The short version of Lyophilisation fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
序列层面的改动同时解决了两个问题，即酶解稳定性与肾脏清除速度。天然 GLP-1 在循环中的半衰期仅约两分钟，主要被二肽基肽酶-4 迅速灭活。酰化侧链与白蛋白的可逆结合形成循环储库，使分子缓慢释放并持续激活受体。这种设计思路后来被广泛用于同类长效肽的开发，属于该类药物化学改造的典型范式。
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。
Receptor activation follows the canonical Gs pathway: binding increases intracellular cyclic AMP, which promotes protein kinase A activity. In pancreatic beta cells this amplifies glucose-dependent insulin release, so secretion rises when blood glucose is high and changes little when it is low. The same signalling suppresses glucagon release from alpha cells and slows gastric emptying. Receptors in the hypothalamus and brainstem are thought to contribute to reduced appetite and lower energy intake. Which of these effects dominates clinical outcomes remains an area of active study.
Semaglutide is a synthetic peptide analogue of glucagon-like peptide-1, a gut hormone released by intestinal L cells after food intake. The natural hormone acts on pancreatic and central receptors but is degraded within minutes by dipeptidyl peptidase-4 and other peptidases. Semaglutide belongs to the class of long-acting GLP-1 receptor agonists, a group distinguished by structural changes that slow breakdown and extend circulation time. Its development followed earlier short-acting analogues and reflects a general strategy in peptide drug design: preserve receptor activity while blocking proteolytic clearance.
| Property | Value | Notes |
|---|---|---|
| 分子式 | C187H291N45O59 | 按主链与 C18 二酸侧链计算 |
| 分子量 | 约 4113.6 道尔顿 | 游离碱形式，随反离子略有差异 |
| 外观 | 白色至类白色冻干粉末 | 具吸湿性，需干燥保存 |
| 溶解性 | 微溶于水，易溶于碱性缓冲液 | 溶解性随 pH 升高而改善 |
| 等电点 | 约 5.4 | 影响缓冲液选择与聚集倾向 |
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 or 280 nanometres is widely used to assess purity and to resolve related impurities. Liquid chromatography coupled to mass spectrometry confirms identity through the protonated molecular ion and fragment ions formed in tandem experiments. Capillary electrophoresis and peptide mapping after enzymatic digestion supply complementary information on charge variants and modification sites. Circular dichroism and nuclear magnetic resonance can report on secondary structure in solution. Absolute quantification usually depends on an external standard, and reported purity depends on the detection wavelength and integration parameters chosen.
Lyophilised material appears as a white to off-white cake or powder that is hygroscopic, and containers are usually equilibrated to room temperature before opening to limit condensation. Dissolution is performed in water, phosphate-buffered saline, or a mildly alkaline buffer, since solubility rises above neutral pH. Gentle inversion or low-speed mixing is preferred, because vigorous vortexing can promote surface denaturation and aggregation. Complete dissolution may require several minutes, and brief sonication is sometimes applied. Passing the solution through a 0.22 micrometre membrane removes particulates but does not by itself sterilise the liquid.
Storage at minus 20 degrees Celsius or lower in a desiccated container preserves the peptide for extended periods, while working solutions are commonly held at two to eight degrees Celsius for short intervals. Light exposure and repeated freeze-thaw cycles accelerate degradation, so dividing material into single-use aliquots is generally recommended. Adsorption to glass and plastic surfaces can lower the measured concentration of dilute solutions, particularly below one milligram per millilitre. The degradation routes most often reported for GLP-1 analogues are deamidation, methionine oxidation, and backbone hydrolysis. Relative rates under specific conditions are frequently described only for individual formulations.
Clinical development of this compound followed earlier short-acting GLP-1 analogues that required frequent injection. Once-weekly subcutaneous formulations entered use after 2017, and an oral formulation using a permeation enhancer later became available. The oral version pairs the peptide with sodium N-(8-[2-hydroxybenzoyl] amino) caprylate, a carrier that improves uptake across the gastric epithelium. Interest has expanded from glycaemic control into weight management and metabolic liver disease. Regulatory status and approved indications differ between countries, and the product remains subject to ongoing safety monitoring.
