Semax and Selank Explained Simply

1. What It Is About

Semax and Selank are two short protein chains produced in the laboratory. Such chains are called peptides. Both were developed in the 1980s and 1990s at the Institute of Molecular Genetics of the Russian Academy of Sciences. Semax is derived from an endogenous hormone, Selank from an endogenous molecule called tuftsin. Both are administered via the nose so that they reach the brain. They belong to the agents intended to influence nerve cells. Research on them takes place predominantly in the laboratory and in animals: 253 papers are recorded in the evaluation, including 0 controlled studies in humans, 26 observational studies, 154 animal experiments and 8 cell-culture studies. This distribution explains why many observations come from the animal field and questions in humans remain open.

2. What Studies Show

Semax is best studied in humans after a stroke. In an observational study, patients received Semax in addition to rehabilitation. Among other things, the Barthel Index was measured, a scale for how independently someone performs tasks such as washing or dressing. This value improved faster in them than in the participants without Semax, and the final values were better 1. In addition, a nerve growth factor called BDNF rose in the blood. Whether this increase explains the better recovery has not yet been clarified.

For Selank there is an observational study with people who suffered from generalised anxiety disorder, that is, severe, persistent anxiety. Selank inhibited the breakdown of endogenous signalling substances, the so-called enkephalins 4. The anxiety of the participants decreased. Typical side effects of usual anxiety medications such as fatigue or memory problems were not observed. In a further study, people with anxiety additionally received a sedative; with Selank its side effects occurred less frequently, for example weakness or dizziness on standing 3.

In review articles a possible significance of Semax in ADHD and in Rett syndrome is discussed. This assessment is based on animal experiments; studies in humans are still outstanding 5. A further review lists Semax among several peptides that are being investigated in connection with ageing 6. Also discussed is a protein called transthyretin that may be involved in the protective effect after stroke; this is so far an assumption 7.

In animal experiments both peptides showed a fairly uniform picture: after oxygen deficiency in the brain, nerve cells were better protected and the nerve growth factor BDNF rose. These results come from the animal and cell field.

3. What Remains Unclear

Studies in which chance decides who receives the agent and who receives a placebo without active substance are lacking for anxiety disorders, ADHD and neurodegenerative diseases. Such studies are still outstanding. Little is also known about longer-term use: the short observations showed no serious side effects; what happens over weeks or months is an open question. There are no studies on which amount is appropriate, and how much of a nasal preparation actually reaches the blood varies strongly from person to person. The protective effects on nerve cells have so far been shown predominantly in animal experiments; whether they occur similarly in humans needs to be examined. A comparison with already established treatments is also missing.

4. What This Means In Everyday Life

The two peptides are widely discussed although they are not approved as medicinal products in many countries. Semax counts among the unapproved peptides 6. Such substances have been found in seized preparations 2. They are therefore offered outside regulated channels, without verified information on content, purity or effect.

Anyone reading the reports should distinguish two things: observations from animal experiments are numerous and point in the same direction. Observations in humans, by contrast, come from individual studies in which no one received a placebo without active substance. What would be needed next are studies in which people randomly receive an agent or a placebo and are followed over a longer period. This would clarify whether the observed changes are produced by the peptides themselves.

All Details With Study Numbers And Sources: Detailed Page On Semax And Selank. For Children: Semax And Selank For Children.