A practical reference on Research chemical: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
Reviewed 2026-04-18. Anything still debated is marked as such rather than presented as settled.
Selank is a hydrophilic peptide and dissolves readily in water and in aqueous buffers. The lyophilised powder is typically a white to off-white solid. Because short peptides are prone to hydrolysis and oxidation, handling benefits from limiting exposure to heat, moisture and strong light. Working solutions are commonly prepared in sterile water or saline, and repeated freeze-thaw cycles are avoided to reduce aggregation and loss of activity. These practices reflect general laboratory convention rather than published stability specifications.
Dry powder is normally held at -20 degrees Celsius or lower, in a sealed container with desiccant and protection from light. Reconstituted solutions are usually kept at 2 to 8 degrees Celsius for short periods and frozen for longer ones. Proline residues at several positions are generally associated with some resistance to peptidase attack, but chemical stability still declines at neutral to alkaline pH and at elevated temperature. Exact shelf-life figures are product-specific and are not standardised across suppliers.
Identity and purity are usually assessed by reversed-phase high-performance liquid chromatography, with mass spectrometry used to confirm molecular mass and sequence information. Amino acid analysis and peptide mapping may supplement these methods. Certified reference standards are scarce, and many commercial lots are sold as research chemicals without a pharmacopoeial monograph. Regulatory treatment differs by country: Selank is a registered prescription medicine in Russia, while in the European Union and the United States it is not an approved drug and may fall under research-chemical or unapproved-product frameworks.
Selank is a synthetic heptapeptide developed in Russia as a structural analogue of tuftsin, a naturally occurring immunomodulatory tetrapeptide. Its sequence, Thr-Lys-Pro-Arg-Pro-Gly-Pro, keeps the tuftsin core at the N-terminus and appends a Pro-Gly-Pro tail. Researchers at the Institute of Molecular Genetics in Moscow synthesized the compound during the 1990s while searching for peptides with combined anxiolytic and immunomodulatory activity. The added tail was intended to resist enzymatic cleavage and prolong the molecule's presence in circulation.
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.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid form |
| Solubility class | Freely soluble in water | Hydrophilic heptapeptide |
| Dry storage temperature | -20 degrees Celsius or lower | Sealed, desiccated, protected from light |
| Solution storage | 2 to 8 degrees Celsius short term | Avoid repeated freeze-thaw cycles |
| Common identification method | Reversed-phase HPLC with mass spectrometry | Confirms purity and molecular mass |
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.
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.
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.
Although rubidium is more abundant in Earth's crust than caesium, the limited applications and the lack of a mineral rich in rubidium limits the production of rubidium compounds to 2 to 4 tonnes per year. Several methods are available for separating potassium, rubidium, and caesium. The fractional crystallization of a rubidium and caesium alum (Cs,Rb)Al(SO4)2·12H2O yields after 30 subsequent steps pure rubidium alum. Two other methods are reported, the chlorostannate process and the ferrocyanide process. For several years in the 1950s and 1960s, a by-product of potassium production called Alkarb was a main source for rubidium. Alkarb contained 21% rubidium, with the rest being potassium and a small amount of caesium. Today the largest producers of caesium produce rubidium as a by-product from pollucite.
Ranirestat (also known as AS-3201) is an aldose reductase inhibitor being developed for the treatment of diabetic neuropathy by Dainippon Sumitomo Pharma and PharmaKyorin. It has been granted orphan drug status. The drug is to be used orally.
As an antagonist at ionotropic AMPA, NMDA and Kainate glutamate receptors in the concentration range of 0.1-2.5 mM. As a noncompetitive antagonist at the glycine site of the NMDA receptor. As an antagonist of the α7 nicotinic acetylcholine receptor. However, recently (2011) direct recording of α7 nicotinic acetylcholine receptor currents in adult (noncultured) hippocampal interneurons by the Cooper laboratory validated a 2009 study that failed to find any blocking effect of kynurenic acid across a wide range of concentrations, thus suggesting that in noncultured, intact preparations from adult animals there is no effect of kynurenic acid on α7 nicotinic acetylcholine receptor currents. As a ligand for the orphan G protein-coupled receptor GPR35. As an agonist for the G protein-coupled receptor HCAR3.