Semaglutide is a synthetic peptide that acts as an agonist at the glucagon-like peptide-1 receptor. It is a structural analogue of human GLP-1(7-37), modified to resist enzymatic degradation by dipeptidyl peptidase-4. The peptide backbone contains alpha-aminoisobutyric acid at position 8, a substitution that stabilises the helix and slows cleavage. A fatty diacid side chain attached through a linker at lysine 34 promotes binding to serum albumin, which extends the circulating half-life. These two modifications together allow less frequent administration than native GLP-1 requires.
Activation of the GLP-1 receptor couples to Gs signalling and raises intracellular cyclic AMP in pancreatic beta cells. The resulting insulin release depends on prevailing glucose concentrations, so the effect is greater when glucose is elevated. Receptor engagement also suppresses glucagon secretion and slows gastric emptying, which flattens post-meal glucose excursions. In the central nervous system, signalling in hypothalamic and brainstem regions is associated with reduced appetite and lower energy intake. Studies continue to examine effects on cardiac, renal and hepatic endpoints; whether those benefits are independent of weight change remains an open question.
As in all other tetrapods, mammals have a larynx that can quickly open and close to produce sounds, and a supralaryngeal vocal tract which filters this sound. The lungs and surrounding musculature provide the air stream and pressure required to phonate. The larynx controls the pitch and volume of sound, but the strength the lungs exert to exhale also contributes to volume. More primitive mammals, such as the echidna, can only hiss, as sound is achieved solely through exhaling through a partially closed larynx. Other mammals phonate using vocal folds. The movement or tenseness of the vocal folds can result in many sounds such as purring and screaming. Mammals can change the position of the larynx, allowing them to breathe through the nose while swallowing through the mouth, and to form both oral and nasal sounds; nasal sounds, such as a dog whine, are generally soft sounds, and oral sounds, such as a dog bark, are generally loud.
Difficulty staying awake Mental confusion Impaired motor functions Impaired reflexes Impaired coordination Impaired balance Dizziness Respiratory depression Low blood pressure Coma Death Coma can be cyclic, with the individual alternating from a comatose state to a hyper-alert state of consciousness, which occurred in a four-year-old boy who overdosed on clonazepam. The combination of clonazepam and certain barbiturates (for example, amobarbital), at prescribed doses has resulted in a synergistic potentiation of the effects of each drug, leading to serious respiratory depression. Overdose symptoms may include extreme drowsiness, confusion, muscle weakness, and fainting.
== Absorption, metabolism and excretion == In the upper small intestine, thiamine phosphate esters present in food are hydrolyzed by alkaline phosphatase enzymes. At low concentrations (<2 μmol l−1), the absorption process is carrier-mediated. At higher concentrations, absorption also occurs via passive diffusion. Active transport can be inhibited by alcohol consumption or by folate deficiency. The majority of thiamine in serum is circulating bound to albumin, with over (90%) in erythrocytes (red blood cells), and is delivered to cells with high metabolic needs—particularly those in the brain, liver, pancreas, heart, and skeletal and smooth muscles, including cardiac muscle cells. A specific binding protein called thiamine-binding protein has been identified in rat serum and is believed to be a hormone-regulated carrier protein important for tissue distribution of thiamine. Uptake of thiamine by cells of the blood and other tissues occurs via active transport and passive diffusion. Two members of the family of transporter proteins encoded by the genes SLC19A2 and SLC19A3 are capable of thiamine transport. In some tissues, thiamine uptake and secretion appear to be mediated by a Na+-dependent transporter and a transcellular proton gradient. Human storage of thiamine is about 25 to 50 mg, with the greatest concentrations in liver, skeletal muscle, heart, brain, and kidneys. ThMP and free (unphosphorylated) thiamine are present in plasma, milk, cerebrospinal fluid, and, it is presumed, all extracellular fluid.
