Glucose-dependent insulin nutritive polypeptide (GIP)
Glucagon-like peptide-1 (GLP-1) receptor

核心概念
¹³C和¹⁵N是自然界中存在的稳定同位素，没有放射性。将它们标记在目标分子（如药物、代谢物）上，相当于为分子提供了一个独特的“身份证”或“追踪器”。这个追踪器在化学性质上与原分子几乎完全一致，但其微小的质量差异可以被质谱仪等精密仪器精确识别和区分。这使得研究人员能够在复杂的生物体系中，精准地追踪目标分子的去向、转化并进行定量。

主要用途
1. 药代动力学研究
这是最核心的用途之一。通过给实验动物或人体使用标记药物，研究人员可以系统性、高精度地研究药物在体内的“一生”，即其吸收、分布、代谢和排泄的全过程。这有助于确定药物的靶向性、在血液和组织中的浓度变化、半衰期以及最终的清除途径，为新药研发和临床用药方案的制定提供关键数据。
2. 代谢组学与代谢通路研究
在代谢研究中，标记物被用作示踪剂。通过追踪¹³C或¹⁵N原子在生物体内复杂代谢网络（如糖代谢、脂代谢、氨基酸代谢）中的流向和转化过程，可以清晰地揭示特定分子的代谢命运，以及药物干预如何影响这些代谢通路。这对于理解药物的作用机理和潜在的副作用至关重要。
3. 生物样本的定量分析（作为内标物）
在利用质谱技术对复杂生物样本（如血浆、尿液、组织）中的药物或其代谢物进行定量时，最大的挑战是样本基质干扰和分析过程的误差。将已知量的¹³C/¹⁵N标记物（作为内标）添加到待测样本中，由于标记物与待测物性质高度一致但可被质谱区分，它们会经历完全相同的处理流程。通过比较两者的信号强度，可以极其精准地计算出待测物的绝对浓度，是目前最可靠的定量方法。
4. 蛋白质组学研究
在蛋白质定量分析中，¹³C/¹⁵N标记的肽段是核心技术工具。例如，在“绝对定量”技术中，合成的标记肽段作为精确已知浓度的内标。更广泛地，在“稳定同位素标记培养”等技术中，通过比较标记样本与未标记样本中蛋白质或肽段的质谱信号比例，可以大规模、高通量地研究不同生理或病理状态下蛋白质表达量的变化，用于发现疾病生物标志物或研究药物作用靶点。

技术总结
总而言之，¹³C和¹⁵N稳定同位素标记是一项强大的平台性技术。其核心价值在于示踪与精确定量。对于像替尔泊肽这样的多肽药物，合成其¹³C,¹⁵N标记版本，主要就是为了在前沿的代谢、药代动力学和定量分析研究中，实现对药物分子行为最清晰、最可靠的揭示。

[1]. Efficacy and safety of LY3298176, a novel dual GIP and GLP-1 receptor agonist, in patients with type 2 diabetes: a randomised, placebo-controlled and active comparator-controlled phase 2 trial. Lancet. 2018 Nov 17;392(10160):2180-2193.
[2]. Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist. JCI Insight. 2020 Sep 3; 5(17): e140532.
[3]. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept. Mol Metab. 2018 Dec:18:3-14.
[4]. Tirzepatide ameliorates spatial learning and memory impairment through modulation of aberrant insulin resistance and inflammation response in diabetic rats. Front Pharmacol. 2023 Aug 28;14:1146960.

Pharmacodynamics
Tirzepatide is a synthetic peptide with glucose-lowering effects. It works to stimulate first- and second-phase insulin secretion, and reduces glucagon levels, both in a glucose-dependent manner. Tirzepatide was also shown to delay gastric emptying, lower fasting and postprandial glucose concentration, decrease food intake, and reduce body weight in patients with type 2 diabetes. Tirzepatide can increase insulin sensitivity. As the peptide is conjugated to a C20 fatty diacid moiety through a hydrophilic linker at the lysine residue at position 20, the drug is highly bound to albumin in the plasma, which prolongs its half-life.\n

