# Selank - Canonical: https://residue.info/c/selank/ - Also called: TP-7, Selank acetate, Thr-Lys-Pro-Arg-Pro-Gly-Pro - Evidence grade: C (Limited / early human data). Small clinical studies in Russian journals, including a 62-patient comparison with medazepam; no large randomized placebo-controlled trial indexed in PubMed. - Status: Not FDA-approved · FDA compounding nomination withdrawn - PubChem CID: 11765600 - Updated: 2026-10-19 · Reviewed by: Residue Editorial Team Selank is the synthetic heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro, studied mainly in Russia for anxiety [1]. In a study of 62 patients with generalized anxiety disorder or neurasthenia, its anxiolytic effect was similar to the benzodiazepine medazepam [2]. Laboratory work suggests it modulates GABA receptors and inhibits enzymes that break down enkephalins [3][1]. It is not FDA-approved. ## Key findings - In 62 patients with GAD or neurasthenia, selank (30) and medazepam (32) had similar anxiolytic effects; selank also showed anti-asthenic and psychostimulant effects [2]. (anchor: https://residue.info/c/selank/#kf-pmid-18454096) - Selank inhibited enzymatic breakdown of plasma enkephalin with an IC50 of 15 µM, more potently than bacitracin or puromycin [1]. (anchor: https://residue.info/c/selank/#kf-pmid-11550013) - It acted as a positive allosteric modulator of GABA binding in laboratory assays [3]. (anchor: https://residue.info/c/selank/#kf-pmid-30255741) - In rat frontal cortex, selank changed the expression of 45 of 84 neurotransmission genes at 1 hour, correlating with the effect of GABA [4]. (anchor: https://residue.info/c/selank/#kf-pmid-26924987) - FDA lists selank acetate among withdrawn compounding nominations and says it lacks important safety information for humans [5]. (anchor: https://residue.info/c/selank/#kf-fda-cat2) ## Effects by system - Anxiety (grade C): Anxiolytic effect similar to medazepam in a 62-patient clinical comparison [2]. (anchor: https://residue.info/c/selank/#effect-anxiety) - Immune (cytokines) (grade C): Changes in Th1/Th2 cytokine balance in patients treated for 14 days [6]. (anchor: https://residue.info/c/selank/#effect-immune-cytokines) - GABA system (lab/rat) (grade D): Allosteric GABA-binding modulation; gene-expression changes in rat cortex [3][4]. (anchor: https://residue.info/c/selank/#effect-gaba-system-lab-rat) - Enkephalin degradation (grade D): Inhibited plasma enkephalinases in vitro (IC50 15 µM) [1]. (anchor: https://residue.info/c/selank/#effect-enkephalin-degradation) ## What is selank? Selank is the heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro [1]. It ends in Pro-Gly-Pro, the same three residues that end semax (compare the sequence figures) [7][8]. Its PubMed record is small, and the clinical papers are published mostly in Russian journals [9]. ## How is Selank thought to work? Two lines of laboratory work exist. In 2001, researchers reported that people with generalized anxiety disorder had a shortened enkephalin half-life and lower total enkephalinase activity, and that selank dose-dependently inhibited enzymatic hydrolysis of plasma enkephalin (IC50 15 µM) [1]. Later work showed selank acting as a positive allosteric modulator of GABA binding, interacting in a non-additive way with benzodiazepines [3]. In rats, selank and GABA produced correlated changes in the expression of neurotransmission genes in the frontal cortex [4]. ## What have studies found? **Anxiety.** The main clinical study compared selank (30 patients) with medazepam (32 patients) in generalized anxiety disorder and neurasthenia, using Hamilton, Zung and CGI scales. Anxiolytic effects were similar; selank also showed anti-asthenic and psychostimulant effects. Patients had low levels of a leu-enkephalin measure that rose with selank treatment [2]. The abstract does not report randomization or blinding. **Immune effects.