(...) To make matters worse, Admiral Thomas Cochrane (British), whose naval services and expenses had remained unpaid, appropriated the reserves of silver bars that had been painfully and arrogantly accumulated during the government of San Martín. Cochrane was the commander of the Chilean "liberation" fleet and also benefited from the capture and hijacking of Peruvian merchant ships. A French diplomat informed his bosses in Paris that the lack of popular support for freedom and independence was explained by the corruption of the new separatist authorities and their infighting. Another diplomatic envoy attributed the weakness of these nascent governments to the distribution of official positions through protection and intrigue instead of recognition of merit. These weak organizational bases provided fertile conditions for corruption and abuse of power." Later, during the founding of the State of Upper Peru, there were anti-Peruvian sectors in Argentina that saw the independence of Bolivia (and the renunciation of its claims by the United Provinces of the Río de la Plata to the sovereignty of that territory) as something tolerable with to avoid the aggrandizement of Peru (coinciding with Bolívar, Sucre and Santander to avoid restoring the power that Peru had during the viceregal era), which had been a great problem for the commercial and military interests of Buenos Aires during the wars that there was between the Junta and the Peruvian Viceroyalty.
== History == The Human Genetics Society of Australasia was founded subsequent to the growth in the field of genetics that occurred during the mid-twentieth century. During this time, the role that genetics plays in human health and disease became increasingly recognized. Genetic diagnostic techniques (in particular, in cytogenetics) were progressing rapidly. This coincided with the appreciation by medical specialists that genetic disorders, especially inborn errors of metabolism and birth defects, were of clinical interest. In 1976, a meeting in clinical genetics was held as part of the celebrations of the Centenary Year of the Adelaide Children's Hospital. The meeting involved several high-profile international speakers, most of the senior medical practitioners with an interest in heritable disease working in Australia and New Zealand, and delegates of the annual meeting of local cytogeneticists. The group agreed that a small working group should be charged with setting up a human genetics society for the region. Subsequently, the Human Genetics Society of Australasia was formally incorporated in South Australia in 1977 to serve the Australia and New Zealand region. The original group consisted of 19 Foundation Members, paying just $A10 per annum for membership.
Sources: en.wikipedia.org
==== Regulation ==== Enzymes can be either activated or inhibited by other molecules. For example, the end product(s) of a metabolic pathway are often inhibitors for one of the first enzymes of the pathway (usually the first irreversible step, called committed step), thus regulating the amount of end product made by the pathways. Such a regulatory mechanism is called a negative feedback mechanism, because the amount of the end product produced is regulated by its own concentration. Negative feedback mechanism can effectively adjust the rate of synthesis of intermediate metabolites according to the demands of the cells. This helps with effective allocations of materials and energy economy, and it prevents the excess manufacture of end products. Like other homeostatic devices, the control of enzymatic action helps to maintain a stable internal environment in living organisms.
== Paregoric, U.S.P. formula == The principal active ingredient in paregoric is powdered opium. In the United States the formula for Paregoric U.S.P. is a tincture of opium 40 mL, anise oil 4 mL, benzoic acid 4 g, camphor 4 g, glycerin 40 mL, alcohol 450 mL, purified water 450 mL, diluted with alcohol to 1000 mL, and contains the equivalent of 0.4 mg/mL of anhydrous morphine; one ounce of paregoric contains 129.6 mg (2 grains) of powdered opium, or the equivalent of 13 mg of anhydrous morphine. The average adult dose is 4 mL by mouth which corresponds to 16 mg of opium, or 1.6 mg of anhydrous morphine. It is unclear when the current formula for Paregoric, U.S.P. was developed in the United States. One formula for "Camphorated Tincture of Opium (Paregoric Elixir)" attributed to the United States Pharmacoepia of 1863 is: "Macerate 1 drachm each powdered opium and benzoic acid, 1 fluid drachm of anise, 2 ounces clarified honey, and 2 scruples camphor, in 2 pints diluted alcohol for 7 days, and filter through paper." A slightly different formula is given in the 1926 pharmacoepia. The current formula for Paregoric, U.S.P. should not be assumed to be universal. For example, in the United Kingdom the formula for Paregoric, B.P. is tincture of opium 5 mL, benzoic acid 500 mg, camphor 300 mg, anise oil 0.3 mL, alcohol (60%) to 100 mL, and contains about 1/30th grain of anhydrous morphine in 60 minims, which is 25% stronger than Paregoric, U.S.P.