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\nBackground: LY3298176 is a novel dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist that is being developed for the treatment of type 2 diabetes. We aimed to examine the efficacy and safety of co-stimulation of the GLP-1 and GIP receptors with LY3298176 compared with placebo or selective stimulation of GLP-1 receptors with dulaglutide in patients with poorly controlled type 2 diabetes.\n\nMethods: In this double-blind, randomised, phase 2 study, patients with type 2 diabetes were randomly assigned (1:1:1:1:1:1) to receive either once-weekly subcutaneous LY3298176 (1 mg, 5 mg, 10 mg, or 15 mg), dulaglutide (1·5 mg), or placebo for 26 weeks. Assignment was stratified by baseline glycated haemoglobin A1c (HbA1c), metformin use, and body-mass index (BMI). Eligible participants (aged 18-75) had type 2 diabetes for at least 6 months (HbA1c 7·0-10·5%, inclusive), that was inadequately controlled with diet and exercise alone or with stable metformin therapy, and a BMI of 23-50 kg/m2. The primary efficacy outcome was change in HbA1c from baseline to 26 weeks in the modified intention-to-treat (mITT) population (all patients who received at least one dose of study drug and had at least one postbaseline measurement of any outcome). Secondary endpoints, measured in the mITT on treatment dataset, were change in HbA1c from baseline to 12 weeks; change in mean bodyweight, fasting plasma glucose, waist circumference, total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides, and proportion of patients reaching the HbA1c target (≤6·5% and <7·0%) from baseline to weeks 12 and 26; and proportion of patients with at least 5% and 10% bodyweight loss from baseline to 26 weeks. This study is registered with ClinicalTrials.gov, number NCT03131687.\n\nFindings: Between May 24, 2017, and March 28, 2018, 555 participants were assessed for eligibility, of whom 318 were randomly assigned to one of the six treatment groups. Because two participants did not receive treatment, the modified intention-to-treat and safety populations included 316 participants. 258 (81·7%) participants completed 26 weeks of treatment, and 283 (89·6%) completed the study. At baseline, mean age was 57 years (SD 9), BMI was 32·6 kg/m2 (5·9), duration from diagnosis of diabetes was 9 years (6), HbA1c was 8·1% (1·0), 53% of patients were men, and 47% were women. At 26 weeks, the effect of LY3298176 on change in HbA1c was dose-dependent and did not plateau. Mean changes from baseline in HbA1c with LY3298176 were -1·06% for 1 mg, -1·73% for 5 mg, -1·89% for 10 mg, and -1·94% for 15 mg, compared with -0·06% for placebo (posterior mean differences [80% credible set] vs placebo: -1·00% [-1·22 to -0·79] for 1 mg, -1·67% [-1·88 to -1·46] for 5 mg, -1·83% [-2·04 to -1·61] for 10 mg, and -1·89% [-2·11 to -1·67] for 15 mg). Compared with dulaglutide (-1·21%) the posterior mean differences (80% credible set) for change in HbA1c from baseline to 26 weeks with the LY3298176 doses were 0·15% (-0·08 to 0·38) for 1 mg, -0·52% (-0·72 to -0·31) for 5 mg, -0·67% (-0·89 to -0·46) for 10 mg, and -0·73% (-0·95 to -0·52) for 15 mg. At 26 weeks, 33-90% of patients treated with LY3298176 achieved the HbA1c target of less than 7·0% (vs 52% with dulaglutide, 12% with placebo) and 15-82% achieved the HbA1c target of at least 6·5% (vs 39% with dulaglutide, 2% with placebo). Changes in fasting plasma glucose ranged from -0·4 mmol/L to -3·4 mmol/L for LY3298176 (vs 0·9 mmol/L for placebo, -1·2 mmol/L for dulaglutide). Changes in mean bodyweight ranged from -0·9 kg to -11·3 kg for LY3298176 (vs -0·4 kg for placebo, -2·7 kg for dulaglutide). At 26 weeks, 14-71% of those treated with LY3298176 achieved the weight loss target of at least 5% (vs 22% with dulaglutide, 0% with placebo) and 6-39% achieved the weight loss target of at least 10% (vs 9% with dulaglutide, 0% with placebo). Changes in waist circumference ranged from -2·1 cm to -10·2 cm for LY3298176 (vs -1·3 cm for placebo, -2·5 cm for dulaglutide). Changes in total cholesterol ranged from 0·2 mmol/L to -0·3 mmol/L for LY3298176 (vs 0·3 mmol/L for placebo, -0·2 mmol/L for dulaglutide). Changes in HDL or LDL cholesterol did not differ between the LY3298176 and placebo groups. Changes in triglyceride concentration ranged from 0 mmol/L to -0·8 mmol/L for LY3298176 (vs 0·3 mmol/L for placebo, -0·3 mmol/L for dulaglutide). The 12-week outcomes were similar to those at 26 weeks for all secondary outcomes. 13 (4%) of 316 participants across the six treatment groups had 23 serious adverse events in total. Gastrointestinal events (nausea, diarrhoea, and vomiting) were the most common treatment-emergent adverse events. The incidence of gastrointestinal events was dose-related (23·1% for 1 mg LY3298176, 32·7% for 5 mg LY3298176, 51·0% for 10 mg LY3298176, and 66·0% for 15 mg LY3298176, 42·6% for dulaglutide, 9·8% for placebo); most events were mild to moderate in intensity and transient. Decreased appetite was the second most common adverse event (3·8% for 1 mg LY3298176, 20·0% for 5 mg LY3298176, 25·5% for 10 mg LY3298176, 18·9% for 15 mg LY3298176, 5·6% for dulaglutide, 2·0% for placebo). There were no reports of severe hypoglycaemia. One patient in the placebo group died from lung adenocarcinoma stage IV, which was unrelated to study treatment.\n\nInterpretation: The dual GIP and GLP-1 receptor agonist, LY3298176, showed significantly better efficacy with regard to glucose control and weight loss than did dulaglutide, with an acceptable safety and tolerability profile. Combined GIP and GLP-1 receptor stimulation might offer a new therapeutic option in the treatment of type 2 diabetes. [1]

