Optimization of pig models for translation of subcutaneous pharmacokinetics of therapeutic proteins: Liraglutide, insulin aspart and insulin detemir

Prediction of human pharmacokinetics (PK) from data obtained in animal studies is essential in drug development. Here, we present a thorough examination of how to achieve good pharmacokinetic data from the pig model for translational purposes by using single-species allometric scaling for selected therapeutic proteins: liraglutide, insulin aspart and insulin detemir. The predictions were based on non-compartmental analysis of intravenous and subcutaneous PK data obtained from two injection regions (neck, thigh) in two pig breeds, domestic pig and Göttingen Minipig, that were compared with PK parameters reported in humans. The effects of pig breed, injection site and injection depth (insulin aspart only) on the PK of these proteins were also assessed. Results show that the prediction error for human PK was within two-fold for most PK parameters in both pig breeds. Furthermore, pig breed significantly influenced the plasma half-life and mean absorption time (MAT), both being longer in Göttingen Minipigs compared to domestic pigs (P <0.01). In both breeds, thigh vs neck dosing was associated with a higher dose-normalized maximum plasma concentration and area under the curve as well as shorter MAT and plasma half-life (P <0.01). Finally, more superficial injections resulted in faster absorption, higher C_max/dose and bioavailability of insulin aspart (P <0.05, 3.0 vs 5.0 mm injection depth). In conclusion, pig breed and injection region affected the PK of liraglutide, insulin aspart and insulin detemir and reliable predictions of human PK were demonstrated when applying single-species allometric scaling with the pig as a pre-clinical animal model.

A subcutaneous insulin pharmacokinetic model for insulin Detemir

BACKGROUND AND OBJECTIVE

Type 2 diabetes (T2D) is rapidly increasing in incidence and has significant social and economic costs. Given the increasing cost of complications, even relatively short delays in the onset of T2D can significantly reduce long-term complications and costs. Equally, recent studies have shown the onset of T2D can be delayed by use of long-acting insulin, despite the risk and concomitant low adherence. Thus, there is a strong potential motivation to develop models of long-acting insulin analogues to enable safe, effective use in model-based dosing systems. In particular, there are no current models of long-acting insulin Detemir and its unique action for model-based control. The objective of this work is to develop a first model of insulin Detemir and its unique action, and validate it against existing data in the literature.

METHODS

This study develops a detailed compartment model for insulin Detemir. Model specific parameters are identified using data from a range of published clinical studies on the pharmacokinetic of insulin Detemir. Model validity and robustness are assessed by identifying the model for each study and using average identified parameters over several dose sizes and study cohorts. Comparisons to peak concentration, time of peak concentration and overall error versus measured plasma concentrations are used to assess model accuracy and validity.

RESULTS

Almost all studies and cohorts fit literature data to within one standard deviation of error, even when using averaged identified model parameters. However, there appears to be a noticeable dose dependent dynamic not included in this first model, nor reported in the literature studies.

CONCLUSIONS

A first model of insulin Detemir including its unique albumin binding kinetics is derived and provisionally validated against clinical pharmacokinetic data. The pharmacokinetic curves are suitable for model-based control and general enough for use. While there are limitations in the studies used for validation that prevent a more complete understanding, the results provide an effective first model and justify the design and implementation of further, more precise human trials.

Comparison of the dose-response pharmacodynamic profiles of detemir and glargine in severely obese patients with type 2 diabetes: A single-blind, randomised cross-over trial

Background

Despite their widespread use in this population, data on the pharmacodynamic (PD) properties of the insulin analogs detemir and glargine in severely obese patients with type 2 diabetes are lacking.

Methods

The primary objective of the study was to compare the PD properties of two different doses of the basal insulin analogs detemir and glargine in patients with type 2 diabetes and a BMI > 35 kg/m². PD data were derived from euglycemic clamp studies over 30 hours and each subject was studied for four times after the subcutaneous injection of a lower (0.8 U/kg body weight) and higher (1.6 U/kg body weight) dose of both detemir and glargine using a single-blind, randomised cross-over design.