** In patients with anxiety-asthenic disorders treated for 14 days, selank shifted the Th1/Th2 cytokine balance; in vitro, it suppressed IL-6 gene expression in blood cells from patients with depression but not controls [6]. **Registered trials.** A ClinicalTrials.gov search returns two records, both brain-stimulation device studies that do not test selank [10]. FDA lists "Selank acetate (TP-7)" among substances whose compounding nominations were withdrawn. It notes possible immunogenicity from aggregation and peptide-related impurities, and states FDA lacks important information regarding any safety issues raised by selank acetate administered to humans [5]. ## What is still unknown? - **Placebo-controlled, blinded trials** of adequate size, published with full methods. - **Pharmacokinetics in humans** are not described in the records we fetched. ## Frequently asked questions **Is selank FDA-approved?** No. FDA lists 'Selank acetate (TP-7)' among withdrawn compounding nominations, citing immunogenicity risk and a lack of important safety information for humans [5]. **Does selank work for anxiety?** One 62-patient study found an anxiolytic effect similar to medazepam in generalized anxiety disorder and neurasthenia [2]. No large placebo-controlled trial is indexed in PubMed, so the evidence is limited. **How does selank work?** Laboratory studies suggest it allosterically modulates GABA receptors [3] and inhibits enzymes that degrade enkephalins [1]. **What is the difference between selank and semax?** Selank is a heptapeptide studied for anxiety [1]; semax is an ACTH(4-7) analog extended with Pro-Gly-Pro, studied for stroke [11]. Both end in Pro-Gly-Pro and both are listed by FDA as withdrawn compounding nominations [5]. ## Sources [1] The inhibitory effect of Selank on enkephalin-degrading enzymes as a possible mechanism of its anxiolytic activity. Zozulya AA et al. Bull Exp Biol Med. 2001. https://pubmed.ncbi.nlm.nih.gov/11550013/ [2] [Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia]. Zozulia AA et al. Zh Nevrol Psikhiatr Im S S Korsakova. 2008. https://pubmed.ncbi.nlm.nih.gov/18454096/ [3] Peptide-based Anxiolytics: The Molecular Aspects of Heptapeptide Selank Biological Activity. Vyunova TV et al. Protein Pept Lett. 2018. https://pubmed.ncbi.nlm.nih.gov/30255741/ [4] Selank Administration Affects the Expression of Some Genes Involved in GABAergic Neurotransmission. Volkova A et al. Front Pharmacol. 2016. https://pubmed.ncbi.nlm.nih.gov/26924987/ [5] Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. U.S. FDA, content current as of 04/22/2026. https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks [6] [Immunomodulatory effects of selank in patients with anxiety-asthenic disorders]. Uchakina ON et al. Zh Nevrol Psikhiatr Im S S Korsakova. 2008. https://pubmed.ncbi.nlm.nih.gov/18577961/ [7] PubChem compound record: Selank. C33H57N11O9 · MW 751.9 g/mol. https://pubchem.ncbi.nlm.nih.gov/compound/11765600 [8] PubChem compound record: ACTH (4-7), Pro-Gly-Pro-. C37H51N9O10S · MW 813.9 g/mol. https://pubchem.ncbi.nlm.nih.gov/compound/9811102 [9] PubMed search: (selank[tiab]). 68 records at fetch. https://pubmed.ncbi.nlm.nih.gov/?term=(selank%5Btiab%5D) [10] ClinicalTrials.gov registry search: selank. 2 registered studies at fetch. https://clinicaltrials.gov/search?intr=selank [11] Semax, an analog of ACTH((4-7)), regulates expression of immune response genes during ischemic brain injury in rats. Medvedeva EV et al. Mol Genet Genomics. 2017. https://pubmed.ncbi.nlm.nih.gov/28255762/ --- From Residue. Research and education only; not medical advice. Quote with attribution and a link to the canonical page.