A practical reference on intranasal delivery: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-11-19 and is reviewed periodically as new material appears.
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.
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 |
|---|---|---|
| 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 |
Lyophilised material kept dry at minus 20 degrees Celsius or colder is the most stable form, and suppliers commonly state a shelf life of two years or more under those conditions. Once dissolved, degradation accelerates through hydrolysis and deamidation, particularly at alkaline pH or elevated temperature. Working solutions are usually divided into single-use aliquots to avoid repeated freeze-thaw cycles. The choice of reconstitution solvent affects both stability and the ionic strength of the final preparation.
Reverse-phase high-performance liquid chromatography with ultraviolet detection near 214 nanometres is the standard purity method. Mass spectrometry, typically electrospray ionisation, confirms identity through the expected mass-to-charge pattern. Amino acid analysis can verify composition independently. Chiral purity requires separate techniques such as derivatisation followed by chromatographic separation, and such data are rarely reported for research-grade material.
Quantification in biological matrices relies on liquid chromatography coupled to tandem mass spectrometry with stable-isotope internal standards. Low plasma concentrations and adsorption to container surfaces both complicate measurement. Solid-phase extraction is often needed to reduce matrix interference before injection. Reported limits of quantification differ widely between laboratories, which makes direct comparison of pharmacokinetic results difficult and limits meta-analysis.
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.
Selank is a synthetic heptapeptide with the sequence Thr-Lys-Pro-Arg-Pro-Gly-Pro. Its four N-terminal residues reproduce tuftsin, a tetrapeptide fragment of the immunoglobulin heavy chain, while the C-terminal Pro-Gly-Pro extension is a synthetic addition. The peptide has a molecular mass near 752 daltons and carries a net positive charge at physiological pH because of the arginine and lysine side chains. Published indexes list it under the name Selank and the sequence abbreviation TKPRPGP. Solid-phase peptide synthesis is the standard production route for research quantities.
Development took place at the Institute of Molecular Genetics of the Russian Academy of Sciences, where a series of short peptides were designed in the 1980s and 1990s. Selank was selected from variants of tuftsin that showed resistance to plasma peptidases. Russian regulatory approval covers it as an anxiolytic agent given intranasally. Outside that market the compound is normally handled as a research chemical rather than a medicine, and no widely recognised international pharmacopoeial monograph exists. The name Selank is a coined trade designation rather than a systematic chemical name.
Enzymatic stability motivates the extra three residues at the carboxyl end. Native tuftsin is cleaved quickly by circulating aminopeptidases and carboxypeptidases, which limits its duration of action and its usefulness as a tool compound. Extending the chain with proline-rich segments is a common design tactic because proline constrains the backbone and slows proteolysis. The same Pro-Gly-Pro motif appears in other Russian-developed peptides of the era. Whether the full seven-residue chain is required for activity, or whether it acts mainly as a prodrug releasing tuftsin, remains unresolved.
==== Criticism ==== David Handelsman has criticized terminology and understanding surrounding AAS in many publications. According to Handelsman, the pharmaceutical industry attempted to dissociate the so-called "androgenic" and "anabolic" effects of AAS in the mid-20th-century in order to create non-masculinizing anabolic agents that would be more suitable for use in women and children. However, this effort was unsuccessful and was abandoned by the 1970s. This was related to the subsequent discovery of a single androgen receptor (AR) mediating the effects of AAS in both muscle and reproductive tissue. In addition, it was related to misinterpretation of flawed animal androgen bioassays that had been employed to distinguish between androgenic or virilizing effects and anabolic or myotrophic effects (i.e., the Hershberger assay involving the unrepresentative levator ani muscle). In actuality, all AAS have essentially similar AR-mediated effects, even if some AAS may vary in potency in certain tissues like skin, hair follicles, and prostate gland based on their susceptibility to 5α-reduction (and associated metabolic amplification, inactivation, or lack thereof). Per Handelsman, the terms "anabolic steroid" and "anabolic–androgenic steroid" are obsolete, meaningless, and falsely distinguish these agents from androgens when there is no physiological basis for such distinction. It has also been noted that the use and distinction of the concepts "anabolic" and "androgenic", as well as the term "anabolic–androgenic steroid", are oxymoronic.
