A practical reference on Intranasal route: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-03-25 and is reviewed periodically as new material appears.
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.
Clinical evidence comes mainly from small studies conducted in Russia, several of which were open-label or lacked robust blinding. Reported outcomes include lower anxiety scores, changes in attention measures, and effects on asthenic states following illness. Sample sizes are typically in the tens of participants, and independent replication outside the region is scarce. Reviews published in English generally note the limited methodological quality of the underlying trials. Whether the compound produces clinically meaningful effects under rigorous conditions remains unresolved.
Pharmacokinetic data are sparse and largely derived from animal work. After intranasal administration the peptide appears in plasma within minutes, and reported half-lives are short, on the order of minutes to tens of minutes. Degradation proceeds through ordinary proteolytic cleavage into constituent amino acids and smaller fragments. Direct evidence that intact Selank reaches brain tissue in meaningful amounts is limited, and the extent of blood-brain barrier penetration is debated. Some authors argue that fragments, not the parent peptide, carry much of the observed activity.
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.
| Property | Value | Notes |
|---|---|---|
| Route studied | Intranasal | Predominant route in published reports |
| Circulation stability | Short, minutes scale | Peptidases cleave it; the tail slows the process |
| Analytical method | RP-HPLC with mass spectrometry | Used for identity and purity assessment |
| Reported outcome domains | Anxiety and cognitive measures | Derived from small, mostly regional trials |
| Regulatory status | Marketed in Russia | Availability outside that market is limited |
Handling follows standard practice for research peptides. Material is weighed in a low-humidity environment because the powder absorbs atmospheric moisture. Purity is reported as the percentage area of the main peak in a chromatogram, with specifications commonly set at 95 percent or higher; values below that threshold indicate the presence of truncated or modified species. Residual trifluoroacetate from purification is often present and may affect mass balance. Certificates of analysis should state the analytical method, the column and gradient used, and the lot-specific retention time so that results can be compared across suppliers.
Identity and purity of selank are established with reversed-phase high-performance liquid chromatography coupled to mass spectrometry. The peptide elutes from C18 columns with acetonitrile gradients in water containing trifluoroacetic acid or formic acid, and detection is usually performed by ultraviolet absorbance near 214 nm. Electrospray ionization in positive mode gives a doubly protonated ion near m/z 377, consistent with a mass of about 752 Da. Amino acid analysis or tandem mass spectrometry of fragment ions confirms the sequence. Because the molecule has no aromatic residues, it lacks a usable 280 nm chromophore, so low-wavelength detection or mass spectrometry is required.
Peptide bonds in selank are susceptible to hydrolysis under strongly acidic or basic conditions, and the terminal proline residues are vulnerable to exopeptidase activity in biological samples. Lyophilized powder stored dry at -20 °C typically remains stable for extended periods, whereas aqueous solutions degrade faster and may lose measurable purity within days to weeks depending on pH, temperature, and microbial load. Repeated freeze-thaw cycles promote aggregation and adsorption to container surfaces. For analytical work, solutions are usually prepared fresh, kept cold, and used within a single working day.
Most published work on selank originates from a small number of research groups in the Russian Federation. A large share of that record appears in Russian-language journals, which limits access for readers who rely on English-indexed databases. Independent replication by laboratories outside the original research network is sparse in publicly available sources. This concentration of origin and language is a frequently noted feature when the compound is summarized in broader reviews of synthetic peptides.
Reported pharmacological effects center on reduced anxiety-like behavior in animal models and on measures of memory and learning. Proposed contributing mechanisms include modulation of GABAergic signaling, shifts in monoamine turnover, and changes in the activity of enzymes that degrade neuropeptides. Effects on the expression of genes linked to neuroplasticity have also been described. No single molecular target is widely accepted, and whether the behavioral findings arise from one pathway or several remains an open question.
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.
