Looking for an expert comparison of the nootropic peptides Semax vs. Selank?
Look no further, as this comprehensive guide examines these two innovative peptides, highlighting their features, similarities, and differences. We’ll address questions like:
- How do Semax and Selank work?
- What are their therapeutic benefits?
- Which of the two nootropic peptides is better for research?
While both Semax and Selank are classified as nootropics and share some similarities in their structure and therapeutic potential, there are notable distinctions between the two. While Selank is noted for its anxiolytic effects, Semax demonstrates potent neuroprotective and gastroprotective properties.
By providing an overview of these similarities and differences, this guide assists researchers in determining which peptide is worth further investigation based on their specific requirements.
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What is Semax?
Its Met-Glu-His-Phe fragment is a common part in the sequence of all melanocortin hormones, including adrenocorticotropic hormone (ACTH). However, it is not associated with the endocrine effects of these hormones.
Semax appears to interact with various neurotrophic factors in the nervous system that support the growth, survival, and maintenance of neurons .
The peptide was developed in the 1980s by scientists at the Institute of Molecular Genetics of the Russian Academy of Sciences as a potential neuroprotective and cognitive-enhancing agent in settings of ischemic stroke, encephalopathy, and optic nerve atrophy .
As of writing, the peptide is available as both and intranasal formulations and laboratory animal studies suggest that both have sufficient bioavailability in brain tissue after administration 
Semax can also be acetylated and amidated as N-Acetyl Semax Amidate, which modifies some of its properties in reacting with agents such as copper ions or redox agents to potentially further improve its stability [9, 10].
What is Selank?
Selank is another heptapeptide discovered at the Institute of Molecular Genetics of the Russian Academy of Sciences. It was developed in the 1990s and approved for human use by the Russian Federation Ministry of Health in 2009 .
Selank is currently available as an anxiolytic and nootropic drug in Russia and Ukraine. It is a synthetic analog of the endogenous human tetrapeptide tuftsin (threonine – lysine – proline – arginine) and contains a Pro-Gly-Pro fragment at its C-terminus .
Tuftsin is an immunomodulatory peptide found in the blood of different mammals and is typically located in the Fc-domain of the heavy chain of immunoglobulin G (residues 289-292) .
Thus, Selank may also possess some immunomodulatory properties in addition to its anxiolytic and nootropic effects .
The peptide is designed to pass through the blood-brain barrier and achieves its effects at central nervous system receptors .
The peptide is also available as an acetylated and amidated version called N-Acetyl Selank Amidate. Similar to Semax, these modifications may improve its stability.
How Do Semax and Selank Work?
Researchers should consider the mechanisms behind both Selank and Semax when determining which peptide merits further investigation for their specific needs:
- Semax may exert its effects by interacting with and upregulating the levels of neurotrophic factors in the central nervous system. Specifically, it may potentiate the expression of Brain-Derived Neurotrophic Factor (BDNF) and Nerve Growth Factor (NGF) .
- Researchers have reported that Semax results in a 1.4-fold increase in BDNF levels accompanied by a 2-fold increase in trkB (tropomyosin receptor kinase B, aka tropomyosin-related kinase B receptor) gene expression. Tropomyosin receptor kinase B is the receptor for BDNF found on the surface of certain neurons in the brain .
- The peptide also appears to affect serotonin and dopamine signaling in the brain, which may benefit mood-related disorders such as depression and anxiety .
Selank and Semax
- One study suggests a potential effect of both peptides on enkephalin signaling . Enkephalins are the natural ligands of opioid receptors, and upregulating them may provide benefits for mood and stress reduction .
- Studies suggest that Selank may also upregulate BDNF expression in the hippocampal area of rat brains following intranasal administration .
- Yet, the peptide appears to have a much more pronounced effect on opioid, serotonergic, and GABA signaling. These mechanisms are likely central to Selank's ability to reduce stress and anxiety levels [11, 20, 21].
- Some researchers suggest that the peptide may also interact with dopamine and norepinephrine, but more research is needed to evaluate these mechanisms .
Comparing Semax and Selank Benefits
Both Semax and Selank have been the subject of clinical trials that showcase their potent effects and benefits as nootropic peptides. Nevertheless, there are some differences regarding the complete spectrum of benefits that researchers may expect to observe.
Keep reading to discover the latest preclinical and clinical data on these popular nootropic peptides.
