Is NA-Semax & NA-Selank safe?

That is the core marketing claim, but it has not been demonstrated in any published study. The chemistry argument — that capping both ends of the peptide slows enzymatic breakdown — is plausible in general terms, but no independent pharmacokinetic comparison between NA-Semax and plain Semax has been published. The specific potency and half-life multipliers seen on vendor sites vary from seller to seller, which suggests they are estimates or marketing figures rather than measured data.

No independent clinical or pharmacokinetic evidence exists for NA-Semax or NA-Selank as distinct compounds. What evidence does exist applies to the parent peptides — Semax and Selank's Russian clinical and registration data — and that data does not automatically transfer to a chemically modified analog. Treat any specific claim about the 'NA-' versions as unverified until an actual comparative study is published.

No. The pharmaceutical companies that manufacture and hold registration for Semax and Selank as approved nasal-spray drugs in Russia produce only the unmodified peptides. NA-Semax and NA-Selank are Western research-chemical products developed and sold independently of those manufacturers, with no formal affiliation or endorsement.

The reasoning is that acetylation and amidation slow the enzymatic breakdown that normally clears Semax and Selank quickly from the body, so a smaller or less frequent dose could theoretically achieve a similar effect. This is a reasonable hypothesis based on general peptide chemistry, but it hasn't been tested for these specific molecules, so any dosing schedule offered by a vendor is an estimate, not a study-derived recommendation.

If you're going to use one of these peptides at all, the parent compounds have a meaningfully larger (though still Russia-centric and limited-by-Western-standards) evidence base than the acetylated/amidated analogs, which currently have none. Choosing the unmodified version means relying on the more-studied — if still imperfect — option rather than an unstudied further modification.