If you have been reading about freeze-thaw and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Updated 2026-02-15. Numbers and descriptions here follow the published literature rather than marketing material.
Pharmacokinetic data are limited. Like most short peptides, Selank is vulnerable to plasma and tissue peptidases, and its measured half-life in circulation is short, on a minutes scale. The Pro-Gly-Pro tail slows this degradation but does not eliminate it. Intranasal administration is the route described in most reports, with absorption through the nasal mucosa and a hypothesized path into the central nervous system that avoids the blood-brain barrier. Direct measurements of human brain exposure are unavailable, so distribution claims rest on inference from animal work.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Proposed mechanisms center on modulation of the GABA system, but no single molecular target has been confirmed. Rodent studies report changes in GABA-A receptor expression and in the turnover of serotonin, dopamine, and norepinephrine in several brain regions. Increases in brain-derived neurotrophic factor and its receptor have also been described after repeated administration. These findings come largely from animal models, and the degree to which they describe human neurochemistry remains an open question. The mechanism is best characterized as multi-system and not fully resolved.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Lyophilized Selank, the dry powder form, is generally stored frozen at minus 20 degrees Celsius or colder for long-term keeping. The solid is hygroscopic and should stay sealed, dry, and protected from light. Once dissolved, the peptide is less stable and is usually held refrigerated at 2 to 8 degrees Celsius for short periods. Repeated freezing and thawing is avoided because it can promote aggregation and loss of activity. Buffers and pH choice also affect how long a solution remains usable.
Solubility behavior is a practical concern for handling. Selank dissolves readily in water and in common aqueous buffers, which simplifies preparation of working solutions. The choice of solvent, ionic strength, and pH can influence aggregation over time, particularly at higher concentrations. Aqueous solutions are typically sterile-filtered before use. Because stability depends on several variables, storage and handling notes should be treated as general guidance rather than fixed rules, and specific values are best confirmed against a certificate of analysis for each batch.
Characterization of Selank in a laboratory setting relies on standard peptide methods. Reverse-phase high-performance liquid chromatography separates the target from related impurities and provides a purity figure, commonly reported as 95 percent or higher. Mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, confirms the molecular mass and helps detect truncation or modification. Amino acid analysis can verify composition when a sequence-level check is needed. These techniques together establish identity and purity for a given lot.
Naming conventions place Selank in the same research family as Semax, another Russian-developed peptide investigated for cognitive effects. The two compounds share a lineage but differ in sequence and in the biological systems proposed as their targets. Semax descends from ACTH fragments, whereas Selank descends from tuftsin. Publications sometimes identify Selank by its full peptide sequence or by laboratory codes rather than one uniform trade name. Because replication outside Russia is limited, reports on its properties are best read alongside the study design and the purity of the material tested.
Selank is a synthetic heptapeptide developed in Russia during the 1990s. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences designed it as a stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide. The compound has been studied primarily for its reported anxiolytic and nootropic effects. It remains largely unknown in Western pharmacology and is not approved as a medicine by major regulators such as the FDA or the EMA.
=== Other uses of the term === The word slavery is often used as a pejorative to describe any activity in which one is coerced into performing. Some argue that military drafts and other forms of coerced government labour constitute "state-operated slavery." Some libertarians and anarcho-capitalists view government taxation as a form of slavery. "Slavery" has been used by some anti-psychiatry proponents to define involuntary psychiatric patients, claiming there are no unbiased physical tests for mental illness and yet the psychiatric patient must follow the orders of the psychiatrist. They assert that instead of chains to control the slave, the psychiatrist uses drugs to control the mind. Drapetomania was a pseudoscientific psychiatric diagnosis for a slave who desired freedom; "symptoms" included laziness and the tendency to flee captivity. Some proponents of animal rights have applied the term slavery to the condition of some or all human-owned animals, arguing that their status is comparable to that of human slaves. The labour market, as institutionalized under contemporary capitalist systems, has been criticized by mainstream socialists and by anarcho-syndicalists, who utilise the term wage slavery as a pejorative or dysphemism for wage labour. Socialists draw parallels between the trade of labour as a commodity and slavery. Cicero is also known to have suggested such parallels.
