intranasal delivery is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Pharmacokinetic accounts emphasize rapid breakdown. After intravenous dosing the intact peptide disappears from blood within minutes, and nasal delivery produces low but measurable concentrations. Metabolites rather than the parent molecule may account for part of the observed activity, although the relative contribution is unresolved. Dosing in the literature varies widely and no optimal schedule has been agreed. These gaps are regularly cited as a reason the findings have not produced broad clinical adoption beyond the original research setting.
Proposed mechanisms center on neurotrophic signaling rather than on classical melanocortin receptor activation. Rodent experiments have reported shifts in the expression of brain-derived neurotrophic factor and nerve growth factor after administration, together with changes in the associated receptor systems. Several authors argue that the peptide acts largely through its degradation products and their interaction with peptidergic pathways, but this remains a hypothesis rather than a settled finding. No single molecular target has been identified in a way that the field broadly accepts.
Published research covers ischemic stroke, traumatic brain injury, cognitive impairment, optic nerve conditions and attention-related measures. Much of the human evidence comes from small trials conducted in one country, which limits how far the results generalize. Animal models supply the larger share of the data, and effects seen in rodents do not transfer automatically to people. Reviews have noted that methodological reporting is often incomplete, making it difficult to pool results or compare treatment schedules across studies.
Later generations of the molecule include an N-acetylated form and an amidated form, both marketed online alongside the parent peptide. These variants differ in terminal chemistry and stability, and they are frequently discussed in the same breath even though they have not been compared in controlled trials. Supply outside formal healthcare systems comes largely from laboratories that synthesize peptides to order. Purity and identity of these materials vary widely, and no single body oversees the international trade.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
| Property | Value | Notes |
|---|---|---|
| Primary research models | Rodent studies | Largest share of published data |
| Reported markers | BDNF and NGF expression | Measured mainly in animal tissue |
| Common administration | Intranasal | Matches the registered formulation |
| Blood residence time | Minutes | Rapid enzymatic degradation |
| Evidence quality | Small trials, limited replication | Noted repeatedly in reviews |
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
Solid semax is typically supplied as a lyophilised powder that is hygroscopic and sensitive to moisture, light, and repeated temperature cycling. Long-term storage of the dry peptide is generally recommended at approximately -20 degrees Celsius, while shorter working periods may use refrigeration at 2 to 8 degrees Celsius. Vials should remain tightly closed and desiccated when brought to room temperature, because condensation can damage the material before it is weighed. Dividing a batch into aliquots is preferable to thawing one container repeatedly.
Dissolution is normally performed in water, phosphate-buffered saline, or normal saline, since the peptide is freely soluble in aqueous media and is rarely handled with strong organic solvents. Solution pH should be kept near neutral, because extreme acidity or alkalinity accelerates backbone hydrolysis and encourages oxidation of the methionine side chain. Once dissolved, the material is less stable than the dry powder and is commonly divided into single-use portions and frozen. Buffers containing primary amines, such as Tris, are often avoided because of possible side reactions.
Scientific literature on semax is unevenly distributed. A substantial share of published work originates from a small number of laboratories in Russia, while independent replication elsewhere is limited. Human data consist mostly of small trials with short follow-up, and several reported outcomes rely on subjective rating scales. Questions about how much intact peptide reaches the central nervous system after nasal administration, and how long it persists there, are still unresolved. The compound is best described as an active research subject rather than a settled pharmacological agent.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. It was derived from the ACTH(4-10) fragment, a short segment of adrenocorticotropic hormone that lacks the hormonal activity associated with the full-length peptide. Researchers at the Institute of Molecular Genetics in Moscow developed the compound during the 1980s. It has been registered as a pharmaceutical product in Russia and several neighbouring countries, where it is supplied as a nasal solution, and it is also sold internationally as a research chemical.
The proposed mechanism centres on neurotrophic signalling rather than direct receptor activation. Semax is reported to increase expression of brain-derived neurotrophic factor and nerve growth factor in several brain regions, and to shift the balance between excitatory and inhibitory neurotransmitter systems. Interaction with melanocortin receptors has been suggested because of the parent ACTH fragment. Many of these findings come from rodent studies, and the extent to which they translate to human physiology remains an open question.
