If you have been reading about Intranasal delivery 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.
Last reviewed on 2026-07-28. Where a claim depends on a specific study, the study is described rather than over-claimed.
Published work on this peptide almost always uses intranasal delivery, with drops or a spray applied to the nasal mucosa. Some animal experiments have used subcutaneous or intraperitoneal injection, and a smaller number have compared routes directly. Oral administration is not a focus of the literature, because short peptides of this size are broken down by digestive enzymes and cross intestinal barriers poorly. How much of an intranasal dose reaches the bloodstream intact in humans remains an open question.
Animal studies have examined behaviour in tests of anxiety, memory retention and stress response, and several report changes in neurotrophic or neurotransmitter-related markers. The human evidence base is much smaller, consisting mainly of short trials conducted in Russia with limited reporting in English-language journals. Sample sizes are modest and outcome measures vary between studies, so the findings are best described as preliminary. Independent replication under modern trial standards has not been widely reported.
Outside its country of origin the compound is generally handled as a research chemical rather than an approved medicine. No regulatory approval from the United States Food and Drug Administration or the European Medicines Agency has been granted for human use. Identity and purity are normally checked by reverse-phase high-performance liquid chromatography, with mass spectrometry used to confirm the molecular mass. Lyophilised material is stored cold and desiccated, and repeated freeze-thaw cycles are avoided.
The primary structure of Selank is Thr-Lys-Pro-Arg-Pro-Gly-Pro, corresponding to the molecular formula C33H57N11O9 and a monoisotopic mass of roughly 751.9 daltons. The N-terminal threonine and the arginine residue in the fourth position are shared with tuftsin, which carries the sequence Thr-Lys-Pro-Arg. The three additional residues at the C-terminus, Pro-Gly-Pro, extend the chain and are associated with greater resistance to enzymatic degradation. This extension also separates Selank from the shorter parent peptide.
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.
| Property | Value | Notes |
|---|---|---|
| Common route | Intranasal | Also injected in some animal work |
| Solubility class | Freely soluble in water | Solid form is hygroscopic |
| Typical storage | About -20 degrees Celsius | Keep desiccated and dark |
| Purity method | Reverse-phase HPLC | Reported as area percent |
| Confirmatory method | Mass spectrometry | Verifies expected molecular mass |
Selank is a synthetic heptapeptide developed in Russia. Its sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, a seven-residue chain built around the natural tetrapeptide tuftsin. Researchers at the Institute of Molecular Genetics of the Russian Academy of Sciences first described the compound in the mid-1990s. The design combined the tuftsin core with an added Pro-Gly-Pro tail, a modification intended to extend the molecule's stability in biological fluids. Published work on the peptide has appeared mainly in Russian-language journals.
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.
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.
Quality assessment of Selank samples typically combines purity determination with identity confirmation and counter-ion analysis. Purity is usually reported as a percentage by chromatographic area, with values above 95 percent often quoted for research-grade material. Water content and residual solvents are checked in lyophilized batches because they affect both stability and accurate mass determination. A reported purity figure does not by itself establish that a sample is the intended sequence, so orthogonal methods are needed to rule out sequence isomers or truncation products.
Protactinium (91Pa) has no stable isotopes. As 231Pa occurs in usable quantity, and comprises virtually all of the element, it defines the standard atomic weight. Thirty radioisotopes of protactinium have been characterized, ranging from 210Pa to 239Pa. The most stable isotopes are 231Pa with a half-life of 32,700 years, 233Pa with a half-life of 26.975 days, and 230Pa with a half-life of 17.4 days. All of the remaining radioactive isotopes have half-lives less than 1.6 days, and the majority of these have half-lives less than 1.8 seconds. This element also has five meta states, 217mPa (t1/2 1.15 milliseconds), 220m1Pa (t1/2 = 308 nanoseconds), 220m2Pa (t1/2 = 69 nanoseconds), 229mPa (t1/2 = 420 nanoseconds), and 234mPa (t1/2 = 1.16 minutes). The only naturally occurring isotopes are 231Pa, 233Pa, 234Pa, and 234mPa. The first occurs as an intermediate decay product of 235U, the second of (rare) 237Np, and the last two as intermediate decay products of 238U. 231Pa dominates solely because of its longer life. The primary decay mode for protactinium isotopes lighter than (and including) the most stable isotope 231Pa is alpha decay to isotopes of actinium, except 228Pa to 230Pa, which primarily decay by electron capture to isotopes of thorium. The primary mode for the heavier isotopes is beta minus (β−) decay to isotopes of uranium.
