If you have been reading about anxiolytic 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 2025-12-31. Numbers and descriptions here follow the published literature rather than marketing material.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed as a stabilized analogue of tuftsin, a naturally occurring tetrapeptide fragment derived from the immunoglobulin heavy chain. The additional Pro-Gly-Pro segment at the carboxyl terminus is intended to slow enzymatic cleavage. The compound is usually described in the literature as a synthetic peptide with anxiolytic and cognitive-related activity, a label that reflects a research context rather than an approved therapeutic category.
Characterization of Selank in laboratory settings relies on standard peptide analytical techniques. Reverse-phase high-performance liquid chromatography separates the peptide from related impurities and degradation products, while mass spectrometry confirms molecular identity through accurate mass measurement. Amino acid analysis and peptide sequencing verify the primary structure when reference material is unavailable. Because Selank is a short chain, fragmentation-based analysis produces a diagnostic ion pattern that supports confident identification.
Peptide stability depends strongly on temperature, moisture, and pH. Lyophilized Selank is generally most stable when stored cold and dry, with freezer temperatures commonly used for long-term storage. In solution, the compound is susceptible to hydrolysis and to microbial growth if it is not handled aseptically. The C-terminal proline-rich extension appears to slow enzymatic cleavage relative to tuftsin, though quantitative degradation rates vary with the matrix and the conditions tested. Published stability data specific to Selank remain sparse.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Derived from the seven-residue sequence |
| Molecular weight | About 751.9 g/mol | Average mass; the monoisotopic value is slightly lower |
| Residue count | Seven amino acids | Thr-Lys-Pro-Arg-Pro-Gly-Pro |
| Parent compound | Tuftsin (Thr-Lys-Pro-Arg) | Selank extends tuftsin at the C-terminus |
| Compound class | Synthetic short peptide | Studied in a research setting; not a licensed drug in most markets |
Purity assessment relies mainly on reverse-phase high-performance liquid chromatography with ultraviolet detection. Because the peptide lacks a strong chromophore, detection often uses backbone absorbance near 214 nm. Identity is confirmed by mass spectrometry, typically electrospray ionization or matrix-assisted laser desorption, comparing the measured mass against the expected value. Amino acid analysis can verify composition after acid hydrolysis. Diastereomer content and residual counterions are reported less often, although both can influence biological assays.
Lyophilized material is generally stable for extended periods when kept dry at or below minus twenty degrees Celsius. Working solutions are less stable, and common practice is to aliquot and freeze them so that repeated freeze-thaw cycles are avoided. Aqueous solutions are sensitive to pH extremes and to microbial growth, so short-term storage at refrigerator temperature is typical. Oxidation and hydrolysis are the principal degradation routes. Reconstitution with sterile water or a mild buffer is standard, and solutions should be protected from light.
Regulatory treatment varies by jurisdiction. In Russia the compound is a registered prescription product, while in the European Union and the United States it is generally handled as a research chemical without a marketing authorization. Suppliers therefore operate outside pharmaceutical oversight, and buyers rely on supplier documentation for purity and identity claims. Chain of custody and third-party testing are the main verification tools. Analysts note that the absence of a pharmacopoeial monograph for research-grade material limits standardization across vendors.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Reported activity for Selank centers on anxiolytic and nootropic effects. Russian clinical reports describe use in anxiety and in cognitive or attention-related complaints. Most of this evidence comes from studies conducted by the same research groups that developed the peptide. Independent replication in other countries remains limited, and no major Western regulatory agency has approved the compound for any indication. The gap between local reports and external verification is a recurring point in discussions of the peptide.
Tuftsin, the parent structure, is a naturally occurring immunomodulatory tetrapeptide released from the Fc region of immunoglobulin G by spleen enzymes. Selank extends this four-residue sequence with three additional amino acids. The stated rationale is that the added tail slows enzymatic breakdown and may influence receptor interactions. How the full heptapeptide behaves at the molecular level is not firmly established, and proposed mechanisms often involve indirect modulation of neurotransmitter or immune signaling rather than a single defined target.
Published clinical evidence is limited. Most controlled trials were conducted in Russia, enrolled modest numbers of participants, and appeared in Russian-language journals, which restricts independent verification. Reported outcomes include lower anxiety scores, improved attention and memory measures, and changes in fatigue ratings. Reviews written in English note methodological limitations such as small samples and inconsistent endpoints. Whether the compound produces clinically meaningful benefit relative to established anxiolytics is therefore an open question rather than an established finding.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. It was designed at the Institute of Molecular Genetics of the Russian Academy of Sciences as a structural analogue of tuftsin, a naturally occurring tetrapeptide fragment of the immunoglobulin heavy chain. The added Pro-Gly-Pro tail was intended to slow enzymatic degradation and extend biological activity. In Russia it is registered as an anxiolytic nasal preparation, while regulators elsewhere have not approved it for clinical use.
