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Semax vs Selank — Trial Data and Evidence Level

Semax and Selank are synthetic heptapeptides developed at the same Russian institute, both approved as prescription medications in Russia, and studied in separate populations for different primary indications. This page reports each compound's key human study, the evidence level each supports, and the doses specified on their Russian-registered labels — each figure attributed to its source.

On this page
  1. 1.Mechanism
  2. 2.Human Evidence
  3. 3.Regulatory Status
  4. 4.Adverse Events
  5. 5.Evidence Level
  6. 6.FAQ
  7. 7.References

Mechanism

Semax is derived from the ACTH(4-7) fragment of adrenocorticotropic hormone. Animal studies report BDNF and TrkB-receptor upregulation in the hippocampus and cortex (Dolotov et al. 2006, PMID 16635254), with no activation of the hypothalamic-pituitary-adrenal axis despite the ACTH-derived structure.

Selank is derived from tuftsin, an endogenous immunomodulatory peptide. It is reported to act as a positive allosteric modulator of GABA-A receptor signaling without binding the benzodiazepine site (Volkova et al. 2016, PMC4757669), alongside BDNF upregulation (Inozemtseva et al. 2008, PMID 18841804).

Human Evidence

SemaxSelank
OriginACTH(4-7) analogTuftsin analog
Reported mechanismBDNF/trkB upregulation; no HPA-axis activationGABA-A allosteric modulation (does not bind the benzodiazepine site); BDNF upregulation
Key human studyGusev et al. 1997 (PMID 11517472) — hemispheric ischemic strokeZozulya et al. 2008 (PMID 18454096) — generalized anxiety disorder and neurasthenia
Study designControlled comparative study (30 Semax-treated vs 80 conventional-therapy patients); abstract does not state randomizationComparative study of Selank vs medazepam in 62 patients (generalized anxiety disorder 30, neurasthenia 32); no randomization, blinding or placebo stated
ComparatorConventional stroke therapyMedazepam (a benzodiazepine)
Reported resultSome improvement in the rate of neurological-function recovery, assessed by clinical rating scales and EEG/evoked-potential monitoringAnxiolytic effect described in the paper as similar to medazepam, plus antiasthenic and psychostimulant effects not seen with medazepam
Russian-approved indicationsIschemic stroke recovery, cognitive impairment, optic nerve disordersGeneralized anxiety disorder, neurasthenia
Registered label dose500–5,000 mcg/day intranasal (RLSNET, Peptogen JSC package insert), 3–5 days, extendable to 14 with medical supervision≈150 mcg per nostril, 3× daily (≈900 mcg/day), 14-day course (RLSNET, Peptogen JSC package insert)
FDA statusNot FDA-approvedNot FDA-approved

Gusev et al. 1997 (PMID 11517472) studied Semax in 30 patients in the acute period of hemispheric ischemic stroke against a control group of 80 patients on conventional therapy, using clinical rating scales plus EEG and somatosensory evoked-potential monitoring. The most effective doses reported were 12 mg/day for moderate-severity stroke (5-day course) and 18 mg/day for severe stroke (10-day course). The abstract reports “some influence” on the rate of recovery of damaged neurological functions; it does not state randomization.

Zozulya et al. 2008 (PMID 18454096) studied Selank in 62 patients — 30 with generalized anxiety disorder and 32 with neurasthenia — comparing it with medazepam using the Hamilton, Zung, and CGI psychometric scales. The abstract describes the anxiolytic effects of both as similar, with Selank additionally producing antiasthenic and psychostimulant effects; it does not state the Selank dose used or randomization/blinding.

Regulatory Status

Both compounds are registered prescription medications in Russia. The RLSNET package insert for Semax 0.1% nasal drops (Peptogen JSC) lists ischemic stroke, cognitive impairment, and optic nerve disorders as indications; a separate 1% formulation is specified for acute ischemic stroke. The RLSNET package insert for Selank 0.15% nasal drops (Peptogen JSC) lists generalized anxiety disorder and neurasthenia. Neither compound has FDA or EMA approval; outside Russia and Ukraine, both are sold as research-grade peptides, not medications.

Adverse Events

Semax: no serious adverse events are reported in the published Russian clinical literature identified for this page. The most commonly reported issues are local (nasal irritation with intranasal dosing) or related to overstimulation. No study identified for this page reports on dependence or withdrawal after stopping Semax.