Results

Six male and four female patients with type 2 diabetes and a mean BMI of 43.2±5.1 kg/m² (mean age 55.7±2 years, mean HbA1c 7.2±0.3%) completed the study. The total GIR_AUC0-30 (mean difference 1224 mg/kg, 95%CI 810–1637, p = 0.00001), GIR_AUC0-24 (mean difference 1040 mg/kg, 95%CI 657–1423; p = 0.00001), GIR_AUC24-30 (mean difference 181 mg/kg, 95%CI 64–298; p = 0.004), GIR_max (mean difference 0.93 mg/kg/min, 95%CI 0.22–1.64, p = 0.01) and time to GIR_max (+1.9 hours, 95%CI 0.5–3.2; p = 0.009) were higher after the higher doses of both insulins, without significant differences between detemir and glargine. However, during the last 6 hours of the clamp the GIR_AUC24-30 was significantly increased with glargine (mean difference 122 mg/kg, 95%CI 6–237, p = 0.043), reflecting a more pronounced late glucose lowering effect.

Conclusions

A clear dose-response relationship can be demonstrated for both insulin analogs, even at very high doses in severely obese patients with type 2 diabetes. Compared to detemir, glargine has a more pronounced late glucose lowering effect 24–30 h after its injection.

Trial registration

Controlled-Trials.comISRCTN57547229.

Pharmacodynamics and pharmacokinetics of insulin detemir and insulin glargine 300 U/mL in healthy dogs

Insulin glargine 300 U/mL and insulin detemir are synthetic long-acting insulin analogs associated with minimal day-to-day variability or episodes of hypoglycemia in people. Here, 8 healthy purpose-bred dogs each received 2.4 nmol/kg subcutaneous injections of insulin detemir (0.1 U/kg) and insulin glargine 300 U/mL (0.4 U/kg) on 2 different days, >1 wk apart, in random order. Blood glucose (BG) was measured every 5 min, and glucose was administered intravenously at a variable rate with the goal of maintaining BG within 10% of baseline BG ("isoglycemic clamp"). Endogenous and exogenous insulin were measured for up to 24 h after insulin injection. The effect of exogenous insulin was defined by glucose infusion rate or a decline in endogenous insulin. Isoglycemic clamps were generated in all 8 dogs after detemir but only in 4 dogs after glargine. Median time to onset of action was delayed with glargine compared to detemir (4.0 h [3.3-5.8 h] vs 0.6 h [0.6-1.2 h], P = 0.002). There was no difference in time to peak (median [range] = 6.3 h [5.0-21.3 h] vs 4.3 h [2.9-7.4 h], P = 0.15) or duration of action (16.3 h [6.1-20.1 h] vs 10.8 h [8.8-14.8 h], P = 0.21) between glargine and detemir, respectively. Glargine demonstrated a peakless time-action profile in 4/8 dogs. The total metabolic effect and peak action of detemir was significantly greater than glargine. Significant concentrations of glargine were detected in all but 1 dog following administration. Glargine might be better suited than detemir as a once-daily insulin formulation in some dogs based on its long duration of action and peakless time-action profile. Day-to-day variability in insulin action should be further assessed for both formulations.

Bioavailability of insulin detemir and human insulin at the level of peripheral interstitial fluid in humans, assessed by open-flow microperfusion

AIMS

To find an explanation for the lower potency of insulin detemir observed in humans compared with unmodified human insulin by investigating insulin detemir and human insulin concentrations directly at the level of peripheral insulin-sensitive tissues in humans in vivo.

METHODS

Euglycaemic-hyperinsulinaemic clamp experiments were performed in healthy volunteers. Human insulin was administered i.v. at 6 pmol/kg/min and insulin detemir at 60 pmol/kg/min, achieving a comparable steady-state pharmacodynamic action. In addition, insulin detemir was doubled to 120 pmol/kg/min. Minimally invasive open-flow microperfusion (OFM) sampling methodology was combined with inulin calibration to quantify human insulin and insulin detemir in the interstitial fluid (ISF) of subcutaneous adipose and skeletal muscle tissue.

RESULTS

The human insulin concentration in the ISF was ∼115 pmol/l or ∼30% of the serum concentration, whereas the insulin detemir concentration in the ISF was ∼680 pmol/l or ∼2% of the serum concentration. The molar insulin detemir interstitial concentration was five to six times higher than the human insulin interstitial concentration and metabolic clearance of insulin detemir from serum was substantially reduced compared with human insulin.

CONCLUSIONS

OFM proved useful for target tissue measurements of human insulin and the analogue insulin detemir. Our tissue data confirm a highly effective retention of insulin detemir in the vascular compartment. The higher insulin detemir relative to human insulin tissue concentrations at comparable pharmacodynamics, however, indicate that the lower potency of insulin detemir in humans is attributable to a reduced effect in peripheral insulin-sensitive tissues and is consistent with the reduced in vitro receptor affinity.