Intranasal delivery raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
This page was last updated on 2025-08-11 and is reviewed periodically as new material appears.
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.
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.
Once dissolved, the peptide is markedly less stable than the dry powder. Aqueous solutions are subject to backbone hydrolysis and to microbial growth when they are handled without sterile technique. Buffered solutions near neutral pH are common for short-term laboratory work, while acidic conditions are sometimes used to improve solubility. Analytical laboratories generally prepare working solutions fresh rather than storing them, and a residual water film left in a reopened vial can seed degradation even when the container appears dry.
Reversed-phase high-performance liquid chromatography is the standard technique for estimating peptide purity. The result is a peak-area percentage, which describes how much of the detected material elutes as the main peak in one run. Mass spectrometry confirms the molecular mass and can reveal truncated, adducted, or otherwise modified species. Amino acid analysis or tandem mass spectrometry can address sequence fidelity when identity is in doubt. None of these measurements, taken alone, establishes that a sample is fit for any specific purpose.
Lyophilized selank is normally supplied as a dry powder and is considered stable for extended periods when kept cold and dry. Moisture uptake is the main practical threat, because absorbed water promotes both hydrolysis and aggregation in the solid state. Vials are usually warmed to room temperature before opening so that condensation does not form on the powder. Supplier documentation commonly specifies -20 °C for routine storage, with -80 °C used for material intended to be archived for years.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C33H57N11O9 | Free peptide form |
| Molecular mass | About 751.9 Da | Calculated average mass |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form TKPRPGP |
| Structural basis | Tuftsin analogue | Extended version of a natural tetrapeptide |
| Development origin | Russian Academy of Sciences | Work carried out from the 1980s onward |
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.
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.
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.
In all the places where they pretend to have the graveclothes, they show a large piece of linen by which the whole body, including the head, was covered, and, accordingly, the figure exhibited is that of an entire body. But the Evangelist John relates that Christ was buried, "as is the manner of the Jews to bury". What that manner was may be learned, not only from the Jews, by whom it is still observed, but also from their books, which explain what the ancient practice was. It was this: The body was wrapped up by itself as far as the shoulders, and then the head by itself was bound round with a napkin, tied by the four corners, into a knot. And this is expressed by the Evangelist, when he says that Peter saw the linen clothes in which the body had been wrapped lying in one place, and the napkin which had been wrapped about the head lying in another. The term napkin may mean either a handkerchief employed to wipe the face, or it may mean a shawl, but never means a large piece of linen in which the whole body may be wrapped. I have, however, used the term in the sense which they improperly give to it. On the whole, either the Evangelist John must have given a false account, or every one of them must be convicted of falsehood, thus making it manifest that they have too impudently imposed on the unlearned. Although pieces said to be of burial cloths of Jesus are held by at least four churches in France and three in Italy, none has gathered as much religious following as the Shroud of Turin.
Canada and Mexico in North America Japan, India, Bangladesh, Pakistan, Sri Lanka, China, Saudi Arabia, United Arab Emirates, Qatar, Philippines, Vietnam, Thailand, Malaysia, Singapore, Indonesia, Brunei, Hong Kong, Taiwan, South Korea, Myanmar, and Macau in Asia United Kingdom, Croatia, and the European Union in Europe Egypt in Africa Pizza Hut's China operations are part of the Yum! spinoff Yum China. Pizza Hut was one of the first American franchises to open in Iraq.
== Further reading == Bud, Robert. "Biotechnology in the Twentieth Century." Social Studies of Science 21.3 (1991), 415–457 doi:10.1177/030631291021003002. Bud, Robert (1989). "History of 'biotechnology". Nature. 337 (6202): 10. Bibcode:1989Natur.337...10B. doi:10.1038/337010a0. PMID 2909886. S2CID 4354445. Dronamraju, Krishna R. Biological and Social Issues in Biotechnology Sharing. Brookfield: Ashgate Publishing Company, 1998. ISBN 9781840148978. Feldbaum, Carl (2002). "Some History Should Be Repeated". Science. 295 (5557): 975. doi:10.1126/science.1069614. PMID 11834802. S2CID 32595222. Rasmussen, Nicolas, Gene Jockeys: Life Science and the rise of Biotech Enterprise, Johns Hopkins University Press, (Baltimore), 2014. ISBN 978-1-42141-340-2.
Different amino-acid sequences have different propensities for forming α-helical structure. Alanine, uncharged glutamate, leucine, charged arginine, methionine and charged lysine have especially high helix-forming propensities, whereas proline and glycine have poor helix-forming propensities. Proline either breaks or kinks a helix, both because it cannot donate an amide hydrogen bond (because it has none) and because its sidechain interferes sterically with the backbone of the preceding turn – inside a helix, which forces a bend of about 30° in the helix's axis. However, proline is often the first residue of a helix, presumably due to its structural rigidity. At the other extreme, glycine also tends to disrupt helices because its high conformational flexibility makes it entropically expensive to adopt the relatively constrained α-helical structure.
