Read This First
This page is not built on clinical evidence. It is built on the FDA's July 2026 evaluation, the regulatory record, and what is known about how this peptide behaves in blood. What MOTS-c does in mice is covered on the library entry; this page is about what is in the vial and whether it can reach anything.
MOTS-c is a 16-residue peptide that human blood breaks down within minutes in vitro, that a well-funded developer could not formulate to its own satisfaction, and that has never been given to a person in its unmodified form in a reported study.12 For this compound the sourcing question is not only what the powder is, but whether the molecule survives the route it is sold for.
Legal Status
Where Does MOTS-c Stand?
Approved nowhere. No marketing authorisation, no USP monograph, not a component of any approved drug, and not recognised in the European or Japanese pharmacopoeias.1
In the United States it was placed in the FDA's Category 2 of nominated compounding substances in September 2023, with an entry stating the agency "has not identified any human exposure data on drug products containing MOTs-C administered via any route." As of April 2026 it appears among substances nominated but withdrawn.3
What Did the July 2026 Vote Change?
Nothing yet. On 23 July 2026 the Pharmacy Compounding Advisory Committee voted 7 to 5, with two abstentions, to recommend MOTS-c free base and acetate for the 503A bulks list for obesity and osteoporosis, against the FDA's recommendation.4 The nomination proposed subcutaneous injection at 5 mg and 10 mg strengths, which is at least the form the market sells.1
The recommendation is advisory, the list can only be amended by rulemaking, and the FDA has not begun one. Until it does, no pharmacy in the United States has a lawful basis on which to compound MOTS-c.
Product Identity
What Did the FDA Find on Characterisation?
That neither form was well characterised. For the free base, the certificates in the public domain lacked impurity, aggregate, bioburden and endotoxin data, and there was no water solubility figure or reconstituted concentration for the proposed injectable, so the agency could not tell whether solubility would be a problem. For the acetate, the substance is a white powder soluble in water at 6.25 mg/mL, with a stated storage condition of -80°C for two years or -20°C for one year, but the same gaps in impurity, aggregate and microbial data, and no information on how the injectable would actually be compounded at a known concentration.1
The storage figure is worth pausing on. It is the raw substance's specification, from a supplier's certificate, and it calls for a deep freezer. A vial that has been shipped at ambient temperature, stored in a refrigerator door and reconstituted for weeks is not being kept under the conditions the only available stability claim describes.
The Stability Problem
This is the compound-specific issue. In vitro, incubating MOTS-c with human whole blood at 37°C for 15 to 60 minutes "results in rapid proteolytic hydrolysis" into shorter peptides. The FDA's conclusion: it is "unclear whether exogenous administration of MOTS-c to humans via the nominated SC route can generate pharmacologically active concentrations of the peptide over time."1
CohBar, the company founded by the peptide's discoverer, designed a modified analogue, CB4211, partly to address that, took it through a Phase 1b, and then told the SEC that the formulation used "is not suitable for further development" and that "efforts to develop an improved formulation have not been successful to date."2
A buyer of gray-market MOTS-c is buying the unmodified peptide, in an unspecified formulation, for a route the developer of a stabilised version could not make work. Purity is not the question that decides whether this product does anything.
Purity Testing Versus Identity Testing
| Test | Question it answers | Question it cannot answer |
|---|---|---|
| HPLC purity | What proportion of the sample is one substance | Whether it is the full 16-residue sequence or a truncated one; whether it survives injection |
| Mass spectrometry identity | Whether the mass matches MOTS-c | How much of the sample it represents |
| Endotoxin assay | Whether bacterial cell-wall fragments are present | Identity or content; missing from the certificates the FDA found |
| Aggregate analysis | Whether the peptide has clumped | Almost never offered; the FDA's specific immunogenicity concern |
Certificates of Analysis
What a Certificate Is
A laboratory report on one batch. Read it for the laboratory's independence from the seller, the lot number and whether it matches the vial, the date, the substance named including free base or acetate, and which tests were run. For MOTS-c, look for endotoxin and microbial results, since the FDA found certificates without them, and for a storage condition, since the only one on record is a freezer.1
What It Cannot Establish
That the vial in hand came from the batch tested, or that it was kept cold between the laboratory and the buyer. Its value rests on a chain of custody the buyer cannot inspect. A certificate is a PDF, and nothing about the format prevents reuse or fabrication; the FDA has documented fabricated labels on gray-market peptide products.5
"Research Use Only"
Does the Label Change Anything?