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\n\nTirzepatide (LY3298176) is a dual GIP and GLP-1 receptor agonist under development for the treatment of type 2 diabetes mellitus (T2DM), obesity, and nonalcoholic steatohepatitis. Early phase trials in T2DM indicate that tirzepatide improves clinical outcomes beyond those achieved by a selective GLP-1 receptor agonist. Therefore, we hypothesized that the integrated potency and signaling properties of tirzepatide provide a unique pharmacological profile tailored for improving broad metabolic control. Here, we establish methodology for calculating occupancy of each receptor for clinically efficacious doses of the drug. This analysis reveals a greater degree of engagement of tirzepatide for the GIP receptor than the GLP-1 receptor, corroborating an imbalanced mechanism of action. Pharmacologically, signaling studies demonstrate that tirzepatide mimics the actions of native GIP at the GIP receptor but shows bias at the GLP-1 receptor to favor cAMP generation over β-arrestin recruitment, coincident with a weaker ability to drive GLP-1 receptor internalization compared with GLP-1. Experiments in primary islets reveal β-arrestin1 limits the insulin response to GLP-1, but not GIP or tirzepatide, suggesting that the biased agonism of tirzepatide enhances insulin secretion. Imbalance toward GIP receptor, combined with distinct signaling properties at the GLP-1 receptor, together may account for the promising efficacy of this investigational agent. [2]