The biosynthetic machinery of an NRPS system is composed of multimodular enzymatic assembly lines that contain one module for each amino acid monomer incorporated. Within each module are catalytic domains that carry out the elongation of the growing peptidyl chain. The growing peptide is covalently tethered to a thiolation domain; here it is termed the peptidyl carrier protein, as it carries the growing peptide from one catalytic domain to the next. Again, the apo-T domain must be primed to the holo-T domain by a PPTase, attaching a flexible phosphopantetheine arm to a conserved serine residue. An adenylation domain selects the amino acid monomer to be incorporated and activates the carboxylate with ATP to make the aminoacyl-AMP. Next, the A domain installs an aminoacyl group on the thiolate of the adjacent T domain. The condensation (C) domain catalyzes the peptide bond forming reaction, which elicits chain elongation. It joins an upstream peptidyl-S-T to the downstream aminoacyl-S-T (Figure 7). Chain elongation by one aminoacyl residue and chain translocation to the next T domain occurs in concert. The order of these domains is C-A-T. In some instances, an epimerization domain is necessary in those modules where L-amino acid monomers are to be incorporated and epimerized to D-amino acids. The domain organization in such modules is C-A-T-E. The first module has a three-domain C-A-T organization; these often occur in assembly lines that make N-acylated peptides. The first C domain catalyzes N-acylation of the initiating amino acid (tryptophan) while it is installed on T.
===== Dipterans ===== If flies are fed serotonin, they are more aggressive; flies depleted of serotonin still exhibit aggression, but they do so much less frequently. In their crops it plays a vital role in digestive motility produced by contraction. Serotonin that acts on the crop is exogenous to the crop itself and 2012 research suggested that it probably originated in the serotonin neural plexus in the thoracic-abdominal synganglion. In 2011 a Drosophila serotonergic mushroom body was found to work in concert with Amnesiac to form memories. In 2007 serotonin was found to promote aggression in Diptera, which was counteracted by neuropeptide F – a surprising find given that they both promote courtship, which is usually similar to aggression in most respects.
=== 1950s === In the 1950s, we saw innovation in technology across all fields, but most importantly there were many breakthroughs which led to modern medicine. On 6 March 1953, Dr. Jonas Salk announced the completion of the first successful killed-virus Polio vaccine. The vaccine was tested on about 1.6 million Canadian, American, and Finnish children in 1954. The vaccine was announced as safe on 12 April 1955. The 1950s saw foundational breakthroughs that reshaped modern molecular biology and clinical medicine. In 1953, James Watson and Francis Crick, drawing on the X-ray diffraction work of Rosalind Franklin and Maurice Wilkins, deduced the double-helix structure of DNA. In December 1953 at the Brigham Hospital in Boston, Dr. Joseph Murray performed the first successful human kidney transplant between identical twins. By 1958, Rune Elmqvist and Ake Senning developed and implanted the first fully internal cardiac pacemaker.
Sources: en.wikipedia.org
Currently metopon, which has a DEA ACSCN of 9260, does not have an annual manufacturing quota listed in the Federal Register and the bulk of the research on the drug at this time is taking place in Germany, Switzerland, and Austria.
