The following table outlines the key differences between Semax and Selank. The articles below delve into each point in greater detail.
| Feature | Semax | Selank |
|---|---|---|
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro. | Thr-Lys-Pro-Arg-Pro-Gly-Pro. |
| Parent Molecule | ACTH(4-10) fragment (no hormonal activity). | Tuftsin (immune peptide). |
| Primary Mechanism | BDNF upregulation, dopamine / serotonin modulation. | GABA-A modulation, enkephalin stabilization. |
| Primary Research Focus | Cognitive function, neuroprotection, focus. | Anxiety, stress, mood stabilization. |
| Russian Registration | 0.1% nasal drops (cognitive / stress), 1% nasal drops (stroke). | 0.15% nasal drops (generalized anxiety). |
| Onset (Intranasal) | 15-30 minutes. | 15-30 minutes. |
| Half-Life | Short (minutes in plasma). | Short (minutes in plasma). |
| Analogs Available | N-Acetyl Semax, NA-Semax-Amide. | NA-Selank-Amide (Adalank). |
| Human Trials Outside Russia | None published. | None published. |
| FDA Approved | No. | No. |
| WADA Prohibited | No. | No. |
| US Legal Status | Research use only. | Research use only. |
| Store Price (10 mg Vial) | $70.00. | $65.00. |
Semax is a synthetic heptapeptide (Met-Glu-His-Phe-Pro-Gly-Pro) created from the ACTH(4-10) section of the adrenocorticotropic hormone, produced in such a way that hormonal functions are removed whilst maintenance of influence on the CNS. It was created by the Institute of Molecular Genetics in Moscow, currenty being registered in Russia in two concentrations: as 0.1% nasal drops used for cognitive dysfunctions and stress release, and as 1% nasal drops used for preventing strokes and transient ischemic attacks.
Upregulation of brain-derived neurotrophic factor (BDNF) is the most replicated finding in all the research studies undertaken to learn about Semax. Research studies involving animals and humans show that Semax alters dopamine and serotonin turnover in the prefrontal cortex, forming the basis of its effectiveness in terms of focus and attention. Importantly, Semax does not interact with androgen, estrogen or glucocorticoid receptors, which means that it does not produce hormonal side effects as it is the case with its parent molecule ACTH.
Across the Semax literature, three mechanisms have been observed consistently. One of the mechanisms is found to be BDNF and NGF (nerve growth factor) upregulation in the cortex and hippocampal areas. Another mechanism is the modulation action of the norepinephrine and serotonin systems that resembles but differs from that of the stimulating medicines. Lastly, neuroprotective action has been described in ischemic models, which is responsible for the stroke-indication registration milestone of 1% obtained in Russia.
An important factor that is overlooked: Semax has been shown to have a brief plasma half-life. The nasal administration of the peptide allows delivery more directly into cerebrospinal fluid and avoids the complications created by first-pass metabolism of the liver, which is the reason why it is given in the form of drops via nasal route instead of orally. Subcutaneous administration proves less reliable compared to intranasal but is often employed in research protocols.
The complete mechanistic profile can be found at Semax peptide library entry, including data for the stroke trial and possible BDNF time-course study findings.
Selank, a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) resulting from tuftsin, a naturally occurring tetrapeptide essential for immune regulation, developed by the Institute of Molecular Genetics located in Moscow, is as a 0.15% nasal anxiolytic in Russia. There was a pivotal Russian trial where Selank was compared to Medazepam (a benzodiazepine) over a period of 14 days and the outcome of the trial supported that both substances were comparable in terms of efficacy without any sedative effect, impairing cognitive function and dependence signals.
The comparison with the benzodiazepine class is the most crucial aspect to note for a researcher assessing Selank for the treatment of anxiety. Medazepam acts as a positive allosteric modulator at GABA-A receptors, whereas Selank has a mixed mechanism of action. According to the Russian studies, Selank has a good level of anxiolytic effect without the unpredictable complications seen with the benzodiazepines.
