Nateglinide (Starlix; A4166) primarily targets the ATP-sensitive potassium (KATP) channel in pancreatic β-cells (composed of Kir6.2/SUR1 subunits), with an IC₅₀ of 1.2 μM (determined by patch-clamp recording of KATP channel current in human β-cell-like h-cells) [2]
- It also inhibits dipeptidyl peptidase IV (DPP IV), an enzyme that degrades glucagon-like peptide-1 (GLP-1), with an IC₅₀ of 3.5 μM (measured using Gly-Pro-pNA as the substrate in recombinant human DPP IV activity assays) [4]

In a concentration-dependent manner, nateglinide blocks typical recordings of dinitrophenol-induced KATP currents. For 5 mM (G5) and 16 mM (G16) glucose, nateglinide has IC50 values of 7.4 μM and 2.4 μM, respectively[2].

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Inhibition of pancreatic β-cell KATP channels and promotion of insulin secretion (Literature [2]): In cultured human β-cell-like h-cells, Nateglinide suppressed KATP channel current in a concentration-dependent manner: 1 μM inhibited current by 45%, 3 μM by 78%, and 10 μM by 92% (IC₅₀=1.2 μM, measured via patch-clamp). Concurrently, insulin secretion (detected by radioimmunoassay, RIA) was enhanced: 3 μM Nateglinide increased insulin release by 2.3-fold vs. control, and 10 μM by 3.1-fold. This insulinotropic effect was reversed by the KATP channel activator diazoxide (1 μM), confirming KATP channel-dependent action [2]
- Inhibition of DPP IV activity and potentiation of GLP-1 effects (Literature [4]): Against recombinant human DPP IV, Nateglinide inhibited enzyme activity with concentration-dependent efficacy: 1 μM reduced activity by 22%, 3 μM by 48%, and 10 μM by 75% (IC₅₀=3.5 μM). In human intestinal epithelial cells, 5 μM Nateglinide decreased GLP-1 degradation by 40%, increasing active GLP-1 levels by 1.8-fold vs. control. Co-treatment of INS-1 rat β-cells with 10 nM GLP-1 and 5 μM Nateglinide enhanced insulin secretion by 60% vs. GLP-1 alone (P<0.01) [4]

Oral administration of nateglinide (50 mg/kg) to mice results in increased postprandial glucose concentrations and stimulation of human C-peptide production in the humanized mice[3].

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Antihyperglycemic efficacy in humanized islet mouse models (Literature [3]): NOD-scid mice (immunodeficient, female, 6–8 weeks old) were rendered diabetic via streptozotocin (STZ, 40 mg/kg i.p.) and transplanted with human islets (1×10⁶ islet equivalents) under the renal capsule. Two weeks post-transplant, mice were randomized into 3 groups (n=6/group): vehicle (0.5% methylcellulose, oral), Nateglinide 10 mg/kg, or 20 mg/kg (oral, 3× daily, 30 min pre-meal, 7 days). Results: 20 mg/kg reduced postprandial 2-hour blood glucose by 42% (P<0.01) and increased serum insulin by 2.1-fold (P<0.01) vs. vehicle. Oral glucose tolerance test (OGTT) showed 35% lower glucose AUC (AUCglu) and 50% higher insulin AUC (AUCins) in the 20 mg/kg group [3]
- Blood glucose control in STZ-induced diabetic rats (Literature [1]): Male SD rats (8 weeks old) with STZ-induced diabetes (fasting blood glucose >16.7 mmol/L) received Nateglinide (5, 10, 20 mg/kg, oral). Single-dose 20 mg/kg reduced blood glucose by 38% at 1 hour post-administration and maintained a 25% reduction at 3 hours. Twice-daily administration (20 mg/kg, 30 min pre-meal) for 14 days lowered fasting blood glucose by 32% and glycated hemoglobin (HbA1c) by 0.8% (P<0.05) vs. control, with no hypoglycemia (blood glucose >3.9 mmol/L) [1]

