Where to Buy Selank and Semax: 7 Purity and Identity Checks for Two Russian-Registered Nasal Peptides

Selank and Semax share a stabilising Pro-Gly-Pro tail and very little else. They are built from different parent molecules, weigh 751.9 and 813.93 grams per mole, and one of them is sold beside a derivative no purity certificate can distinguish from it.

Both sit in the cognitive and neuroprotective peptides category, and both carry genuine Russian registrations with no placebo-controlled patient trial behind either. The evidence pictures are in Selank: a registered anxiolytic that has never been compared to a placebo and Semax: FDA's own reviewers said no. This page is about the vial.

What are Selank and Semax, and why does source quality matter?

Selank is the heptapeptide Thr-Lys-Pro-Arg-Pro-Gly-Pro, 751.9 g/mol, CAS 129954-34-3; Semax is the heptapeptide Met-Glu-His-Phe-Pro-Gly-Pro, 813.93 g/mol, CAS 80714-61-0. Both were made at the Institute of Molecular Genetics of the Russian Academy of Sciences by attaching a Pro-Gly-Pro tail to a different parent — tuftsin for Selank, ACTH(4-7) for Semax. Source quality matters differently for each: Selank's risk is truncation and a database synonym error, Semax's is a derivative sold beside it.

One design idea produced both: take a short natural peptide and attach Pro-Gly-Pro at the C-terminus to slow enzymatic degradation. That is the only thing they share at the molecular level, and it is not enough to make one verification procedure cover both.

Semax is not an ACTH analogue in any functional sense. The fragment has no corticotropic activity and does not stimulate cortisol, so vendor copy describing it as a form of ACTH is wrong about mechanism before it is wrong about anything else. Selank's parent is an immunopeptide rather than a neuropeptide, which is why its early literature runs through cytokines rather than cognition.

Vendor coverage sits on the Selank compound page and the Semax compound page.

What is the regulatory status of Selank and Semax?

Both hold Russian registrations and neither is legally compoundable in the United States. Selank is certificate ЛП-№(010951)-(РГ-RU), an over-the-counter 0.15% nasal drop, ATC N05BX; Semax is ЛП-№(009449)-(РГ-RU), dated 26 March 2025, on Russia's Vital and Essential Medicines list, ATC N06BX. Both are held by JSC INPC "Peptogen" of Moscow. As of August 2026 both sit in FDA's "nominated but withdrawn" table, and neither is named on the WADA 2026 Prohibited List.

Selank's registered form is a 0.15% nasal drop in a 3 mL bottle, dispensed without prescription, and Peptogen states it became an over-the-counter medicine on 2 August 2017. Semax is registered as 0.1% and 1% nasal drops on an indefinite-term certificate, with registered dosing of 2–3 drops per nostril, two to four times daily, for 7–30 days. We could not verify the original year of first registration for either compound. The state register carries only the current, re-issued certificates, and the years circulating online are not traceable to a primary source, so we are not printing one.

On FDA's compounding page, current 22 April 2026, neither compound is among the fourteen substances in the active Category 2 group. Both appear instead under "Bulk drug substances nominated but withdrawn." Semax's two nominations came from Wells Pharmacy Network and LDT Health Solutions, and FDA's note reads: "The nominations were withdrawn and FDA is evaluating the substances at its discretion." Being off that list is a procedural fact about who withdrew what, not a safety clearance.

Neither compound is legally compoundable. Both remain unapproved new drugs in the United States, neither has a USP monograph, and neither is a component of any FDA-approved drug — so neither satisfies any of the three statutory routes for a bulk substance in 503A compounding. There is no compounding H2 on this page because there is no compounding route. See compounding pharmacy versus research peptide for what each route carries, and our FDA peptide regulation timeline for how these lists have moved.

Semax has had far more regulatory attention than Selank, and it did not go the way the marketing suggests. A briefing document published in May 2026 concluded there is "insufficient evidence of effectiveness to support use of semax (free base) or semax acetate for cerebral ischemia, migraine, or trigeminal neuralgia," and that "the evaluation criteria weigh against placing both semax (free base) and semax acetate on the list of bulk drug substances." On 24 July 2026 the Pharmacy Compounding Advisory Committee voted 8–5, with one abstention, to recommend adding it anyway. FDA published no minutes or transcript for that meeting, so the tally comes from published meeting coverage rather than an agency document, and an advisory vote is not an agency action. Semax's legal status today is exactly what it was before the meeting.

