The short version of Intranasal route fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-07-19. Anything still debated is marked as such rather than presented as settled.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro, frequently abbreviated as TKPRPGP. It was designed as a structural analogue of tuftsin, a naturally occurring tetrapeptide released by enzymatic cleavage of the immunoglobulin heavy chain. The two additional proline residues at the C-terminal end extend the parent chain and change how the molecule behaves in solution. The free peptide has a calculated molecular mass of approximately 751.9 g/mol and is generally supplied as a lyophilised white to off-white powder.
Development work on the compound began in the 1980s and 1990s at the Institute of Molecular Genetics in Moscow, within the same research programme that produced the peptide Semax. Early investigators sought a tuftsin derivative with improved resistance to enzymatic breakdown and with activity in the central nervous system after peripheral administration. Most of the primary literature from this period was published in Russian, a factor that still shapes how easily the findings can be checked by outside groups.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue |
| Sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Single-letter form: TKPRPGP |
| Molecular formula | C33H57N11O9 | Calculated for the free peptide |
| Molecular weight | About 751.9 g/mol | Derived from the sequence |
| Appearance | White to off-white powder | Typical lyophilised form |
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.
The compound has a calculated molecular weight near 751.9 daltons and carries a net positive charge at physiological pH because of its arginine residue. It dissolves freely in water and in common aqueous buffers, and typically appears as a white or off-white lyophilized powder. The amide backbone makes the molecule susceptible to peptidases, which limits oral use and favors intranasal or parenteral routes. Nomenclature in the literature varies: the substance is also described by the sequence abbreviation TP-7 and by a Russian trade designation.
Regulatory status differs sharply by region. Selank holds a Russian marketing authorization, where it is supplied mainly as nasal drops, while authorities elsewhere have not approved it for medical use. Material sold internationally is therefore usually labeled as a research chemical rather than a medicine. Peer-reviewed publications come predominantly from Russian laboratories, and sample sizes are generally small. Whether the compound produces comparable effects under independent, well-controlled replication remains an open question that the broader literature has not settled.
== History == Examination of cells in body fluids was historically performed using a hemocytometer, a chamber designed for counting cells microscopically. This technique was limited by poor discrimination between cell types (cells could only be classified as mononuclear or polymorphonuclear) and the low number of cells present in unconcentrated body fluids. Moreover, this technique did not produce a permanent record of the specimen. In a 1966 paper, Watson P. described the first cytocentrifuge, calling it "an apparatus for concentrating cells in suspension onto a microscope slide". The device was sold commercially in the 1970s and in 1983 it was patented by Shandon (now Thermo Scientific). As of 2012, numerous brands of cytocentrifuge exist on the market.
Combinatorial chemistry involves simultaneously synthesizing a large number of related compounds for high-throughput analysis. Chemical biologists are able to use principles from combinatorial chemistry in synthesizing active drug compounds and maximizing screening efficiency. Similarly, these principles can be used in areas of agriculture and food research, specifically in the syntheses of unnatural products and in generating novel enzyme inhibitors.
=== SSRIs and SNRIs === Both selective serotonin reuptake inhibitors (SSRI) and serotonin and norepinephrine reuptake inhibitors (SNRI) are reuptake inhibitors of a class of nerve signal transduction chemical called neurotransmitters. Serotonin and norepinephrine are neurotransmitters that are related to nervous control in mood regulation. The level of these neurotransmitters is regulated by the nerve through reuptake to avoid accumulation of the neurotransmitter at the endings of nerve fibers. By reuptaking the neurotransmitter, the level of neuronal activity will go back down and be ready to go back up upon excitation from a new nerve signal. However the neurotransmitter level of patients with anxiety disorders is usually low or the patients' nerve fibers are insensitive to the neurotransmitters. SSRIs and SNRIs will then block the channel of reuptake and increase the level of the neurotransmitter. The nerve fibers will inhibit further production of neurotransmitters upon the increase. However the prolonged increase will eventually desensitize the nerve about the change in level. Therefore, the action of both SSRIs and SNRIs will take 4–6 weeks to exert their full effect.
Sources: en.wikipedia.org
The body is able to substantially reduce the amount of iron it absorbs across the mucosa. It does not seem to be able to entirely shut down the iron transport process. Also, in situations where excess iron damages the intestinal lining itself (for instance, when children eat a large quantity of iron tablets produced for adult consumption), even more iron can enter the bloodstream and cause a potentially deadly syndrome of iron overload. Large amounts of free iron in the circulation will cause damage to critical cells in the liver, the heart and other metabolically active organs. Iron toxicity results when the amount of circulating iron exceeds the amount of transferrin available to bind it, but the body is able to vigorously regulate its iron uptake. Thus, iron toxicity from ingestion is usually the result of extraordinary circumstances like iron tablet over-consumption[1] rather than variations in diet. The type of acute toxicity from iron ingestion causes severe mucosal damage in the gastrointestinal tract, among other problems. Excess iron has been linked to higher rates of disease and mortality. For example, breast cancer patients with low ferroportin expression (leading to higher concentrations of intracellular iron) survive for a shorter period of time on average, while high ferroportin expression predicts 90% 10-year survival in breast cancer patients. Similarly, genetic variations in iron transporter genes known to increase serum iron levels also reduce lifespan and the average number of years spent in good health.
==== SAINT ==== Possibly as a response to the Soviet programme, the United States began Project SAINT, which was intended to provide anti-satellite capability to be used in the case of war with the Soviet Union. However, less is known about the mission profiles of this project compared to the Soviet programme, and the project was cancelled due to budget constraints.
As of 2025, Pakistan's nominal GDP stood at US$407.79 billion, while GDP (PPP) was US$1.8 trillion in 2026. The nominal per capita GDP was US$1,700, and the GDP (PPP)/capita amounted to US$6,950 (international dollars). Around 44.7% of the population live below the international poverty line of US$4.20 a day, 16.5% live in extreme poverty on less than US$3 a day, 8% of the total labour force is unemployed, and CPI inflation in 2025 was 4.5%. Pakistan ranks near the bottom globally on the Global Gender Gap Index's economic participation and opportunity sub-index for women, reflecting very low female labour force participation and limited representation of women in senior economic roles. Pakistan's middle class is estimated to be around 40–50 million people, representing 15–20 per cent of the population. Among South Asian countries, Pakistan's GDP growth rate of 2.5% in 2024 was the second lowest after Afghanistan. Pakistan has strong potential to produce diverse food commodities due to its vast natural resource base across varied ecological and climatic zones. It has the world's 7th-largest labour force, and its diaspora of around 10 million, sent US$38.3 billion in remittances in fiscal year 2024–25, as reported by the Special Investment Facilitation Council. Pakistan's share of global exports averaged 0.14% between 1990 and 2023 and was 0.12% in 2023.
Sources: en.wikipedia.org
The sequence is Thr-Lys-Pro-Arg-Pro-Gly-Pro, commonly written as TKPRPGP. It shares the first four residues with tuftsin and carries three prolines in the chain. The proline-rich tail is the main structural feature that separates it from the parent tetrapeptide.
Selank is a synthetic analogue built on the tuftsin tetrapeptide Thr-Lys-Pro-Arg. Extra proline residues were added to the C-terminus during design work. That modification is intended to make the peptide less vulnerable to rapid enzymatic degradation.
Transliteration from Russian produces variant spellings such as Selanc. Many suppliers avoid the trade-style name entirely and list the peptide sequence. Comparing sequences rather than names is the reliable way to confirm two entries describe the same molecule.
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.