This is a working overview of Intranasal delivery, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-02-02. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | Tuftsin analogue with a C-terminal Pro-Gly-Pro tail |
| Amino acid sequence | Thr-Lys-Pro-Arg-Pro-Gly-Pro | Abbreviated TKPRPGP in most catalogues |
| Molecular mass | About 752 Da | Value for the free peptide |
| Solubility | Freely soluble in water | Aqueous solutions are kept cold and used promptly |
| Typical storage | -20 °C, dry, protected from light | Applies to the lyophilised powder before reconstitution |
Laboratory work relies on standard behavioral paradigms. Rodents are tested in the elevated plus maze, open field, and passive avoidance tasks, with outcomes compared against diazepam or vehicle controls. Intranasal dosing is used most often because it bypasses first-pass metabolism, though intraperitoneal and intravenous routes also appear in published protocols. Biochemical endpoints include tissue BDNF concentrations, cytokine levels, and monoamine metabolites. Human data are limited to small Russian trials reporting reduced anxiety scores; most were not prospectively registered, and few employed independent outcome assessment.
Measuring peptide exposure inside the brain is technically difficult. Selank is degraded rapidly in plasma, and assays must separate intact peptide from fragments, which favors targeted mass spectrometry over immunoassays alone. Reported half-lives are short, on the order of minutes, so effects observed hours later are attributed to downstream signaling rather than to the parent compound. Blood-brain barrier permeability is debated and rarely quantified directly. Gaps include absent dose-response characterization, inconsistent reporting of purity, and almost no pharmacokinetic data from human participants.
Selank is studied chiefly as an animal-model anxiolytic with proposed secondary effects on memory and immune signaling. Reported mechanisms include modulation of the GABA-A receptor complex, inhibition of enkephalin-degrading enzymes, and shifts in monoamine turnover within limbic structures. Some experiments describe increased expression of brain-derived neurotrophic factor in the hippocampus after repeated dosing. No single molecular target has been confirmed, and the peptide does not bind any receptor with the selectivity typical of a conventional small-molecule drug. Mechanism therefore remains a set of hypotheses rather than an established pathway.
Published clinical work is concentrated in Russian-language journals and generally involves small samples without independent replication. Systematic reviews in English note the shortage of randomised, placebo-controlled trials and the difficulty of verifying methods from translated reports. Outcome measures vary between studies, which complicates pooling of results. Interest in the compound as a cognitive or anxiolytic agent therefore rests on a thinner evidence base than the volume of citations suggests. Replication in well-powered trials with preregistered endpoints would be needed before firm conclusions about efficacy can be drawn.
Proposed mechanisms centre on the GABAergic system. Animal and tissue studies report changes in GABA-A receptor expression and reduced activity of GABA transaminase, the enzyme that degrades GABA. Effects on monoamine turnover, including serotonin and dopamine pathways, are also described, and a separate line of work links the peptide to increased expression of brain-derived neurotrophic factor in hippocampal tissue. Most of these findings come from rodent models and cell preparations. How the individual observations combine into a single coherent mode of action is not settled.
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.
== Scope == Medical genetics encompasses many different areas, including clinical practice of physicians, genetic counselors, and nutritionists, clinical diagnostic laboratory activities, and research into the causes and inheritance of genetic disorders. Examples of conditions that fall within the scope of medical genetics include birth defects and dysmorphology, intellectual disabilities, autism, mitochondrial disorders, skeletal dysplasia, connective tissue disorders, cancer genetics, and prenatal diagnosis. Medical genetics is increasingly becoming relevant to many common diseases. Overlaps with other medical specialties are beginning to emerge, as recent advances in genetics are revealing etiologies for morphologic, endocrine, cardiovascular, pulmonary, ophthalmologist, renal, psychiatric, and dermatologic conditions. The medical genetics community is increasingly involved with individuals who have undertaken elective genetic and genomic testing.
==== Step 3: Capping ==== The capping step is performed by treating the solid support-bound material with a mixture of acetic anhydride and 1-methylimidazole or, less often, DMAP as catalysts and, in the phosphoramidite method, serves two purposes.
=== United Kingdom === Since 15 January 2025 it is covered by the UK's generic definition on 2-benzyl benzimidazole derived opioids because it contains the 2-(2-benzyl-benzimidazol-1-yl)ethanamine backbone with only the following modification:
MicroRNAs (miRNAs) are small RNAs that typically are partially complementary to sequences in metazoan messenger RNAs. Binding of a miRNA to a message can repress translation of that message and accelerate poly(A) tail removal, thereby hastening mRNA degradation. The mechanism of action of miRNAs is the subject of active research.
Several genetic and environmental risk factors exist for developing an addiction. Genetic and environmental risk factors each account for roughly half of an individual's risk for developing an addiction; the contribution from epigenetic risk factors to the total risk is unknown. Even in individuals with a relatively low genetic risk, exposure to sufficiently high doses of an addictive drug for a long period of time (e.g., weeks–months) can result in an addiction.
