This is a working overview of half-life, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-02-21. Anything still debated is marked as such rather than presented as settled.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1, a hormone released from intestinal L-cells after food intake. It contains 31 amino acids and differs from native GLP-1 through modifications that slow enzymatic breakdown. The peptide was developed to extend the short circulating half-life of endogenous GLP-1, which is measured in minutes. Researchers introduced the compound in the early 2010s. Two backbone changes and a fatty acid side chain define its structure, distinguishing it from earlier GLP-1 receptor agonists.
The compound binds the GLP-1 receptor on pancreatic beta cells and other tissues, activating a G-protein signaling cascade that raises intracellular cyclic AMP. This action increases glucose-dependent insulin secretion when blood glucose is elevated, while binding also slows gastric emptying and reduces glucagon release. In the central nervous system, receptor activation in the hypothalamus and brainstem contributes to reduced appetite. The fatty acid chain binds albumin, which protects the peptide from renal filtration and enzymatic degradation. This albumin binding is central to its extended circulation time.
Native GLP-1 is degraded rapidly by dipeptidyl peptidase-4. Semaglutide resists this cleavage because alanine at position 8 is replaced by alpha-aminoisobutyric acid. A second substitution at position 34 introduces arginine, which further stabilizes the peptide. The most distinctive modification is a spacer and C18 fatty diacid attached at lysine 26, enabling strong albumin affinity. These three changes together produce a half-life measured in days rather than minutes, and the same structural logic underlies other long-acting analogs in this class.
Semaglutide 是一种经结构修饰的胰高血糖素样肽-1 类似物，其主链与内源性 GLP-1(7-36) 约有百分之九十四的序列一致性。第 8 位丙氨酸被 α-氨基异丁酸取代，使二肽基肽酶-4 无法识别原有切割位点。第 34 位赖氨酸换为精氨酸，进一步降低酶解速率。第 26 位赖氨酸经间隔基连接一条含十八个碳的二酸脂肪链，该侧链赋予分子与血浆白蛋白结合的能力。
该分子作为 GLP-1 受体的选择性激动剂发挥作用，受体属于 B 类 G 蛋白偶联受体家族，激活后经 Gs 通路提升细胞内环腺苷酸水平。在胰腺 β 细胞，信号促进葡萄糖依赖性的胰岛素释放，血糖偏低时该作用明显减弱。在胰岛 α 细胞，胰高血糖素分泌受到抑制。中枢神经系统与胃肠道同样存在受体表达，相应信号参与食欲调节以及胃排空速率的降低。
| Property | Value | Notes |
|---|---|---|
| Molecular class | Synthetic peptide | 31 amino acids |
| Backbone modification | Aib at position 8 | Blocks DPP-4 cleavage |
| Fatty acid chain | C18 diacid | Supports albumin binding |
| Native half-life | 1 to 2 minutes | Endogenous GLP-1 |
| Analog half-life | Approximately one week | Extended by albumin binding |
Solid peptide material is generally kept at reduced temperature to limit degradation. Short-term storage at 2 to 8 degrees Celsius is common, while longer archival storage at minus 20 degrees Celsius or below is typical for lyophilised powder. Vials should remain sealed and protected from light, because ultraviolet exposure can oxidise susceptible residues. Repeated freeze-thaw cycles are avoided, as they promote aggregation and loss of soluble material. Solutions are less stable than solids and are usually prepared close to the time of use.
Reversed-phase high-performance liquid chromatography is widely used to assess purity and to separate the parent peptide from related substances. Mass spectrometry confirms identity and can resolve modifications that differ by a few daltons. Size-exclusion chromatography detects dimers and higher aggregates, which are relevant to both stability and immunogenicity questions. Peptide mapping with enzymatic digestion locates specific modifications along the sequence. Circular dichroism provides a secondary-structure profile, although it gives limited information about local conformational changes.
Semaglutide is a synthetic peptide analog of glucagon-like peptide-1 (GLP-1), a hormone released from intestinal L-cells after food intake. The compound belongs to the incretin mimetic class and acts at GLP-1 receptors distributed across pancreatic, gastrointestinal, cardiovascular, and central nervous system tissues. Compared with native GLP-1, the molecule carries structural changes that extend its activity from minutes to roughly one week. It is studied for glycemic control in type 2 diabetes and for weight management, and its effects on cardiovascular and other outcomes remain active research areas.
Receptor binding triggers G protein signaling that raises intracellular cyclic AMP in pancreatic beta cells. Insulin release follows in a glucose-dependent manner, so secretion increases when blood glucose is elevated and diminishes when it is not. The same signaling suppresses glucagon release from alpha cells and slows gastric emptying, which blunts the post-meal glucose rise. In the brain, receptor activation in regions such as the arcuate nucleus is associated with reduced appetite and lower energy intake. How much each of these effects contributes to overall weight change is not fully settled.