No. It is a liability position adopted by the seller, not a regulatory category. The FDA has held in warning letters that the disclaimer does not survive product copy establishing human use.6 The FDA's own survey found MOTS-c offered online for "regulating mitochondrial energy, promoting the metabolism of fatty acid in the liver, promoting metabolic homeostasis, improving glucose regulation, aiding in the resistance of metabolic stress, protecting against insulin resistance, promoting weight loss, and improving physical performance."1 None of those is a research use.
Storage and Handling
What Is Known
The raw substance: -80°C for two years or -20°C for one, according to the supplier certificate the FDA reviewed.1 Nothing else. No reconstituted stability, no in-use period, no validated data for any product a consumer can buy. General peptide chemistry applies: lyophilised powder is more stable than solution; heat and freeze-thaw cycles degrade peptides; and a peptide that blood hydrolyses in minutes is not likely to be robust in a warm vial either.
Multi-Dose Vials
The FDA's guidance for compounded injectables is to discard a multi-dose vial within 28 days of first use regardless of what remains, and to use a new sterile needle and syringe for every dose.5
Signs to Stop Rather Than Proceed
A product shipped or stored at room temperature when the only stability claim on record is a freezer
A certificate without endotoxin or microbial results, for an injectable
Powder that does not dissolve cleanly, or a solution that turns cloudy or develops particles, which in a 16-residue peptide suggests aggregation
Injection-site reactions that grow with successive doses
A label describing CB4211, "stabilised MOTS-c" or an analogue; the analogue was never sold and its developer could not formulate it
Community Language
MOTS-c
Mitochondrial open reading frame of the 12S rRNA type-c. A 16-residue peptide the body makes; the subject of this page.
Exercise mimetic, exercise in a vial
Marketing language derived from mouse studies. In humans, exercise raises the body's own MOTS-c; nobody has shown injection does what exercise does.
CB4211
CohBar's modified analogue, the only MOTS-c-related molecule ever given to people in a trial. Not for sale; its formulation was abandoned.2
Mitochondrial-derived peptide, MDP
The class: peptides encoded in mitochondrial DNA, including humanin and MOTS-c. A description of origin, not of evidence.
Category 2
The FDA's interim classification for nominated compounding substances that may present significant safety risks. MOTS-c was placed there in 2023 and is now listed as nominated but withdrawn.3
Certificate of analysis
A laboratory report on one batch. It describes the batch tested, not necessarily the vial received, and not how the vial was stored since.
Related ONPEPS Coverage
MOTS-c library entry: the mouse data, the genetic evidence and the analogue that stalled
MOTS-c cost and access: paying for a Phase 2 that has not reported
Compounded, gray market and counterfeit semaglutide: what the regulators have documented
FDA peptide news July 2026: the votes, the dissent and what happens next
Sources
US Food and Drug Administration. MOTS-c-related bulk drug substances (MOTS-c (free base) and MOTS-c acetate): FDA presentation to the Pharmacy Compounding Advisory Committee, 23 July 2026. Docket FDA-2025-N-6895. fda.gov
CohBar, Inc. Form 10-Q for the quarter ended March 31, 2023, filed 11 May 2023. sec.gov
US Food and Drug Administration. Category 2 of the Bulk Substances Nominated Under Sections 503A or 503B of the Federal Food, Drug, and Cosmetic Act. Entry for MOTs-C. Content current as of 22 April 2026. fda.gov
ONPEPS. FDA peptide news July 2026: the only source you need. Records the 7 to 5 vote with two abstentions on MOTS-c. onpeps.com
US Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Drug Alerts and Statements. Cited for the agency's general guidance on multi-dose vials and fabricated labels. fda.gov
US Food and Drug Administration. Warning Letter: Gram Peptides. MARCS-CMS 721806, 31 March 2026. fda.gov
Not Medical Advice
MOTS-c holds no marketing authorisation for human use in any jurisdiction. If you are already using a product obtained outside a pharmacy, the route back to oversight is a clinician who knows what you have taken.
Regulatory sources verified 16 September 2026. The FDA had not acted on the July 2026 advisory recommendation as of that date, and the compounding record changes frequently. Re-verify before relying on any statement here.