Sources: en.wikipedia.org
=== Alkylation === Although the sulfur atom is relatively unreactive, the flanking carbon centers, the 2- and 5-positions, are highly susceptible to attack by electrophiles. Halogens give initially 2-halo derivatives followed by 2,5-dihalothiophenes; perhalogenation is easily accomplished to give C4X4S (X = Cl, Br, I). Thiophene brominates 107 times faster than does benzene. Acetylation occurs readily to give 2-acetylthiophene, precursor to thiophene-2-carboxylic acid and thiophene-2-acetic acid. Chloromethylation and chloroethylation occur readily at the 2,5-positions. Reduction of the chloromethyl product gives 2-methylthiophene. Hydrolysis followed by dehydration of the chloroethyl species gives 2-vinylthiophene.
== Clinical indications == TOPS is generally indicated for patients with lumbar spinal stenosis, with or without grade I spondylolisthesis. Higher-grade instability is usually treated with spinal fusion rather than motion-preserving devices.
Vicuña wool is considered the rarest and most expensive legal wool in the world; in 2010, raw wool traded for about 7-15 dollars per ounce. The sorted and spun yarn trades at about $300 per ounce. It is usually processed in its natural color, as the structure of vicuña hair suffers from bleaching or dyeing. Northern populations of vicuñas display a more cinnamon-like coat color on the back, southern ones a beige hue; the hair on the belly represents a smaller portion that is much lighter in color. White wool is traded at higher prices. In addition to knitted sweaters and socks, vicuña wool is also used to weave fabrics that are made into exclusive tailored clothing. A sport coat can cost up to $21,000, a made-to-measure suit starts at $32,000.
== Society and culture == Certain preparations of famotidine are available over-the-counter (OTC) in various countries. In the United States and Canada, 10 mg and 20 mg tablets, sometimes in combination with an antacid, are available OTC. Larger doses still require a prescription. Famotidine is generally restricted to prescription only in the United Kingdom, although the medication is legally allowed to be sold OTC to persons aged over 16 in supplies lasting no more than a fortnight. Formulations of famotidine in combination with ibuprofen were marketed by Horizon Pharma under the trade name Duexis.
Sources: en.wikipedia.org
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, especially Aspergillus species such as Aspergillus flavus and Aspergillus parasiticus. According to the USDA, "They are probably the best known and most intensively researched mycotoxins in the world." The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, maize (corn), peanuts, coffee, wheat, millet, sorghum, cassava, rice, chili peppers, cottonseed, tree nuts, sesame seeds, sunflower seeds, and various cereal grains and oil seeds. They have been found in both pet and human foods, as well as in feedstocks for agricultural animals. Animals fed contaminated food can pass aflatoxin transformation products into milk, milk products, and meat. For example, contaminated poultry feed is the suspected source of aflatoxin-contaminated chicken meat and eggs in Pakistan. Children are particularly vulnerable to aflatoxin exposure, which is linked to immune suppression, stunted growth, delayed development, aflatoxicosis, and liver cancer. Some studies have reported an association between childhood stunting and aflatoxin exposure, although this link has not been consistently detected in all studies. Furthermore, a causal relationship between childhood stunting and aflatoxin exposure has yet to be conclusively shown by epidemiological studies, though such investigations are underway. Adults have a higher tolerance to exposure, but are also at risk. No animal species is known to be immune. Aflatoxins are among the most carcinogenic substances known.
Creatinine-based equations should be used with caution in cachectic patients and patients with cirrhosis. They often have very low muscle mass and a much lower creatinine excretion rate than predicted by the equations below, such that a cirrhotic patient with a serum creatinine of 0.9 mg/dL may have a moderately severe degree of chronic kidney disease. Estimated GFR (eGFR) is recommended by clinical practice guidelines and regulatory agencies for routine evaluation of GFR whereas measured GFR (mGFR) is recommended as a confirmatory test when more accurate assessment is required.
=== Modelling === Doillon started modelling at the age of 16, becoming the ambassador of Givenchy. She has since been the "face" of Vanessa Bruno, Eres, Mango, H&M, Miu Miu, JBrand, Barney's, Gap, Maje and Chloé. She was featured alongside Sophia Loren and Penélope Cruz in the Pirelli Calendar. Doillon has worked with photographers Inez and Vinoodh, Mario Sorrenti, Mario Testino, Terry Richardson, Bruce Webber, Paolo Reversi, Corinne Day, Mert and Marcus, Ryan McGinley and Glen Lunchford. She has collaborated with Lee Cooper and La Redoute as a creative consultant and designer for six collections.
== External links == Fluka ionophores for ion-selective electrodes Medical Information database Reference.MD Structures and Properties of Naturally Occurring Polyether Antibiotics, J. Rutkowski, B. Brzezinski; open access review article Polyether ionophores—promising bioactive molecules for cancer therapy, A. Huczyński; open access review article Archived 2019-03-29 at the Wayback Machine
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Sources: en.wikipedia.org
Selank is a seven-amino-acid peptide built from the tuftsin sequence plus a Pro-Gly-Pro tail. It is produced by chemical synthesis rather than extracted from a natural source. The free peptide is usually supplied as a lyophilised powder or in an aqueous formulation.
Tuftsin is a natural tetrapeptide derived from the Fc portion of immunoglobulin G. Selank retains that tetrapeptide at its N-terminus and adds three residues to improve resistance to enzymatic breakdown. The relationship is structural, and the two molecules are not interchangeable in experimental work.
It holds a product registration in Russia for intranasal use as an anxiolytic. Registrations of that kind are not automatically accepted by regulators elsewhere. In most other countries it is treated as an unapproved substance or a research material.
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.