Proposed mechanisms centre on modulation of the GABAergic system, with reports of altered expression of genes related to GABA-A receptor subunits and changed monoamine turnover. Some studies describe inhibition of enkephalinase, the enzyme that degrades endogenous enkephalins, which may prolong opioid peptide signalling. Effects on brain-derived neurotrophic factor and on cytokine expression have also been reported. These findings come largely from animal models and small human studies, and the precise primary target remains unresolved.
The pancreas plays a vital role in the digestive system. It does this by secreting pancreatic juice, a fluid that contains digestive enzymes, into the duodenum, the first part of the small intestine that receives food from the stomach. These enzymes help to break down carbohydrates, proteins and lipids (fats). This is the exocrine role of the pancreas. The cells responsible for this are acinar cells arranged in clusters called acini. Secretions into the middle of the acinus accumulate in intralobular ducts, which drain to the main pancreatic duct, which drains directly into the duodenum. About 1.5–3 liters of fluid are secreted in this manner every day. The cells in each acinus are filled with granules containing the digestive enzymes. These are secreted in an inactive form termed zymogens or proenzymes. When released into the duodenum, they are activated by the enzyme enterokinase present in the lining of the duodenum. The proenzymes are cleaved, creating a cascade of activating enzymes.
This reaction engages penile reflexes (such as erection and ejaculation) that aid in sperm competition when more than one male is present in mating encounters, allowing for more production of successful sperm and a higher chance of reproduction.
Despite the vulture crisis, diclofenac remains available in other countries including many in Europe. It was controversially approved for veterinary use in Spain in 2013 and continues to be available, despite Spain being home to around 90% of the European vulture population and an independent simulation showing that the drug could reduce the population of vultures by 1–8% annually. Spain's medicines agency presented simulations suggesting that the number of deaths would be quite small. A paper published in 2021 identified the first authenticated death of a vulture from diclofenac in Spain, a cinereous vulture. Diclofenac is on the European Union's watch list because it pollutes the Baltic Sea. When the substance enters fresh water, it has an environmental impact and is considered more difficult to remove in wastewater treatment plants than, for example, ibuprofen. Diclofenac has been shown also to harm freshwater fish species such as rainbow trout. Harmful residues have been found in fish, blue mussels, and other aquatic organisms, where it has been found to cause damage to internal organs such as the gills, kidneys and liver.
Sources: en.wikipedia.org
Carbon monoxide and phosphorus trifluoride are poisonous to humans because they bind to hemoglobin similarly to oxygen, but with much more strength, so that oxygen can no longer be transported throughout the body. Hemoglobin bound to carbon monoxide is known as carboxyhemoglobin. This effect also plays a minor role in the toxicity of cyanide, but there the major effect is by far its interference with the proper functioning of the electron transport protein cytochrome a. The cytochrome proteins also involve heme groups and are involved in the metabolic oxidation of glucose by oxygen. The sixth coordination site is then occupied by either another imidazole nitrogen or a methionine sulfur, so that these proteins are largely inert to oxygen – with the exception of cytochrome a, which bonds directly to oxygen and thus is very easily poisoned by cyanide. Here, the electron transfer takes place as the iron remains in low spin but changes between the +2 and +3 oxidation states. Since the reduction potential of each step is slightly greater than the previous one, the energy is released step-by-step and can thus be stored in adenosine triphosphate. Cytochrome a is slightly distinct, as it occurs at the mitochondrial membrane, binds directly to oxygen, and transports protons as well as electrons, as follows:
Federal Prime Minister Milan Panić became frustrated with Milošević's domineering behaviour during diplomatic talks in 1992 and told Milošević to "shut up" because Milošević's position was officially subordinate to his position. Milošević later forced Panić to resign. This situation changed after 1997 when Milošević's second and last legal term as Serbian President ended. He then had himself elected Federal President, thus entrenching the power that he already de facto held. After the Federal Republic was reconstituted as a State Union, the new Assembly of the State Union was created. It was unicameral and was made up of 126 deputies, of which 91 were from Serbia and 35 were from Montenegro. The Assembly convened in the building of the old Federal Assembly of Yugoslavia, which now houses the National Assembly of Serbia. A direct, nationwide election was planned for 2005, but was subsequently delayed to 2006 in Montenegro and 2007 in Serbia to coincide with local parliamentary elections. Since the State Union dissolved before either was held, direct parliamentary elections were never held and the deputies were instead elected indirectly by the parliament of their respective republic. In 2003, after the constitutional changes and creation of the State Union of Serbia and Montenegro, a new President of Serbia and Montenegro was elected. He was also president of the Council of Ministers of Serbia and Montenegro. Svetozar Marović was the first and last President of Serbia and Montenegro until its breakup in 2006.