Semax and Selank for Cognitive Enhancement
According to the available clinical research, both Semax and Selank may offer nootropic benefits:
- One study investigated the peptide’s effect on memory and attention in fatigued study volunteers who have worked eight-hour shifts. A single intranasal administration at 16mcg/kg of body weight resulted in a sustained effect lasting up to 24 hours, with the researchers reporting that those who received Selank had 71% correct answers on a memory test compared to 41% of those in the control group .
- Another study also investigated the effects of Semax on the brain's neuronal network using resting-state functional magnetic resonance imaging (fMRI). The research involved 24 middle-aged volunteers and included three resting state fMRI scans. The Semax group exhibited a larger volume of the default mode network rostral (medial frontal cortex) subcomponent compared to the control group .
- A clinical study on Selank also reported potent nootropic effects in patients with anxiety-phobic, hypochondriac, and somatoform disorders. The peptide was given intranasally alongside oral phenazepam, which significantly increased its efficacy while preventing the attention and memory impairment, asthenia, and sedation that typically occur with benzodiazepine use .
- In another publication, the same researchers also noted Selank’s nootropic effects when used as a standalone therapy, while noting that Selank resulted in anxiolytic effects comparable to those of phenazepam .
- According to research in rodents, Selank may enhance memory storage processes due to an ability to improve serotonin metabolism .
Selank for Stress and Anxiety Reduction
Currently, only Selank has been studied in humans regarding its potential anxiolytic and anti-stress effects.
One noninferiority trial involving 62 patients with generalized anxiety disorder (GAD) and neurasthenia aimed to compare the anxiolytic effect of intranasal Selank to that of medazepam. The study revealed that Selank may be noninferior to medazepam, meaning that the two agents produced comparable benefits, particularly in patients with GAD.
Additionally, in patients with both disorders, Selank treatment was associated with decreased level of tau(1/2) leu-enkephalin, which, in turn, correlated with disease duration and symptom severity .
Semax for Neuroprotection Against Ischaemia and Toxins
As of writing, only Semax has shown a protective effect in clinical trials with stroke patients and neurotoxins such as alcohol.
- For example, one study investigated the effect of Semax administered intranasally in two courses of 6,000 mcg/day for 10 days with a 20-day wash-out interval on 110 patients who have suffered from acute stroke. The researchers noted increased plasma BDNF levels as a result of Semax administration, resulting in improved motor performance and Barthel index scores. Early rehabilitation also correlated with better motor performance .
- Another trial in acute ischemic stroke reveals that Semax provides significant anti-inflammatory benefits, such as increasing the prevalence of the anti-inflammatory agents (interleukin-10, tumor necrosis factor-alpha) over proinflammatory factors (interleukin-8, C-reactive protein) .
- In a smaller study with 30 patients with chronic ischemia affecting the brain, which often leads to dementia, Semax was administered alongside adenosine diphosphate (ADP) and collagen. The patients in the treatment group achieved better recovery compared to the controls.Тhe researchers that conducted the study reported that the peptide improved the condition by providing both neurotrophic and anti-platelet effects .
- Intranasal Semax has also been shown to protect against pressure-induced nerve damage, such as in glaucoma, as well as in toxin-induced nerve damage, such as in alcohol intoxication [30, 31].
A caveat to the aforementioned studies is that the non-treatment arms in each study consisted merely of placebo groups (groups of patients receiving no definitive treatment).
The next step would be non-inferiority studies, meaning studies designed to determine whether Semax produces benefits at least matching those achieved with standard of care, such as antiplatelet therapy or mechanical thrombectomy for ischemic stroke.
Semax for Gastroprotection
Semax also appears to possess gastroprotective and anti-ulcer properties that have not been observed with Selank. A 2002 study published in Bulletin of Experimental Biology and Medicine revealed that Semax is almost 3 times more effective than placebo in speeding up healing in 32 patients with peptic ulcers.
Semax was administered intranasally as a 1% solution in a dose of 2-4 drops in both nostrils three times a day for ten days. The results showed ulcer healing in almost 90 % of the treatment group compared to just over 30% in the placebo group. The researchers speculated that these beneficial effects might be due to a not-fully-explored effect of Semax on regulating blood flow, microcirculation, and vascular permeability .
As with the stroke applications, however, demonstration of superiority over a placebo does not necessarily warrant entry of an investigational agent into clinical use, since established treatments also are superior to placebos. In the case of peptic ulcer disease, the bar is set fairly high, as efficacy of triple therapy and quadruple therapy that constitute standard-of-care can be as high as 93 percent, depending on the particular clinical setting .
