Kinetics of biosynthetic human proinsulin in patients with terminal renal insufficiency.

Eight volunteers with terminal renal insufficiency having consented to the investigation, were given an i.v. bolus administration of 40 pmol biosynthetic human proinsulin on their dialysis-free day. Intravenous blood for the determination of blood glucose proinsulin, insulin and C-peptide was collected in short intervals for 6 hours and thereafter in longer intervals for 24 hours. Proinsulin was determined by immunoradiometric assay with monoclonal antibodies. The proinsulin kinetics were compared with the kinetics of normal volunteers. The behaviour of proinsulin concentration-time is best described with a 3-compartment model. The dominant biological half-life in terminal renal insufficiency was 6.8 hours which signifies a 4.4-fold increase of the normal half-life. The distribution volumes (V1) in the central compartment do not differ in the two groups, whereas the distribution volume after complete distribution (Vss) is significantly increased in renal insufficiency. The total metabolic clearance in renal insufficiency namely 0.63 ml/kg/min is 2.6 times lower compared to normal subjects with 1.67 ml/kg/min. The extra-renal clearance is 39% of the total metabolic clearance rate, whereas the renal clearance comprises 61%. Peripheral conversion from proinsulin to insulin and C-peptide does not occur in terminal renal insufficiency. The basal endogenous proinsulin secretion rate in renal insufficiency does not differ from that of normal volunteers. The following conclusions can be drawn: 1) Hyperinsulinism observed in renal insufficiency can be explained by circulating proinsulin. 2) In the potential therapeutic use of biosynthetic human proinsulin in diabetics with renal insufficiency dosis adjustment according to the remaining renal function would probably be required.

Action profile of biosynthetic human proinsulin trials with the BIOSTATOR in metabolically normal subjects.

Studies to examine the pharmacokinetics and pharmacodynamic properties of biosynthetic human proinsulin were conducted with the aid of the "glucose-controlled insulin infusion system BIOSTATOR". Seven metabolically normal healthy volunteers were given subcutaneous injections of 0.1 mg human proinsulin per kg body weight, and the subsequent behaviour of the serum proinsulin concentration was monitored over a period of 21 hours. The drop in the blood-sugar levels was counteracted by corresponding infusions of glucose by the BIOSTATOR via a special clamp technique. The intensity and frequency of the glucose infusions given by the BIOSTATOR equipment enable us to draw conclusions regarding the hypoglycaemic efficacy of human proinsulin. Two to three hours after the subcutaneous injection, the serum proinsulin concentration had reached its plateau-like maximum value. After approximately 5 hours it had dropped to 2/3 of the maximum, and after another 3 to 4 hours it had fallen further to 1/3 of the maximum. It returned virtually to its initial value after a total of 14 to 16 hours. The dextrose infusion rate calculated by the BIOSTATOR reflects these changes in the form of an "action profile". Proinsulin has a mean transit time (MTT) of 322 minutes. This is longer than the MTT of normal insulin (188 minutes) but markedly shorter than that of NPH insulin (625 minutes). If the hypoglycaemic effects of insulin and human proinsulin are compared on the basis of the areas under their respective action profile curves, the hypoglycaemic effect of 1 mg human proinsulin corresponds to 5.2 IU insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacokinetics of biosynthetic human proinsulin following intravenous and subcutaneous administration in metabolically healthy volunteers.

40 pmol of biosynthetic human proinsulin was administered to 8 healthy volunteers by intravenous and by subcutaneous route. Following proinsulin administration, venous blood was collected in regular intervals within which proinsulin was determined by a specific radioimmunometric assay with monoclonal antibodies. The proinsulin concentration was determined simultaneously with the insulin and C-peptide radioimmunoassay. Through this investigation the following kinetic parameters were found: The kinetics of the biosynthetic human proinsulin can be best described by the 3-compartment model. The dominant biological half-life was 92 minutes. In intravenous proinsulin administration a proinsulin mean transit time of 80 minutes was found, whereas in subcutaneous administration a proinsulin retention time of 225 minutes was measured. The mean resorption velocity of the subcutaneously applied proinsulin amounted to 145 minutes. Two lag times for subcutaneous resorption can be described, a short one with 9.4 minutes and a long one with 65 minutes. The initial distribution volume for proinsulin was 3.8 l, whereas the distribution volume after complete distribution was 9.3 l. The mean total metabolic clearance was determined with 120 ml/min. Since no difference for the proinsulin concentration was found using the 3 different determination methods a peripheral proinsulin conversion to insulin and C-peptide is not likely. The basal endogenous secretion rate for proinsulin is 68.7 pmol per hour.