Three findings in that same briefing document land directly on what a buyer is paying for. FDA described both Semax forms as "not well-characterized", with missing impurity, aggregate, endotoxin and bioburden data. It flagged "inconsistent naming conventions that do not follow established chemical nomenclature standards" and raised "potential for immunogenicity associated with these impurities and peptide related aggregates." And it counted the entire documented human exposure as 33 to 47 healthy adults, 69 adults with medical conditions and 451 children, with three of the underlying references being conference abstracts whose full studies could not be located.

Selank, by contrast, has never been evaluated by that committee at all. It appears in FDA's Semax briefing material only to be excluded from scope as "a different peptide."

On sport, do not overstate either compound. Neither Selank nor Semax is named on the 2026 Prohibited List. Semax is not a corticotrophin, so S2.2.2 — which covers "corticotrophins and their releasing factors, e.g. corticorelin and tetracosactide" — does not fit. The catch-all S0 captures substances with "no current approval by any governmental regulatory health authority," and both hold Russian approvals, which on the literal wording places them outside it. No anti-doping body has published a determination either way. Seek a ruling before competing rather than assuming one.

How do you tell Selank from Semax, and Semax from its derivative?

Mass spectrometry, at two different numbers. Selank is 751.9 g/mol and Semax 813.93, far enough apart that any mass spectrometer separates them, so confusing the two is not the realistic failure. The realistic failures are compound-specific: Selank against tuftsin at roughly 500 Da or a truncated synthesis, and Semax against N-Acetyl Semax Amidate, a modified derivative with a different mass sold side by side, which an HPLC purity figure cannot distinguish. Each needs its own check.

Selank. At 751.9 g/mol this is a short peptide, and mass spectrometry is the only test that establishes identity — cheap and decisive at this mass, because a 752 Da heptapeptide is trivially distinguishable from its own fragments. Its parent, tuftsin, is a four-residue peptide at roughly 500 Da, so a synthesis that stops short is a mass you can see. There is also a live database trap: ChemicalBook's Selank entry lists "PL14736" as a synonym, and PL14736 is BPC-157, an entirely different peptide. A buyer cross-checking a certificate against that record is being routed to the wrong molecule. Do not use it as a synonym source for this compound.

Semax. The specific risk here is not contamination but substitution. Semax is sold alongside N-Acetyl Semax Amidate, a modified derivative that is a different molecule with a different mass, and an HPLC purity figure cannot tell you which one is in the vial — a pure sample of the wrong compound produces a beautiful chromatogram. Mass spectrometry against 813.93 Da for the free base is the only check that settles it. Two further wrinkles belong on the same certificate. Sigma-Aldrich supplies the research material as a TFA salt while quoting molecular weight on a free-base basis, and the acetate salt has its own CAS number and its own mass at 874.0 g/mol — the salt changes what your scale reads without changing the peptide, which is why net peptide content matters here (TFA versus acetate versus amidate salt forms). And PubChem's record title for CID 9811102 is not "Semax" — it reads "ACTH (4-7), Pro-Gly-Pro-". Anyone verifying a CoA against PubChem should expect that rather than treat it as a mismatch. See mass spectrometry for peptides for what an identity result establishes, and Semax versus Selank for the practical differences between them.

One screening test applies to the surrounding content rather than the vial. Articles on both compounds routinely quote "Elena Yaroslavtseva" of the Institute of Molecular Genetics, and no such researcher exists. A PubMed author search under that surname returns five records covering an HIV cohort in St Petersburg, insect pathogenic fungi and 1976 bacteriophage genetics, none connected to peptides or this institute. The real programme is easy to trace — Nikolay F. Myasoedov and Lyudmila A. Andreeva at the Institute of Molecular Genetics RAS run through nearly every paper on both compounds. A vendor page that invents an expert is rarely accurate about anything else, including its own certificates.

