Semax Half-Life & Stability
Part of the full Semax guide - a synthetic melanocortin reference compound, identity-verified with a COA on every vial.
In brief
Pharmacokinetic and stability characterization of Semax in the provided data centers on a structural design feature rather than a measured circulating half-life: the C-terminal Pro-Gly-Pro tripeptide tail. The entry does not supply a specific numeric half-life value for Semax, so this section describes its stability and degradation behavior using the structural rationale that is provided, supplemented where noted by general peptide-class principles clearly identified as such. The defining claim is that the Pro-Gly-Pro tail shields the peptide from aminopeptidase degradation, increasing metabolic stability relative to native ACTH(4-10). That enzymatic resistance is the central pharmacologically relevant stability property in the supplied record, and it is what distinguishes Semax from the unmodified ACTH fragment it is derived from. The discussion below separates what the data specifically supports about Semax's enzymatic stability from the broader, generally applicable handling and degradation principles that govern small peptides in vitro, so that nothing peptide-specific is implied where the data is silent.
The detail
A closer look
01
Enzymatic stability conferred by the Pro-Gly-Pro tail
The clearest stability statement in the data is structural. Semax is built from the ACTH(4-7) fragment plus a C-terminal Pro-Gly-Pro tripeptide, and that PGP tail is specifically described as conferring resistance to aminopeptidase cleavage. Aminopeptidases trim residues from the ends of peptides; the proline-containing C-terminal cap impedes this exopeptidase attack, prolonging in-vitro and ex-vivo stability relative to native ACTH(4-10). The entry attributes the degradation characterization to a 2006 Amino Acids study and notes the rationale appears across multiple reviews. Functionally, this means that in cell-free and ex-vivo systems Semax persists longer than the unmodified fragment, which is the design intent behind appending Pro-Gly-Pro. This is an enzymatic-stability property rather than a measured plasma half-life, and the data does not provide a numeric clearance or half-life value to report.
02
General peptide-class stability and storage principles
Where Semax-specific kinetics are not provided, general peptide-class principles apply and are flagged as general here. Small lyophilized peptides are most stable as the dry solid and least stable once dissolved, where hydrolysis, oxidation (relevant given Semax's methionine residue, the sulfur-bearing Met that can be oxidation-sensitive), and microbial action become possible. Repeated freeze-thaw cycling of reconstituted stock is a common degradation source, so single-use aliquoting, cold storage, and light protection are standard mitigations. These are bench-handling generalizations rather than measured Semax parameters. The one peptide-specific advantage the data does establish is the aminopeptidase resistance from the PGP tail, which improves enzymatic durability in the assay environments studied but does not substitute for proper cold-chain and aliquot discipline once the lyophilized material is reconstituted.
The fine print: products are sold for laboratory research use only and are not for human or animal consumption. Bodily introduction into humans or animals is strictly prohibited by law. Semax is not a drug and is not intended to diagnose, treat, cure, or prevent any disease. These statements have not been evaluated by the FDA.