Insulin concentrations and time-action profiles of three different intermediate-acting insulin preparations in nondiabetic volunteers under glucose-controlled glucose infusion technique.

This study describes the pharmacokinetics of three intermediate-acting insulin preparations, NPH porcine insulin, NPH human insulin (recombinant DNA), and "Depot-A" insulin, a mixture of 20% regular and 80% NPH human insulin from Eli Lilly and Company. Metabolic healthy normal weight volunteers were selected for the study. After overnight fasting, each test person received 0.4 U of each insulin per kg body weight injected subcutaneously in the triceps area of the arm. To prevent severe hypoglycemia, the test persons were connected to a "GCIIS Biostator" with blood glucose clamp at the 60 mg/dl level. Peripheral blood was sampled at regular intervals for glucose, insulin, and C-peptide determination. More elevated insulin levels were measured after application of both NPH human insulin and "Depot-A" insulin than after NPH porcine insulin. A more rapid decrease in the blood glucose concentration was observed after injection of both human insulin preparations than after porcine insulin. The dextrose output of the "GCIIS Biostator" was more pronounced in both human insulins than after the porcine preparation. After the injection of NPH human and NPH porcine insulin, significant differences were calculated between the concentrations of these two insulins in the blood, from the 2nd to the 10th hour (P less than 0.05-P less than 0.005) and between the dextrose output of the "GCIIS Biostator" from the 3rd to the 8.5th hour (P less than 0.05). The fall of the C-peptide concentration to the lower detection limit of the assay reflects suppression of the endogenous B-cell secretion and confirms the measure of peripheral insulin concentrations as a result of the exogenously applied insulin. Although all investigations were performed under identical experimental conditions and equal dosages of each insulin were injected, higher insulin concentrations and a stronger biologic effect, shown by larger amount of dextrose delivered, were observed in both human insulins than in porcine insulin. Why this phenomenon occurs is as yet unclear. The clamp technique used with the "GCIIS Biostator" enables establishment of the biologic profile of any insulin, and thus represents a valuable tool in comparative studies.

Pharmacokinetics of biosynthetic human insulin and characteristics of its effect.

In the last 2 years we have developed a new method for determining insulin biologic activity with the help of the glucose-controlled insulin infusion system (GCIIS). Primarily this closed-loop system infuses insulin. But to prevent hypoglycemia, it can in addition, infuse glucose below a certain blood glucose minimum. This effect is used to reproduce insulin biologic activity. After subcutaneous injection of the insulin to be tested in healthy persons (not in insulin-dependent diabetic subjects), the blood glucose level falls, and this is checked by the counterregulatory glucose delivery from the apparatus. The time and intensity of glucose delivery from the GCIIS reflect the insulin effect, so that each insulin manifests its own particular biologic activity.

[Pharmacokinetics of insulin administered intraperitoneal in a bolus form (author's transl)]. / Verhalten der Insulinkonzentration im peripher-venösen Blut nach intraperitonealer Bolusgabe von Insulin.

Although carbohydrate-intake and subcutaneous insulin injection in the insulin dependent diabetics are brought to match with one another, there is often an incongruity between the momentary insulin need and the actual insulin supply, because insulin is resorbed relatively slow from the subcutaneous injection site. While the plasma insulin concentration in healthy persons after carbohydrate-intake reaches its maximum after ca. 45 min, the maximum insulin concentration after subcutaneous application of regular insulin is observed only after ca. 2 h. For this reason, we studied whether a faster rise in the insulin concentration can be obtained by intraperitoneal bolus application of insulin. 5 metabolic healthy volunteers received 20 UI regular insulin diluted in isotonic saline solution injected intraperitoneal. The insulin concentration in the peripherovenous system was examined. In order to prevent severe hypoglycaemia the test persons were connected to a Biostator (so-called artificial Beta-cell), which delivered glucose automatically when the blood glucose concentration fell below the 60 mg/dl - level, and thus avoided a drastic fall of the blood glucose. A rapid increase in the plasma insulin concentration was observed within a few minutes after the intraperitoneal bolus injection of insulin. After ca. 20 min the maximal insulin concentration was reached. Already after ca. 2 h the plasma insulin levels fell off and approached the initial values. Consequently, the changes of insulin concentration after intraperitoneal bolus application of insulin correspond widely to the insulin curve characteristic of metabolic healthy persons after carbohydrate-intake. Thus, the intraperitoneal bolus injection of insulin presents a mode of application, which must be pursued further in the treatment of insulin dependent diabetics.