Storage guidance for the finished injectable product distinguishes the unused state from the in-use state. Before first use, pens are kept refrigerated between 2 and 8 degrees Celsius, protected from light, and never frozen, since freezing can disrupt the peptide or the device. After first use, label instructions in several markets permit storage at room temperature up to about 30 degrees Celsius for a limited number of days. Solid research-grade material is normally held at or below minus 20 degrees Celsius, often with desiccant, and allowed to equilibrate before opening.
Quantification and purity assessment rely on separation methods coupled to optical or mass detection. Reversed-phase high-performance liquid chromatography resolves the intact peptide from related impurities and is the standard assay technique. Size-exclusion chromatography measures aggregates, while ion-exchange chromatography separates charge variants produced by deamidation. Mass spectrometry confirms identity and detects mass shifts of a few daltons. In biological matrices, liquid chromatography with tandem mass spectrometry is often used because immunoassays can cross-react with endogenous GLP-1 or with circulating fragments.
1000, 25 July 1990 – On 25 July 1990, the SENSEX touched the four-digit figure for the first time and closed at 1,001 in the wake of a good monsoon and excellent corporate results. 2000, 15 January 1992 – On 15 January 1992, the SENSEX crossed the 2,000 mark and closed at 2,020 followed by the liberal economic policy initiatives undertaken, under the leadership of the then prime minister PV Narasimha Rao, by the then finance minister and former Prime Minister of India Dr. Manmohan Singh. 3000, 29 February 1992 – On 29 February 1992, the SENSEX surged past the 3,000 mark in the wake of the market-friendly budget announced by Manmohan Singh. 4000, 30 March 1992 – On 30 March 1992, the SENSEX crossed the 4,000 mark and closed at 4,091 on the expectations of a liberal export-import policy. It was then that the Harshad Mehta scam hit the markets and SENSEX witnessed unabated selling. 5000, 11 October 1999 – On 11 October 1999, the SENSEX crossed the 5,000 mark, as the Bharatiya Janata Party-led coalition won the majority in the 13th Lok Sabha election. 6000, 11 February 2000 – On 11 February 2000, the information technology boom helped the SENSEX to cross the 6,000 mark and hit an all-time high of 6,006 points. This record would stand for nearly four years, until 2 January 2004, when the SENSEX closed at 6,026.59 points. 7000, 21 June 2005 – On 20 June 2005, the news of the settlement between the Ambani brothers boosted investor sentiments and the scrips of RIL, Reliance Energy, Reliance Capital and IPCL made huge gains.
He noted its use in Ancient Rome in religious ceremonies to purify homes by fumigation (something also briefly evoked in a line of Ovid's Ars Amatoria about purifying houses with eggs and sulfur). The use of sulfur for fumigation is very ancient and was already a practice in preclassical Greece; this is mentioned in the Odyssey. Several Roman authors of the second half of the first century, such as Martial and Statius, reference a type of street trade seemingly common at the time, where peddlers in the streets would exchange pieces of sulfur or sulfur "matches" (actually some kind of sulfured wooden splints used as a fire starter, rather than friction matches) for broken glass. The Persian army used sulfur as a chemical weapon during the siege of Dura-Europos, in the 3rd century. They burned pitch and sulfur in tunnels, creating a toxic cloud of sulfur dioxide which killed the Roman soldiers in the tunnels. A natural form of sulfur known as shiliuhuang (Chinese: 石硫黃; pinyin: shí liú huáng) was known in China since the 6th century BC and found in Hanzhong. By the 3rd century, the Chinese had discovered that sulfur could be extracted from pyrite. Chinese Daoists were interested in sulfur's flammability and its reactivity with certain metals, yet its earliest practical uses were found in traditional Chinese medicine.
Powerful hydrolytic enzymes, for instance, digestive enzymes, are activated by proteolysis so we can ensure that they are unable to hydrolyze any unwilling protein until they get to the right place: hydrolyzing protein zymogens are synthesized at the pancreas and accumulated in vesicles where they remain harmless. When they are needed, some hormonal or nervous stimulus triggers the release of the zymogens right to the intestine and they are activated. Some eventual responses must be immediate so enzymes that catalyze those reactions need to be prepared but not active, for that reason a zymogene is synthesized and stays ready for being rapidly activated. Coagulation response is based on enzymatic cascade proteolysis maturation. So, by activating one first catalyzing enzyme a big amount of the following enzymes is activated and the amount of product required is achieved as it is needed. Connective tissues proteins as collagen (zymogen: procolagen), hormones like insulin (zymogen: proinsulin) and proteins involved in development processes and apoptosis (programmed cell death) are activated by proteolysis too. Proteolysis is irreversible, which implies the need of a process of enzyme deactivation. Specific inhibitors, analogous to the substrate, will strongly join the enzyme, blocking the substrate to join the enzyme. This union may last for months.
