Semax and Selank: where the cognition evidence stands
Two peptides developed in Russia share a stabilizing Pro-Gly-Pro tail. Their English-language clinical record is thin.
Two related designs
Semax (MEHFPGP) is built from a short fragment of the hormone ACTH. Selank (TKPRPGP) is built from tuftsin, an immune-system peptide. Both end in Pro-Gly-Pro, a tail that helps protect them from being broken down.
The evidence for Semax
An independent review by the Alzheimer’s Drug Discovery Foundation found few English-language human studies — mostly small pilot trials in healthy volunteers and studies in stroke patients. It reported no evidence for Alzheimer’s disease and little evidence that Semax improves cognition in healthy people. Long-term side effects are unknown.
Selank
Selank has a similar profile: developed and used in Russia, with a limited body of clinical research available in English.
Regulatory status
Both are used in Russia. Neither is approved by the FDA.
Bottom line
Evidence ladder: Human pilot. Plausible biology, small studies, many open questions.
Sources
Educational content only — not medical advice. See our Medical disclaimer and Editorial policy.