Sources: en.wikipedia.org
=== Pseudohyperkalemia === Pseudohyperkalemia occurs when the measured potassium level is falsely elevated. Mechanical trauma during blood drawing can cause potassium leakage out of the red blood cells due to haemolysis of the blood sample. Fist clenching during the blood draw can cause a rise in potassium levels in the venous blood as it is sampled; this difference may be as much as 1 mmol/L. Differences of this order of magnitude cause problems (false positive results for clinically-important hyperkalemia) for patients with low glomerular filtration rate (GFR; a measure of kidney function), type IV renal tubular acidosis (RTA), or on evidence-based medication for cardio-renal risk (RASi, MRAs). The practice, widespread in laboratories in North America, should be discontinued. Prolonged storage of blood samples or agitation in transit is also associated with red cell lysis that can increase serum potassium levels. Hyperkalemia may become apparent when a person's platelet concentration is more than 500,000/microL in a clotted blood sample (serum blood sample). Potassium leaks out of platelets after clotting has occurred. A high white cell count (greater than 120,000/microL) in people with chronic lymphocytic leukemia increases the fragility of red blood cells, thus causing pseudohyperkalemia during blood processing. This problem can be avoided by processing serum samples, because clot formation protects the cells from haemolysis during processing.
=== Statistics === The OECD is known as a statistical agency, as it publishes comparable statistics on numerous subjects. In July 2014, the OECD publicly released its main statistical databases through the OECD Data Portal, an online platform that allows visitors to create custom charts based on official OECD indicators. OECD statistics are available in several forms:
Glutathione S-transferase A2 is an enzyme that in humans is encoded by the GSTA2 gene. Cytosolic and membrane-bound forms of glutathione S-transferase are encoded by two distinct supergene families. These enzymes function in the detoxification of electrophilic compounds, including carcinogens, therapeutic drugs, environmental toxins and products of oxidative stress, by conjugation with glutathione. The genes encoding these enzymes are known to be highly polymorphic. These genetic variations can change an individual's susceptibility to carcinogens and toxins as well as affect the toxicity and efficacy of some drugs. At present, eight distinct classes of the soluble cytoplasmic mammalian glutathione S-transferases have been identified: alpha, kappa, mu, omega, pi, sigma, theta and zeta. This gene encodes a glutathione S-transferase belonging to the alpha class. The alpha class genes, located in a cluster mapped to chromosome 6, are the most abundantly expressed glutathione S-transferases in liver. In addition to metabolizing bilirubin and certain anti-cancer drugs in the liver, the alpha class of these enzymes exhibit glutathione peroxidase activity thereby protecting the cells from reactive oxygen species and the products of peroxidation.
Sources: en.wikipedia.org
=== Pharmacokinetics === When inhaled, dimethocaine starts working in 10–30 minutes, with highest effects at 60–120 minutes and until 4–6 hours there is a period of action with the 'after-effects'. The after effects include fatigue and slight mental impairment.
=== Pharmacodynamics === Suvorexant acts as a selective dual antagonist of the orexin (hypocretin) receptors OX1 and OX2. These receptors are the biological targets of the endogenous wakefulness-promoting orexin neuropeptides orexin-A and orexin-B. The binding affinities (Ki) of suvorexant at the human orexin receptors are 0.55 nM for the OX1 receptor and 0.35 nM for the OX2 receptor. The antagonistic potencies or functional inhibition (Kb) of suvorexant at the human orexin receptors are 65 nM for the OX1 receptor and 41 nM for the OX2 receptor. Hence, suvorexant shows similar affinities and antagonistic activities at the OX1 and OX2 receptors in vitro. Suvorexant is highly selective for the orexin receptors over a large number of other targets (170 screened off-target receptors, enzymes, and transporters). In contrast to certain other sedatives and hypnotics, suvorexant is not a benzodiazepine or Z-drug and does not interact with GABA receptors.
Also, there is no surface tension in a supercritical fluid, as there is no liquid/gas phase boundary. By changing the pressure and temperature of the fluid, the properties can be "tuned" to be more liquid-like or more gas-like. One of the most important properties is the solubility of material in the fluid. Solubility in a supercritical fluid tends to increase with density of the fluid (at constant temperature). Since density increases with pressure, solubility tends to increase with pressure. The relationship with temperature is a little more complicated. At constant density, solubility will increase with temperature. However, close to the critical point, the density can drop sharply with a slight increase in temperature. Therefore, close to the critical temperature, solubility often drops with increasing temperature, then rises again.
Sources: en.wikipedia.org
Dry powder is normally held at -20 degrees Celsius or below in a sealed, light-protected container with desiccant. Brief room-temperature handling during weighing is generally tolerated. Storage instructions vary between suppliers, so the accompanying certificate of analysis should be followed.
Reversed-phase HPLC establishes purity, while mass spectrometry confirms the expected molecular mass. Sequence confirmation may use tandem mass spectrometry or peptide mapping. A certificate of analysis typically reports these results alongside the analytical method applied.
In Russia it is a registered medicine available by prescription. In many other countries it is not approved for human use and is supplied only as a research chemical. Import and possession rules differ by jurisdiction, and buyers are responsible for checking local requirements.
Selank is a synthetic seven-amino-acid peptide modeled on tuftsin, a fragment of the immunoglobulin G heavy chain. It was designed in Russia to combine anxiolytic and immunomodulatory properties in one molecule.