FLGR-242 is a vendor code name, not an identified compound. It has no published literature in any scientific index, no entry in any chemical registry we can search, no agreed parent protein, no published sequence and no molecular weight anyone agrees on.
It is sold under the name of follistatin, described elsewhere as a modified follistatin fragment, and elsewhere again as an FSTL3 analogue — three descriptions that cannot all be true.
Nothing that can be stated from evidence. There is no published study of FLGR-242 in any species, no toxicology, no pharmacokinetics and no registered trial, so there is no population for which a benefit has been shown and no basis on which to describe a use. This entry exists because the compound is sold and people search for it, not because there is a case for it.
Unknowable. No pharmacokinetic study of FLGR-242 exists in any species, so there is no measured time to peak, no duration and no half-life.
An extended half-life is claimed for it on the basis of an albumin-binding element; the published albumin-binding literature does not support the figures in circulation, and no measurement of this compound has ever been made.
Nothing, on any evidence basis. Combining an unidentified compound with anything else compounds the unknown rather than managing it — there is no characterised mechanism to predict an interaction from, and no way to attribute an effect or an adverse event to one input rather than the other.
No dose of FLGR-242 has ever been published, in any species, by any route — so nothing below is a recommendation, and this page invents nothing.
One protocol does circulate widely, and since it is what most people arrive here holding, it is worth setting out and checking rather than ignoring: 2.5 mg once a week for four weeks, then 5 mg weekly for eight, then 10 mg weekly for twelve. It carries no source, and no study of this compound exists to have produced one.
Three things about it are checkable by anyone. First, a milligram figure presupposes a known molecule: with no agreed identity, no published sequence and no molecular weight, “10 mg” describes a mass of powder, not a quantity of a named substance.
Second, it contradicts the marketing it travels with — the roughly 19-day half-life claimed for this compound would make weekly dosing accumulate to about 4.4 times the stated dose at steady state, so either that half-life claim is wrong or the weekly schedule is; nobody has measured either. Third, the arithmetic: vials are labelled 5 mg, so the final rung is two vials per injection, and the full 24 weeks comes to 34 vials — the escalation curve and the reorder curve are the same curve.
There is also no stated endpoint, no monitoring and no stopping rule anywhere in it.
The same numbers the goodtides app and the Dose Calc use — a research reference, not a prescription. Responses are individual; research protocols start at the low end.
There is no mechanism to describe, and the reason is worth stating precisely: no molecule has been identified. A mechanism is a claim about how a specific structure interacts with a specific target, and FLGR-242 has no published structure.
The descriptions in circulation do not even agree on what the starting protein is. Three passages in it describe oxytocin, including an LD50 and a warning that women of childbearing potential should exercise extreme caution because the substance may induce uterine contractions; section 2 carries each of its entries twice, an oxytocin version beside a generic one, which reads as an oxytocin template only partly rewritten.
Searched on 6 September 2026 and re-checked in full on 11 September 2026, it returns zero records in PubMed, PubMed Central, Europe PMC (which indexes preprints and patents), OpenAlex, Crossref, PubChem's compound and substance databases, UniProt, ClinicalTrials.gov and DailyMed, across three spellings. The indexes are working — the bare token FLGR returns forty PubMed records, all of them about flgR, a sigma-54-dependent transcriptional activator controlling flagellar assembly in bacteria such as Campylobacter and Helicobacter, which has nothing to do with peptides or muscle.
What exists instead is a mechanism borrowed from a real protein. FLGR-242 is sold under the name follistatin, and follistatin biology is genuine and well characterised: follistatin (UniProt P19883, gene FST, 344 amino acids) binds and neutralises members of the TGF-beta superfamily including myostatin, the negative regulator of skeletal muscle mass, and follistatin gene therapy has been taken into human trials — a phase 1/2a study in Becker muscular dystrophy, published in Molecular Therapy in 2015.
None of that is evidence about FLGR-242. It is evidence about follistatin, and the two are connected only by a product name.
The compound is variously described as a modified fragment of follistatin-344 fused to an albumin-binding construct, as an FSTL3-derived analogue, and simply as follistatin itself. Follistatin-related protein 3 (UniProt O95633, gene FSTL3, 263 amino acids) is a different gene product with a similar name.
A fragment of a protein is not the protein. A compound with no agreed parent cannot have an agreed sequence, and without a sequence there is no molecular weight, no theoretical mass, and nothing for a laboratory to measure against.
The extended half-life attributed to an albumin-binding element is checkable, and the check does not support the claim. In the 2002 Journal of Biological Chemistry paper that established the albumin-binding strategy, an albumin-binding peptide fused to an antibody fragment extended that fragment's half-life 37-fold, to 32.4 hours in rabbits, and 26-fold, to 10.4 hours in mice — which the authors describe as 25 to 43 percent of the albumin half-life in those animals, not the carrier's own duration.
The mechanism does not hand a molecule albumin's lifetime, and multi-week figures quoted for an uncharacterised peptide on the strength of it claim considerably more than the strategy has been shown to deliver, in a species nobody has tested, for a molecule with no published structure to do the binding.
Four documents circulate in place of a literature, and we read all four on 11 September 2026. Three are certificates of analysis from MDx BioAnalytical Laboratory for BioLongevity Labs — a real laboratory, professionally produced documents carrying chromatography and mass-spectrometry traces, a vial photograph and a named signatory.
They report a single dominant peak, purities of 99.71 to 99.79 percent, about 5 mg of material against a 5 mg label, and endotoxin results under the stated threshold. Those are real measurements of purity and quantity.
They are not measurements of identity: in each certificate the determined identity restates the identity written on the vial that was sent, because no reference standard exists to compare against. Read together the three also disagree.
One is headed FLGR232 and carries CAS 3108438-94-1 while the mass-spectrometry trace printed inside it is captioned FLGR242. Another records its batch number as the string FLGR — a product code, not a lot — and gives receipt and reporting dates a year apart.
The CAS number appears on that one certificate and on neither of the others; it has a valid check digit, which is trivial to construct, and we found no matching record in PubChem's compound or substance databases or in Europe PMC. The fourth document, from the other vendor, is a safety data sheet rather than a certificate of analysis — a hazard-communication document supplied by the seller, not third-party analytical evidence — and it is partly about a different molecule.
That is evidence about the paperwork and not about the contents — nothing indicates the material is oxytocin — but it leaves the one document written to explain safe handling unreliable. The same sheet contradicts itself on toxicology, reasoning from a specific LD50 in section 2 while section 11 states that no acute toxicity data is available for this compound, and it records the CAS number as "Proprietary / research compound", which cannot be squared with the CAS printed on the other vendor's certificate.
Its molecular weight and sequence are deferred to the certificates, and the certificates carry neither.
One line on those certificates is read more generously than it should be. An endotoxin pass is not a sterility result and not a safety clearance; it tests for one class of bacterial breakdown product against a threshold, and says nothing about what else is in the vial.
None of this establishes that the vials are empty or that the material is dangerous. Something is in them, and three laboratory reports say that something is a single, highly pure substance of roughly the stated mass.
What no document establishes is what that substance is. An absent safety record is also not a clean safety record: there is no toxicology to cite in either direction, and the two are routinely confused in this market.
Log every dose, count every vial, and verify your batches — free in the goodtides app.
This page is educational reference material about compounds studied in research settings. It is not medical advice, and nothing here is a recommendation to buy, possess, or use any compound. Research findings described are from published literature; individual compounds may not be approved for human use. Talk to a licensed clinician about anything that affects your health.