Selank · tuftsin analog · pharmacokinetics · research use only
Selank half-life: the anxiolytic counterpart to Semax's two-clock profile.
Selank is a synthetic analog of the immunomodulatory tetrapeptide tuftsin, extended with a stabilising terminus that resists rapid enzymatic breakdown. Like its better-known sibling Semax, its plasma clearance is short — reported on the order of minutes — yet its studied effects are described in the literature as outlasting the circulating peptide. The resolution is the same two-clock pattern: a fast plasma clock and a longer functional one. What makes Selank a distinct page rather than a copy of Semax is lineage and focus — Selank descends from tuftsin and is studied for anxiolytic and immunomodulatory pathways rather than the neurotrophic angle that defines Semax. This page explains Selank's clearance, why its stabilised structure extends the studied window, and what its COA must confirm. It is a laboratory reference, not a human protocol or medical advice.
Short in plasma — minutes
Selank's plasma clearance is short — reported on the order of minutes, like most small linear peptides. If circulating concentration were the only variable, it would appear to act and vanish almost at once. As with Semax, the reason it is studied on a longer functional window is structural rather than a slower bloodstream clock — see the next card.
How that shapes timing →A stabilised tuftsin analog
Selank is built from tuftsin — a four-residue immunomodulatory peptide — extended with a terminus that resists peptidase degradation, giving it greater stability than native tuftsin. That stabilising modification is the structural reason its studied activity extends past what raw plasma clearance alone would predict, the same mechanism by which Semax's Pro-Gly-Pro tail works on a different parent sequence.
Why the sequence matters on a COA →Anxiolytic lineage, not neurotrophic
This is what separates Selank from Semax as a research compound: Selank descends from tuftsin and is studied for anxiolytic and immunomodulatory pathways, whereas Semax is studied around neurotrophic signalling. Same two-clock kinetic pattern, different functional literature — which is why the two pages complement rather than duplicate each other.
Semax vs Selank compared →Acute, modelled timing in research
Because plasma exposure is short and intranasal absorption is fast, Selank research protocols tend to model acute timing rather than building a steady-state level — the cadence follows the fast on/off plasma profile while accounting for the longer functional tail. Distinct from a multi-day accumulation peptide, and aligned with how the other nootropic-class nasal peptides are studied.
Nootropic nasal peptides →Identity, not just purity
Because Selank's stability advantage comes from a specific terminal modification on the tuftsin core, a sequence-confirming COA matters more than a bare purity number — native tuftsin or a truncated analogue would not carry the same kinetics. Titan's Selank nasal spray ships against an HPLC main-peak result with a ≥99% internal purity target and mass-spec identity confirmation on a lot-matched release sheet.
See the testing workflow →Research-use framing
Selank is supplied strictly as a research-use-only reagent. The half-life and stability figures here are reproduced as a laboratory reference for in-vitro and modelling work — not instructions for human use, and not a claim about anxiety, immune function, or any physiological effect. Nothing on this page is medical or dosing advice.
Research-use policy →The detail, in plain terms
Two clocks: plasma and function.
Selank's kinetics only make sense when rapid plasma clearance and the structural stability of its tuftsin-analog terminus are read as separate variables. These are the figures a research protocol weighs, reproduced as a reference, not a human protocol.
- Compound
- Selank — synthetic analog of tuftsin with a stabilising terminus.
- Plasma clearance
- Short — reported on the order of minutes.
- Stability vs native tuftsin
- Greater — the terminal modification resists peptidases.
- Functional persistence
- Studied anxiolytic/immunomodulatory effects reported to outlast plasma clearance.
- Resulting cadence
- Acute, modelled timing in research — not multi-day accumulation.
- Titan format
- Metered nasal spray, $59.99 — no reconstitution required.
Questions researchers ask
Before you order.
- What is the half-life of Selank?
- Selank's plasma clearance is short — reported on the order of minutes, like most small linear peptides. But its stabilising terminus makes it more durable than native tuftsin, and studied effects are reported to outlast the circulating peptide. The two figures describe different things: how fast it leaves the blood versus how long its functional effect is modelled to last.
- How is Selank's half-life different from Semax's?
- Kinetically they follow the same pattern — short plasma clearance with a longer functional window created by a stabilising modification. The difference is lineage and focus: Selank is a tuftsin analog studied for anxiolytic and immunomodulatory pathways, while Semax derives from ACTH(4-10) and is studied around neurotrophic signalling. Same two clocks, different research literature.
- Why does Selank act longer than its plasma half-life suggests?
- Because of its structure. Selank is tuftsin extended with a terminus that resists enzymatic degradation, giving it greater stability than the native peptide. Combined with downstream activity that the literature treats as outlasting the circulating peptide, the studied window is longer than raw plasma clearance alone would predict.
- Why does Selank identity matter more than a purity number?
- Because its stability advantage comes from a specific terminal modification on the tuftsin core. Native tuftsin or a truncated analogue would not carry the same kinetics, so a sequence-confirming COA matters more than a bare purity figure. Titan's Selank ships with an HPLC main-peak result against a ≥99% internal purity target and mass-spec identity confirmation on a lot-matched release sheet.
- Is Selank approved for human use?
- Titan Peptide Lab supplies Selank strictly as a research-use-only reagent for in-vitro laboratory work — not for human or animal consumption, and not for diagnostic, therapeutic, or preventative use. The kinetic figures on this page are a laboratory reference, not medical or dosing advice.