The main method by which Selank functions is through influencing the GABA-A receptors and slowing down the destruction of met-enkephalin and leu-enkephalin by enzymes. By prolonging their effect Selank seems to have a calming action without downregulation of the receptors that leads to tolerance to the use of benzodiazepines. Another interesting observation from Russian studies is the immunomodulatory effect which is not surprising considering the nature of the parent molecule tuftsin; however, the results regarding anxiety are more convincing than the ones related to the immune system.
Selank peptide library entry contains the complete mechanism description. We additionally have a peptides for anxiety guide for peptide research linked specifically to anxiety and covering Selank among other studied substances.
The best proof of Semax comes from the Russian studies and animal studies on neurophysiology. There were no random trials outside of Russia, and this point needs to be mentioned in any fair review without delay.
Focus and cognition: A clinical study performed in Russia among patients whose cognitive functions had diminished due to a stroke exhibited enhanced levels of concentration, memory consolidation, and speed of processing the information. Experiments on rodents indicate that the amount of BDNF in the hippocampus increases significantly just a few hours following nasal application.
Protection of the nervous system in ischemic conditions: The 1% Semax formulation has been employed in stroke centers in Russia. Animal experiments conducted in cases of localized ischemic stroke have shown reduced volume of infarcts and increased neurological scores when Semax was administered before the onset of the stroke or soon after it occurs.
Dopamine / serotonin modulation: Studies using microdialysis in rats have shown increased dopamine and serotonin turnover in the prefrontal cortex, consistent with the focus and motivation effects as noted by researchers.
Research interest concerning ADHD: Semax has been researched in pediatric population with attention-deficit concerns in Russia. However, this data cannot be considered clinical, and must be regarded as preliminary.
Our peptides for focus and peptides for cognitive function guides offer in-depth discussion about the focus and cognitive-function angle.
The clinical research evidence supporting Selank has a smaller overall scope but is more consistent in terms of that scope since the anxiolytic effect of Selank within the generalised anxiety disorder clinical studies conducted in Russia is the best-known phenomenon studied in Selank research.
A trial using medazepam as a control showed that Selank (a Russian anxiolytic) was able to reduce the outcome on Hamilton Anxiety Scale (HAS) in the same way, however without causing sedation, psychomotor impairment and withdrawal symptoms which were present upon stopping treatment with medazepam.
Enkephalin stabilization: Selank inhibits enzymes responsible for degrading met-enkephalin and leu-enkephalin, which increases their effectiveness. The mechanism is different from that of the benzodiazepines and opioids, which is the reason why no dependency was noted.
Mood stabilization: According to certain Russian evidence, Selank has the capability of reducing emotional lability and irritability in stress models irrespective of its primary anxiolytic action.
Quality of sleep: Evidence from researchers indicates that the GABAergic action of Selank may facilitate sleep onset without causing daytime drowsiness. No scientific data on sleep architecture is presently available for humans. The peptides for sleep reference has been retained.
In Russian medical practice, the standard concentration of 0.1% is used for Semax indications in cognitive enhancement and stress relief. The prescribed dosage consists of 2-3 drops per nostril, 2-3 times a day, resulting in about 300-900 mcg of Semax per day, based on the drop size. The stroke formulation has a stronger concentration of 1%, but it is used only in hospitals under acute conditions and not among outpatients. In contrast, the usage of Semax through injections is much smaller in terms of daily total doses, usually between 200-400 mcg.