Intracellular Ang II is generated within cardiac cells either through internalization of circulating Ang II or by intracellular synthesis via non-secreted renin and angiotensinogen. Unlike its extracellular counterpart, intracrine Ang II does not rely on traditional cell surface receptors; instead, it binds to nuclear AT1 receptors, modulating gene transcription and intracellular signaling pathways. Studies have demonstrated that intracrine Ang II localizes to the nucleus and mitochondria of cardiac myocytes, where it influences cellular metabolism, oxidative stress, and calcium homeostasis. Additionally, intracellular Ang II has been shown to enhance the transcription of genes involved in hypertrophy and fibrosis, contributing to pathological cardiac remodeling.
At the end of the fourth century, Ausonius enumerated Aquileia as the ninth among the great cities of the world, placing Rome, Constantinople, Carthage, Antioch, Alexandria, Trier, Mediolanum, and Capua before it. However, such prominence made it a target and Alaric and the Visigoths besieged it in 401, during which time some of its residents fled to the nearby lagoons. Alaric again attacked it in 408. Attila attacked the city in 452. During this invasion, on July 18, Attila and his Huns so utterly destroyed the city that it was afterwards hard to recognize its original site. The fall of Aquileia was the first of Attila's incursions into Roman territory; followed by cities like Mediolanum and Ticinum. The Roman inhabitants, together with those of smaller towns in the neighbourhood, fled en masse to the lagoons, where they laid the foundations of the cities of Venice and nearby Grado. Yet Aquileia would rise again, though much diminished, and continue to exist until the Lombards invaded in 568; the Lombards destroyed it a second time in 590. Meanwhile, the patriarch fled to the island town of Grado, which was under the protection of the Byzantines. When the patriarch residing in Grado reconciled with Rome in 606, those continuing in the Schism of the Three Chapters, rejecting the Second Council of Constantinople, elected a patriarch at Aquileia.
The republics would determine their own national-state and administrative territorial structure. The republics would also be given ownership of their natural resources, except gold and diamond resources, along with the right to establish direct diplomatic and trade relations with foreign states. The Republics and the central government would jointly determine military and foreign policy and work out policies on economy, fuel, and energy resources.
Sources: en.wikipedia.org
While AM could be an important biomarker for bacterial infections like sepsis, AM has diminished value in its utility for cardiovascular diseases (CVD), attributable to its minimal increase in these conditions and reduced half-life. AM is associated with controlling vascular integrity, blood pressure, and general cardiovascular function. Since AM has been noted for its exacerbated levels in intense diseases with an elevated concern for mortality, AM could still have some value as a predictive biomarker of harmful clinical consequences for an array of cardiovascular illnesses. AM has conservatory effects against arteriosclerosis and vascular harm. Extended AM administration or hyper-expression of its target gene in rodent model organisms diminishes vascular hyperplasia, fatty streak construction, and intimal expansion. AM also has angiogenic characteristics, leading to organ and tissue maintenance by reducing the risk of ischemic diseases. AM binds to particular receptors like calcitonin gene-related peptide (CGRP) receptors, which affects the cardiovascular system by contributing to vasodilation as well as elevated heart rate and blood pressure.
=== US NRC general license === US Nuclear Regulatory Commission regulations at 10 CFR 40.25 establish a general license for the use of depleted uranium contained in industrial products or devices for mass-volume applications. This general license allows anyone to possess or use depleted uranium for authorized purposes. Generally, a registration form is required, along with a commitment to not abandon the material. Agreement states may have similar, or more stringent, regulations.