=== Spectrum of activity and susceptibility data === Bacitracin is a narrow-spectrum antibiotic. It targets Gram-positive bacteria, especially those that cause skin infections. The following represents susceptibility data for a few medically significant microorganisms.
== Biological activity == Cortisol acts as an agonist of the corticosteroid receptors, including the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR). Cortisol is also an agonist of membrane corticosteroid receptors, including membrane glucocorticoid receptors (mGRs) and membrane mineralocorticoid receptors (mMRs). In addition to its corticosteroid receptor agonism, cortisol has been reported to be a highly potent biphasic regulator of the GABAA receptor, acting as a positive allosteric modulator at low concentrations (1–10 pM) and as a negative allosteric modulator at high concentrations (10–1,000 nM).
Sources: en.wikipedia.org
Later, in the 1970s, there was a high possibility of conflict between Chile and Peru, between Chile and Argentina, and between Peru and Ecuador, which were feared that they would become entangled in a war on a continental scale. During the government of the dictator Augusto Pinochet, there were tensions between the two countries, due not only to the geopolitical rivalry in the South Pacific and the nationalist sentiments of both countries, but also due to certain ideological differences between the right-wing Pinochet regime and the leftist regime of the Peruvian dictator, Juan Velasco Alvarado, in the framework of the Cold War, to whom the Chilean military leadership attributed a determined military will to recover the provinces of Arica and Tarapacá before the centenary of the War of the Pacific, even before the Coup de State against Allende. There is a record of at least 2 occasions in which Pinochet came to seriously consider the idea of starting a preventive war against Peru. In 1974, Pinochet summoned the General Staff of the National Defense of Chile to analyze the possibility of attempting a massive military attack on Peru (preventing the Peruvians from attacking first), however, he only obtained the support of the Army, but not that of the Navy or Air Force, whose officers feared the Peruvian military superiority of back then.
The idea of initiating the institute was elaborated in 1960 via high council of science, owing to the magnitude of schistosomiasis problem in Egypt specially in the rural population and its impact on the socioeconomic life. The objective of the institute was to tackle this diseases from all its aspects : control, diagnosis and management. In 1960, Ahmed Hafez Mousa, the real originator of the institute and one of the world's pioneers in the field of Tropical Medicine was charged to fulfill this idea. He appointed the Tropical Medicine Department at Kasr El Aini, Faculty of Medicine a preliminary location for a small nuclear start of this project. This was followed by the establishment of a "Laboratory for Schisosomiasis Research" in the chemistry building of the National Research Center. In April 1962, the foundation stone of the institute was implemented at Warak El Hader's village in Giza governorate. Meanwhile, the building of the institute was constructed by Egyptian Government, the laboratories and hospital were equipped through an agreement between the governments of Federal Republic of Germany and Egypt in 1964. The TBRI was built on 25,000 m2 formed of four main buildings in front of the west bank of the Great River Nile in Giza governorate. In 1977 The institute construction was accomplished, and opened for public, headed by Ali Zain El-Abdeen. in 1979. Ahmad Algarim became the head of the institute, and until 1987. In 1987, Aly Zain Al- Abdeen headed the institute and till his retirement in 1994.
For example, if the first residue is a phenylalanine then the enzyme chymotrypsin will cleave at site 1, and if the third residue of the tripeptide is a lysine then trypsin would cleave at the third cleavage site.
A highly abundant weed species in Papaver somniferum fields was shown to be Papaver rhoeas. Papaver somniferum and Papaver rhoeas are congeners and belong to the same plant family, which impedes the chemical control of this weed species. Therefore, weed management represents a big challenge and requires technological knowledge from the farmer. In order to increase the efficiency of weed control not only chemical weed control should be applied but also mechanical weed control. For P. somniferum, a growth density of 70 to 80 plants per square metre is recommended. Latex-to-biomass yield is greatest under conditions of slight water deficit.
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.
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.