This is a working overview of cold chain, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2026-08-01 and is reviewed periodically as new material appears.
皮下注射后吸收相对缓慢，绝对生物利用度约为百分之八十九，血药浓度峰值通常出现在给药后一到三天。与白蛋白结合使清除减慢，终末半衰期约为一百六十五小时，接近一周。连续给药约四到五周后达到稳态暴露水平。表观分布容积约为每千克零点二五升，血浆蛋白结合率超过百分之九十九。代谢以蛋白水解切割和脂肪二酸侧链的 β-氧化为主，相关产物主要经尿液与粪便排出。
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。
Reconstituted solutions are less stable than the dry powder, and stability depends on concentration, pH, buffer composition, and container material. Low-protein-binding tubes reduce loss of peptide to plastic surfaces. Some researchers add a carrier protein to limit adsorption at low concentrations. The exact shelf life of a given solution is best determined empirically through a stability study rather than assumed from general guidance, because published data cover only a limited set of conditions.
Storage conditions for semaglutide depend heavily on the presentation. Lyophilized research powder is generally kept at two to eight degrees Celsius in a sealed container, protected from light and moisture. Manufacturer labeling for finished injectable products specifies refrigeration before first use, with defined in-use periods at room temperature afterward. The oral tablet form is stored at controlled room temperature and is more tolerant of short excursions. Temperature excursions should be documented rather than inferred.
| 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 |
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.
Three structural changes define the molecule. At position 8 an alpha-aminoisobutyric acid residue replaces alanine, which blocks dipeptidyl peptidase-4 cleavage. At position 34 arginine replaces lysine, and at position 26 a lysine carries a C18 fatty diacid attached through a short linker. The fatty chain binds serum albumin, and this albumin association reduces renal filtration and enzymatic attack. The unchanged backbone retains the receptor contacts that produce signalling. The free base has the formula C187H291N45O59 and a molecular weight near 4114 daltons.
关于降解产物的免疫原性风险，文献中仍有讨论空间。体外聚集水平与临床免疫反应之间的定量关系尚未确立。多数公开研究只报告理化指标，缺少长期随访的对应数据。这一问题在生物类似物比对中尤其受到关注。
市售注射用制剂通常要求在二至八摄氏度冷藏保存，并避免光照与冻结。部分多剂量笔在首次使用后允许在不超过三十摄氏度的环境中存放有限周数，具体期限由辅料与防腐剂体系决定。反复冻融会促进肽链聚集并改变可见颗粒计数，因此应予避免。冻干粉末在干燥、避光、低温条件下更为稳定。溶液配制后宜使用低吸附容器，以减少肽类在塑料或玻璃表面的损失。
纯度评价多采用反相高效液相色谱，流动相常加入三氟乙酸或甲酸作为离子对改性剂，检测波长设在二百一十四纳米或二百二十纳米。分子量确认依靠电喷雾电离质谱或基质辅助激光解吸电离质谱，实测值应与理论值在数 ppm 内吻合。肽图分析通过酶切后液相色谱串联质谱完成，用于核查序列与修饰位点。体积排阻色谱用于定量共价与非共价聚集体。生物基质浓度测定则采用免疫分析或液相色谱串联质谱。
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.
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.
As a peptide, semaglutide is sensitive to conditions that break amide bonds or modify side chains. Deamidation of asparagine and glutamine residues, oxidation of methionine and tryptophan, and non-covalent aggregation are the main degradation routes described in published stability work. Rate depends strongly on pH, buffer species, ionic strength, temperature and exposure to light. Formulators therefore choose a defined solution pH and often add excipients such as phosphate buffer, propylene glycol and phenol, each of which plays a separate role in pH control, tonicity or preservation.
Another less measurable difference that are subject to more debate and questions of winemakers preference is the influence of strain selection on the varietal flavors of certainly grape varieties such as Sauvignon blanc and Sémillon. It is believed that these wines can be influenced by thiols produced by the hydrolysis of certain cysteine-linked compounds by enzymes that are more prevalent in particular strains. Other aromatic varieties such as Gewürztraminer, Riesling and Muscat may also be influenced by yeast strains containing high levels of glycosidases enzymes that can modify monoterpenes. Similarly, though potentially to a much smaller extent, other varieties could be influenced by hydrolytic enzymes working on aliphatics, norisoprenoids, and benzene derivatives such as polyphenols in the must. In sparkling wine production some winemakers select strains (such as one known as Épernay named after the town in the Champagne wine region of France and California Champagne, also known as UC-Davis strain 505) that are known to flocculate well, allowing the dead yeast cells to be removed easily by riddling and disgorgement. In Sherry production, the surface film of yeast known as flor used to make the distinctive style of fino and manzanilla sherries comes from different strains of Saccharomyces cerevisiae, though the commercial flor yeast available for inoculation is often from different species of Saccharomyces, Saccharomyces beticus, Saccharomyces fermentati and Saccharomyces bayanus.