Selank: Zozulya et al. 2008 reports Selank adverse events as isolated and short-lived, against adverse events in 65% of medazepam patients, and no withdrawal syndrome or dependence after Selank was stopped (assessments to day 14). No study of tolerance was identified for this page.

Western-standard long-term safety data is limited for both compounds; the adverse-event record above comes from Russian clinical use and the cited trials, not from independent Western post-marketing surveillance.

Evidence Level

Semax: Human Observational (Gusev et al. 1997, PMID 11517472) — a controlled comparative study whose own abstract does not state randomization. Selank: Human Observational (Zozulya et al. 2008, PMID 18454096) — a controlled comparative study whose own abstract does not state randomization or blinding. Neither compound has a confirmed Human RCT identified for this page.

FAQ

Was the Gusev 1997 Semax stroke study a randomized controlled trial?

Gusev et al. 1997 (PMID 11517472) compared 30 Semax-treated hemispheric-ischemic-stroke patients against 80 patients on conventional therapy. The paper's own abstract does not state randomization, and no “Phase 3” or multi-center designation appears in the text. This is a controlled comparative study, Human Observational level, not a confirmed randomized trial.

Was the Zozulya 2008 Selank trial randomized?

Zozulya et al. 2008 (PMID 18454096) compared Selank with medazepam, a benzodiazepine, in 62 patients — 30 with generalized anxiety disorder and 32 with neurasthenia — assessed by psychometric scales (Hamilton, Zung, CGI). The paper's own abstract does not state randomization or blinding. This is a controlled comparative study, Human Observational level, not a confirmed RCT.

What doses do the Russian-registered labels specify?

The RLSNET package insert for Semax 0.1% nasal drops (Peptogen JSC) specifies a general/cognitive-disorder daily dose of 500–5,000 mcg for 3–5 days, extendable to 14 days with medical supervision, and a separate 1% formulation for the acute-stroke indication. The RLSNET package insert for Selank 0.15% nasal drops (Peptogen JSC) specifies approximately 150 mcg per nostril, three times daily, for a 14-day course. Neither trial cited above (Gusev 1997, Zozulya 2008) reports the specific dose administered in its own abstract for the indication studied.

Are Semax and Selank FDA-approved?

No. Both are approved as prescription medications in Russia — Semax for ischemic stroke recovery, cognitive impairment, and optic nerve disorders; Selank for generalized anxiety disorder and neurasthenia. Neither has FDA or EMA approval; outside Russia, both are sold as research-grade peptides.

References

  1. Gusev EI, Skvortsova VI, Miasoedov NF, et al. Effectiveness of Semax in the acute period of hemispheric ischemic stroke (a clinical and electrophysiological study). Zh Nevrol Psikhiatr Im S S Korsakova. 1997;97(6):26-34. https://pubmed.ncbi.nlm.nih.gov/11517472/
  2. Zozulia AA, Neznamov GG, Siuniakov TS, et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia. Zh Nevrol Psikhiatr Im S S Korsakova. 2008;108(4):38-48. https://pubmed.ncbi.nlm.nih.gov/18454096/
  3. Dolotov OV, Karpenko EA, Inozemtseva LS, et al. Semax, an analog of adrenocorticotropin (4-10), binds specifically and increases levels of brain-derived neurotrophic factor protein in rat basal forebrain. J Neurochem. 2006;97(suppl 1):82-86. https://pubmed.ncbi.nlm.nih.gov/16635254/
  4. Volkova A, Shadrina M, Kolomin T, et al. Selank Administration Affects the Expression of Some Genes Involved in GABAergic Neurotransmission. Front Pharmacol. 2016. https://pmc.ncbi.nlm.nih.gov/articles/PMC4757669/
  5. Inozemtseva LS, Karpenko EA, Dolotov OV, et al. Intranasal administration of the peptide Selank regulates BDNF expression in the rat hippocampus in vivo. Dokl Biol Sci. 2008;421:241-3. https://pubmed.ncbi.nlm.nih.gov/18841804/
  6. RLSNET. Semax (Семакс), package insert — nasal drops 0.1%. Registration holder: Peptogen JSC. https://www.rlsnet.ru/drugs/semaks-5420
  7. RLSNET. Selank (Селанк), package insert — nasal drops 0.15%. Registration holder: Peptogen JSC. https://www.rlsnet.ru/drugs/selank-36612
Semax ProfileSelank Profile

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