In cellular biology, haptotaxis (from Greek ἅπτω (hapto) 'touch, fasten' and τάξις (taxis) 'arrangement, order') is the directional motility or outgrowth of cells, e.g. in the case of axonal outgrowth, usually up a gradient of cellular adhesion sites or substrate-bound chemoattractants (the gradient of the chemoattractant being expressed or bound on a surface, in contrast to the classical model of chemotaxis, in which the gradient develops in a soluble fluid). These gradients are naturally present in the extracellular matrix (ECM) of the body during processes such as angiogenesis, or artificially present in biomaterials where gradients are established by altering the concentration of adhesion sites on a polymer substrate.
=== Human Diseases and Gene Mutations === Greenspan has conducted various research projects directly on the molecular bases of human diseases. A collaborative study with a group at Jefferson Medical College showed mutations in the COL7A1 gene, for type VII collagen, to be the basis of the disabling and fatal skin disease dystrophic epidermolysis bullosa These studies also led to elucidation of the complete intron-exon structure of COL7A1 which at the time had more exons than any previously described gene. His lab was the first to clone and characterize the α1 chain of type V collagen and was also key in the first demonstration that mutations in a type V collagen gene can cause the heritable connective tissue disorder classic Ehers-Danlos syndrome. Accompanying and following these studies, the Greenspan lab has performed studies on collagen V genes and on the biosynthesis of type V collagen and on the molecular mechanisms whereby mutations in type V collagen result in defects in mammalian tissues. Their studies have also shown autoimmunity against type V collagen to be involved in organ transplant rejection and atherosclerosis, and that induction of immune tolerance to type V collagen can help ameliorate atherosclerosis. The Greenspan lab was also the first to clone and characterize the α3 chain of type V collagen and showed the α3(V) chain to be important to the functioning of certain highly specialized cell types and to be important to tumor growth and survival times in breast cancer.
On August 6, 1945, the uranium-type nuclear weapon codenamed "Little Boy" was detonated over the Japanese city of Hiroshima with an energy of about 15 kilotons of TNT (63,000 gigajoules), destroying nearly 50,000 buildings (including the headquarters of the 2nd General Army and Fifth Division) and killing approximately 70,000 people, including 20,000 Japanese combatants and 20,000 Korean slave laborers. Three days later, on August 9, a plutonium-type nuclear weapon codenamed "Fat Man" was used against the Japanese city of Nagasaki, with the explosion equivalent to about 20 kilotons of TNT (84,000 gigajoules), destroying 60% of the city and killing approximately 35,000 people, including 23,200–28,200 Japanese munitions workers, 2,000 Korean slave laborers, and 150 Japanese combatants. The industrial damage in Nagasaki was high, partly owing to the inadvertent targeting of the industrial zone, leaving 68–80 percent of the non-dock industrial production destroyed. The U.S., despite not having a third device ready to be dropped, gave Japan one last warning that there would be another bombing if they did not surrender, and the target would be Tokyo. Six days after the detonation over Nagasaki, Japan announced its surrender to the Allied Powers on August 15, 1945, signing the Instrument of Surrender on September 2, 1945, officially ending the Pacific War and, therefore, World War II, as Germany had already signed its Instrument of Surrender on May 8, 1945, ending the war in Europe.
Dihexa (developmental code PNB-0408; also known as N-hexanoic-Tyr-Ile-(6) aminohexanoic amide) is an oligopeptide drug derived from angiotensin IV that binds with high affinity to hepatocyte growth factor (HGF) and potentiates its activity at its receptor, c-Met. The compound has been found to potently improve cognitive function in animal models of Alzheimer's disease-like mental impairment. In an assay of neurotrophic activity, dihexa was found to be seven orders of magnitude more potent than brain-derived neurotrophic factor. According to a patent, "Short duration safety studies with dihexa have uncovered no apparent toxicity. Of particular note is a lack of neoplastic induction, since c-Met is recognized as an oncogene. This is unsurprising since oncogenesis requires multiple mutations including both oncogene induction and tumor suppressor attenuation."
