SS-31 Peptide (Elamipretide)
A tetrapeptide that parks itself on cardiolipin, the lipid mitochondria keep for themselves. FDA approved it in September 2025 for Barth syndrome, on data from 12 patients, which is a story about rare-disease medicine.
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For research use only. Not for human or veterinary use.
What SS-31 Peptide (Elamipretide) is
The plain-language version, first.
One of the newest approvals in peptide medicine, for one of the rarest diseases.
SS-31 is elamipretide, a four amino acid peptide that concentrates in the inner mitochondrial membrane and binds cardiolipin, the phospholipid required for normal cristae structure and electron transport chain function. Its 218 patient phase 3 trial in primary mitochondrial myopathy failed its prespecified endpoints, and it was later granted FDA approval for Barth syndrome on the basis of a much smaller patient database.
In September 2025 this molecule did something almost nothing on this shelf has ever done: it got approved.
FDA approval, for Barth syndrome, an ultra-rare inherited mitochondrial disease. The pivotal data involved twelve patients, because twelve was a meaningful fraction of the diagnosed population.
SS-31, elamipretide by its generic name, is a four-residue peptide with an unusual address: it accumulates in mitochondria and binds cardiolipin, a lipid found almost nowhere else.
Rare-disease approvals run by different rules for honest reasons: you cannot run a thousand-patient trial on a disease with a few hundred known cases.
A real approval, a real molecule, and a data package whose size is a fact about the disease rather than a shortcut.
What is SS-31?
Mechanism studied, not outcome promised.
A four-tailed phospholipid found almost exclusively in the inner mitochondrial membrane, structurally necessary for cristae folds and respiratory complex organisation.
The compound was originally developed as a reactive oxygen species scavenger. That explanation has been superseded by the cardiolipin interaction in the current literature.
It targets a lipid, not a receptor, which is genuinely unusual.
Nearly everything on this shelf targets a protein. This targets a lipid, and that is worth slowing down for.
Cardiolipin is a structural lipid of the inner mitochondrial membrane, essential to how the energy-production machinery folds and functions.
SS-31 concentrates in mitochondria and binds cardiolipin, with the proposed effect of stabilising that membrane machinery under stress.
A peptide that targets a lipid environment rather than a receptor pocket is a genuinely different mechanism class, and it is why this molecule spent years being tried against many mitochondrial conditions.
Here's the honest part. Most of those other trials did not succeed.
The approval is real and narrow. The heart-failure and other larger programmes read out negative or equivocal along the way, and those results are part of the same file.
The research so far for SS-31 Peptide (Elamipretide)
Where the evidence is thin, we say so.
MMPOWER-3, 218 patients, primary mitochondrial myopathy, both co-primary endpoints missed. And the randomised portion of TAZPOWER in Barth syndrome, where the authors write that neither primary endpoint was met.
Accelerated approval on 19 September 2025 for Barth syndrome, in patients weighing at least 30 kilograms, on an intermediate muscle strength endpoint, with a confirmatory randomised trial required by FDA.
MMPOWER-3 randomised 218 patients and missed both co-primary endpoints, with six minute walk at minus 3.2 metres and p equals 0.69, graded Class I evidence of no effect. FDA then granted accelerated approval in September 2025 for Barth syndrome, on knee extensor strength as an intermediate endpoint, with a total clinical safety database of twelve male patients.
Approved on twelve patients. That sentence deserves its own explanation.
This file has both endings in it, which makes it unusually instructive.
The failures: larger trials in heart failure and other mitochondrial conditions that did not meet their endpoints through the late 2010s and early 2020s.
The success: Barth syndrome, September 2025, an approval built on twelve patients in a disease where twelve is a cohort.
Both are real. The molecule is not a fraud that finally slipped through, and it is not a panacea that was always destined to win. It is a targeted tool that found the one context narrow enough to show its worth.
Approved for one ultra-rare disease, failed in several common ones, and honest pages carry both halves.
Have a look at current stock and vial sizes.
SS-31 Peptide (Elamipretide) specs
The chemistry, exactly as released.
Who studies SS-31 Peptide (Elamipretide)
Who tends to order this one, and why.
A research compound does not have one audience. It has a handful of rooms where the same question keeps coming up, and the question is a different question in each of them.
Mitochondrial medicine
The largest and best-designed trial programme in this space, which is why its failure is informative rather than ambiguous.
Barth syndrome
An ultra-rare X-linked condition affecting cardiolipin remodelling, and the only approved indication for this compound anywhere.
Membrane biophysics
Cardiolipin and cristae architecture, and how a small molecule associating with a phospholipid can alter organelle structure.
Regulatory reviewers
A case study in accelerated approval on an intermediate endpoint, in a disease with no alternative, from a twelve patient database, with a confirmatory trial required.
Sold for laboratory research only. This is not guidance for personal use, and nothing here is a recommendation.
SS-31 Peptide (Elamipretide) backstory
How it got here.