Sources: en.wikipedia.org
== Abuse == The abuse of exogenous insulin carries with it an attendant risk of hypoglycemic coma and death when the amount used is in excess of that required to handle ingested carbohydrate. Acute risks include brain damage, paralysis, and death. Symptoms may include dizziness, weakness, trembling, palpitations, seizures, confusion, headache, drowsiness, coma, diaphoresis and nausea. All persons with overdoses should be referred for medical assessment and treatment, which may last for hours or days. Data from the US National Poison Data System (2013) indicates that 89.3% of insulin cases reported to poison centers are unintentional, as a result of therapeutic error. Another 10% of cases are intentional, and may reflect attempted suicide, abuse, criminal intent, secondary gain or other unknown reasons. Hypoglycemia that has been induced by exogenous insulin can be chemically detected by examining the ratio of insulin to C-peptide in peripheral circulation. It has been suggested that this type of approach could be used to detect exogenous insulin abuse by athletes.
== External links == Large+Neutral+Amino+Acid-Transporter+1 at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Amino+Acid+Transport+System+L at the U.S. National Library of Medicine Medical Subject Headings (MeSH) This article incorporates text from the United States National Library of Medicine, which is in the public domain.
=== Water softener === The reduction of water hardness in laundry applications and the dissolution of scale in boilers both rely on EDTA and related complexants to bind Ca2+, Mg2+, as well as other metal ions. Once bound to EDTA, these metal complexes are less likely to form precipitates or to interfere with the action of the soaps and detergents. For similar reasons, cleaning solutions often contain EDTA. In a similar manner EDTA is used in the cement industry for the determination of free lime and free magnesia in cement and clinkers. The solvation of Fe3+ ions at or below near neutral pH can be accomplished using EDTA. This property is useful in agriculture including hydroponics. However, given the pH dependence of ligand formation, EDTA is not helpful for improving iron solubility in above neutral soils. Otherwise, at near-neutral pH and above, iron(III) forms insoluble salts, which are less bioavailable to susceptible plant species.
Sources: en.wikipedia.org
Some GLP-1 agonists, such as tirzepatide, are also agonists of the GIP receptor, glucagon receptor, and/or amylin receptor. These additional targets are hoped to increase the amount of weight loss the drugs cause.
== Chemistry == Naltrexone, also known as N-cyclopropylmethylnoroxymorphone, is a derivative of oxymorphone (14-hydroxydihydromorphinone). It is specifically the derivative of oxymorphone in which the tertiary amine methyl substituent is replaced with methylcyclopropane.
=== Uracil substitution for thymine === Whereas DNA contains thymine (T), RNA contains uracil (U). During the process of transcription, the enzyme RNA polymerase incorporates uracil opposite adenine bases located on the DNA template strand. Therefore, the resulting RNA transcript contains uracil in the positions where the coding DNA strand contains thymine. Structurally, uracil–adenine (U–A) base pairs closely resemble thymine–adenine (T–A) base pairs, which ensures that the genetic information carried by the sequence is faithfully preserved. A frequently cited explanation for the presence of thymine in DNA involves the necessity of genome maintenance. Because cytosine can spontaneously deaminate to form uracil, DNA repair systems recognize uracil as a form of damage. The utilization of thymine as a standard base allows the cell to distinguish legitimate bases from errors, thereby maintaining uracil as a specific signal for repair.
According to Travis Hirschi's social control theory, adolescents with stronger attachments to family, religious, academic, and other social institutions are less likely to engage in delinquent and maladaptive behavior, such as drug use leading to addiction.
Sources: en.wikipedia.org
It is a seven-amino-acid peptide, Thr-Lys-Pro-Arg-Pro-Gly-Pro, produced by chemical synthesis rather than extracted from biological tissue. Its design is based on tuftsin, a natural immunomodulatory tetrapeptide. The C-terminal Pro-Gly-Pro segment is a common stabilising motif in short regulatory peptides.
The core four residues correspond to tuftsin, which occurs naturally as part of immunoglobulin G. The full seven-residue sequence, however, is not a known endogenous peptide. It is a laboratory-designed analogue intended to combine tuftsin-like activity with greater resistance to breakdown.
No single receptor has been confirmed as the primary target. Reports describe involvement of the GABAergic system, interference with enkephalin degradation, and shifts in neurotrophic factor expression. Because these observations come from different models and assays, they have not yet been integrated into one accepted mechanism.
Sealed, desiccated storage at -20 °C or colder is the standard recommendation for research-grade material. Vials should reach room temperature before they are opened, which limits condensation. Repeated temperature cycling is discouraged.