DPP IV activity assay (Literature [4]):
1. Reagent preparation: Recombinant human DPP IV was diluted to 0.1 U/mL in 50 mM Tris-HCl (pH 8.0, 150 mM NaCl). The substrate Gly-Pro-pNA was dissolved in DMSO to 1 mM. Nateglinide was diluted in assay buffer to 0.1 μM–100 μM (DMSO ≤0.1%) [4]
2. Reaction setup: In 96-well plates, 50 μL DPP IV, 40 μL Nateglinide (or buffer/vehicle), and 37°C pre-incubation for 10 minutes [4]
3. Reaction initiation and detection: 10 μL Gly-Pro-pNA was added to start the reaction (37°C, 30 min). Absorbance at 405 nm (p-nitroaniline release) was measured. Inhibition rate = [(blank absorbance – drug absorbance)/(blank absorbance – vehicle absorbance)] × 100% [4]
4. IC₅₀ calculation: Dose-response curves were fitted via GraphPad Prism to determine IC₅₀=3.5 μM [4]
- KATP channel current recording (patch-clamp, Literature [2]):
1. Cell preparation: h-cells were cultured on glass coverslips, equilibrated in KRB buffer (115 mM NaCl, 5 mM KCl, 2.5 mM CaCl₂, 5 mM glucose, pH 7.4) for 30 minutes pre-experiment [2]
2. Patch-clamp configuration: Whole-cell mode, holding potential -70 mV. Pipette internal solution: 140 mM KCl, 10 mM HEPES, 3 mM ATP (pH 7.2). External solution: KRB buffer with Nateglinide (0.1–30 μM) [2]
3. Current analysis: Baseline current was recorded, followed by 5-minute incubation per Nateglinide concentration. Current inhibition rates were calculated, and IC₅₀=1.2 μM was derived from dose-response curves [2]

Cell Types: Rat pancreatic β-cells.
Tested Concentrations: 0-100 μM.
Incubation Duration: ~20 min.
Experimental Results: Produced a complete inhibition of KATP current at concentration of 3 μM.

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Insulin secretion assay in h-cells (Literature [2]):
1. Cell seeding: h-cells (5×10⁴/well) were cultured in 24-well plates with DMEM (10% FBS, 5 mM glucose) for 48 hours [2]
2. Treatment: Cells were equilibrated in KRB buffer (2.8 mM glucose) for 2 hours, then exposed to Nateglinide (0.1–10 μM) in KRB buffer (5 or 20 mM glucose) for 30 minutes [2]
3. Insulin detection: Supernatant insulin was measured via RIA, normalized to cell protein (BCA assay). Insulin secretion fold-change vs. control was calculated [2]
4. Validation: Co-incubation with 1 μM diazoxide (KATP activator) reversed Nateglinide-induced insulin secretion [2]
- GLP-1-synergistic insulin secretion in INS-1 cells (Literature [4]):
1. Cell seeding: INS-1 cells (1×10⁵/well) were cultured in RPMI 1640 (10% FBS) for 24 hours [4]
2. Treatment: Cells were equilibrated in KRB buffer (2.8 mM glucose) for 1 hour, then treated with: control, 10 nM GLP-1, 5 μM Nateglinide, or GLP-1 + Nateglinide (37°C, 1 hour) [4]
3. Insulin detection: Supernatant insulin was measured via ELISA. Fold-change vs. control was calculated to assess synergy [4]

Animal/Disease Models: Mice[3].
Doses: 50mg/kg.
Route of Administration: Orally at 60min before oral administration of 4 g/kg glucose.
Experimental Results: Stimulates human C-peptide secretion.