Effects of low-dose gestagen (lynestrenol 0.5 mg) and combination-type oral contraception (lynestrenol 1 mg and ethinyloestradiol 0.05 mg) on blood glucose and serum insulin levels after a glucose load.

Forty 3-h oral glucose tolerance tests (OGTTs) were performed in 10 apparently healthy female volunteers aged 21--34 years, each serving four times as her own control. Each subject was taking either a low-dose gestagen contraceptive (lynestrenol 0.5 mg) or a combination-type pill (lynestrenol 1 mg + ethinyloestradiol 0.05 mg) alternatingly in four consecutive treatment cycles. Blood glucose and serum insulin did not differ significantly with either contraceptive (paired t-test).

PIP: The effects on oral glucose tolerance and serum insulin levels of gestagens alone and gestagens with added estrogen were studied im 10 healthy female volunteers. The volunteers, aged 21-34 years, were given a total of 40 3-hour oral glucose tolerance tests, so that each volunteer served as her own control. Each subject was given either lynestrenol .5 mg (low dose) or lynestrenol, 1 mg, plus ethinylestradiol, .05 mg, alternatively in 4 consecutive treatment cycles. Neither the blood glucose nor the serum insulin concentrations differed significantly with either contraceptive regimen (paired t-test results).

The influence of high doses of oral medroxyprogesterone acetate on glucose tolerance, serum insulin levels and adrenal response to ACTH. A study of 17 patients under treatment for endometrial cancer.

Seventeen women aged 55 to 76 years who had been treated for endometrial cancer by surgery or radiotherapy or a combination of both were given 300 mg of medroxyprogesterone acetate (MPA) daily by mouth. Before treatment and again during the 3rd week of treatment an oral glucose tolerance test (with measurement of serum insulin levels) and an ACTH-stimulation test were done. All blood glucose levels tended to be higher with MOA therapy and serum insulin levels were significantly increased 3 h after a glucose load. The rise of serum cortisol 30 min after ACTH-stimulation was significantly less with MPA therapy. Oral MPA thus appeared to have a glucocorticoid-like action.

[Concentration of C-peptide and insulin in serum of patients with acute virus hepatitis (author's transl)]. / C-Peptide- und Insulinkonzentration im Serum bei akuter Virushepatitis.

Intravenous glucose tolerance tests were performed in 10 patients with acute virus hepatitis. The assimilation coefficient of glucose and the level of insulin and C-peptide in serum were determined before and in the course of the glucose tolerance tests. In comparison to healthy normal weight persons C-peptide concentration in patients with acute hepatitis increased twice as high whereas the pattern of insulin secretion did not differ significantly. The higher levels of C-peptide indicate an increase of the beta-cell secretion in acute hepatitis. One could suppose an increased hepatic destruction of insulin in acute hepatitis, because there is no significant difference among the insulin levels. More likely, there is a reactive increase of secretion of the beta-cell due to a reduction of insulin sensitivity and this is indicated much better by C-peptide- than insulin levels because of the longer half live of the the C-peptide molecule.

Comparison of ethinylestradiol and mestranol in sequential-type oral contraceptives in their effects on blood glucose and serum insulin in oral glucose tolerance tests.

Forty 3-hour oral glucose tolerance tests (OGTTs) were performed in 10 assumedly healthy female volunteers 19 to 30 years old, each serving four times as her own control. Each subject was taking a sequential type oral contraceptive containing either 50 microgram of ethinylestradiol or 80 microgram of mestranol alternatingly in four consecutive treatment cycles. The OGTTs were performed on the 6th day of each cycle, during pure estrogen medication. Blood glucose and serum insulin values did not differ significantly under either estrogen as tested by the t-test for paired observations. Our results do not support the findings of others that mestranol has a more pronounced or even exclusively adverse effect on glucose tolerance as compared with ethinylestradiol.

PIP: 10 female volunteers (19-30 years) received ethinyl estradiol (EE) and mestranol (ME) in order to determine whether treatment would influence carbohydrate metabolism. EE dose was 50 mcg and ME dose was 80 mcg. In each treatment cycle the estrogenic compound was given for 7 days, followed by 15 days of combined treatment with a gestagenic compound and a treatment-free interval of 6 days during which withdrawal bleeding occurred. On the 6th day of each treatment cycle on oral glucose tolerance test (OGTT) was performed. Blood smaples were obtained every 30 minutes over 3 hours and assayed for blood glucose and for serum insulin. The differences in blood glucose levels or serum insulin between EE cycles and ME cycles were insignificant.

[Studies on the question of a possible autoregulation of insulin secretion (author's transl)]. / Untersuchungen zur Frage einer Autoregulation der Insulinsekretion.