Alkaloid-containing plants have been used by humans since ancient times for therapeutic and recreational purposes. For example, medicinal plants have been known in Mesopotamia from about 2000 BC. The Odyssey of Homer referred to a gift given to Helen by the Egyptian queen, a drug bringing oblivion. It is believed that the gift was an opium-containing drug. A Chinese book on houseplants written in 1st–3rd centuries BC mentioned a medical use of ephedra and opium poppies. Also, coca leaves have been used by Indigenous South Americans since ancient times. Extracts from plants containing toxic alkaloids, such as aconitine and tubocurarine, were used since antiquity for poisoning arrows. Studies of alkaloids began in the 19th century. In 1804, the German chemist Friedrich Sertürner isolated from opium a "soporific principle" (Latin: principium somniferum), which he called "morphium", referring to Morpheus, the Greek god of dreams; in German and some other Central-European languages, this is still the name of the drug. The term "morphine", used in English and French, was given by the French physicist Joseph Louis Gay-Lussac. A significant contribution to the chemistry of alkaloids in the early years of its development was made by the French researchers Pierre Joseph Pelletier and Joseph Bienaimé Caventou, who discovered quinine (1820) and strychnine (1818). Several other alkaloids were discovered around that time, including xanthine (1817), atropine (1819), caffeine (1820), coniine (1827), nicotine (1828), colchicine (1833), sparteine (1851), and cocaine (1860).
These syndromes are caused by mutations that affect the maturation of the hematopoietic progenitor cells, which are the precursors of both B and T cells. Several genetic defects can cause SCID, including IL-2 receptor gene loss of function, and mutation resulting in deficiency of the enzyme adenine deaminase.
=== Depression === The evidence overall supports the effectiveness of bupropion over placebo for the treatment of depression. Evidence-based guidelines consistently recommend bupropion as a treatment option for adults with major depressive disorder; some support first-line use for major depressive disorder, but there is limited guidance for treatment-resistant depression. Some peer-reviewed studies suggest the quality of evidence is low. Some meta-analyses report that bupropion has an at-most small effect size for depression. Evidence suggests that the effectiveness of bupropion for depression is similar to that of other antidepressants. Over the autumn and winter months, bupropion can prevent the development of depression in those who have recurring seasonal affective disorder: 15% of participants on bupropion experienced a major depressive episode vs. 27% of those on placebo. Bupropion also improves depression in bipolar disorder, however the risk of an affective switch is similar to other antidepressants. Bupropion has several features that distinguish it from other antidepressants: for instance, unlike the majority of antidepressants, it does not usually cause sexual dysfunction, and the occurrence of sexual side effects is not different from placebo. Bupropion treatment is not associated with weight gain; on the contrary, the majority of studies observed significant weight loss in bupropion-treated participants. Bupropion treatment also is not associated with the sleepiness that may be produced by other antidepressants.
Sources: en.wikipedia.org
== Recruitment == Finding a potential sperm donor, and motivating him to donate sperm, is referred to as recruitment. A sperm bank can recruit donors by advertising—-often in colleges, in local newspapers, and on the internet. A donor must be a fit and healthy male, normally between 18 and 45 years of age, willing to undergo frequent rigorous testing. The donor must also be willing to donate his sperm so that it can be used to impregnate people who are unrelated to him whom he does not know. Some sperm banks require two screenings and a laboratory screening before a donor is eligible. The donor must agree to relinquish all legal rights to all children who result from his donations. The donor must produce his sperm at the sperm bank, thus enabling the identity of the donor, once proven, to be ascertained. Some sperm banks have been accused of heightism due to minimum height requirements.
Choh Hao Li (sometimes Cho Hao Li) (Chinese: 李卓皓; pinyin: Lǐ Zhuōhào; April 21, 1913 – November 28, 1987) was a Chinese-born American biochemist who discovered in 1966 that human pituitary growth hormone (somatotropin) consists of a chain of 256 amino acids. In 1970, he succeeded in synthesizing this hormone, the largest protein molecule synthesized up to that time.
Opioid receptors are a group of inhibitory G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. Even though at the cellular level they are inhibitory, their activation is not always inhibitory: for example, activation of mu-opioid receptors activates (not inhibits) dopamine release, and activation of kappa-opioid receptors can lead to noradrenaline release, due to the location of these receptors on suppressor-cells releasing these neurotransmitters . The opioid receptors are ~40% identical to somatostatin receptors (SSTRs). Opioid receptors are distributed widely in the brain, in the spinal cord, on peripheral neurons, and digestive tract.
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。
Sealed, protected from light, and refrigerated at two to eight degrees Celsius for most research material. Desiccated storage limits moisture uptake. Allow the vial to reach room temperature before opening to prevent condensation.