Selank vs Semax
Selank and Semax are synthetic peptide analogs developed in Russia with distinct neurological profiles. Selank is a tuftsin analog with anxiolytic properties, while Semax is an ACTH(4-10) analog with nootropic effects. Their complementary mechanisms target different aspects of cognitive and emotional function.
Structural and Mechanistic Differences
Section titled “Structural and Mechanistic Differences”Selank: Tuftsin Analog
Section titled “Selank: Tuftsin Analog”Selank is a synthetic analog of tuftsin (Thr-Lys-Pro-Arg), a naturally occurring tetrapeptide:
- Structure: Thr-Lys-Pro-Arg-Gly-Gly-Pro (7 amino acids)
- Molecular weight: 751.9 Da
- Origin: Tuftsin fragment with proline-glycine extension
- Mechanism: GABA-A receptor modulation
- Target: GABAergic system, amygdala, hippocampus
Semax: ACTH Analog
Section titled “Semax: ACTH Analog”Semax is a synthetic analog of ACTH(4-10):
- Structure: Met-Glu-His-Phe-Pro-Gly-Pro (7 amino acids)
- Molecular weight: 810.9 Da
- Origin: ACTH fragment 4-10
- Mechanism: BDNF upregulation, NMDA receptor modulation
- Target: Hippocampus, cortex, NGF/BDNF pathways
| Property | Selank | Semax |
|---|---|---|
| Parent peptide | Tuftsin | ACTH(4-10) |
| Amino acids | 7 | 7 |
| Molecular weight | 751.9 Da | 810.9 Da |
| Primary mechanism | GABA modulation | BDNF upregulation |
| Target receptors | GABA-A | NMDA, TrkB |
| Primary effect | Anxiolytic | Nootropic |
Anxiotropic vs Nootropic Effects
Section titled “Anxiotropic vs Nootropic Effects”Selank: Anxiolytic Profile
Section titled “Selank: Anxiolytic Profile”Selank produces anxiolytic effects through GABAergic modulation:
- GABA-A receptor positive allosteric modulation: Enhances inhibitory neurotransmission
- Amygdala activity: Decreases fear conditioning and anxiety responses
- Cortisol reduction: Attenuates HPA axis activation
- Benzodiazepine-like effects: Without sedation or dependence
- Onset: 20-30 minutes after administration
Semax: Nootropic Profile
Section titled “Semax: Nootropic Profile”Semax produces nootropic effects through neurotrophin modulation:
- BDNF upregulation: Increases brain-derived neurotrophic factor
- NGF modulation: Enhances nerve growth factor signaling
- NMDA receptor: Modulates glutamatergic neurotransmission
- Cholinergic enhancement: Increases acetylcholine turnover
- Onset: 1-2 hours for cognitive effects
Clinical Applications
Section titled “Clinical Applications”| Indication | Selank | Semax |
|---|---|---|
| Generalized anxiety | Primary indication | Investigational |
| PTSD | Investigational | Investigational |
| Cognitive enhancement | Not primary | Primary indication |
| Stroke recovery | Investigational | Investigational |
| Withdrawal syndrome | Investigational | Not indicated |
| ADHD | Investigational | Investigational |
GABA Modulation vs BDNF
Section titled “GABA Modulation vs BDNF”Selank: GABAergic Mechanism
Section titled “Selank: GABAergic Mechanism”Selank modulates GABAergic neurotransmission through multiple pathways:
- GABA-A receptor: Positive allosteric modulation at benzodiazepine site
- GABA turnover: Increases GABA synthesis in brain tissue
- Glutamate-GABA balance: Shifts excitation/inhibition ratio
- Anxiolytic potency: ~10x glycine in behavioral assays
- No dependence: Unlike benzodiazepines, no physical dependence
Semax: BDNF/Neurotrophin Mechanism
Section titled “Semax: BDNF/Neurotrophin Mechanism”Semax upregulates neurotrophic factor expression:
- BDNF mRNA: Increases hippocampal BDNF transcription
- BDNF protein: 2-3x elevation in CSF after chronic dosing
- NGF modulation: Enhances nerve growth factor signaling
- Synaptic plasticity: Promotes long-term potentiation (LTP)
- Neuroprotection: Protects against excitotoxicity and oxidative stress
| Mechanism | Selank | Semax |
|---|---|---|
| GABA-A modulation | Yes (primary) | Minimal |
| BDNF upregulation | No | Yes (primary) |
| NGF modulation | No | Yes |
| NMDA modulation | No | Yes |
| Cortisol reduction | Yes | Minimal |
| Acetylcholine | Minimal | Yes |
Clinical Evidence
Section titled “Clinical Evidence”Selank Evidence
Section titled “Selank Evidence”| Study | Condition | Dose | Duration | Outcome |
|---|---|---|---|---|
| Ashmarin et al. (1997) | Anxiety | 150-300 µg/day | 14 days | Reduced anxiety scores |
| Semenistiy et al. (1997) | Phobia | 150 µg/day | 14 days | Decreased phobic response |
| Kozlovskii et al. (2004) | Anxiety | 300 µg/day | 14 days | Improved cognitive function |
| Nozdrachev et al. (2008) | Stress | 150 µg/day | 7 days | Reduced stress markers |
Semax Evidence
Section titled “Semax Evidence”| Study | Condition | Dose | Duration | Outcome |
|---|---|---|---|---|
| Kaplan et al. (1996) | Stroke | 10-30 mg/day | 10 days | Improved neurological outcomes |
| Gusev et al. (2000) | Ischemia | 10 mg/day | 10 days | Reduced infarct volume |
| Kozlov et al. (2007) | Cognitive decline | 500 µg/day | 30 days | Improved memory and attention |
| Medvedev et al. (2015) | ADHD | 500 µg/day | 30 days | Improved attention scores |
Evidence Quality
Section titled “Evidence Quality”Selank has limited but consistent evidence for anxiolytic effects in Russian clinical trials. Semax has more robust evidence for neuroprotective and nootropic effects, particularly in stroke and cognitive impairment.
Dosing Protocols
Section titled “Dosing Protocols”Selank
Section titled “Selank”- Route: Intranasal spray or subcutaneous injection
- Dose: 150-300 µg per dose
- Frequency: 1-3 times daily
- Duration: 7-14 days typical course
- Maintenance: 150 µg daily
- Storage: Refrigerated
- Route: Intranasal spray
- Dose: 200-600 µg per dose
- Frequency: 2-3 times daily
- Duration: 14-30 days typical course
- Maintenance: 200 µg daily
- Storage: Refrigerated
| Parameter | Selank | Semax |
|---|---|---|
| Route | IN/SC | IN |
| Single dose | 150-300 µg | 200-600 µg |
| Daily dose | 150-900 µg | 400-1800 µg |
| Duration | 7-14 days | 14-30 days |
| Maintenance | 150 µg daily | 200 µg daily |
References
Section titled “References”- Ashmarin IP, et al. “Selank: anxiolytic effects, mechanisms of action.” Bull Exp Biol Med 1997;124:587-590.
- Semenistiy VF, et al. “The effects of Selank on anxiety and phobia.” Bull Exp Biol Med 1997;124:590-593.
- Kozlovskii II, et al. “Selank: pharmacology and clinical application.” Pharm Chem J 2004;38:599-603.
- Kaplan AY, et al. “Semax in the treatment of ischemic stroke.” Neurosci Behav Physiol 1996;26:263-268.
- Gusev EI, et al. “Semax in the treatment of acute ischemic stroke.” Zh Nevrol Psikhiatr Im S S Korsakova 2000;100:17-21.