Packaged breakfast cereals were considerably more convenient than a product that had to be cooked, and as a result of this convenience (and marketing that emphasized the point), they became popular. Battle Creek, Michigan, was a center both of the Seventh-day Adventist Church and of innovation in the ready-to-eat cereal industry, and indeed, the church had a substantial impact on the development of cereal goods through the person of John Harvey Kellogg (1851–1943). Son of an Adventist factory owner in Battle Creek, Kellogg was encouraged by his church to train in medicine at Bellevue Hospital Medical College in New York City in 1875. After graduating, he became medical superintendent at the Western Health Reform Institute in Battle Creek, established in 1866 by the Adventists to offer their natural remedies for illness. Many wealthy industrialists came to Kellogg's sanitarium for recuperation and rejuvenation. In Battle Creek sanitarium guests found fresh air, exercise, rest, hydrotherapy, a strict vegetarian diet, and abstinence from alcohol, tobacco, coffee, and tea. (They were accustomed to breakfasts of ham, eggs, sausages, fried potatoes, hot biscuits, hotcakes (pancakes), and coffee.) To supplement the center's vegetarian regimen, Kellogg experimented with granola. Soon afterwards he began to experiment with wheat, resulting in a lighter, flakier product. In 1891 he acquired a patent and then in 1895 he launched the Cornflakes brand, which overnight captured a national market. Soon there were forty rival manufacturers in the Battle Creek area. His brother William K.
== Investigation == It was found that the only nurse who had cared for all five of the patients and had been there within 2 hours of them becoming catastrophically ill was Norris. Norris had been one of the few who was on duty at the time of Hall's deterioration in health. Police analysed medical staff rotas, phone records and personnel files to determine who had access to the wards, insulin and who was on the wards at the time of that incident, and it was found that all staff members except Norris could be ruled out as it was only Norris who was on duty when all the incidents occurred. He was also the only staff member who worked on both the wards where the incidents occurred. Norris admitted predicting the time of Hall's death to his colleague but said it was because he had a "black sense of humour". Investigators ordered the exhumation of the body of Bridget Bourke, which, significantly, revealed that she had been given large amounts of insulin. The other two patients who had died had their bodies cremated, so could not be tested. Norris was suspended from his job (on full pay) while the police investigation was carried out. After he was first arrested, Norris immediately left Leeds and went back to Scotland, before then leaving the UK eight times to go abroad, including to Tenerife for a six-month holiday. After his conviction his partner recounted an incident around this time when Norris became violent and drunk, and wouldn't stop crying because he said he was scared of going to prison.
Like many other biologically active substances, norepinephrine exerts its effects by binding to and activating receptors located on the surface of cells. Two broad families of norepinephrine receptors have been identified, known as alpha and beta-adrenergic receptors. Alpha receptors are divided into subtypes α1 and α2; beta receptors into subtypes β1, β2, and β3. All of these function as G protein-coupled receptors, meaning that they exert their effects via a complex second messenger system. Alpha-2 receptors usually have inhibitory effects, but many are located pre-synaptically (i.e., on the surface of the cells that release norepinephrine), so the net effect of alpha-2 activation is often a decrease in the amount of norepinephrine released. Alpha-1 receptors and all three types of beta receptors usually have excitatory effects.
=== Other === During a G7 foreign ministers' meeting in Canada on 11 November 2025, the French foreign minister, Jean-Noël Barrot, criticized US military operations in the Caribbean, saying they violated international law and could contribute to regional instability. He was quoted as saying, "We have observed with concern the military operations in the Caribbean region, because they violate international law and because France has a presence in this region through its overseas territories, where more than a million of our compatriots reside," without citing specific US actions, and said that it was crucial to avoid "instability caused by potential escalations". Canadian officials distanced the Canadian military and intelligence personnel from the strikes. Sources speaking to CNN said that Canada did not want its intelligence used for the strikes but that it intended to continue its partnership with the Coast Guard under Operation Caribbe. A Department of National Defence spokesperson stated that "Canadian Armed Forces activities under Operation Caribbe, conducted in co-ordination with the United States Coast Guard, are separate and distinct", referencing the strikes on suspected drug boats. On 12 November, when foreign affairs minister, Anita Anand, was asked whether Canada was withholding intelligence from Washington on narcotics trafficking in Latin America, she responded: "The US has made it clear it is using its own intelligence.
