A practical reference on Reversed-phase HPLC: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2025-10-23 and is reviewed periodically as new material appears.
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
Semax is normally supplied as a lyophilized powder, and that form is the most stable. Suppliers commonly recommend storage at -20 °C in a desiccated container protected from light, with short-term handling at room temperature limited to weighing and transfer. Powder that has absorbed moisture degrades faster, so vials should be warmed to ambient temperature before opening to prevent condensation on the contents. Hygroscopic behavior is typical of short hydrophilic peptides, and humidity control matters more than temperature alone for long-term retention.
Once dissolved, the peptide is considerably less stable than the solid. Aqueous solutions are usually prepared at neutral to slightly acidic pH, filtered, and divided into single-use aliquots before freezing. Repeated freeze-thaw cycles are a common cause of avoidable loss and are best prevented by never refreezing a thawed aliquot. Adsorption to plastic and glass surfaces can lower the measured concentration of dilute solutions, particularly below roughly 0.1 mg/mL. Buffer choice, salt content, and container material all influence how much peptide remains detectable after storage.
Identity and purity are established with standard peptide methods. Reversed-phase HPLC with ultraviolet detection near 214 nm resolves the parent peak from deletion and truncation byproducts, and reports typically quote a main-peak percentage. Mass spectrometry by electrospray or MALDI-TOF confirms the expected molecular mass, while amino acid analysis or peptide mapping can verify composition when the sequence itself is in question. A certificate of analysis that pairs a chromatogram with a mass spectrum is more informative than a purity figure alone. Counter-ion content and residual solvents are separate specifications and are frequently omitted.
| Property | Value | Notes |
|---|---|---|
| Molecular formula | C37H51N9O10S | Free acid form of the heptapeptide; depends on terminal groups |
| Molecular mass | About 813.9 g/mol | Average mass used for mass spectrometry confirmation |
| Appearance | White to off-white solid | Supplied as a lyophilised powder; hygroscopic |
| Solubility class | Freely soluble in aqueous media | Water, saline, and phosphate buffers; limited organic solubility |
| Typical storage temperature | -20 degrees Celsius | Long term and dry; short working periods may use 2 to 8 degrees Celsius |
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.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
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.
Identity and purity of Semax are established mainly by reversed-phase high-performance liquid chromatography coupled with mass spectrometry. The chromatographic trace gives a purity estimate as a percentage of total peak area, while electrospray or matrix-assisted laser desorption ionization confirms the molecular mass against the calculated value. Amino acid analysis and sequence-specific fragmentation provide further confirmation when a supplier's chain of custody is unclear. Vendors frequently quote a purity figure without stating the detection wavelength or the integration method, which limits how far one number can be compared with another.
Stability depends heavily on physical state. Lyophilized powder held dry, cold and dark retains its content over long periods, whereas dissolved peptide begins to change within days at room temperature. The most cited degradation route is oxidation of the methionine residue, which converts the peptide to a sulfoxide form that elutes differently on chromatography. Hydrolysis of amide bonds and adsorption onto container walls contribute smaller losses. Buffers that exclude oxygen from the headspace slow the oxidation pathway, but no single condition prevents all change indefinitely.
The thiazolidinediones , abbreviated as TZD, also known as glitazones after the prototypical drug ciglitazone, are a class of heterocyclic compounds consisting of a five-membered C3NS ring. The term usually refers to a family of drugs used in the treatment of diabetes mellitus type 2 that were introduced in the late 1990s. As of 2024, there are two FDA-approved drugs in this class, pioglitazone and rosiglitazone.
Khrulyov also said that the first battalion passed the Roki Tunnel at 01:40 AM on 8 August and the second battalion had just entered the tunnel. The battalions reached the Gufta bridge at 04:40 AM on 8 August, when the Georgians had just approached from the other side. In 2012, one Russian soldier wrote in his memoirs that his military unit received the order to deploy to the Georgian border on 5 August 2008 and early in the morning of August 5th, they had already left the base.
=== Thermal intervention === There are two types of common thermal intervention for nipple pain, one is a warm compress while another is a cold compress. A warm compress such as a hot tea bag compress can be applied to the breast before breastfeeding to unblock the blocked milk ducts. By common practice, the solid lump that blocks the milk ducts should be resolved after 48 to 72 hours. Otherwise, assessing other possible causes of nipple pain such as lactating adenoma or malignancy is needed. It can also be applied to breast fissure sites as the vasodilation caused by the rise in temperature allows more oxygen and nutrients to help relieve pain and boost wound healing. Applying a cold compress can resolve breast engorgement. A cold gel pack, for example, can slightly reduce nipple pain caused by breast engorgement despite the effect has not yet been proved.
Sources: en.wikipedia.org
In the name NAD+, the superscripted plus sign indicates the positive formal charge on one of its nitrogen atoms. Some NAD is converted into the coenzyme nicotinamide adenine dinucleotide phosphate (NADP), whose chemistry largely parallels that of NAD, though its predominant role is as a coenzyme in anabolic metabolism. NADP is a reducing agent in anabolic reactions like the Calvin cycle and lipid and nucleic acid syntheses. NADP exists in two forms: NADP+, the oxidized form, and NADPH, the reduced form. NADP is similar to nicotinamide adenine dinucleotide (NAD), but NADP has a phosphate group at the C-2′ position of the adenosyl.
