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Semax Half-Life: How Long It Stays in Your System

How long Semax stays in the body, how that shapes dosing frequency, and what is known about drug testing.

Medically reviewed by Juan Pablo Frías, MD · · DisclosureACTH(4-10) analogUpdated
Half-life
Not found
No published half-life found (PubMed search, 2 Oct 2026)
Dosing interval
Varies by study
as used in studies
WADA
Unclear
Not named on the 2026 list
Detection window
Not found
None reported as of 2 Oct 2026

Semax half-life

Half-life: no published half-life found (PubMed search, 2 Oct 2026). A half-life depends on the route (under the skin, into a vein, by mouth or nasal spray), so we report it per route with the study it came from.

Other pharmacokinetic findings (these are not half-life values):

Semax: other pharmacokinetic findings
RouteHalf-lifeMeasured inSource
intranasalNo half-life reported; 80% of brain radioactivity was intact semax 2 min after dosing, with rapid enzymatic degradationAnimal · ratBioorganicheskaia khimiia 2006, PMID 16523722

What half-life means

Half-life is the time it takes for the amount of a drug in the blood to fall by half. After one half-life, about 50% is left; after two, about 25%; after four to five, only a few percent remain.

  • A long half-life lets a drug be dosed less often, for example once a week.
  • A short half-life means levels rise and fall quickly, which is why some peptides are given daily or more often.
  • Effects can outlast blood levels, so half-life alone does not tell you how long a drug works.

What it means for dosing frequency

Dosing intervals used in published studies of Semax:

Changing the interval changes how much drug builds up between doses, so it is not a free choice.

Drug tests and sport

WADA status unclear

Semax: This is not named on the 2026 list. The catch-all class S0 prohibits any drug with no approval anywhere for human use, so it would be banned if no health authority has approved it, but we have not verified that for this substance.

Anti-doping labs use tests built for specific substances. Whether a given test detects Semax, and for how long, is not reported in the anti-doping literature we checked (as of 2 Oct 2026).

Common questions

How long does Semax stay in your system?

We found no published half-life for Semax (PubMed search, 2 Oct 2026). As a rule, most of a dose is cleared after about four to five half-lives.

What is the half-life of Semax?

No published half-life was found in our PubMed search, 2 Oct 2026. We add one with its source and route if a study reports it.

Is Semax on the WADA prohibited list?

It is unclear. Semax: This is not named on the 2026 list. The catch-all class S0 prohibits any drug with no approval anywhere for human use, so it would be banned if no health authority has approved it, but we have not verified that for this substance.

More on Semax

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.StoragePowder and mixed vials: temperature and shelf life.

Sources

  1. 1Certain bulk drug substances for use in compounding that may present significant safety risks (Category 2; 'nominated but withdrawn' table, content current as of 22 Apr 2026)U.S. Food and Drug Administration · 2026fda.govAccessed 2 Oct 2026
  2. 2Pharmacy Compounding Advisory Committee meeting, 23–24 Jul 2026 (agenda and materials)U.S. Food and Drug Administration · 2026fda.govAccessed 2 Oct 2026
  3. 3World Anti-Doping Code International Standard Prohibited List 2026World Anti-Doping Agency · 2026wada-ama.orgAccessed 2 Oct 2026
  4. 4[Kinetics of Semax penetration into the brain and blood of rats after its intranasal administration].Bioorganicheskaia khimiia · 2006PMID 16523722Accessed 2 Oct 2026
  5. 5[The efficacy of semax in the tretament of patients at different stages of ischemic stroke].Zhurnal nevrologii i psikhiatrii imeni S.S. Korsakova · 2018PMID 29798983Accessed 2 Oct 2026
  6. 6Effects of Semax on the Default Mode Network of the Brain.Bulletin of experimental biology and medicine · 2018PMID 30225715Accessed 2 Oct 2026
  7. 7Therapy of peptic ulcer with semax peptide.Bulletin of experimental biology and medicine · 2002PMID 12459874Accessed 2 Oct 2026
  8. 8Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress.European journal of pharmacology · 2024PMID 39442746Accessed 2 Oct 2026
  9. 9PubMed search: semax[tiab] (208 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  10. 10PubMed search: semax[tiab] AND (half-life[tiab] OR pharmacokinetic*[tiab]) (4 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  11. 11PubMed search: (selank[tiab] OR semax[tiab]) AND (randomized[tiab] OR patients[tiab] OR clinical[tiab]) (48 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026

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