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ABSTRACT: This study was conducted to assess the suitability of insulin analogs acylated by various cholic acid derivatives for use as basal insulin, and to test the most promising of these, LysB29(Nepsilon-lithocholyl-gamma-Glu) des(B30) human insulin (NN344) in pigs.
Circular dichroism spectroscopy and size-exclusion chromatography were used to explore the physicochemical properties of the analogs, and affinities for albumin and insulin receptors were determined. After subcutaneous injection in pigs, disappearance half-times were measured, and the plasma profile and glucose-lowering effect in a euglycemic clamp were assessed for NN344.
NN344 showed glucose-lowering activity lasting more than 24 h. Glucose infusion rate was essentially constant from 5 to 19 h after injection. NN344 seemed to be a dodecamer in the presence of zinc ions and phenol. Without phenol, the apparent molecular mass was >5000 kDa. Formation of such a self-assembly at the site of s.c. injection and its subsequent slow decomposition might explain the long duration of action of NN344. A measurable affinity for albumin of the lithocholic acid ligand may also contribute to the prolonged action.
NN344 is a candidate for a neutral soluble basal insulin that might offer people with diabetes a prolonged duration, smooth, and predictable basal insulin supplement.
Pharmaceutical Research 02/2006; 23(1):49-55. · 4.74 Impact Factor
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ABSTRACT: NN304 [Lys(B29)-tetradecanoyl des(B30) human insulin] is a potentially therapeutic insulin analog designed to exhibit protracted glucose-lowering action. In dogs with infusion rates similar to insulin itself, NN304 exhibits similar glucose uptake (R(d)) stimulation with delayed onset of action. This compartmental modeling study was to determine if NN304 action could be accounted for by the approximately 2% unbound NN304 concentration. NN304 (or human insulin) (n = 6 each) was infused at 10.2 pmol center dot min(-1) center dot kg(-1) under euglycemic clamp conditions in anesthetized dogs. NN304 appearance in lymph, representing interstitial fluid (ISF), was slow compared with insulin (t(1/2) = 70 +/- 7 vs. 14 +/- 1 min, P < 0.001). R(d) was highly correlated with the ISF concentration for insulin and NN304 (r = 0.86 and 0.93, respectively), suggesting that slow transendothelial transport (TET) is responsible for sluggish NN304 action. Insulin and NN304 concentration data were fit to a two-compartment (plasma and ISF) model. NN304 plasma elimination and TET were reduced to 10 and 7% of insulin, respectively. Thus, there was reduction of NN304 transport, but not to the degree expected. In ISF, there was no reduction in NN304 elimination. Thus, this acylated insulin analog demonstrates blunted kinetics in plasma, and full efficacy in the compartment of action, ISF.
Diabetes 04/2002; 51(3):762-9. · 7.90 Impact Factor
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ABSTRACT: A defect in transcapillary transport of insulin in skeletal muscle and adipose tissue has been proposed to play a role in the insulin resistance that leads to type 2 diabetes, yet the mechanism of insulin transfer across the capillary endothelium from plasma to interstitium continues to be debated. This study examined in vivo the interstitial appearance of insulin in hindlimb using the fatty acid acylated insulin analog Lys(B29)-tetradecanoyl des-(B30) human insulin, or NN304, as a marker for insulin transport. If the insulin transport were a saturable process, then "swamping" the capillary endothelial insulin receptors with native insulin would suppress the subsequent appearance in interstitial fluid of the insulin analog NN304. This analog binds to insulin receptors with an affinity of about 50% of native insulin. Experimental conditions established a physiologic NN304 dose in the absence or presence of pharmacologic and saturating concentrations of regular human insulin. Euglycemic clamps were performed in dogs under inhalant anesthesia with deep hindlimb lymphatic sampling, representative of skeletal muscle interstitial fluid (ISF). In group 1 (n = 8), NN304 alone was infused (3.6 pmol center dot min(-1) center dot kg(-1)) from 60 to 360 min. In group 2 (n = 6), starting at time 0, human insulin was infused at a pharmacologic dose (60 pmol center dot min(-1) center dot kg(-1)) with the addition of NN304 infusion (3.6 pmol center dot min(-1) center dot kg(-1)) from 60 to 360 min. In group 3 (n = 4), the human insulin infusion was increased to a saturating dose (120 pmol center dot min(-1) center dot kg(-1)). Pharmacologic insulin infusion (group 2) established steady-state human insulin concentrations of 6,300 plus minus 510 pmol/l in plasma and 5,300 plus minus 540 pmol/l in ISF. Saturating insulin infusion (group 3) achieved steady-state human insulin concentrations of 22,000 plus minus 1,800 pmol/l in plasma and 19,000 plus minus 1,500 pmol/l in ISF. Total (bound and unbound) NN304 plasma concentrations rose from a steady state of 1,900 plus minus 110 (group 1) to 2,400 plus minus 200 pmol/l (group 2) and 3,100 plus minus 580 pmol/l (group 3), consistent with a competition-driven decline in NN304 clearance from plasma as the human insulin level increased (P < 0.05 by ANOVA). Steady-state interstitial NN304 concentrations also rose with increasing human insulin levels but did not achieve significance in comparison with analog alone (162 plus minus 15 vs. 196 plus minus 22 and 241 plus minus 53 pmol/l for group 1 versus groups 2 and 3, respectively; P = 0.20), yet the steady-state plasma:ISF ratio for NN304 remained essentially unchanged in the absence and presence of elevated human insulin levels (12.6 plus minus 1.2 vs. 12.4 plus minus 0.5 and 13.1 plus minus 1.5 for group 1 versus groups 2 and 3, respectively; P = 0.93). Last, NN304 rate of appearance in interstitial fluid (i.e., half-time to steady state) was similar between groups; mean half-time of 92 plus minus 4 min (NS between groups). In conclusion, appearance of the insulin analog NN304 in skeletal muscle interstitial fluid was constant whether in the absence or presence of human insulin concentrations sufficient to saturate the endothelial insulin receptors. These findings support the hypothesis, provided that the mechanism of insulin and NN304 transcapillary transport is similar, that transcapillary transport of insulin in skeletal muscle occurs primarily via a nonsaturable process such as passive diffusion via a paracellular or transcellular route.
Diabetes 04/2002; 51(3):574-82. · 7.90 Impact Factor
Diabetes Research and Clinical Practice - DIABETES RES CLIN PRACT. 01/2000; 50:81-81.