== Medical uses == Canagliflozin is indicated to be used with diet and exercise to lower blood sugar in adults with type 2 diabetes; to reduce the risk of major heart-related events such as heart attack, stroke, or death in people with type 2 diabetes who have known heart disease; and to reduce the risk of end-stage kidney disease, worsening of kidney function, heart-related death, and being hospitalized for heart failure in certain people with type 2 diabetes and diabetic kidney disease. Canagliflozin is an anti-diabetic medication used to improve blood sugar control in people with type 2 diabetes. It is a third-line medication to metformin. Per the British National Formulary it is also less preferred than a sulfonylurea as of 2019, while the American Diabetes Association and European Association for the Study of Diabetes consider either a SGLT2 inhibitor or GLP-1 receptor agonist a reasonable second line medication in those with heart disease. Canagliflozin decreases HbA1c levels by 0.77% to 1.16% when given by itself, in combination with metformin, in combination with metformin and a sulfonylurea, in combination with metformin and pioglitazone, or in combination with insulin, from initial HbA1c levels of 7.8% to 8.1%. When added to metformin, canagliflozin does not appear worse than sitagliptin or glimepiride in reducing HbA1c levels, while canagliflozin maybe better than sitagliptin and glimiperide in decreasing HbA1c. It is unclear whether or not it has any unique cardiovascular benefits beyond lowering blood sugar.
Sources: en.wikipedia.org
== Pathology == Nerve biopsy would show axonal neuropathy, but it is no longer indicated. A muscle biopsy of critical illness myopathy would show selective loss of thick filaments in muscle, demonstrating the loss of myosin and the presence of muscle cell death (necrosis). When muscles lose stimulation from neurons, they can undergo degeneration. However, when critical illness myopathy occurs, it is not solely due to loss of innervation of the muscle. With critical illness myopathy, no other cause of the muscle degeneration can be found. Unlike Guillain–Barre syndrome, another neurological disorder that causes weakness, patients with critical illness polyneuropathy do not have loss of the myelin sheath that normally surrounds neurons (demyelination).
== Definition of statistical coupling energy == Statistical coupling energy measures how a perturbation of amino acid distribution at one site in an MSA affects the amino acid distribution at another site. For example, consider a multiple sequence alignment with sites (or columns) a through z, where each site has some distribution of amino acids. At position i, 60% of the sequences have a valine and the remaining 40% of sequences have a leucine, at position j the distribution is 40% isoleucine, 40% histidine and 20% methionine, k has an average distribution (the 20 amino acids are present at roughly the same frequencies seen in all proteins), and l has 80% histidine, 20% valine. Since positions i, j and l have an amino acid distribution different from the mean distribution observed in all proteins, they are said to have some degree of conservation. In statistical coupling analysis, the conservation (ΔGstat) at each site (i) is defined as:
===== Legal categorization and legal issues in a near future ===== Currently, both miRNA and SiRNA are currently chemically synthesized and so, are legally categorized inside EU and in USA as "simple" medicinal products. But as bioengineered siRNA (BERAs) are in development, these would be classified as biological medicinal products, at least in EU. The development of the BERAs technology raises the question of the categorization of drugs having the same mechanism of action but being produced chemically or biologically. This lack of consistency should be addressed.
Sources: en.wikipedia.org
Most published work uses intranasal application, either as drops or as a nasal spray. Injection routes appear in a smaller set of animal experiments. Oral use is uncommon in the literature because peptide breakdown and poor absorption limit this route.
Reported human trials are few, brief and originate mainly from one country. They describe effects on anxiety-related measures, but sample sizes are small and reporting is limited. The results are widely regarded as preliminary rather than confirmed.
Reverse-phase liquid chromatography is used to assess purity and separation of related impurities. Mass spectrometry confirms that the observed molecular mass matches the expected peptide. A certificate of analysis from the supplier is the usual document of record.
Selank is a synthetic heptapeptide designed as a stabilized analog of the natural tetrapeptide tuftsin. It has been investigated mainly for anxiolytic and cognitive effects. It is not an approved pharmaceutical in most countries.