Mechanism of action

Semax is the ACTH(4-7) fragment Met-Glu-His-Phe extended at the C-terminus by Pro-Gly-Pro, a modification the literature describes as increasing resistance to enzymatic degradation. Unlike the parent hormone it is reported to be largely devoid of corticotropic activity, and it lacks the Arg-Trp motif of the melanocortin pharmacophore, so an action mediated by melanocortin receptors is not established. Radioligand work on rat basal forebrain membranes instead identified specific, reversible and calcium-dependent binding sites of nanomolar affinity that were not assigned to any cloned receptor (Dolotov et al., J Neurochem 2006). The best-characterised downstream signal is neurotrophin signalling: in rat hippocampus and basal forebrain, intranasally applied Semax raised BDNF protein levels and altered trkB expression. Rodent studies additionally describe modulation of monoaminergic and cholinergic transmission and of inflammation- and vasculature-related gene expression in focal ischemia models.

State of evidence

The mechanistic basis of Semax research is mainly preclinical: cell and rodent studies examine specific binding sites, BDNF and trkB expression, and responses after experimental focal cerebral ischemia (Dolotov et al., 2006; Romanova et al., 2006). Limited human reports address stroke and rehabilitation. Miasoedova et al. (1999) describe a retrospective comparative clinical and immunobiochemical analysis rather than a randomized placebo-controlled trial. Gusev et al. (2018) examined 110 patients divided by early or late rehabilitation and Semax exposure; the report describes higher plasma BDNF and differences in Barthel-index recovery in the Semax subgroups. Its abstract does not report randomization, blinding or placebo control, limiting causal inference and separation of treatment effects from rehabilitation timing. Publication language or country does not by itself determine evidence quality; design, reporting and independent replication do. Historical Peptogen information concerns a named nasal-drop formulation and its stated registration number, not an independently verified current authorization. These sources do not establish broad clinical efficacy, safety or authorization of a particular Semax research product.

Questions about the research

What is Semax investigated for in research?

Semax is investigated mainly in research on cognition, learning and memory, and on neuroprotection after cerebral ischemia. The central question is whether the peptide influences neurotrophin signalling, in particular BDNF and its receptor trkB. A further strand examines the expression of inflammation- and vasculature-related genes in stroke models.

What is the state of the evidence on Semax?

Most mechanistic findings come from cells and rodents. The 1999 stroke report is retrospective and comparative, while the 2018 report in 110 rehabilitation patients does not describe randomization, blinding or placebo control in its abstract. These are methodological limitations, not limitations based on language or country. Historical manufacturer documentation concerns formulated nasal drops and does not independently establish current registration or authorize other Semax products. Broad efficacy and safety are not established by this evidence.

Sources

1. Filippenkov et al., Genes 2023 (immune gene expression in rat brain)DOI: 10.3390/genes14071382PMID: 37510287
2. Dolotov et al., Brain Res 2006DOI: 10.1016/j.brainres.2006.07.108PMID: 16996037
3. Dolotov et al., J Neurochem 2006DOI: 10.1111/j.1471-4159.2006.03658.xPMID: 16635254
4. Romanova et al., Bull Exp Biol Med 2006DOI: 10.1007/s10517-006-0445-0PMID: 17603664
5. Miasoedova et al., Zh Nevrol Psikhiatr Im S S Korsakova 1999PMID: 10358912
6. Gusev et al., Zh Nevrol Psikhiatr Im S S Korsakova 2018DOI: 10.17116/jnevro20181183261-68PMID: 29798983
7. Peptogen: historical prescribing information for Semax 1% nasal drops, registration number П N000812/01; not a current registry record

Mechanism of action

Semax is the ACTH(4-7) fragment Met-Glu-His-Phe extended at the C-terminus by Pro-Gly-Pro, a modification the literature describes as increasing resistance to enzymatic degradation. Unlike the parent hormone it is reported to be largely devoid of corticotropic activity, and it lacks the Arg-Trp motif of the melanocortin pharmacophore, so an action mediated by melanocortin receptors is not established. Radioligand work on rat basal forebrain membranes instead identified specific, reversible and calcium-dependent binding sites of nanomolar affinity that were not assigned to any cloned receptor (Dolotov et al., J Neurochem 2006). The best-characterised downstream signal is neurotrophin signalling: in rat hippocampus and basal forebrain, intranasally applied Semax raised BDNF protein levels and altered trkB expression. Rodent studies additionally describe modulation of monoaminergic and cholinergic transmission and of inflammation- and vasculature-related gene expression in focal ischemia models.

State of evidence

The mechanistic basis of Semax research is mainly preclinical: cell and rodent studies examine specific binding sites, BDNF and trkB expression, and responses after experimental focal cerebral ischemia (Dolotov et al., 2006; Romanova et al., 2006). Limited human reports address stroke and rehabilitation. Miasoedova et al. (1999) describe a retrospective comparative clinical and immunobiochemical analysis rather than a randomized placebo-controlled trial. Gusev et al. (2018) examined 110 patients divided by early or late rehabilitation and Semax exposure; the report describes higher plasma BDNF and differences in Barthel-index recovery in the Semax subgroups. Its abstract does not report randomization, blinding or placebo control, limiting causal inference and separation of treatment effects from rehabilitation timing. Publication language or country does not by itself determine evidence quality; design, reporting and independent replication do. Historical Peptogen information concerns a named nasal-drop formulation and its stated registration number, not an independently verified current authorization. These sources do not establish broad clinical efficacy, safety or authorization of a particular Semax research product.

Questions about the research

What is Semax investigated for in research?

Semax is investigated mainly in research on cognition, learning and memory, and on neuroprotection after cerebral ischemia. The central question is whether the peptide influences neurotrophin signalling, in particular BDNF and its receptor trkB. A further strand examines the expression of inflammation- and vasculature-related genes in stroke models.

What is the state of the evidence on Semax?

Most mechanistic findings come from cells and rodents. The 1999 stroke report is retrospective and comparative, while the 2018 report in 110 rehabilitation patients does not describe randomization, blinding or placebo control in its abstract. These are methodological limitations, not limitations based on language or country. Historical manufacturer documentation concerns formulated nasal drops and does not independently establish current registration or authorize other Semax products. Broad efficacy and safety are not established by this evidence.

Sources

1. Filippenkov et al., Genes 2023 (immune gene expression in rat brain)DOI: 10.3390/genes14071382PMID: 37510287
2. Dolotov et al., Brain Res 2006DOI: 10.1016/j.brainres.2006.07.108PMID: 16996037
3. Dolotov et al., J Neurochem 2006DOI: 10.1111/j.1471-4159.2006.03658.xPMID: 16635254
4. Romanova et al., Bull Exp Biol Med 2006DOI: 10.1007/s10517-006-0445-0PMID: 17603664
5. Miasoedova et al., Zh Nevrol Psikhiatr Im S S Korsakova 1999PMID: 10358912
6. Gusev et al., Zh Nevrol Psikhiatr Im S S Korsakova 2018DOI: 10.17116/jnevro20181183261-68PMID: 29798983
7. Peptogen: historical prescribing information for Semax 1% nasal drops, registration number П N000812/01; not a current registry record