Semax and Selank Side Effects and Safety
As of writing, the majority of trials investigating the intranasal application of Selank and Semax report excellent tolerance and no toxicity after up to 30 days of use:
- Selank: In a 2015 trial, patients with anxiety-phobic, hypochondriac, and somatoform disorders who received Selank alongside phenazepam. The researchers reported that the peptide did not cause any additional side effects and even prevented some of the most common adverse reactions to phenazepam, such as sedation and asthenia .
- Semax: A safety and efficacy trial investigating the neuroprotective effects of Semax against glaucoma also reported that a month of intranasal administration did not cause any adverse effects . Another smaller trial involving a single Semax intranasal dose of 16.0mcg/kg of body weight reported that the peptide may slightly increase anxiety as the patients who received Semax started making more mistakes during work. The researchers assumed that there is some anxiogenic component in the spectrum of Semax's behavioral effects, manifesting itself as an increase in false responses .
Some studies investigating the potential side effects of elevated BDNF levels also report a potentially increased risk of hair loss in patients susceptible to baldness . Both Selank and Semax upregulate BDNF, but the risk of such side effects is currently unknown.
Researchers should also note that the aforementioned studies are relatively small and do not last for longer than 30 days of intranasal application .
Choosing Between Semax and Selank
When deciding whether to investigate Semax or Selank, researchers should consider their specific research objectives and the individual characteristics of their test subjects:
- Nootropic Research: Both Semax and Selank have demonstrated cognitive enhancement and nootropic effects. Semax has been shown to improve memory, attention, and neuronal network function. Selank has also exhibited nootropic effects and memory enhancement while also improving serotonin metabolism.
- Neuroprotection: Semax excels in its neuroprotective and gastroprotective properties, making it a potential choice for conditions such as ischemic diseases of the brain and exposure to neurotoxins like alcohol and peptic ulcers.
- Stress Reduction: tSelank is known for its combination of nootropic and stress-reducing effects, making it suitable for anxiety-related disorders. If stress and anxiety reduction are also part of the research objective, Selank may be the preferred nootropic.
Scientists should also note that individual responses to Semax and Selank may vary among test subjects, and further research is needed to fully understand their mechanisms of action and potential applications.
Where to Buy Research Peptides Online? | Semax vs. Selank
When searching for a reliable source of Semax and Selank for research, it is crucial to evaluate various vendors.
Analysis should encompass factors like cost-effectiveness, customer support availability, shipping and return policies, and testimonials.
Here are the two top vendors we have found:
We recommend Limitless Life as our trusted vendor of both Semax and Selank nasal spray products.
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- USA-Made Semax and Selank: The nootropic nasal spray formulations provided by Limitless Life are made in the USA in accredited facilities.
- Resourceful Website: Limitless Life’s user-friendly website is packed full of valuable information and resources concerning peptides and how to best handle and store them.
- Third-Party Tested Peptides: Limitless Life ensures the highest standards of quality and purity for their peptides by subjecting them to rigorous third-party lab testing and providing Certificates of Analysis for peace of mind.
- Researcher-Oriented Policies: In the event of a mistaken shipment or unforeseen issue, the vendor offers returns and exchanges at its own discretion. Researchers are required to inform the company of any issues with their product within seven days of receiving it.
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For high-quality lyophilized powder nootropic peptides, we recommend PureRawz as our preferred source.
They have consistently proven to be a trusted supplier of research-grade nootropics and other peptides for these reasons:
- Lab-Tested Peptides (over 99% purity): PureRawz provides top-quality Selank and Semax in lyophilized powder form, ensured via state-of-the-art mass spectrometry analysis.
- Convenient Payments: Researchers can choose from options such as PayPal, Venmo, and even cryptocurrency payments. Additionally, PureRawz currently offers a discount for purchases made with select methods.
- Free Domestic Shipping ($100+) and Discounts: This vendor provides free shipping on orders over $100. Further, they offer discounts for first-time buyers and newsletter subscribers.
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Semax vs. Selank | Verdict
Both Semax and Selank are potent nootropic peptides that help improve memory and cognition by increasing BDNF levels and interacting with various neurotransmitters.
Semax appears to help boost attention, provide neuroprotective benefits, and even aid in healing peptic ulcers. On the other hand, Selank provides anxiolytic and anti-stress benefits without the side effects of sedatives.
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