Selank Acetate (Systemic)

Selank Acetate is the acetate salt form of Selank, a synthetic heptapeptide (Thr-Lys-Pro-Arg-Pro-Gly-Pro) developed by the Institute of Molecular Genetics of the Russian Academy of Sciences as a metabolically stabilized analog of tuftsin, a naturally occurring immunomodulatory tetrapeptide (Thr-Lys-Pro-Arg). This profile specifically addresses systemic (parenteral, non-intranasal) administration research, as distinct from this site's main Selank profile, which covers the compound's better-established intranasal research and clinical use.

At Verified Peptides, we want to directly flag why this distinction matters: Selank is approved in Russia (as a nasal spray, marketed under the name Stimul, among others) for anxiety disorders and neurasthenia, and the substantial majority of its human clinical trial evidence is specific to this intranasal delivery route. Systemic administration (intraperitoneal injection in animal research; subcutaneous or intramuscular injection in the comparatively rare human research contexts where it has been used) represents a genuinely distinct research question with its own separate, and currently thinner, evidence base — not simply an alternative delivery method for the same established intranasal findings.

Chemically, Selank has molecular formula C33H57N11O9, molecular weight approximately 751.9 g/mol, CAS number 129954-34-3 (free peptide); the acetate salt form specifically addressed in this profile carries CAS number 2703745-90-6. PubChem CID 11765600.

Selank was designed as an extension of tuftsin (Thr-Lys-Pro-Arg), a naturally occurring tetrapeptide fragment of the immunoglobulin G heavy chain with immunomodulatory activity, by adding a Pro-Gly-Pro tripeptide extension to the C-terminus. This extension was specifically intended to increase the molecule's resistance to enzymatic degradation and prolong its biological half-life relative to native tuftsin, while retaining and, in some research, augmenting tuftsin's original immunomodulatory activity alongside newly characterized anxiolytic and nootropic effects not documented for native tuftsin itself.

At Verified Peptides, we want to be fully transparent about the evidence picture specific to systemic Selank administration. The most direct, quantitatively detailed citation we identified for systemic (intraperitoneal) Selank is Kolik et al. (2022, Bulletin of Experimental Biology and Medicine, PMID 36322304, volume 173, issue 6, pages 730-733), which tested a single intraperitoneal injection of Selank (0.3 mg/kg, an anxiolytic dose established in prior rat research) in a naloxone-precipitated morphine withdrawal model in outbred rats, finding a 39.6% reduction in total withdrawal syndrome index, significantly attenuated convulsive reactions, ptosis, and posture disorders, and a 9-fold increase in tactile sensitivity threshold compared to controls — a real, quantitatively rigorous systemic-administration finding, though modestly less effective than diazepam (2 mg/kg produced a 49.3% reduction) in the same model. We also identified additional real, peer-reviewed animal research using systemic (intraperitoneal) Selank administration in alcohol-dependence models, including a study on withdrawal syndrome modeling in rats with stable alcoholic motivation and a separate study finding Selank inhibited ethanol-induced hyperlocomotion and behavioral sensitization in DBA/2 mice (both published in Bulletin of Experimental Biology and Medicine). These represent genuine, additional systemic-route animal findings beyond the anxiolytic and opioid-withdrawal contexts discussed above, though, like those studies, they remain preclinical animal research rather than human clinical evidence.

We also want to directly reference the Vasileva et al. (2020) route-comparison study discussed in the mechanism section above, since it is the most directly relevant systemic-versus-intranasal comparison we identified; we were unable to locate a PMID for this specific paper during this research process (it is indexed via DOI 10.1134/S1819712420030113 rather than a readily located PubMed entry), and we are noting this transparently rather than fabricating a PMID or omitting the finding entirely.

We want to be equally direct about the limitation on the human side: we could not locate any published, controlled human clinical trial specifically evaluating systemic (subcutaneous or intramuscular) Selank administration, in contrast to the substantial Russian clinical trial literature supporting intranasal Selank's approval for anxiety disorders and neurasthenia. Research and informal use of systemic Selank in humans currently rests on extrapolation from intranasal human data and from the animal intraperitoneal research discussed above, not on dedicated human systemic-route trials. We think this is a materially different evidentiary situation from, for example, GHK-Cu or other well-established peptides in this catalog where both animal and human data converge on a consistent picture — here, the animal data (largely intraperitoneal) and the human data (exclusively intranasal) come from genuinely different administration routes with a documented route-dependent effect-profile difference, meaning neither dataset should be treated as directly validating the other. At Verified Peptides, we sell research-grade Selank Acetate exclusively for laboratory research, and we think this evidence gap between animal systemic data and human systemic data is an important, honest distinction for researchers to understand before drawing conclusions about human systemic use from either the intranasal human literature or the animal parenteral literature alone.

Selank's development history traces to earlier Russian research on ACTH(4-10) fragment analogs and tuftsin-family immunomodulatory peptides conducted at the Institute of Molecular Genetics, part of a broader Soviet-era and post-Soviet Russian research tradition in peptide neuropharmacology that also produced Semax (built elsewhere in this catalog), a structurally distinct ACTH-fragment-derived peptide developed by an overlapping research community.

The finding that intraperitoneal administration favors anxiolytic effects while intranasal administration favors nootropic effects (per Vasileva et al. 2020) is consistent with a broader pharmacological principle: different administration routes can result in meaningfully different tissue distribution patterns and relative exposure of different brain regions or receptor populations, even for the identical molecule, since intranasal delivery is proposed to allow some direct nose-to-brain transport bypassing the bloodstream for certain peptides, while systemic injection relies on bloodstream distribution and blood-brain-barrier crossing more generally.

Mouse strain-dependent variability in Selank's behavioral effects (responsive BALB/c mice versus non-responsive C57BL/6 mice in the Vasileva et al. 2020 study) is a recurring theme in rodent behavioral pharmacology generally, reflecting known genetic differences in baseline anxiety-like behavior and neurotransmitter system function between common laboratory mouse strains, a general methodological consideration relevant to interpreting any single-strain rodent behavioral study.

At Verified Peptides, we require independent third-party HPLC purity testing and mass spectrometry identity confirmation for every batch of research-grade Selank Acetate we offer, with a Certificate of Analysis (COA) available for each lot. Researchers should confirm whether a given lot's documentation specifies the acetate salt (CAS 2703745-90-6) or the free peptide (CAS 129954-34-3), since both are commercially available under similar naming.

We source exclusively from manufacturers operating under Good Manufacturing Practice (GMP)-aligned quality systems, and every lot is independently verified rather than accepted solely on a supplier's internal documentation. Researchers should always request and review the specific COA for the lot they receive, confirming purity percentage and molecular identity before use in any experimental protocol, including whether the lot documentation specifically supports parenteral (injectable) research use.

Lyophilized Selank Acetate is stable when stored at -20°C, protected from light and moisture. At Verified Peptides, we ship lyophilized peptide with appropriate cold-chain packaging to preserve stability in transit.

Once reconstituted, solution should be stored refrigerated at 2–8°C and used within the timeframe indicated on the product's documentation, avoiding repeated freeze-thaw cycles. Researchers preparing solutions specifically for systemic (parenteral) research applications should follow sterile technique and appropriate solvent selection consistent with their institution's animal research protocols, distinct from the aqueous nasal-spray-compatible formulation approaches used in intranasal human research.