The synthetic neuroactive peptide class — Semax, Selank, P21, Dihexa, Cerebrolysin, and several less-developed candidates — represents an unusual convergence of central nervous system pharmacology. Most members of the class were developed outside the Western pharmaceutical mainstream, principally at the Russian Academy of Sciences (Semax, Selank), Washington State University (Dihexa), and Ever Neuro Pharma in Austria (Cerebrolysin).
What unites these otherwise disparate peptides is a shared downstream pharmacological signature centered on neurotrophic-factor potentiation. Semax administration produces rapid and substantial elevation of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) in cortex and hippocampus; Selank shares the BDNF effect with a stronger anxiolytic signature attributable to modulation of GABA-A subunit expression; P21 engages the CNTF receptor directly; Dihexa potentiates HGF/c-Met signaling and drives substantial synaptogenesis in preclinical models; Cerebrolysin’s defined peptide mixture produces broad neurotrophic-mimetic effects on cortical neurons in culture.
The pharmacokinetic profiles vary widely. Semax and Selank are typically administered intranasally because of poor oral bioavailability and the practical advantages of nose-to-brain transit. Dihexa was engineered specifically for blood-brain-barrier penetration. Cerebrolysin is administered parenterally as a defined mixture. Across the class, plasma half-lives are short, but CNS effects often persist beyond what plasma kinetics would suggest, consistent with rapid initiation of transcriptional cascades.
Clinical translation is geographically uneven. Semax and Cerebrolysin are approved in multiple jurisdictions for stroke recovery and cognitive impairment; Selank is approved in Russia for generalized anxiety disorder. None has FDA or EMA approval. The class merits sustained attention as a model of how peptide-based interventions can engage neurotrophic biology with a different therapeutic index than traditional small-molecule psychoactive agents.