Nootropic peptides
Also called: brain peptide, cognitive peptides
Clinical reviewer: Jacob Moore, MD · Last checked September 22, 2026
What are brain peptides?
Nootropic peptides refers to peptides marketed for cognitive or mood effects, including Semax, Selank, dihexa and P21, none of which is FDA-approved. Human evidence comes mostly from small Russian studies of Selank; our September 2026 search found no human study of dihexa or P21, and FDA has found no or limited human safety data for Semax, Selank and dihexa.
What human evidence exists for these peptides?
Selank has been studied in small Russian trials; a 2008 study of 62 patients with generalized anxiety disorder or neurasthenia reported anxiety relief similar to the benzodiazepine medazepam [1]. Dihexa has no comparable human record: FDA states it "has not identified any human exposure data on drug products containing dihexa acetate" [4]. P21, written P021 in the scientific literature, is a neurotrophic peptide mimetic studied in mouse models of Alzheimer's disease [3]; no human study of P021 was found in our search as of September 2026.
What is each peptide's FDA compounding status?
None of the four is FDA-approved. FDA's Category 2 list, current as of April 22, 2026, records Semax's nomination as withdrawn, citing "no, or limited, safety-related information," and Selank's as withdrawn over immunogenicity and impurity concerns [4]. On July 24, 2026, FDA's Pharmacy Compounding Advisory Committee reviewed Semax, as free base and acetate, at its public meeting [2]. Advisory committee votes are non-binding, and adding a substance to the 503A bulks list still requires FDA rulemaking.
Related terms
Sources
- Zozulia AA et al. Efficacy and possible mechanisms of action of a new peptide anxiolytic selank in the therapy of generalized anxiety disorders and neurasthenia. Zh Nevrol Psikhiatr Im S S Korsakova, 2008.
- FDA — July 23-24, 2026 Meeting of the Pharmacy Compounding Advisory Committee.
- Baazaoui N, Iqbal K. Alzheimer's Disease, Challenges and a Therapeutic Opportunity to Treat It with a Neurotrophic Compound. Biomolecules, 2022.
- FDA — Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2), current as of April 22, 2026
This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