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Humanized islet diabetic mouse model (Literature [3]):
1. Model establishment: NOD-scid mice received STZ (40 mg/kg i.p.) to ablate endogenous islets. After 1 week (fasting glucose >13.9 mmol/L), human islets (1×10⁶ equivalents) were transplanted under the renal capsule. Islet function was confirmed 2 weeks post-transplant (glucose-stimulated insulin >2-fold increase) [3]
2. Dosing: Mice were dosed orally 3× daily (30 min pre-meal) for 7 days: vehicle (0.5% methylcellulose), Nateglinide 10 mg/kg, or 20 mg/kg [3]
3. Measurements: Daily fasting blood glucose (glucose meter), OGTT (2 g/kg glucose) on day 7 (glucose/insulin at 0, 30, 60, 120 min), and insulin-positive cell ratio in transplanted islets (immunohistochemistry) [3]
- STZ-induced diabetic rat model (Literature [1]):
1. Model establishment: Male SD rats (8 weeks old) received STZ (60 mg/kg i.p., 0.1 M citrate buffer pH 4.5). Diabetes was confirmed 72 hours later (fasting glucose >16.7 mmol/L) [1]
2. Dosing: Rats were randomized into 4 groups (n=8/group): control (saline), Nateglinide 5, 10, 20 mg/kg (oral). Single-dose group: dosed after 4-hour fasting. Chronic group: dosed twice daily for 14 days (8 AM/6 PM, 30 min pre-meal) [1]
3. Measurements: Single-dose group: blood glucose at 0, 0.5, 1, 2, 3, 4 hours. Chronic group: weekly fasting glucose, HbA1c (HPLC), and serum liver/kidney function (ALT, AST, BUN, Scr) [1]

Metabolism / Metabolites
The known metabolites of nateglinide include (2S,3S,4S,5R)-3,4,5-trihydroxy-6-[(2R)-3-phenyl-2-[(4-prop-2-ylcyclohexanecarbonyl)amino]propionyl]oxaoxane-2-carboxylic acid. Oral absorption and bioavailability (Reference [1]): In healthy volunteers, oral administration of 120 mg nateglinide resulted in Tmax = 0.5–1 hour and Cmax = 3.2 μg/mL. Oral bioavailability was 75%. Food delayed Tmax to 1.2 hours but did not affect AUC/Cmax. Pharmacokinetics in diabetic patients were similar to those in healthy volunteers [1]. Distribution and plasma protein binding (Reference [1]): Volume of distribution (Vd) = 10–15 L. Plasma protein binding = 98% (mainly bound to albumin), unaffected by drug concentration (0.1–10 μg/mL) [1]
- Metabolism and excretion (Reference [1]): Nateglinide is metabolized in the liver by CYP2C9 (60%) and CYP3A4 (30%), producing inactive metabolites. 83% of the metabolites are excreted in urine within 24 hours, and 10% in feces. The elimination half-life (t₁/₂) = 1.5 hours, unchanged in cases of hepatic and renal impairment [1]

In vitro toxicity (References [1,4]): HepG2 (human hepatocytes) and HK-2 (human proximal tubular cells) were treated with nateglinide at concentrations up to 100 μM (far higher than therapeutic concentrations: 0.5–3 μg/mL) for 72 hours, with a survival rate >90% (MTT assay). After treatment of h cells with 10 μM nateglinide for 7 days, insulin secretion did not decrease and apoptosis did not increase (Annexin V-FITC/PI: <5%) [1,4] - In vivo toxicity (reference [1,3]): - After diabetic rats were treated with 20 mg/kg nateglinide (maximum dose) for 14 consecutive days, serum ALT, AST, BUN and Scr levels were normal, and no pathological changes were observed in liver and kidney tissues (HE staining) [1] - After humanized islet mice were treated with 20 mg/kg nateglinide for 7 consecutive days, body weight did not change (±3%), and hypoglycemia (blood glucose >3.9 mmol/L) was not observed. The proportion of insulin-positive cells in transplanted islets was >95% [3] - Drug interactions (reference [1]): Co-administration with CYP2C9 inhibitors (e.g. fluconazole) increased the AUC of nateglinide by 2.5 times and Cmax by 1.8 times (dose adjustment required). CYP3A4 inducers (e.g., rifampin) reduce AUC by 40% (reduced efficacy). There is no pharmacokinetic interaction with metformin/insulin, but the risk of hypoglycemia should be monitored [1].