Mitochondrial medicine has been a difficult field to develop drugs in. The diseases are rare, heterogeneous, and endpoint selection is genuinely hard, because what patients experience is fatigue and exercise intolerance rather than something a lab value captures cleanly.
Elamipretide, developed by Stealth BioTherapeutics, was the most advanced candidate in that space for years. It went into primary mitochondrial myopathy as the lead indication, the largest addressable population, and into Barth syndrome, an ultra-rare X-linked condition affecting cardiolipin remodelling, as a second.
The large indication failed and the ultra-rare one produced an approval, which is an unusual sequence and reflects both the mechanism fit in Barth and the different evidentiary standards that apply when a disease affects a very small number of people and has no alternative. A European orphan designation exists for Barth syndrome.
There is no European marketing authorisation and no Health Canada product.
- 1
A hard field
Mitochondrial diseases are rare, heterogeneous and difficult to design endpoints for, because what patients experience is fatigue and exercise intolerance rather than a clean lab value.
- 2
The big indication failed
Primary mitochondrial myopathy was the lead programme and the largest population. MMPOWER-3 returned a clean negative in 218 patients.
- 3
The rare one got approved
Barth syndrome involves cardiolipin remodelling, which is exactly where the mechanism fits. FDA granted accelerated approval in September 2025 on a twelve patient database.
Buying SS-31 Peptide (Elamipretide) in Canada
What ships, how fast, and the paperwork.
The hard part of buying research material is almost never the compound. It is the logistics. What leaves the building, how fast it moves, and what is in the box beside the vial. Here is ours, plainly.
Same day out of British Columbia
Our building, our cold packs, our people, and nothing sitting in a customs queue while you refresh a tracking page.
Then into the fridge
Keep it cold and keep it dark. Sealed and freeze-dried it handles a rough trip without ice. Once it lands, fridge.
The failure is the useful part
Most compounds here have thin evidence, which leaves room for hope. This one had 218 patients, randomisation, placebo and prespecified endpoints, and came back clean and negative in primary mitochondrial myopathy. That is a closed question rather than an open one, and it is worth more than an ambiguous file.
Stuff people ask about SS-31 Peptide (Elamipretide)
If your question is not here, email us. Real human answers.
No. MMPOWER-3, published in Neurology in 2023, randomised 218 patients with primary mitochondrial myopathy to elamipretide 40 milligrams daily or placebo for 24 weeks. Both co-primary endpoints failed. Six minute walk distance was minus 3.2 metres, numerically favouring placebo, p equals 0.69, and the fatigue score gave p equals 0.37. The paper is graded Class I evidence that elamipretide does not improve those outcomes.
The approval is for a different disease. FDA granted accelerated approval on 19 September 2025 for Barth syndrome, an ultra-rare X-linked condition, to improve muscle strength in patients weighing at least 30 kilograms. It was granted on knee extensor muscle strength, an intermediate endpoint FDA described as reasonably likely to predict benefit, and the entire clinical safety database on the label is twelve male patients. FDA requires a confirmatory randomised trial.
A distinctive four-tailed phospholipid found almost exclusively in the inner mitochondrial membrane, where it is structurally necessary for the cristae folds to form and for the respiratory complexes to organise. Elamipretide associates with it and is described as stabilising that architecture. Barth syndrome is caused by mutations affecting cardiolipin remodelling, which is why the mechanism and that indication line up.
Yes, and it is worth knowing. The compound was originally developed on a reactive oxygen species scavenging hypothesis. That explanation has been superseded in the current literature by the cardiolipin interaction. A revised mechanism mid-development is not unusual but it does affect how confidently anyone should extrapolate to new indications.
The randomised portion missed too. TAZPOWER, published in Genetics in Medicine in 2021, enrolled twelve male patients in a double-blind placebo-controlled crossover, and the authors write that in part one neither primary endpoint was met. The positive figures came from the open-label extension, where six minute walk improved by 95.9 metres at 36 weeks with no control arm.
No. There is one registered phase 2 study of elamipretide in healthy ageing and physical function with an estimated 30 participants, recruiting, with no results. Nobody has demonstrated a benefit in people without a mitochondrial disease.
Good pairing options with SS-31 Peptide (Elamipretide)
What researchers stack alongside it.
Pairing is where research gets ahead of itself. These are the compounds researchers put in the same order as SS-31 Peptide (Elamipretide), which is a statement about ordering habits, not about evidence. Two things in one cart have not been studied together unless somebody studied them together.
Without a zinc atom it is completely inert. Not less active. Inert. The metal is not a supporting player here, it is half the molecule's identity.
It has no sequence and no CAS number, because it is not a molecule. It is an extract of calf thymus, still in clinical use across Russia, and that combination is genuinely unusual.
Order SS-31 Peptide (Elamipretide) right now
One last look before you decide.
Freeze-dried, COA on the page, ships cold
If you are researching SS-31 Peptide (Elamipretide) and you want a source you do not have to second-guess, start with the paperwork on this page. For research use only.
Not for human consumption. Not approved by Health Canada or any other regulatory body.
Page last updated August 19, 2026
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