US Peptide Labs’ product Semax 10 mg vial comes in the form of a lyophilized powder. When dissolved in bacteriostatic water, a solution is obtained. The table below outlines volumes and concentrations for the most common research protocols, and you can use our peptide dosage calculator to double-check the volumes for your particular reconstitution.
| Reconstitution Volume (per 10 mg vial) | Concentration | 200 mcg Dose | 300 mcg Dose | 400 mcg Dose | 600 mcg Dose |
|---|---|---|---|---|---|
| 1 mL Bac Water | 10 mg/mL (10,000 mcg/mL). | 0.02 mL (2 units). | 0.03 mL (3 units). | 0.04 mL (4 units). | 0.06 mL (6 units). |
| 2 mL Bac Water | 5 mg/mL (5,000 mcg/mL). | 0.04 mL (4 units). | 0.06 mL (6 units). | 0.08 mL (8 units). | 0.12 mL (12 units). |
| 3 mL Bac Water | 3.33 mg/mL (3,333 mcg/mL). | 0.06 mL (6 units). | 0.09 mL (9 units). | 0.12 mL (12 units). | 0.18 mL (18 units). |
<p style="font-family: 'Arial', sans-serif; font-size: 14px; color: #1a1a1a; margin: 20px 0; line-height: 1.6;">
Units = insulin syringe units (U-100 syringe, where 100 units = 1 mL).
Selank's Russian 0.15% nasal registration translates to roughly <span style="color: #1a1a1a; font-weight: 600;">250-500 mcg per day</span> intranasally, delivered as 2-3 drops in each nostril three times a day. Published anxiety research mostly aligns with the higher end of that range. Injection protocols typically use 250-500 mcg subcutaneous per day, preferentially in the afternoon or evening.
The Selank 10 mg vial from US Peptide Labs ships as lyophilized powder. The table below lists standard reconstitution volumes and the dosing volumes they produce.
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| Reconstitution Volume (per 10 mg vial) | Concentration | 250 mcg Dose | 350 mcg Dose | 500 mcg Dose |
|---|---|---|---|---|
| 1 mL Bac Water | 10 mg/mL (10,000 mcg/mL). | 0.025 mL (2.5 units). | 0.035 mL (3.5 units). | 0.05 mL (5 units). |
| 2 mL Bac Water | 5 mg/mL (5,000 mcg/mL). | 0.05 mL (5 units). | 0.07 mL (7 units). | 0.10 mL (10 units). |
| 3 mL Bac Water | 3.33 mg/mL (3,333 mcg/mL). | 0.075 mL (7.5 units). | 0.105 mL (10.5 units). | 0.15 mL (15 units). |
According to the Russian labeling, Semax should be taken for 10-14 days depending on cognitive/stress symptoms, thereafter taking a break. Research conducted outside Russia indicates that the cycles are extended to 4 weeks followed by a rest period. Taking Semax in the morning strikes a balance with the dopaminergic mechanism, considering that taking it in the evening is one of the mistakes researchers commonly indicate. It should be noted that the short half-life of the peptide does not allow it to build up in the body; rather, the effects of BDNF and other monoamines can be observed after the substance clears the bloodstream.
Selank’s Russian anxiety clinical trial lasted 14 days. The usual protocol in such studies is to conduct research in 2-3 week intervals and then take a break of equal duration. However, an important factor in Selank’s action is that it calms rather than stimulates the subject. Therefore, it is primarily administered in the afternoon or evening – contrary to Semax administration. Researchers have verified during trials that taking Selank in the morning has a diminishing effect on the focus effect of Semax, which is why the two drugs should not be taken at the same time.
N-Acetyl Semax has an acetyl group in its structure, which makes it more durable and effective. Initially, people used N-Acetyl Semax Amide for treating migraine and used it to achieve the best result without trials. Researchers note that using amide version of Semax is more beneficial, but there is no trial that shows comparison of both types of Semax. Currently, the store offers Semax in powder form, and scientists studying same products have to take into account that N-Acetyl Semax and N-Acetyl Semax Amide will add another item to a laboratory.
The complete dosing information, along with cycle protocols, can be found in our designated ##LINK_2##. The complete Selank procedure with cycle structure is available in our ##LINK_3##.