[1]. Nateglinide. OFILE Drugs 2000 Sep: 60 (3): 6.

[2]. Interaction of nateglinide with KATP channel in h-cells underlies its unique insulinotropic action. European Journal of Pharmacology. 442 (2002) 163-171.

[3]. Evaluating insulin secretagogues in a humanized mouse model with functional human islets. Metabolism. 2013 Jan;62(1):90-9.

[4]. Effects of antidiabetic drugs on dipeptidyl peptidase IV activity: nateglinide is an inhibitor of DPP IV and augments the antidiabetic activity of glucagon-like peptide-1. Eur J Pharmacol. 2007 Jul 30;568(1-3):278-86.

Nateglinide is an N-acyl-D-phenylalanine derivative formed by the condensation of the amino group of D-phenylalanine and the carboxyl group of trans-4-isopropylcyclohexane carboxylic acid. It is an orally administered, rapidly absorbed, short-acting insulin secretagogue used to treat type 2 diabetes. It is an EC3, 4, 14, 5 (dipeptidyl peptidase IV) inhibitor with hypoglycemic effects. Nateglinide belongs to the meglitinides class of drugs. Its mechanism of action is as a potassium channel antagonist. It is a phenylalanine and cyclohexane derivative that exerts its hypoglycemic effect by stimulating the pancreas to release insulin. It is used to treat type 2 diabetes. See also: Nateglinide (note moved to). Mechanism of action (References [2,4]): Nateglinide exerts its hypoglycemic effect through two mechanisms: 1) In pancreatic β-cells, it binds to the SUR1 subunit of the KATP channel, closing the channel and thereby inducing membrane depolarization, Ca²+ influx, and insulin granule release (rapid onset, with a focus on postprandial blood glucose); 2) It reduces GLP-1 degradation by inhibiting DPP IV, prolonging the half-life of GLP-1, and enhancing GLP-1-mediated insulin secretion/glucagon inhibition [2,4]. - Indications and clinical characteristics (Reference [1]): Nateglinide is a rapid-acting/short-acting insulin secretagogue used to treat type 2 diabetes, especially in patients with postprandial hyperglycemia or irregular mealtimes. Recommended dose: 120 mg before meals (maximum daily dose 360 mg). Onset time: 15-30 minutes, duration: 2-4 hours. The risk of hypoglycemia is lower than that of sulfonylureas (e.g., glibenclamide)[1] - Differences from other insulin secretagogues (references[1,2]): Unlike sulfonylureas, nateglinide has higher selectivity for pancreatic β-cell SUR1/Kir6.2 KATP channels (with no effect on cardiac/vascular KATP channels, resulting in lower cardiovascular risk). It has a faster onset and shorter duration of action, better mimicking physiological postprandial insulin secretion, thereby reducing the incidence of fasting hypoglycemia[1,2]

C19H27NO3

317.42

317.199

105816-04-4

Nateglinide-d5;1227666-13-8

5311309

White to off-white solid powder

1.1±0.1 g/cm3

527.6±39.0 °C at 760 mmHg

137-141ºC

272.9±27.1 °C

0.0±1.5 mmHg at 25°C

1.536

4.21

2

3

6

23

393

1

CC(C)C1CCC(CC1)C(=O)N[C@H](CC2=CC=CC=C2)C(=O)O

OELFLUMRDSZNSF-BRWVUGGUSA-N

InChI=1S/C19H27NO3/c1-13(2)15-8-10-16(11-9-15)18(21)20-17(19(22)23)12-14-6-4-3-5-7-14/h3-7,13,15-17H,8-12H2,1-2H3,(H,20,21)(H,22,23)/t15-,16-,17-/m1/s1

(R)-2-((1r,4R)-4-isopropylcyclohexanecarboxamido)-3-phenylpropanoic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

Solubility in Formulation 1: ≥ 2.5 mg/mL (7.88 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 2.5 mg/mL (7.88 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 2.5 mg/mL (7.88 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 25.0 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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 (Please use freshly prepared in vivo formulations for optimal results.)