== Overdose == An overdose of methaqualone can lead to coma and death. Additional effects are delirium, convulsions, hypertonia, hyperreflexia, vomiting, kidney failure, and death through cardiac or respiratory arrest. Methaqualone overdose resembles barbiturate poisoning, but with increased motor difficulties and a lower incidence of cardiac or respiratory depression. The standard single tablet adult dose of Quaalude brand of methaqualone was 300 mg when made by Lemmon. A dose of 8000 mg is lethal and a dose as little as 2000 mg could induce a coma if taken with an alcoholic beverage.
== Cause == Growth hormone-producing acidophilic pituitary adenomas are the cause of hypersomatotropism in the vast majority of cats. Both dense and sparse granulated cells has been observed in the adenomas of cats with diabetes mellitus and elevated IGF-1 levels; however, it is not known whether this is because of different variants of the disease or not. It is also not known what percentage of tumours are mixed or plurihormonal tumours. This information has only been reported in studies with a small number of cases. In dogs growth hormone is not just derived from the anterior pituitary gland, it also derives from the mammary gland. Mammary gland production of growth hormone is stimulated by progestogen, this occurs naturally in intact bitches. Synthetic progestogens can cause excessive growth hormone secretion and higher IGF-1 levels which may lead to acromegaly and diabetes mellitus. Progestogens are used to prevent oestrus in bitches and to treat certain hyperplasias. Growth hormone excess can occur in the luteal phase of the oestrous cycle in older bitches. Somatotrophic adenomas have only been described in two dogs. In 1996 a 9-year-old male Doberman Pinscher with difficult to manage diabetes mellitus but no signs of acromegaly was euthanised. Necropsy later revealed an acidophilic adenoma with immunohistochemical staining for growth hormone, adrenocorticotropic hormone, and prolactin.
== Causes == Polymyositis is an inflammatory myopathy mediated by cytotoxic T cells with an as yet unknown autoantigen, while dermatomyositis is a humorally mediated angiopathy resulting in myositis and a typical dermatitis. The cause of polymyositis is unknown and may involve viruses and autoimmune factors. Cancer may trigger polymyositis and dermatomyositis, possibly through an immune reaction against cancer that also attacks a component of muscles. There is tentative evidence of an association with celiac disease.
A synthesis of (+)-protolichesterinic acid was later developed through a 10-step process with 16.4% overall yield, using a diastereoselective orthoester Johnson–Claisen rearrangement as the key step. The synthesis concluded with α-methylenation using methoxy magnesium methylcarbonate and formaldehyde. In 2014, Zeller, Riener and Nicewicz introduced a more environmentally friendly approach using a polar radical crossover cycloaddition reaction. Their method employed a photooxidant system with 450 nm LEDs to achieve diastereoselective synthesis under mild conditions. In 2016, Fernandes and Nallasivam reported a protecting-group-free synthesis using palladium-catalysed Suzuki-Miyaura coupling to install a phenyl group as a masked carboxylic acid, followed by ruthenium-catalysed Sharpless epoxidation. The synthesis began with chiral reduction using (R)-alpine borane and concluded with α-methylenation, achieving 60% yield in the final step and 9.5% overall yield.
Sources: en.wikipedia.org
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。
胰岛素释放需要细胞内环腺苷酸与钙信号升高，同时依赖葡萄糖代谢产生的协同信号。血糖水平较低时协同信号不足，分泌增强有限。这一机制在降糖效果与低血糖风险之间提供了缓冲。
白蛋白结合是主要原因，它减少肾小球滤过并保护分子免受蛋白酶降解。序列修饰带来的酶解抵抗同样不可忽略，二者共同作用。脂肪链的疏水性还会影响组织分布，但其对总半衰期的贡献程度仍在研究之中。
Native GLP-1 is a short-lived peptide cleared within one to two minutes by dipeptidyl peptidase-4 and related enzymes. Semaglutide keeps the receptor-binding backbone but adds substitutions and a lipid chain. These changes block the main cleavage site and allow reversible albumin binding, extending the half-life to roughly 165 hours.