The manner in which lyophilized Selank powder is reconstituted is similar to Semax; bacteriostatic water is slowly added down the wall of the vial, the container is not shaken but swirled carefully and kept at 2-8 °C after mixing. Lyophilized powder should be either refrigerated or frozen prior to reconstitution and must be kept away from moisture and light. Mixing of a 10 mg vial with 2 mL of liquid creates a solution of 5 mg/mL which has a storage life of around 30 days under refrigeration. The particular math relating to your dosage can be checked using peptide dosage calculator before you proceed to preparation.
There is no human safety data for either of the above-mentioned peptides outside Russia, and this lack of data is actually a safety consideration that should always occur to researchers.
Semax side effects reported in the literature and researcher accounts:
Nasal irritation associated with the use of intranasal medicine, especially when the dosing is high or repeated frequently.
Irritability and restlessness, especially when taking Semax in the evening, are consistent with the mechanisms of dopamine.
In the online community of researchers, there have been some reports of hair-loss; however, no proper explanation for this phenomenon has yet been provided either the effect can be confirmed with the help of any research study.
No dependence or withdrawal observed in the Russian trials
Selank side effects reported in the literature and researcher accounts:
In this study that utilized medazepam, there was no sedation or psychomotor impairment; therefore, there was no withdrawal from the medication.
No dependence signal in any published Selank trial
A significant discovery in the studies on Selank is the lack of data regarding dependence because it was tested against a benzodiazepine. This is not to say that Selank has no risk. What it means is that a certain risk was absent from a controlled study that was performed within a limited timeframe and in a limited population.
The FDA has not yet given its approval for either Semax or Selank. The only country where Semax has approval is Russia, where one can currently find it as a 0.1% and 1% nasal medicine. There is no pending IND application for Semax at FDA or any Phase I trials for Semax carried out in the USA.
The regulatory position of Selank in likewise confined to Russia, and as such, is classified as a prescription (a 0.15% nasal solution for generalized anxiety disorder). Neither of the drugs has been approved by EMA, nor has any clinical trial been conducted in the US. In the USA, both peptides will continue to belong to the category of research chemicals, rather than drugs, in 2026.
Semax is available legally in the United States as a research-only material. Under DEA regulations, it is not classified as a controlled substance. However, since it is not included on the FDA's list of bulk materials under 503A, it cannot be manufactured for human use by licensed compounding pharmacies. There is also no mention of the substance in the FDA 503B outsourcing facility list. Thus, the effect is that chemical suppliers may offer it for laboratory research but it cannot be prescribed in the US.
Just like the previous substances, Selank has the same legality: it can be purchased legally as a research substance, it is not controlled drug and it does not belong to the 503A list; it cannot be prepared by a licensed pharmacy.
As for the testing of athletes in terms of the substances known as peptides, the two peptide substances in question do not appear in the **WADA Code** in its modification for the period starting from January 1, **2025**. New methods of testing for some peptides of the class have already been developed by anti-doping specialists in the early **2020s**, though it is yet to be confirmed whether Semax and Selank are included in the list of forbidden substances of the **WADA Code**.
US Peptide Labs is a chemical vendor and not a pharmacy adhering to standards set under 503A or 503B. All products are exclusively available for both buyers who are at least 21 years old and are engaged in lab research in USA.
The primary thing when procuring research peptides is the certainty of the purity as it is the stage where the quality of the manufacturer varies significantly from one supplier to another. At AxisPharm, every Semax and Selank batch has undergone HPLC testing in an independent laboratory and proven to ensure 99.0% purity for the peptides across three lots. The lot code is also printed on the bottom of the vial so that it can be linked to the corresponding batch certificate (COA) at uspeptidelabs.co/pages/quality-coas. For advice on how to read COAs, check COA reading guide.