Sources: en.wikipedia.org
The purest metal is obtained from nickel oxide by the Mond process, which gives a purity of over 99.99%. The process was patented by Ludwig Mond and has been in industrial use since before the beginning of the 20th century. In this process, nickel is treated with carbon monoxide in the presence of a sulfur catalyst at around 40–80 °C to form nickel carbonyl. In a similar reaction with iron, iron pentacarbonyl can form, though this reaction is slow. If necessary, the nickel may be separated by distillation. Dicobalt octacarbonyl is also formed in nickel distillation as a by-product, but it decomposes to tetracobalt dodecacarbonyl at the reaction temperature to give a non-volatile solid. Nickel is obtained from nickel carbonyl by one of two processes. It may be passed through a large chamber at high temperatures in which tens of thousands of nickel spheres (pellets) are constantly stirred. The carbonyl decomposes and deposits pure nickel onto the spheres. In the alternate process, nickel carbonyl is decomposed in a smaller chamber at 230 °C to create a fine nickel powder. The byproduct carbon monoxide is recirculated and reused. The highly pure nickel product is known as "carbonyl nickel".
Cannabis had been decriminalised by the Prayut government in 2022, with the move being most supported by the Bhumjaithai Party (BJT) as one of its flagship policies. The Pheu Thai party had run in 2023 on an anti-drug policy and opposed the use of cannabis except for medical use and, under Srettha, had proposed legislation aimed at restricting the use of cannabis. The party's stance on cannabis thus led to tension with the BJT – creating a rift between the two parties which remained in a coalition when Paetongtarn became prime minister. The Thai government had hoped that decriminalising cannabis would turn it into a cash crop. A lack of laws governing cannabis were blamed for the rise in illegal distribution and the creation of a saturated market. Shortly after becoming prime minister, the Ministry of Public Health proposed a new bill on 12 September 2024 restricting cannabis to medical and research reasons. It also proposed the establishment of a Cannabis Control Board (CCB) to regulate the industry. The bill did not pass and Paetongtarn pledged that the government would not reverse its policy on cannabis again. However, by 2025, tourists smuggling cannabis out from Thailand was on the rise. Somsak Thepsuthin, the Minister of Public Health, listed in May that Hong Kong, India, Pakistan and the United Kingdom were the main destinations. On 22 May, the Paetongtarn government announced it planned to introduce new restrictions limiting cannabis usage to individuals (including foreigners) with medical prescriptions from doctors.
=== Pharmacogenetics === Serious skin reactions such as Stevens–Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN) due to carbamazepine therapy are more common in people with a particular human leukocyte antigen gene-variant (allele), HLA-B*1502. Odds ratios for the development of SJS or TEN in people who carry the allele can be in the double, triple or even quadruple digits, depending on the population studied. HLA-B*1502 occurs almost exclusively in people with ancestry across broad areas of Asia, but has a very low or absent frequency in European, Japanese, Korean and African populations. However, the HLA-A*31:01 allele has been shown to be a strong predictor of both mild and severe adverse reactions, such as the DRESS form of severe cutaneous reactions, to carbamazepine among Japanese, Chinese, Korean, and Europeans. It is suggested that carbamazepine acts as a potent antigen that binds to the antigen-presenting area of HLA-B*1502 alike, triggering an everlasting activation signal on immature CD8-T cells, thus resulting in widespread cytotoxic reactions like SJS/TEN.
Sources: en.wikipedia.org
It is a synthetic analog of GLP-1 produced through medicinal chemistry to resist enzymatic degradation. The design goal was longer circulation than the native hormone.
A fatty acid side chain attaches the peptide to serum albumin, which shields it from kidney filtration and protease activity. This interaction is the main reason its circulation time is extended.
No. The native hormone is GLP-1, and semaglutide is an engineered variant with three deliberate structural alterations. It does not appear in unmodified biological sources.
差别集中在三处：第 8 位残基被非天然氨基酸取代，第 34 位换成精氨酸，第 26 位增加一条脂肪酸侧链。前两处改动降低酶解速率，侧链则通过白蛋白结合延长循环时间。综合结果是半衰期从约两分钟延长到约一周。