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\n\nObjective: A novel dual GIP and GLP-1 receptor agonist, LY3298176, was developed to determine whether the metabolic action of GIP adds to the established clinical benefits of selective GLP-1 receptor agonists in type 2 diabetes mellitus (T2DM).\n\nMethods: LY3298176 is a fatty acid modified peptide with dual GIP and GLP-1 receptor agonist activity designed for once-weekly subcutaneous administration. LY3298176 was characterised in vitro, using signaling and functional assays in cell lines expressing recombinant or endogenous incretin receptors, and in vivo using body weight, food intake, insulin secretion and glycemic profiles in mice. A Phase 1, randomised, placebo-controlled, double-blind study was comprised of three parts: a single-ascending dose (SAD; doses 0.25-8 mg) and 4-week multiple-ascending dose (MAD; doses 0.5-10 mg) studies in healthy subjects (HS), followed by a 4-week multiple-dose Phase 1 b proof-of-concept (POC; doses 0.5-15 mg) in patients with T2DM (ClinicalTrials.gov no. NCT02759107). Doses higher than 5 mg were attained by titration, dulaglutide (DU) was used as a positive control. The primary objective was to investigate safety and tolerability of LY3298176.\n\nResults: LY3298176 activated both GIP and GLP-1 receptor signaling in vitro and showed glucose-dependent insulin secretion and improved glucose tolerance by acting on both GIP and GLP-1 receptors in mice. With chronic administration to mice, LY3298176 potently decreased body weight and food intake; these effects were significantly greater than the effects of a GLP-1 receptor agonist. A total of 142 human subjects received at least 1 dose of LY3298176, dulaglutide, or placebo. The PK profile of LY3298176 was investigated over a wide dose range (0.25-15 mg) and supports once-weekly administration. In the Phase 1 b trial of diabetic subjects, LY3298176 doses of 10 mg and 15 mg significantly reduced fasting serum glucose compared to placebo (least square mean [LSM] difference [95% CI]: -49.12 mg/dL [-78.14, -20.12] and -43.15 mg/dL [-73.06, -13.21], respectively). Reductions in body weight were significantly greater with the LY3298176 1.5 mg, 4.5 mg and 10 mg doses versus placebo in MAD HS (LSM difference [95% CI]: -1.75 kg [-3.38, -0.12], -5.09 kg [-6.72, -3.46] and -4.61 kg [-6.21, -3.01], respectively) and doses of 10 mg and 15 mg had a relevant effect in T2DM patients (LSM difference [95% CI]: -2.62 kg [-3.79, -1.45] and -2.07 kg [-3.25, -0.88], respectively. The most frequent side effects reported with LY3298176 were gastrointestinal (vomiting, nausea, decreased appetite, diarrhoea, and abdominal distension) in both HS and patients with T2DM; all were dose-dependent and considered mild to moderate in severity.\n\nConclusions: Based on these results, the pharmacology of LY3298176 translates from preclinical to clinical studies. LY3298176 has the potential to deliver clinically meaningful improvement in glycaemic control and body weight. The data warrant further clinical evaluation of LY3298176 for the treatment of T2DM and potentially obesity. [3]

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Tirzepatide is a single peptide engineered by integrating GLP-1 activity into the GIP sequence. It is described as an "imbalanced and biased" dual agonist. The imbalance refers to its stronger affinity and potency at the GIPR compared to the GLP-1R. The bias refers to its signaling profile at the GLP-1R, where it preferentially activates the cAMP pathway over β-arrestin recruitment, unlike the native ligand GLP-1. [2]
The biased agonism at the GLP-1R results in reduced GLP-1R internalization compared to GLP-1. Ex vivo perfusion of pancreatic islets from Arrb1βcell-/- mice showed that deletion of β-arrestin1 enhanced the insulin secretory response to GLP-1 but not to GIP or Tirzepatide, suggesting that the biased signaling of Tirzepatide at the GLP-1R may enhance its insulinotropic effect by avoiding β-arrestin-mediated limitation. [2]
The promising clinical efficacy of Tirzepatide is hypothesized to result from the combination of: 1) Full and potent GIPR agonism, 2) Imbalanced engagement favoring the GIPR, allowing higher dosing with potentially better tolerability, and 3) Biased signaling at the GLP-1R that may lead to enhanced insulin secretion. [2]
Tirzepatide is under development for the treatment of type 2 diabetes mellitus (T2DM), obesity, and nonalcoholic steatohepatitis (NASH). [2]

C219[13C]6H347N47[15N]1NAO68

4842.38 (Sodium salt)

4817.5420

2023788-19-2;13C,15N Tirzepatide;Tirzepatide hydrochloride (LY3298176 hydrochloride)

Solid powder

Tirzepatide internal standard; Labeled tirzepatide;isotope labeled tirzepatide;fluorescently labeled tirzepatide

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)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

注意: 如下所列的是一些常用的体内动物实验溶解配方，主要用于溶解难溶或不溶于水的产品（水溶度<1 mg/mL）。 建议您先取少量样品进行尝试，如该配方可行，再根据实验需求增加样品量。