Sources: en.wikipedia.org
Pyridine carboxylic acids: The pyridine carboxylic acids are more acidic than benzoic acid. They undergo reactions ordinarily associated with carboxylic acids, i.e. esterification, amide formation, acid chloride formation. Vinylpyridines: The dominant reaction of 2-vinylpyridine is its copolymerization with styrene and butadiene for the production of rubber tires.
Primary reconstruction: to correct the breast hemisphere by repairing chest-and-breast tissues damaged by breast cancer, by blunt trauma and penetrating trauma, by a blast injury, and the failed anatomic development of the chest, such as a tuberous breast deformity. Revision and reconstruction: to correct the unsuccessful outcome of a previous mammoplasty procedure. Primary augmentation: to enhance the aesthetic qualities of the breasts (cup-size, form, and texture). The type of breast reconstruction approach is determined by the severity of the mastectomy. The type of breast-augmentation surgery is determined by the procedure for emplacing the prosthetic breasts, the type of surgical incision, the type and model of the prosthetic breast, and the location of the implant-pocket in the chest of the woman.
=== Pharmacokinetics === Following oral administration, sarcosine is absorbed from the gastrointestinal tract. It is metabolised to glycine primarily by SARDH in the mitochondrial matrix and to a lesser extent by PIPOX in peroxisomes.
Two major sources of noise in PET are scatter (a detected pair of photons, at least one of which was deflected from its original path by interaction with matter in the field of view, leading to the pair being assigned to an incorrect LOR) and random events (photons originating from two different annihilation events but incorrectly recorded as a coincidence pair because their arrival at their respective detectors occurred within a coincidence timing window). In practice, considerable pre-processing of the data is required – correction for random coincidences, estimation and subtraction of scattered photons, detector dead-time correction (after the detection of a photon, the detector must "cool down" again) and detector-sensitivity correction (for both inherent detector sensitivity and changes in sensitivity due to angle of incidence). Filtered back projection (FBP) has been frequently used to reconstruct images from the projections. This algorithm has the advantage of being simple while having a low requirement for computing resources. Disadvantages are that shot noise in the raw data is prominent in the reconstructed images, and areas of high tracer uptake tend to form streaks across the image. Also, FBP treats the data deterministically – it does not account for the inherent randomness associated with PET data, thus requiring all the pre-reconstruction corrections described above.
Lean finely textured beef (LFTB)—also called finely textured beef, boneless lean beef trimmings (BLBT), and colloquially known as pink slime—is a meat by-product used as a food additive to ground beef and beef-based processed meats, as a filler, or to reduce the overall fat content of ground beef. As part of the production process, heat and centrifuges remove the fat from the meat in beef trimmings. The resulting paste, without the fat, is exposed to ammonium hydroxide or citric acid to kill bacteria. In 2001, the United States Department of Agriculture (USDA) approved the product for limited human consumption. The product, when prepared using ammonia gas, is banned for human consumption in Canada, and production of all mechanically separated meat from ruminants, including cattle, is prohibited in the European Union. In March 2012, an ABC News series about "pink slime" included claims that approximately 70% of ground beef sold in US supermarkets contained the additive at that time. Some companies and organizations stopped offering ground beef with the product. "Pink slime" was claimed by some originally to have been used as pet food and cooking oil and later approved for public consumption, but this was disputed in April 2012, by both the Food and Drug Administration (FDA) administrator responsible for approving the product, and by Beef Products, Inc. (BPI), the largest US producer of the additive. In September 2012, BPI filed a defamation lawsuit against ABC for false claims about the product. By 2017, BPI was seeking $1.9 billion in damages.
Sources: en.wikipedia.org
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.
Intranasal delivery is the route described in most published work. It is used because the peptide is degraded quickly once it reaches circulation. Direct evidence of brain penetration in humans is lacking.
Most trials are small, regionally concentrated, and often lack rigorous blinding or placebo control. Independent replication is limited. Reviews in English generally rate the evidence as preliminary.
Reports describe modulation of GABA signalling, changes in monoamine turnover and effects on neurotrophic factor expression. These observations come mainly from animal and cell studies. A single unifying mechanism has not been demonstrated.