== Prognosis == The mortality rate from paracetamol overdose increases two days after the ingestion, reaches a maximum on day four, and then gradually decreases. Acidosis is the most important single indicator of probable mortality and the need for transplantation. A mortality rate of 95% without transplant was reported in patients who had a documented pH less than 7.30. Other indicators of poor prognosis include chronic kidney disease (stage 3 or worse), hepatic encephalopathy, a markedly elevated prothrombin time, or an elevated blood lactic acid level (lactic acidosis). One study has shown that a factor V level less than 10% of normal indicated a poor prognosis (91% mortality), whereas a ratio of factor VIII to factor V of less than 30 indicated a good prognosis (100% survival). Patients with a poor prognosis are usually identified for likely liver transplantation. Patients that do not die are expected to fully recover and have a normal life expectancy and quality of life. Fertility may deteriorate. There is evidence of acetaminophen gonadotoxicity and a persistent negative effect of poisoning on the ability to conceive due to deterioration in sperm quality (impaired sperm morphology) in a previously healthy person.
Sources: en.wikipedia.org
=== Recovery and aftercare === The time it takes for an individual to recover depends on the severity of the injury being treated and lasts anywhere from two weeks to two months, with a possibility of vigorous exercise being barred for up to six months. Distal femoral bone graft takes up to six months to heal.
=== Staff and infrastructure issues === In May 2024, The New Yorker published a feature article by staff writer Rachel Aviv that questioned aspects of Letby's conviction. Aviv highlighted chronic staffing shortages on the unit, noting that staff were "overtaxed" and that only one specialist neonatologist was available. She also referred to hygiene concerns, including an earlier inquest finding that an infant had died in 2014 after a breathing tube was inserted incorrectly, and drainage problems that caused blocked pipes and occasional sewage backflow in sinks, issues that had been raised by the defence at trial. Aviv also discussed a 2016 review by the Royal College of Paediatrics and Child Health (RCPCH) into increased mortality on the unit. After interviewing staff, the RCPCH concluded that medical and nursing staffing levels were inadequate and that the rise in mortality in 2015 was not confined to the neonatal unit. The report described Letby as "enthusiastic, capable and committed" and noted that staff were "very upset" about her removal from clinical duties. It characterised the suspicions held by some doctors as a "subjective view with no other evidence". In its public response, the hospital acknowledged problems with "staffing, competencies, leadership, team working and culture". Because of reporting restrictions linked to Letby's impending retrial, the online version of the New Yorker article was blocked for UK readers, a decision questioned in Parliament by Conservative MP David Davis.
Early in the twentieth century Walter Cannon, who had popularized the idea of a sympathoadrenal system preparing the body for fight and flight, and his colleague Arturo Rosenblueth developed a theory of two sympathins, sympathin E (excitatory) and sympathin I (inhibitory), responsible for these actions. The Belgian pharmacologist Zénon Bacq as well as Canadian and U.S. pharmacologists between 1934 and 1938 suggested that noradrenaline might be a sympathetic transmitter. In 1939, Hermann Blaschko and Peter Holtz independently identified the biosynthetic mechanism for norepinephrine in the vertebrate body. In 1945 Ulf von Euler published the first of a series of papers that established the role of norepinephrine as a neurotransmitter. He demonstrated the presence of norepinephrine in sympathetically innervated tissues and brain, and adduced evidence that it is the sympathin of Cannon and Rosenblueth. Stanley Peart was the first to demonstrate the release of noradrenaline after the stimulation of sympathetic nerves.
Sources: en.wikipedia.org
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, designed as a metabolically stabilized analogue of the endogenous tetrapeptide tuftsin. It has been studied mainly against anxiety-related and cognitive endpoints rather than as an approved medicine in most jurisdictions.
Tuftsin contains four residues, while selank carries an additional Pro-Gly-Pro segment at the carboxyl end. That extension is intended to reduce enzymatic cleavage. Comparative pharmacokinetic data in humans remain limited.
No single receptor target is widely accepted as the definitive mediator of the reported effects. Proposed contributors include GABAergic modulation, shifts in monoamine turnover, and altered neuropeptide degradation. The mechanism is treated in the literature as unresolved.
The most common approach combines reverse-phase liquid chromatography with mass spectrometry. Chromatography separates the components while mass spectrometry confirms the molecular mass. Peptide sequencing or tandem mass analysis can further verify the amino acid order.