== Adverse effects == Modafinil is generally well-tolerated but can have potential risks and side effects. Common adverse effects of modafinil, experienced by less than 10% of users, include headaches, nausea, and reduced appetite. Anxiety, insomnia, dizziness, diarrhea, and rhinitis (nasal congestion) are also reported in 5%–10% of users. Psychiatric reactions have occurred in individuals with and without a preexisting psychiatric history. Urinary retention (difficulty emptying the bladder) and paresthesia (tingling or numbness) have also been reported. Modafinil has been found to have sympathomimetic effects, including increasing heart rate, blood pressure, and orthostatic elevations in norepinephrine levels. Modafinil can cause a slight increase in aminotransferase enzymes, indicative of liver function, but there is no evidence of serious liver damage when levels are within reference ranges. Case reports of modafinil-associated hypersexuality and spontaneous orgasms and ejaculations exist. Rare but serious adverse effects include severe skin rashes and allergy-related symptoms. Between December 1998 and January 2007, the US Food and Drug Administration (FDA) received reports of six cases of severe cutaneous adverse reactions, including erythema multiforme (target-shaped skin lesions), Stevens–Johnson syndrome, toxic epidermal necrolysis (widespread skin peeling), and DRESS syndrome (a drug reaction involving rash and organ inflammation).
=== 23 February === The RSF, the SPLM-N (al-Hilu) and allied groups signed a charter to establish the Government of Peace and Unity following a meeting in Nairobi. The SAF's Sayyad Force lifted the two-year siege of El Obeid. The SAF also recaptured El Geteina.
Sources: en.wikipedia.org
Afghanistan was formerly the primary producer of the drug. Having regularly producing 70 percent of the world's opium, Afghanistan decreased production to 74 tons per year under a ban by the Taliban in 2000, a move which cut production by 94 percent. A year later, after American and British troops invaded Afghanistan, removed the Taliban and installed the interim government, the land under cultivation leapt back to 285 square miles (740 km2), with Afghanistan supplanting Burma to become the world's largest opium producer once more. Opium production increased rapidly in Afghanistan from that point, reaching an all-time high in 2006. According to DEA statistics, Afghanistan's production of oven-dried opium increased to 1,278 tons in 2002, more than doubled by 2003, and nearly doubled again during 2004. In late 2004, the U.S. government estimated that 206,000 hectares were under poppy cultivation, 4.5 percent of the country's total cropland, and produced 4,200 metric tons of opium, 76 percent of the world's supply, yielding 60 percent of Afghanistan's gross domestic product. In 2006, the UN Office on Drugs and Crime estimated production to have risen 59 percent to 165,000 hectares (407,000 acres) in cultivation, yielding 6,100 tons of opium, 82 percent of the world's supply. The value of the resulting heroin was estimated at US$3.5 billion, of which Afghan farmers were estimated to have received US$700 million in revenue. For farmers, the crop can be up to ten times more profitable than wheat. The price of opium is around US$138 per kilo.
Efficacy was based on DESTINY-Breast03 (NCT03529110), a multicenter, open-label, randomized trial that enrolled 524 participants with HER2-positive, unresectable, and/or metastatic breast cancer who received prior trastuzumab and taxane therapy for metastatic disease or developed disease recurrence during or within six months of completing neoadjuvant or adjuvant therapy. Participants were randomized 1:1 to receive either trastuzumab deruxtecan or trastuzumab emtansine by intravenous infusion every three weeks until unacceptable toxicity or disease progression. Randomization was stratified by hormone receptor status, prior treatment with pertuzumab, and history of visceral disease. The FDA approved trastuzumab deruxtecan for the treatment of HER2-low breast cancer based on DESTINY-Breast04, a randomized, multicenter, open label clinical trial that enrolled 557 adult participants with unresectable or metastatic HER2-low breast cancer. The trial included two cohorts: 494 hormone receptor positive (HR+) participants and 63 hormone receptor negative (HR-) participants. Of these participants, 373 randomly received trastuzumab deruxtecan by intravenous infusion every three weeks and 184 randomly received physician's choice of chemotherapy (eribulin, capecitabine, gemcitabine, nab paclitaxel, or paclitaxel). The results showed improvement in both progression-free survival and overall survival in people with unresectable or metastatic HER2-low breast cancer.
Extremely high levels of serotonin or activation of certain serotonin receptors can cause a condition known as serotonin syndrome, with toxic and potentially fatal effects. In practice, such toxic levels are essentially impossible to reach through an overdose of a single antidepressant drug, but require a combination of serotonergic agents, such as an SSRI with a MAOI, which may occur in therapeutic doses. However, serotonin syndrome can occur with overdose of certain serotonin receptor agonists, like the NBOMe series of serotonergic psychedelics. The intensity of the symptoms of serotonin syndrome vary over a wide spectrum, and the milder forms are seen even at nontoxic levels. It is estimated that 14% of patients experiencing serotonin syndrome overdose on SSRIs; while the fatality rate is between 2% and 12%.
Sources: en.wikipedia.org
It is described as a synthetic analogue of the ACTH(4–10) fragment, a short segment of adrenocorticotropic hormone. Its sequence differs from that fragment and includes two proline residues, which influence stability and behaviour in solution.
It appears in Russian pharmaceutical listings as a nasal formulation, but it is not an authorised medicine in the United States or the European Union. Outside those markets it is normally encountered as a research chemical rather than a prescription product.
Laboratory and animal work points to melanocortin signalling and changes in neurotrophic factor levels, especially brain-derived neurotrophic factor. The exact receptor targets and the degree to which these findings transfer to humans are still unresolved.
Each freeze-thaw cycle can degrade a fraction of the peptide and promote aggregation. Dividing a stock solution into single-use volumes removes repeated cycling as a variable. It also limits the time a thawed solution spends at room temperature.