Semax

Semax is a drug which is used mostly in Russia and Ukraine for a broad range of conditions but predominantly for its purported nootropic, neuroprotective, and neurorestorative properties. Semax has not been evaluated, approved for use, or marketed in most other countries such as the United States.
Medical uses.
Semax has undergone extensive study in Russia and is on the Russian "List of Vital & Essential Drugs" approved by the Russian Federation government on December 7, 2011. Medical uses for Semax include treatment of stroke, transient ischemic attack, memory and cognitive disorders, peptic ulcers, optic nerve disease, and to boost the immune system.
Pharmacology.
Pharmacodynamics.
In animals, Semax rapidly elevates the levels and expression of brain-derived neurotrophic factor (BDNF) and its signaling receptor TrkB in the hippocampus, and rapidly activates serotonergic and dopaminergic brain systems. Accordingly, it has been found to produce antidepressant-like and anxiolytic-like effects, attenuate the behavioral effects of exposure to chronic stress, and potentiate the locomotor activity produced by -amphetamine. As such, it has been suggested that Semax may be effective in the treatment of depression.
Though the exact mechanism of action of Semax is unclear, there is evidence that it may act through melanocortin receptors. Specifically, there is a report of Semax competitively antagonizing the action of the melanocortin receptor full agonist α-melanocyte-stimulating hormone (α-MSH) at the MC4 and MC5 receptors in both "in vitro" and "in vivo" experimental conditions, indicating that it may act as an antagonist or partial agonist of these receptors. Semax did not antagonize α-MSH at the MC3 receptor, though this receptor could still be a target of the drug. As for the MC1 and MC2 receptors, they were not assayed. In addition to actions at receptors, Semax, as well as a related peptide drug, Selank, have been found to inhibit enzymes involved in the degradation of enkephalins and other endogenous regulatory peptides (IC50 = 10 μM), though the clinical significance of this property is uncertain.
Pharmacokinetics.
As a peptide, Semax has poor oral bioavailability and hence is administered parenterally as a nasal spray or subcutaneous injection.
Chemistry.
Semax is a heptapeptide and synthetic analogue of a fragment of adrenocorticotropic hormone (ACTH), ACTH (4-10), of the following amino acid sequence: Met-Glu-His-Phe-Pro-Gly-Pro ( in single-letter form).