioactivity which was not recovered in the urine at the end of 48 hrs., e.g., on the average 25 per cent, was probably excreted in the stools, resulting from the failure of a small quantity of the tablet to be absorbed and from biliary excretion. The blood and urine data agree with those reported by Sheldon, Anderson and Stoner and confirm the report by Smith, Vecchio and Forist that the half-life of acetohexamide (AH) plus hydroxyhexamide (HH) is comparable to that of tolbutamide. In spite of this relatively short half-life, limited blood sugar data indicate definite hypoglycemic effects up to 24 hrs. after a single 1.0-gm. dose. These findings indicate that the duration of action of AH and its metabolites are not necessarily related to drug levels.

A Comparison of Acid Regular and Neutral Regular Insulin: Responses of Normal Fasted Subjects to Varying Doses of Regular Insulin

Acid Regular insulin (ARI) and neutral Regular insulin (NRI) were compared in normalfasting subjects by means of a Latin-square experimental design. Both blood glucose and serum immunoreactive insulin were measured after the administration of 0.1 and 0.2 U. per kilogram intravenously, and 0.1, 0.2, and 0.3 U. per kilogram subcutaneously. No statistically significant differences were detected between ARI and NRI. Analysis of blood glucose and serum insulin data pooled from the ARI and NRI treatments disclosed resistance to increasing doses of insulin as the blood glucose fell below 50 to 60 mg. per 100 ml. Thus, relatively small increments in hypoglycemic activity occurred when the intravenous dose was doubled from 0.1 to 0.2 U. per kilogram or the subcutaneous dose increased from 0.2 to 0.3 U. per kilogram in spite of doubling the hypoglycemic effect when the subcutaneous dose was doubled from 0.1 to 0.2 U. per kilogram. In addition, for each 0.1 U. per kilogram of subcutaneouslyadministered insulin the maximum serum levels were approximately 15 to 30 μU. per milliliter andthe duration of effect was extended by one hour. Therefore, following 0.1 U. per kilogram the maximum effect was over by three hours, after 0.2 U. per kilogram by four hours, and 0.3 U. per kilogram by five hours. These results demonstrate the feasibility of studying the time action of insulin in normal subjects and document the conclusion that duration of effect is a function of the dose given.

Current trends in diabetes therapy

Abstract The first dose of insulin was administered to a diabetic patient in January 1923. Since then, although important insights into the nature of diabetes and its treatment with insulin have accrued, a method of treatment which produces continuous euglycemia for all patients has not yet been developed. Moreover, strict dietary adherence and skilful use of insulin regimens are still vital to the treatment of all insulin-requiring patients. This article will briefly review insulin treatment, including the use of human insulin and infusion devices, from the point of view of a physician with a clinical pharmacology orientation.

THE USE OF BIOSYNTHETIC HUMAN INSULIN IN MAN

Publisher Summary Insulin was the first substance to be administered as replacement therapy in a deficiency disorder—diabetes mellitus—the first peptide hormone to be sequenced, and among the first peptide hormones to be produced by recombinant technology. This chapter provides an overview of insulin, which is the first product of recombinant research to be studied extensively in clinical tests. It discusses the difficulties encountered in the radioimmunoassay (RIA) for human and pork insulin in the serum of volunteers who received these two types of insulin. The chapter also presents preliminary information on patients who never received insulin and were treated with biosynthetic human insulin (BHI) for six months. The BHI was all derived from human A and human β chain material produced by recombinant techniques combined and purified by chemical methods.