If you have been reading about pharmacokinetics and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
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 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.
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 |
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.
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.
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.
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.
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.
Work on the game began with a Kickstarter funding campaign in 2015, before the developers were acquired by Microsoft Studios in 2018, supporting the developers to work on a version for the Xbox One. We Happy Few received mixed reviews from critics.
τν is the spectral optical depth in frequency, and τλ is the spectral optical depth in wavelength. Although absorbance is properly unitless, it is sometimes reported in "absorbance units", or AU. Many people, including scientific researchers, wrongly state the results from absorbance measurement experiments in terms of these made-up units.
== Pathway == This enzyme acts as the second step of a biochemical pathway initiated by the creation of N-acylphosphatidylethanolamine, by means of the transfer of an acyl group from the sn-1 position of glycerophospholipid onto the amino group of phosphatidylethanolamine. While NAPE-PLD contributes to the biosynthesis of several NAEs in the mammalian central nervous system, it is not clear if this enzyme is not responsible for the formation of the endocannabinoid anandamide, since NAPE-PLD knockout mice have been reported to have wild-type levels or very reduced levels of anandamide. The N-acylethanolamines released by this enzyme become potential substrates for fatty acid amide hydrolase (FAAH), which hydrolyzes the free fatty acids from ethanolamine. Defects in this enzyme can cause NAPE-PLD products such as anandamide to build up to levels 15-fold higher than normally observed.
Sources: en.wikipedia.org
As a proof of concept orthogonal deprotection is demonstrated in a photochemical transesterification by trimethylsilyldiazomethane utilizing the kinetic isotope effect: Due to this effect the quantum yield for deprotection of the right-side ester group is reduced and it stays intact. Significantly by placing the deuterium atoms next to the left-side ester group or by changing the wavelength to 254 nm the other monoarene is obtained.
== Medical uses == Seven controlled efficacy trials were conducted of vilazodone for treatment of major depressive disorder. Five of these trials showed no significant influence of vilazodone over placebo on depressive symptoms. In the remaining two trials, small but significant advantages of vilazodone over placebo were found. According to these two eight-week trials in adults, vilazodone has an antidepressant response after one week of treatment. After eight weeks it resulted in a 13% greater response than placebo. Remission rates, however, were not significantly different versus placebo. According to the US Food and Drug Administration (FDA) in 2011, "it is unknown whether vilazodone has any advantages compared to other drugs in the antidepressant class." A 2019 review stated that "present studies do not suggest the superiority of vilazodone compared with other antidepressants." Development of vilazodone for generalized anxiety disorder has been stopped as of 2017. While there is tentative evidence of a small benefit in generalized anxiety disorder, there is a high rate of side effects.
=== Non-TB conditions === Tentative evidence exists for a beneficial non-specific effect of intradermal BCG vaccination on overall mortality in low-income countries, or for its reducing other health problems including sepsis and respiratory infections when given early, with greater benefit the earlier it is used. There is also tentative evidence of intravesical (injected into the bladder) BCG providing some protection against future dementia.
The Captagon was all destroyed by the new government; "Khattab", a pseudonym of one of the former rebels said "We destroyed and burned it because it's harmful to people. It harms nature and people and humans." The New York Times reported in December 2021 that the Syrian Army's elite 4th Armoured Division, commanded by Maher al-Assad, the brother of Syrian President Bashar al-Assad, oversaw much of the production and distribution of fenethylline, among other drugs. The unit controlled manufacturing facilities, packing plants, and smuggling networks all across Syria, and had started to deal in crystal meth. The division's security bureau, headed by Maj. Gen. Ghassan Bilal, provided protection for factories and along smuggling routes to the port city Latakia and to border crossings with Jordan and Lebanon. Jihad Yazigi, editor of The Syria Report, reported that fenethylline had "probably become Syria's most important source of foreign currency."
Sources: en.wikipedia.org
In 2016, Tim Hortons announced that they would be opening stores in the United Kingdom starting in 2017. Glasgow saw the first UK store open its doors on June 2, 2017, with a further store opening in Bishopbriggs in November 2017. In November 2017, two stores in Cardiff opened, as well as a store opening in Dunfermline. In December 2017, two further stores were opened in Trafford in the towns of Sale and Altrincham. On December 20, 2017, the chain opened a store in the Golden Square Shopping Centre in Warrington. Tim Hortons opened its first two stores in Northern Ireland in 2018: one on Fountain Street in Belfast city centre, and another drive-thru store at the Connswater Retail Park in East Belfast. With the opening of the Braintree and Stockport (Greater Manchester) branches in February 2022, Tim Hortons had 47 locations in the United Kingdom. By January this had increased to 73 locations, with at least a further three locations in development. In March 2023 they opened a branch in Westwood Cross in Thanet, Kent. The first Tim Hortons location in the Republic of Ireland was reported to be opening in Limerick in 2022, however this did not materialize.
In September 2025, following an Israeli strike against suspected Hamas terrorists in Qatar's capital city of Doha, President Trump signed an executive order which stated, "The United States shall regard any armed attack on the territory, sovereignty, or critical infrastructure of the State of Qatar as a threat to the peace and security of the United States." President Biden had begun a closer relationship with Qatar following their help with the 2001 American withdrawal from Afghanistan. In January 2022, Biden named Qatar a major non-NATO ally. The editorial board of The Wall Street Journal wrote, "This is a decision that can be and should have been debated. Instead it comes out of the blue — an executive order following no public debate." In October, Defense Secretary Hegseth announced a training agreement that the Qatar Air Force will build a facility at the Mountain Home Air Force Base in Idaho. The United States has a similar arrangement with Singapore, at the same base. Hegseth emphasized that the U.S. will remain in charge of the facility "like we do with all partners".
Various leukocytes, particularly neutrophils, are critically involved in the initiation and maintenance of inflammation. These cells must be able to move to the site of injury from their usual location in the blood, therefore mechanisms exist to recruit and direct leukocytes to the appropriate place. The process of leukocyte movement from the blood to the tissues through the blood vessels is known as extravasation and can be broadly divided up into a number of steps:
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.