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注射用配方1: DMSO : Tween 80： Saline = 10 : 5 : 85 (如： 100 μL DMSO → 50 μL Tween 80 → 850 μL Saline)
*生理盐水/Saline的制备：将0.9g氯化钠/NaCl溶解在100 mL ddH ₂ O中，得到澄清溶液。
注射用配方 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL DMSO → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)
注射用配方 3: DMSO : Corn oil = 10 : 90 (如： 100 μL DMSO → 900 μL Corn oil)
示例: 以注射用配方 3 (DMSO : Corn oil = 10 : 90) 为例说明, 如果要配制 1 mL 2.5 mg/mL的工作液, 您可以取 100 μL 25 mg/mL 澄清的 DMSO 储备液，加到 900 μL Corn oil/玉米油中, 混合均匀。

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注射用配方 4: DMSO : 20% SBE-β-CD in Saline = 10 : 90 [如：100 μL DMSO → 900 μL (20% SBE-β-CD in Saline)]
*20% SBE-β-CD in Saline的制备（4°C，储存1周）：将2g SBE-β-CD (磺丁基-β-环糊精) 溶解于10mL生理盐水中，得到澄清溶液。
注射用配方 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (如： 500 μL 2-Hydroxypropyl-β-cyclodextrin (羟丙基环胡精)→ 500 μL Saline)
注射用配方 6: DMSO : PEG300 : Castor oil : Saline = 5 : 10 : 20 : 65 (如： 50 μL DMSO → 100 μL PEG300 → 200 μL Castor oil → 650 μL Saline)
注射用配方 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (如： 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
注射用配方 8: 溶解于Cremophor/Ethanol (50 : 50), 然后用生理盐水稀释。
注射用配方 9: EtOH : Corn oil = 10 : 90 (如： 100 μL EtOH → 900 μL Corn oil)
注射用配方 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (如： 100 μL EtOH → 400 μL PEG300 → 50 μL Tween 80 → 450 μL Saline)

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口服配方 1: 悬浮于0.5% CMC Na (羧甲基纤维素钠)
口服配方 2: 悬浮于0.5% Carboxymethyl cellulose (羧甲基纤维素)
示例: 以口服配方 1 (悬浮于 0.5% CMC Na)为例说明, 如果要配制 100 mL 2.5 mg/mL 的工作液, 您可以先取0.5g CMC Na并将其溶解于100mL ddH2O中，得到0.5%CMC-Na澄清溶液；然后将250 mg待测化合物加到100 mL前述 0.5%CMC Na溶液中，得到悬浮液。

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口服配方 3: 溶解于 PEG400 (聚乙二醇400)
口服配方 4: 悬浮于0.2% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 5: 溶解于0.25% Tween 80 and 0.5% Carboxymethyl cellulose (羧甲基纤维素)
口服配方 6: 做成粉末与食物混合

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注意: 以上为较为常见方法，仅供参考， InvivoChem并未独立验证这些配方的准确性。具体溶剂的选择首先应参照文献已报道溶解方法、配方或剂型，对于某些尚未有文献报道溶解方法的化合物，需通过前期实验来确定（建议先取少量样品进行尝试），包括产品的溶解情况、梯度设置、动物的耐受性等。

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请根据您的实验动物和给药方式选择适当的溶解配方/方案：
1、请先配制澄清的储备液(如：用DMSO配置50 或 100 mg/mL母液(储备液));
2、取适量母液，按从左到右的顺序依次添加助溶剂，澄清后再加入下一助溶剂。以 下列配方为例说明 (注意此配方只用于说明，并不一定代表此产品 的实际溶解配方):
10% DMSO → 40% PEG300 → 5% Tween-80 → 45% ddH2O (或 saline);
假设最终工作液的体积为 1 mL, 浓度为5 mg/mL: 取 100 μL 50 mg/mL 的澄清 DMSO 储备液加到 400 μL PEG300 中，混合均匀/澄清；向上述体系中加入50 μL Tween-80，混合均匀/澄清；然后继续加入450 μL ddH2O (或 saline)定容至 1 mL；
3、溶剂前显示的百分比是指该溶剂在最终溶液/工作液中的体积所占比例;
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