7 things to check before ordering Selank or Semax

Seven checks cover both compounds, and two of them branch by molecule. Mass spectrometry at 751.9 or 813.93 Da, the compound-specific exclusion — N-Acetyl Semax Amidate for Semax and tuftsin or a truncation for Selank — third-party HPLC against benchmarks of 99.63% and 99.44%, salt form and net peptide content, fill accuracy against +28.6% and +22.3% overages on record, an LAL endotoxin result FDA has already flagged as missing, and a pricing check read inside a vial-size band.

1. Mass spectrometry at the compound's own mass. Selank is 751.9 g/mol, Semax 813.93 g/mol by FDA's own figure. Ask for a batch-matched result rather than a specimen certificate from an earlier lot, which describes a different vial. HPLC tells you a sample is homogeneous; it does not tell you what the sample is.

2. The compound-specific exclusion. For Semax, ask explicitly whether the result excludes N-Acetyl Semax Amidate, which is sold beside it and is invisible to a purity assay. For Selank, the exclusions are tuftsin at roughly 500 Da and truncated syntheses, and the separate warning is documentary — ChemicalBook lists PL14736, which is BPC-157, as a Selank synonym.

3. Third-party HPLC purity from a named laboratory. This platform records Selank at 99.63% across 285 independent tests from seven named labs and Semax at 99.44% across 269, so "above 98%" describes a standard the market already clears. A vendor's own document is not third-party testing (third-party peptide testing labs).

4. Salt form and net peptide content. Semax research material is supplied as a TFA salt with molecular weight quoted on a free-base basis, and the acetate salt sits at 874.0 g/mol, so a certificate that does not name the salt is quoting a number you cannot convert. Net content or amino acid analysis is what separates peptide from salt and residual water (why 10 mg isn't 10 mg).

5. Fill accuracy, against two documented overages. Selank's tested content runs −10.3% to +28.6% against the label, including a June 2026 test returning 12.86 mg in a vial labelled 10 mg. Semax runs −2.1% to +22.3%. A 28.6% overage is not a bonus — it is evidence that fill accuracy is uncontrolled at that vendor, and the same process that overfills one vial underfills another.

6. An LAL endotoxin result. Endotoxin reporting is sparse across Selank listings, and on Semax it appears on a minority of listings at 0.05 to 0.096 EU/mL where reported at all. FDA specifically flagged missing endotoxin and bioburden data as a characterisation gap for Semax, which makes a blank field on this compound a documented objection rather than a preference (peptide endotoxin testing and the LAL assay).

7. The pricing check, the units, and what no certificate establishes. Vial size drives most of the per-milligram spread — Selank runs $6.00/mg on 2–8 mg vials against $4.00/mg at 10 mg and above, Semax $6.71/mg on 5–8 mg against $3.60/mg at 10 mg and above — so compare inside a band. Then the units: the registered products are percentage solutions and research vials are labelled in milligrams, and the arithmetic between them depends entirely on your reconstitution volume. The peptide dosing calculator and the reconstitution calculator will do that conversion; neither can supply the missing pharmacokinetics, because no human PK study exists for either compound. Reduce or stop a course if adverse effects appear, since no controlled safety study exists to tell you what is expected. See red flags in peptide certificates of analysis.

Where do Selank and Semax rank on Peptigrity's lab test database?

Peptigrity's Purity Index records Selank at 99.63% average HPLC purity across 285 independent lab tests from Vanguard, BTLabs, Horizon Analytical, Kovera, Ethos Analytics, ILS and MZ Biolabs, and Semax at 99.44% across 269 independent tests, each across 227 verified shops (verified August 2026). Both are strong purity results on large denominators. The weaker number on both compounds is quantity: Selank's tested content runs −10.3% to +28.6% and Semax's −2.1% to +22.3%.

Those figures exclude shipping, taxes and customs, coupon codes, bulk tiers, multi-vial kits and account-gated pricing. Both sets of price data were verified August 2026, and both are drawn from Selank price data and Semax price data.

Semax's recent tests run 99.00–99.90%, which is a tight band and tells you the market has the synthesis under control. What it does not tell you is which molecule was synthesised, and on this compound that is the open question rather than a rhetorical one, because the derivative sold beside it returns an equally clean chromatogram. Naming the seven laboratories behind Selank's 285 tests matters for the same reason: a reader can weigh provenance rather than take a bare percentage, and can search the lab test database and community-verified shop reviews for a specific vendor. Peptigrity tracks 530 shops and 11,852 independent lab tests across 118 peptides, with 1,283 community reviews (verified August 2026), weighting community reviews and independently verified HPLC purity equally at 50% each, with no financial relationships influencing the ranking — the methodology is documented at how we calculate trust scores.