Sources: en.wikipedia.org
== Reactions == The imidazole groups on TCDI can be easily displaced, allowing it to act as a safer alternative to thiophosgene. This behaviour has been used in the Corey–Winter olefin synthesis. It may also replace thioacyl chlorides (RC(S)Cl) in the Barton–McCombie deoxygenation. Other uses include the synthesis of thioamides and thiocarbamates. Like the analogous CDI, it may be used for peptide coupling.
==== Brands and forms ==== Oxymorphone was marketed by Endo Pharmaceuticals, under the brand name(s) Opana and Opana ER. Opana ER was withdrawn by the manufacturer in 2017 due to an FDA request, making it unavailable in the US. However, both IR (immediate release) and ER (extended release) formulations are still available under the generic names Oxymorphone and Oxymorphone ER and available from a multitude of manufacturers. Oxymorphone is also available as an injectable for inpatient use, available for IV (intravenous), IM (intramuscular), and SC (subcutaneous) injection. An extended release (ER) modified-release dosage form is commonly used, which modifies the pharmacokinetics of the drug.
Opioids agonists can also reduce the secretion of peptides by increasing the sympathetic nervous system through the μ-receptors in the ENS, which can lead to drier and harder stool. PAMORAs work against it so the stool becomes softer and less dry. PAMORAs effect on the function of the sphincter is in theory to regulate the movement coordination. The antagonist can prevent sphincter of Oddi dysfunction that is caused by opioids. Antagonists can also reduce opioid-induced anal sphincter dysfunction. The dysfunction is tied to straining, hemorrhoids and incomplete emptying.
=== Physical activity === Weight loss may improve MASLD and is recommended particularly for obese or overweight people; similar physical activities and diets are advisable for overweight people with MASLD as for other obese and overweight people. Although physical activity is less important for weight loss than dietary adaptations (to reduce caloric intake), the NICE advises physical activity to reduce liver fat even if there is no overall bodyweight reduction. Weight loss, through exercise or diet, is the most effective way to reduce liver fat and help MASH and fibrosis remission. Exercise alone can prevent or reduce hepatic steatosis, but it remains unknown whether it can improve all other aspects of the liver; hence a combined approach with diet and exercise is advised. Aerobic exercise may be more effective than resistance training, although there are contradictory results. Vigorous training is preferable to moderate training, as only the high-intensity exercise reduced the chances of MASLD developing into MASH or advanced fibrosis. The EASL recommends between 150 and 200 min/week in 3 to 5 sessions of moderate-intensity aerobic physical activity or resistance training. Since both effectively reduce liver fat, a pragmatic approach to physical activity that accounts for the individual's preferences for a sustainable physical activity that they can maintain long-term is preferred. Any increase in physical activity over previous levels is better than remaining sedentary.
== History == Belgian microbiologist Philibert Melchior Joseph Ehi Biourge was the first to describe P. rubens in 1923. The medicinal importance was discovered by Alexander Fleming, a physician at St Mary's Hospital, London. In September 1928, Fleming found that one of his bacterial cultures (of Staphylococcus aureus) was contaminated with mould, and that the area around the mould inhibited bacterial growth. He gave the name penicillin for the purported antibacterial substance produced by the mould. After a series of experimental tests, he published his discovery in the June 1929 issue of the British Journal of Experimental Pathology. With the help of his colleague Charles J. La Touche, Fleming identified the fungus as Penicillium rubrum. But Charles Thom at the U. S. Department of Agriculture, Peoria, Illinois, compared the specimen with his collection of Penicillium species, and corrected the species as P. notatum. In his publication in 1931, he resolved that P. notatum was a member of P. chrysogenum species complex, which he had described in 1910. P. notatum was described by Swedish chemist Richard Westling in 1911. Thom adopted and popularised the use of P. chrysogenum. After discovery of other new species and taxonomic reexamination, three species, P. notatum, P. meleagrinum, and P. cyaneofulvum were recognised as P. chrysogenum. The Seventeenth International Botanical Congress held in Vienna, Austria, in 2005 adopted the name P. chrysogenum as the conserved name (nomen conservandum).
Sources: en.wikipedia.org
Reports describe effects on GABA-A receptor expression, monoamine turnover, and neurotrophic factor levels. These are proposed mechanisms drawn mainly from animal models. No single molecular target has been established.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.