Evidence is limited to animal or in-vitro work. No human pharmacokinetics. Any human dose in circulation is extrapolated, and extrapolation across species routinely fails.
No measured plasma half-life or absorption PK found. One in-vitro finding: intestinal peptide hydrolases did not appreciably hydrolyze Livagen (PMID 16075683), suggesting relative proteolytic stability in a gut-enzyme assay, not a measured in-vivo half-life.
PMID 16075683 reports oral dosing in rats for 2 weeks but does not state the mg/kg dose in the accessible abstract. No human dosing study found on any allowed host.
Single Russian lineage (Khavinson, Linkova, Popovich et al.). Allowed-host evidence: in-vitro human-serum enzyme-inhibition assay (PMID 12942748); ex-vivo human-lymphocyte chromatin-decondensation studies in elderly donors; rat-liver organotypic explant culture; small in-vivo rat digestive-enzyme studies (PMID 16075683). No RCT, no independent non-Russian replication. Sequence Lys-Glu-Asp-Ala and MW 461.5 Da confirmed on PubChem (CID 87919683).
No human safety/toxicology trial found on allowed hosts. A 2020 Russian review characterizes Livagen/KEDA as 'harmless', but this is a narrative characterization from the same lineage, not an independent controlled safety study. Absence of reported harm is not evidence of safety.
- [Effect of new peptide bioregulators livagen and epitalon on enkephalin-degrading enzymes in human serum] · pubmed
- [Effect of peptide Livagen on activity of digestive enzymes in gastrointestinal tract and non-digestive organs in rats of different ages] · pubmed
- Tissue-specific effects of peptides · pubmed
- PubChem Compound Summary CID 87919683, H-Lys-Glu-Asp-Ala-OH (MW 461.5) · other