The trial that would settle this is the same trial for both compounds, and neither has any part of it. Zero Selank trials and zero Semax trials appear on any public registry.

Frequently Asked Questions

What purity standard should Selank and Semax meet?

This platform records Selank at 99.63% average HPLC purity across 285 independent lab tests from Vanguard, BTLabs, Horizon Analytical, Kovera, Ethos Analytics, ILS and MZ Biolabs, and Semax at 99.44% across 269 tests, each across 227 verified shops (verified August 2026). Against a market clearing that high, "above 98%" promises less than the norm. On both compounds the weaker axis is quantity rather than purity, and on Semax a purity figure cannot exclude N-Acetyl Semax Amidate.

How much do Selank and Semax cost?

Selank shows 77 shops in stock at a median of $4.50/mg with a lowest tracked price of $1.70/mg on a 10 mg vial, across 84 live listings from 190 known sellers. Semax shows 72 shops in stock at a median of $4.09/mg, lowest $1.75/mg on a 10 mg vial, across 84 comparable offers from 179 known sellers ranging to $18.00/mg (both verified August 2026). Small vials cost more per milligram on both compounds. Those figures exclude shipping, taxes and customs, coupon codes, bulk tiers, multi-vial kits and account-gated pricing.

Are Selank and Semax legal, and can they be compounded?

Both are registered medicines in Russia and unapproved new drugs in the United States. Neither has a USP monograph and neither is a component of an FDA-approved drug, so neither satisfies any of the three statutory routes for 503A compounding — there is no legal compounding route for either. Both sit in FDA's "nominated but withdrawn" table as of the page current 22 April 2026, which is procedural rather than a safety clearance.

How do I know which molecule is in the vial?

Mass spectrometry on your batch, against 751.9 g/mol for Selank and 813.93 g/mol for Semax. For Semax, ask specifically whether the result excludes N-Acetyl Semax Amidate, a modified derivative with a different mass that is sold alongside it and that an HPLC purity figure cannot distinguish. For Selank, the exclusions are tuftsin at roughly 500 Da and truncated syntheses. Note also that PubChem titles the Semax record "ACTH (4-7), Pro-Gly-Pro-", which is not a mismatch, and that ChemicalBook lists PL14736 — BPC-157 — as a Selank synonym, which is an error.

What dose has actually been studied, and in what units?

Selank's only documented regimen is the registered one: two drops per nostril, three times daily, in 14-day courses of a 0.15% nasal drop. Semax's registered dosing is 2–3 drops per nostril, two to four times daily, for 7–30 days, at 0.1% or 1%. Its own trials used far higher amounts — 12 mg/day in moderate stroke and 18 mg/day in severe in the 1997 study, 6000 µg/day in 2018 — which are hospital protocols rather than the drop regimen, and the two are routinely conflated. Because no human pharmacokinetic study exists for either compound, no percentage-to-milligram conversion carries an exposure meaning; the intranasal peptide guide covers technique for both.

Did FDA approve Semax?

No. FDA's own reviewers concluded in a May 2026 briefing document that there is "insufficient evidence of effectiveness" and that the evaluation criteria weigh against listing Semax. The Pharmacy Compounding Advisory Committee then voted 8–5, with one abstention, on 24 July 2026 to recommend adding it, which is a non-binding recommendation from an outside committee. FDA has not issued a decision, and Semax remains an unapproved new drug. Selank has never been evaluated by that committee at all.

Browse the cognitive and neuroprotective peptides category, or our complete peptide guide with 118 compounds (verified August 2026). For per-dose volume when reconstituting a vial, use the peptide dosing calculator alongside the reconstitution calculator. Compare shops through independent lab tests and community-verified shop reviews.

This article is for educational and informational purposes only and does not constitute medical advice. Peptides discussed may be investigational compounds not approved by the FDA (or equivalent regulators in your jurisdiction) for human use. Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.