=== Developmental stage === Adolescence is the period of greatest risk both for first use of an addictive drug and for the transition to disordered use. The prefrontal cortex, which supports planning, inhibitory control and the weighing of long-term consequences, develops more slowly than the brain's reward circuitry and is not fully mature until the mid-twenties. During this window sensitivity to reward is high while cognitive control is still developing, which contributes to greater risk-taking, including experimentation with drugs. Drug exposure in early adolescence can in turn disturb cortical development and delay prefrontal maturation, and prefrontal dysfunction in adolescents is itself associated with a higher risk of substance use disorder.
== Management == There is currently no cure for PFBC nor a standard course of treatment. The available treatment is directed symptomatic control. If parkinsonian features develop, there is generally poor response to levodopa therapy. Case reports have suggested that haloperidol or lithium carbonate may help with psychotic symptoms. One case report described an improvement with the use of a bisphosphonate.
The Northern Ireland Executive is restored after the DUP ends its two-year boycott; Sinn Féin's Michelle O'Neill is appointed First Minister, becoming the first nationalist politician to hold the post, while the DUP's Emma Little-Pengelly is appointed deputy. A third round of joint UK–US air strikes are launched against Houthi rebels, targeting three sites in Yemen. Defence Secretary Grant Shapps says the latest strikes are "not an escalation" of the conflict. Esther Martin, a 68-year-old woman, is killed by dogs while visiting her grandson for the weekend in Jaywick, near Clacton-on-Sea, Essex. 4 February – CCTV footage of alkali attack suspect Abdul Shakoor Ezedi in a Tesco store is shown by the police, as a reward of £20,000 is offered for information leading to his capture. 5 February Buckingham Palace announces that King Charles III has been diagnosed with cancer and will postpone public duties while undergoing treatment. The Met Office issues a yellow weather warning for snow for large parts of north Wales, and northern and central England, for 8 February as unseasonably mild temperatures are replaced by colder weather. A 16-year-old boy is found guilty of plotting to launch a terrorist attack at the Isle of Wight Festival following a trial at Kingston Crown Court. The UK government launches a six-week consultation on plans for Martyn's Law, which would make provisions to better protect the public against potential acts of terrorism.
Nandrolone is an agonist of the AR, the biological target of androgens like testosterone and DHTTooltip dihydrotestosterone. Unlike testosterone and certain other anabolic steroids, nandrolone is not potentiated in androgenic tissues like the scalp, skin, and prostate, hence deleterious effects in these tissues are lessened. This is because nandrolone is metabolized by 5α-reductase to the much weaker AR ligand 5α-dihydronandrolone (DHN), which has both reduced affinity for the androgen receptor (AR) relative to nandrolone in vitro and weaker AR agonistic potency in vivo. The lack of alkylation on the 17α-carbon drastically reduces the hepatotoxic potential of nandrolone. Estrogen effects resulting from reaction with aromatase are also reduced due to lessened enzyme interaction, but effects such as gynecomastia and reduced libido may still occur at sufficiently high doses. In addition to its AR agonistic activity, unlike many other anabolic steroids, nandrolone is also a potent progestogen. It binds to the progesterone receptor with approximately 22% of the affinity of progesterone. The progestogenic activity of nandrolone serves to augment its antigonadotropic effects, as antigonadotropic action is a known property of progestogens.
Flotufolastat (18F), sold under the brand name Posluma, is a radioactive diagnostic agent for use with positron emission tomography (PET) imaging for prostate cancer. The active ingredient is flotufolastat (18F). Flotufolastat (18F) was approved for medical use in the United States in May 2023.
Sources: en.wikipedia.org
In MM2K Phillips highly endorsed MET-Rx (a meal replacement supplement), and this relationship with readers helped it become the highest selling bodybuilding supplement ever at that time. It was later revealed however, that Phillips and the creator of MET-Rx, Dr. A. Scott Connelly, were in fact business partners, and the endorsements clever marketing. This partnership also included bodybuilders Lee Labrada and Jeff Everson. It was around this time that Phillips began working with James Bradshaw (later of SoCal Supplements). Bradshaw was convicted of dispensing human and animal steroids without prescriptions in 1986. This eventually would lead to Bradshaw serving four years in a Louisiana prison, where he educated himself on marketing. According to former Muscle Media 2000 editor-in-chief TC Luoma, it was Bradshaw who convinced Phillips to market MET-Rx heavily in the Natural Supplement Review, Phillips' supposedly unbiased review of numerous bodybuilding supplements. He also had the idea for Phillips to give the Review away for free to readers of Muscle Media 2000, thus obtaining the addresses of potential MET-Rx buyers and toward which a large amount of advertising may be targeted. Sales of MET-Rx rose exponentially. Bradshaw and Phillips had stumbled upon a very successful method of marketing to bodybuilders, and they, and original investors Everson and Connelly, got very wealthy. Their partnership was short-lived however.
