Everything below concerns 有关物质. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-07-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Tirzepatide is a synthetic peptide of 39 amino acids engineered from the native glucose-dependent insulinotropic polypeptide sequence. Its structure incorporates several non-natural residues and a C-terminal segment derived from glucagon-like peptide-1, together with a C20 fatty diacid moiety attached through a linker. The lipophilic side chain promotes binding to serum albumin, which slows renal clearance after administration. The compound is classified as a dual incretin receptor agonist and is supplied as a lyophilized powder for reconstitution or as a preformulated solution, depending on the presentation.
The peptide activates two G protein-coupled receptors, GIPR and GLP-1R. Binding triggers adenylyl cyclase activity and raises intracellular cyclic AMP in pancreatic beta cells, which potentiates insulin release when glucose is elevated. Signaling in the central nervous system is associated with reduced appetite and lower energy intake, while effects on gastric emptying and glucagon secretion are also reported. Because activity at both receptors is retained, the pharmacological profile is often described as incretin-based rather than selective for a single receptor.
After subcutaneous injection, absorption is gradual, and peak plasma levels are generally reached within one to three days. Albumin binding extends the apparent half-life to roughly five days, which supports a weekly administration schedule. Metabolism proceeds mainly through proteolytic cleavage of the peptide backbone and beta-oxidation of the fatty acid chain, rather than through cytochrome P450 pathways. Eliminated fragments are largely recycled through general protein turnover, and excretion of intact drug in urine is minimal. These properties distinguish the molecule from short-acting incretin mimetics.
The GIP receptor is expressed in pancreatic islets, adipose tissue, and the central nervous system, while GLP-1 receptors are found in pancreatic islets, the gastrointestinal tract, and the brain. Activation of both receptors can enhance glucose-dependent insulin secretion and reduce glucagon release. The relative contribution of each receptor to the overall pharmacological effect remains an area of ongoing investigation. Preclinical studies suggest that GIP receptor agonism may modulate appetite and energy balance, but the precise mechanisms in humans are not fully established.
In clinical research, tirzepatide has been studied in randomized controlled trials for glycemic control and body weight reduction. These trials typically measure changes in hemoglobin A1c and body weight over periods of several months. The drug is administered by subcutaneous injection, and its pharmacokinetic profile supports once-weekly dosing. Post-marketing surveillance continues to evaluate long-term outcomes and rare adverse events.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C225H348N48O68 | Approximate composition of the free peptide |
| Molecular weight | Approximately 4813 Da | Calculated for the free base |
| Structural class | Synthetic linear peptide | 39 residues with modified backbone |
| Solubility | Soluble in water and polar solvents | Behavior of the lyophilized solid |
| Typical storage temperature | -20 degrees Celsius or below | Solid form, protected from light |
定量分析的主流方法是反相高效液相色谱联用紫外或质谱检测，利用肽在疏水固定相上的保留行为确定纯度与含量。对于生物基质中的浓度测定，常采用液相色谱串联质谱，并配合固相萃取或蛋白沉淀进行样品前处理。免疫分析法也可使用，但可能受到结构相关肽的交叉反应干扰。
纯度评估通常综合反相色谱、体积排阻色谱与质谱三方面信息：前者反映疏水性杂质，后者反映聚集体，质谱则确认分子量与主要降解产物。有关降解途径的完整图谱——例如脱酰胺、氧化与水解各占多大比例——在不同储存条件下仍有差异，属于需要逐案验证的问题。
质量控制环节关注外观、含量、纯度、有关物质、水分与微生物限度等项目。检测结果需要有对照品和系统适用性数据支持，单次测定不足以判定批次的稳定性。实验室之间方法转移时，色谱柱品牌与梯度差异常导致保留时间漂移，因此方法验证十分必要。
Development of tirzepatide took place under a research program that sought to test whether simultaneous engagement of two incretin receptors would produce greater metabolic effects than single-receptor agonism. Clinical trials were organized into the SURPASS series for type 2 diabetes and the SURMOUNT series for obesity and weight management. Regulatory clearance for type 2 diabetes came in 2022 in the United States, followed by approval for chronic weight management in 2023. The trial programs reported reductions in glycated hemoglobin and body weight relative to comparators, though long-term cardiovascular and durability data continue to accumulate.
The peptide backbone contains 39 amino acids and includes alpha-aminoisobutyric acid residues, which are not among the standard proteinogenic set. A C20 fatty diacid moiety is attached through a linker, allowing the compound to bind serum albumin and extend its circulation time. This albumin binding is the main reason the molecule supports once-weekly administration rather than more frequent dosing. The measured molecular mass is approximately 4,813 daltons, placing it firmly in the peptide rather than small-molecule class.