In eight normal weight healthy volunteers it was proved by C-peptide assay whether high concentrations of insulin in serum would suppress the secretion of insulin in an autoregulative manner. Insulin combined with glucose, therefore was given intravenously as a single bolus injection as well as an infusion over a period of two hours. Moreover it was proved whether high levels of insulin would suppress the reactivity of the B-cell to sulphonylurea administration. It was demonstrated that the secretion of the B-cell is regulated only by the concentration of the blood sugar, but not by the level of serum insulin. Likewise the stimulation of the B-cell by sulphonyl-urea administration is not suppressed by high concentrations of insulin.

[Concentration of C-peptide in correlation to kidney function (author's transl)]. / C-Peptid-Konzentration im Serum in Abhängigkeit von der Nierenfunktion.

Recently, the radioimmunological determination of C-peptide came into interest because of the jugdement of the remaining function of the islet apparatus in insulin-dependent diabetics. As the degradation of C-peptide preferably takes place in the kidney we performed an intravenous glucose load in 32 patients with kidney diseases. The following results were obtained: 1. In patients with a healthy carbohydrate metabolism a clear correlation exists between the concentration of creatinine on the one hand, the creatinine-clearance and the fasting C-peptide concentration respectively the measured amount of C-peptide on the other hand. 2. The more advanced the renal insufficiency the better is the correlation between the parameter of the kidney function and the C-peptide concentration. 3. In diabetic patients there shows to be no clear correlation between the C-peptide levels and the kidney function. --In insulin-dependent diabetics the amount of C-peptide is only of diagnostic use if the renal function is well known.

[Investigations of the mode action of buformin using a 3H-labelled glucose in people with a healthy metabolism (author's transl)]. / Untersuchungen zum Wirkungsmechanismus von Buformin mit Hilfe tritiierter Glucose bei stoffwechselgesunden Personen

In a total of 13 volunteers the changes in carbohydrate metabolism was investigated after administration of prednisolone, of buformin, and of a combination of prednisolone and buformin using 3H-labelled glucose. Under steady-state-conditions the glucose-turnover was estimated. Although, the changes of glucose assimilation of labelled and unlabelled glucose was observed to see the magnitude of glucose utilisation and of gluconeogenesis. It was concluded that biguanides enhance the glucose utilisation. Depending on the glucose level at the same time the gluconeogenesis is stimulated or inhibited.

[Radioimmunological determination of insulin in patients with manifest diabetes mellitus as a guide for the planning of therapy (author's transl)]. / Radioimmunologische Seruminsulinbestimmung beim manifesten Diabetes mellitus als Parameter der Therapieplanung

Intravenous glucose tolerance test followed by combined intravenous glucose-glibenclamid tolerance test were performed to differentiate between sulfonylurea-dependent and insulin-dependent diabetics. As a criterion of sufficient sulfonylurea-induced insulin secretion the extent of the difference of the insulin secretion between both tests was taken. If the difference is more than 600/muE/h insulin treatment seems not to be necessary and oral treatment with sulfonylurea derivates seems to be successful. In comparison with the clinical course of 55 patients the criterion was right in 50 cases. 5 patients could not be classified by the clinical course. Their more-secretion of insulin was in between 200 and 550 muE/mlhour.

[Antagonistic action of prednisolone and buformin in the carbohydrate metabolism of healthy persons (author's transl)]. / Funktioneller Antagonismus von Prednisolon und Buformin auf den Kohlenhydratstoffwechsel gesunder Personen

Intravenous glucose tolerance tests were performed and changes of blood glucose and insulin concentration were measured to examine whether the diabetogenic effect of glucocorticoides can be compensated by biguanides. Seven standard weight volunteers with a healthy metabolism were given prednisolone and buformin as well as a combination of both. In spite of the reactively higher insulin secretion after treatment with prednisolone the glucose tolerance was reduced. In contrast, treatment with biguanide improved the glucose tolerance while decreasing the insulin secretion. It was nearly possible to compensate the negative effect of prednisolone on the carbohydrate metabolism by biguanides. We, therefore, consider a preventive administration of biguanides to be effective in long term or high dosage administration of glucocorticoides.

[Effect of gliquidone and glibenclamide following oral administration]. / Wirkung von Gliqudon und Glibenclamid nach oraler Anwendung

Gliquidone shows a good blood sugar lowering effect over the wide dose range of 30-60 mg in fasting subjects with a healthy metabolism, in spite of the wide range. This behavior suggests that a good therapeutic application is to be expected in diabetics being treated with sulfonylureas.