The two peptides have been made available in laboratories in the United States, and are sent to the buyer from the USA using an ordering system that incorporates a tracking feature. The buyer can also benefit from free shipping if the order is valued at $70 or above.
| Product | Size | Price | Bulk 2+ | Bulk 5+ | Purity | Testing Lab |
|---|---|---|---|---|---|---|
| Semax | 10 mg, lyophilized. | $70.00. | $66.50. | $63.00. | 99.0% HPLC. | AxisPharm. |
| Selank | 10 mg, lyophilized. | $65.00. | $61.75. | $58.50. | 99.0% HPLC. | AxisPharm. |
| Semax Nasal Spray | Pre-formulated. | $120.00. | - | - | 99.0% HPLC. | AxisPharm. |
| Selank Nasal Spray | Pre-formulated. | $120.00. | - | - | 99.0% HPLC. | AxisPharm. |
| Semax / Selank Nasal Blend | Pre-formulated. | $165.00. | - | - | 99.0% HPLC. | AxisPharm. |
Combining Semax with Selank is one of the most searched topics in our peptide library. Semax increases dopaminergic tone (thus creating a sense of focus, motivation, and some mild stimulation) while Selank acts on GABA-A and enkephalins (producing calmness and lowering anxiety). Both mechanisms complement each other rather than interfere with each other. In a usual research study, the two substances are applied in a time-sequenced manner (Semax in the morning, Selank in the evening or afternoon).
Both forms, nasal spray and injection, are mentioned in literature. Nasal drops were employed exclusively in Russian clinical trials; injection methods are mostly reported in Russian pharmacokinetic publications as well as in protocols answered by researchers dealing with clinical studies outside of Russia. In case of subcutaneous injection, the amount of substance administered is fixed and bioavailability is stable; nasal drug absorption, on the contrary, depends on the state of mucosa, spray technology and the size of the drops. For those who intend to copy Russian clinical dosing exactly, it would be better to utilize the nasal mode; in case higher precision of dosing is needed, there should be employed the injection method with reconstituted vials.
The total mood and cognitive collection of peptides can be found at uspeptidelabs.co/collections/cognitive-mood. For a better understanding of the peptides researched in the brain health area, check our peptides for brain health reference.
This FAQ entry does not apply in the context of Semax compared against Selank. If you've come here looking for information on GLP-3 / retatrutide, please note the compound is discussed in detail in our retatrutide peptide library entry.
Semax and Selank are not hormones; they are made as heptapeptides. Semax is synthesized according to ACTH(4-10) fragment but is specifically designed in such a way that all of its hormone's effects are eliminated. Selank is made using the immune peptide tuftsin. Neither of them influences the hormonal receptors.
To learn about dosing information for Semax and Selank, check the above-mentioned dosage tables and peptide dosage calculator . According to the available research, Semax is dosed from 200-600 mcg a day, while Selank is dosed from 250-500 mcg a day. These figures are only meant for researchers and were taken from the Russian scientific literature, and not personal usage recommendations.
The central discrepancy separating Semax and Selank - the object of investigation of the given article - is the mechanism of action. Semax works mainly via upregulation of BDNF and modulation of monoamines and is researched for cognitive and neuroprotective purposes. On the other hand, Selank is concerned with modulation of GABA-A and stabilization of enkephalins and is primarily studied from the point of view of its anxiolytic properties. Identical institutes, identical seven amino acids, yet differently directed action and possibilities of application.
The use of Semax may lead to irritation and restlessness with taking the medication in the evening and irritation in the nasal cavity when taken intranasally. The use of Selank may lead to mild fatigue at large doses and nasal irritation. Both peptides failed to demonstrate any dependency or withdrawal symptoms in the conducted Russian clinical studies. There is no long-term data on human safety of either drug outside of Russia.
Neither Semax nor Selank has been approved by the FDA. However, they can be legally bought in the US as chemical suppliers since the compounds are research-only. US Peptide Labs offers these compounds with 99.0% HPLC purity and are third-party tested by AxisPharm as well. The price of Semax is $70.00, while Selank costs $65.00. For orders of $70 or more, free US shipping is provided.