Tirzepatide is a synthetic peptide of 39 amino acids that carries a C20 fatty diacid side chain attached through a linker. Its molecular formula is C225H348N48O68, and its molecular weight is about 4813 daltons. The compound belongs to the incretin mimetic class and is administered by subcutaneous injection. The fatty acid chain promotes binding to serum albumin, which slows renal clearance and extends the circulation time of the molecule. It was identified during screening of sequences derived from glucose-dependent insulinotropic polypeptide.
Tirzepatide activates both the glucose-dependent insulinotropic polypeptide receptor and the glucagon-like peptide-1 receptor, making it a dual agonist rather than a selective agent. Engagement of the GLP-1 receptor is linked to glucose-dependent insulin release, slower gastric emptying, and reduced appetite signalling. The relative contribution of the GIP arm remains an active research question; proposed roles include improved insulin sensitivity and altered adipose tissue handling. Receptor occupancy studies suggest the molecule interacts with both targets at circulating concentrations achieved during therapy.
=== Occurrence === Glutathione is the most abundant non-protein thiol (R−SH-containing compound) in animal cells, ranging from 0.5 to 10 mmol/L. It is present in the cytosol and organelles. The concentration of glutathione in the cytoplasm is significantly higher (ranging from 0.5-10 mM) compared to extracellular fluids (2-20 μM), reaching levels up to 1000 times greater. In healthy cells and tissue, more than 90% of the total glutathione pool is in the reduced form (GSH), with the remainder in the disulfide form (GSSG). The cytosol holds 80-85% of cellular GSH, and the mitochondria hold 10-15%. Human beings synthesize glutathione, but a few eukaryotes do not, including some members of Fabaceae, Entamoeba, and Giardia. The only known archaea that make glutathione are halobacteria. Some bacteria, such as "Cyanobacteria" and Pseudomonadota, can biosynthesize glutathione. The systemic availability of orally administered glutathione is poor. It has low bioavailability because the tripeptide is the substrate of proteases (peptidases) of the alimentary canal, and due to the absence of a specific carrier of glutathione at the level of the cell membrane. The administration of N-acetylcysteine (NAC), a cysteine prodrug, helps replenish intracellular GSH levels.
== Biochemical function == Glutathione exists in reduced (GSH) and oxidized (GSSG) states. The ratio of reduced glutathione to oxidized glutathione within cells is a measure of cellular oxidative stress where increased GSSG-to-GSH ratio is indicative of greater oxidative stress. In the reduced state, the thiol group of cysteinyl residue is a source of one reducing equivalent. Glutathione disulfide (GSSG) is thereby generated. The oxidized state is converted to the reduced state by NADPH. This conversion is catalyzed by glutathione reductase:
GSH + R• → RH + GS• → 1/2 GSSG Thiyl radicals (such as glutathionyl radicals) are themselves oxidizing species in biology, with a single-electron reduction potential sufficient for oxidation of nucleic acids, proteins and polyunsaturated lipids. Therefore, GSH itself may not be effective at direct reduction of reactive oxygen species under physiological conditions. Under oxidizing conditions, hydrogen sulfide may react with glutathione (or other electrophilic oxidized forms of glutathione) to form glutathione hydropersulfide (GS–SH), which is a superior radical-trapping antioxidant and reductant. GSH is a highly important indirect antioxidant by acting as a coenzyme for various enzymes that couple GSH-to-GSSG oxidation to the reduction of harmful oxidizing species. Such enzymes include the glutathione peroxidase family, the glutaredoxin family, the peroxiredoxin family, and others.
=== Regulation === Aside from deactivating radicals and reactive oxidants, glutathione participates in thiol protection and redox regulation of cellular thiol proteins under oxidative stress by protein S-glutathionylation, a redox-regulated post-translational thiol modification. The general reaction involves formation of an unsymmetrical disulfide from the protectable protein (RSH) and GSH:
Sources: en.wikipedia.org
It is a synthetic linear peptide that acts as a dual agonist at the GIP and GLP-1 receptors. It combines a modified incretin backbone with a fatty diacid side chain that extends its circulation time. It is not a small-molecule drug and is not orally absorbed in its native form.
Single-receptor agents act predominantly at GLP-1R. Tirzepatide retains activity at GIPR, which is expressed in pancreatic islets, adipose tissue, and the central nervous system. The contribution of each receptor to the overall response is still an area of active study, and the relative weight of GIPR signaling in humans is not fully settled.
The fatty diacid moiety binds serum albumin, which reduces renal filtration of the active peptide. Additional resistance to enzymatic breakdown comes from non-natural residues in the backbone. Together these features produce an apparent half-life of about five days and permit weekly dosing intervals.
It activates both GIP and GLP-1 receptors. This dual action differentiates it from selective GLP-1 agonists.