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Glyn Ford and Jonathan Simnett, Silver from the Sea, September/October 1982, Volume 33, Number 5, Saudi Aramco World Archived 2006-11-12 at the Wayback Machine Accessed 17 October 2005 Ballard, Robert D., 2000, The Eternal Darkness, Princeton University Press. Csotonyi, J. T.; Stackebrandt, E.; Yurkov, V. (4 July 2006). "Anaerobic Respiration on Tellurate and Other Metalloids in Bacteria from Hydrothermal Vent Fields in the Eastern Pacific Ocean". Applied and Environmental Microbiology. 72 (7): 4950–4956. Bibcode:2006ApEnM..72.4950C. doi:10.1128/AEM.00223-06. PMC 1489322. PMID 16820492. Koschinsky, Andrea; Garbe-Schönberg, Dieter; Sander, Sylvia; Schmidt, Katja; Gennerich, Hans-Hermann; Strauss, Harald (2008). "Hydrothermal venting at pressure-temperature conditions above the critical point of seawater, 5°S on the Mid-Atlantic Ridge". Geology. 36 (8): 615. Bibcode:2008Geo....36..615K. doi:10.1130/G24726A.1. Catherine Brahic (4 August 2008). "Found: The hottest water on Earth". New Scientist. Retrieved 18 June 2010.
Biopanning is an affinity selection technique which selects for peptides that bind to a given target. All peptide sequences obtained from biopanning using combinatorial peptide libraries have been stored in a special freely available database named BDB. This technique is often used for the selection of antibodies too. Biopanning involves 4 major steps for peptide selection. The first step is to have phage display libraries prepared. This involves inserting foreign desired gene segments into a region of the bacteriophage genome, so that the peptide product will be displayed on the surface of the bacteriophage virion. The most often used are genes pIII or pVIII of bacteriophage M13. The next step is the capturing step. It involves conjugating the phage library to the desired target. This procedure is termed panning. It utilizes the binding interactions so that only specific peptides presented by bacteriophage are bound to the target. For example, selecting antibody presented by bacteriophage with coated antigen in microtiter plates. The washing step comes after the capturing step to wash away the unbound phages from solid surface. Only the bound phages with strong affinity are kept. The final step involves the elution step where the bound phages are eluted through changing of pH or other environment conditions. The result is the peptides produced by bacteriophage are specific. The resulting filamentous phages can infect gram-negative bacteria once again to produce phage libraries. The cycle can occur many times resulting with strong affinity binding peptides to the target.
α, catalytic domain, has two paralogous versions: α1 and α2 which are encoded from PRKAA1 and PRKAA2 β, regulatory domain, has two paralogous versions: β1 and β2 which are encoded from PRKAB1 and PRKAB2 γ, regulatory domain, has three paralogous versions: γ1, γ2, and γ3 which are encoded from PRKAG1, PRKAG2, and PRKAG3 In human skeletal muscle, the preferred form is α2β2γ1. But in the human liver, the most abundant form is α1β2γ1.
Sources: en.wikipedia.org
The main proposal is modulation of neurotrophic factors such as brain-derived neurotrophic factor, supported largely by animal experiments. Receptor-level targets have not been firmly established. Most reviews describe the mechanism as only partially characterized.
The compound is registered as a medicine in Russia, so clinical work has concentrated there. Trials elsewhere are few and generally small. This geographic concentration is a recognized limitation in evidence reviews.
Some fraction may reach the central nervous system through olfactory pathways, and this is often cited as the rationale for the nasal route. The size of that fraction in humans is not well quantified. Blood concentrations after nasal dosing are low, which complicates measurement.
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.