SS-31

Elamipretide

SS-31 (Elamipretide) is a longevity & bioregulators research compound. Mitochondria-targeted tetrapeptide that binds cardiolipin on the inner membrane, stabilizing cristae and restoring efficient ATP production.

How SS-31 works

Mitochondria-targeted tetrapeptide that binds cardiolipin on the inner membrane, stabilizing cristae and restoring efficient ATP production.

Proposed benefits

Mitochondrial repair and efficient ATP production (in clinical development).

Where to get SS-31

SS-31 is sold in 2 forms. They are not interchangeable — the dose and the route differ, so pick the one this page describes unless you know why you want another.

SS-31 reconstitution calculator

The evidence for SS-31

Graded by what exists behind each claim.

✅ Clinically validated

• Real, registered human trials — and the most instructive mixed record in the Vault. Elamipretide (the drug name for SS-31) has been through multiple phase 2 and phase 3 programs in primary mitochondrial myopathy, Barth syndrome and dry AMD.
• MMPOWER-3 in primary mitochondrial myopathy missed its primary endpoint — six-minute walk distance. What that miss means is worth being careful about. Primary mitochondrial myopathy is an umbrella over dozens of distinct genetic defects, and a walk test is a blunt instrument for a population that heterogeneous; the earlier MMPOWER-2 crossover had shown a signal on the same measure, and patient-reported fatigue moved in the direction of benefit.
• The Barth syndrome program — a single, defined cardiolipin-remodeling defect, which is exactly what the mechanism targets — reported functional improvement and reached FDA advisory committee review. That contrast is the actual lesson: the compound did better in the population its mechanism predicts, and worse in the one that was mostly a diagnostic category.

📊 Correlative data

• Research-community use for mitochondrial and recovery goals. Reported experience is subtle — as expected for something targeting an organelle rather than a symptom.

🧪 Theoretical / extrapolated

• A tetrapeptide that concentrates in the inner mitochondrial membrane and binds cardiolipin — the phospholipid that organizes the electron transport chain. Stabilizing cardiolipin is proposed to improve ATP production and reduce electron leak.
• The mechanism predicts where it should work best: tissues where mitochondrial dysfunction is the actual bottleneck. That is also why the trials succeeded in a rare cardiolipin-remodeling disease and struggled in broader populations.

How to read these tiers: they say how much human evidence exists, not how well something works — and ✗ flags harm, never a disappointing trial. How the evidence tiers work →

What SS-31 actually does

SS-31 does not scavenge a free radical, does not donate an electron, and does not enter the mitochondrion because of the membrane potential. It binds a lipid. That is what separates it from every other compound sold as mitochondrial support, and it is the reason its effects are structural rather than antioxidant.

The molecule. SS-31, developed as elamipretide, is a tetrapeptide with an alternating aromatic-cationic motif: D-Arg-Dmt-Lys-Phe-NH2, where Dmt is 2',6'-dimethyltyrosine. Three features matter. The D-arginine and the C-terminal amide make it resistant to peptidases. The two basic residues give a net positive charge at physiological pH. And the two bulky aromatics give it a hydrophobic face. A small peptide that is both cationic and amphipathic crosses membranes without a transporter, which is why a four-residue peptide gets inside a cell at all.

The target is cardiolipin, and cardiolipin is not an ordinary phospholipid. Cardiolipin has four acyl chains and two phosphate groups on a glycerol backbone, is found essentially only in the inner mitochondrial membrane, and its conical shape is what allows that membrane to fold into cristae. It is also the scaffold that holds respiratory complexes together into supercomplexes and the lipid that anchors cytochrome c to the membrane surface Tung 2025.

How the binding works, and why it is selective without needing a receptor. The cationic residues make an electrostatic contact with cardiolipin's anionic phosphates while the aromatics insert into the acyl region. Because cardiolipin is confined to the inner mitochondrial membrane, a molecule that binds cardiolipin concentrates there by orders of magnitude — without depending on membrane potential, which is the failure mode of triphenylphosphonium-targeted antioxidants. A potential-driven compound abandons exactly the sick, depolarized mitochondria it was meant to reach. A lipid-binding one does not Sabbah 2025.

And three consequences follow from one binding event. One: cristae curvature is stabilized, so the membrane keeps the geometry that concentrates the respiratory chain. Two: supercomplex assembly is preserved, which shortens the diffusion distance for electron carriers and reduces electron leak. Three: the cardiolipin-cytochrome c complex is prevented from adopting the conformation in which cytochrome c acts as a peroxidase and oxidizes cardiolipin itself — the self-amplifying step that commits a mitochondrion to releasing cytochrome c and starting apoptosis Tung 2025. Blocking one lipid-protein interaction interrupts a feed-forward loop, which is a far better mechanism than mopping up radicals downstream of it.

Cell, rodent, human — and where it stops

Step one, biophysics and cells: characterized, and recently reviewed twice. Structure, mechanism and therapeutic potential Tung 2025, and the mitochondrial mechanism of action specifically Sabbah 2025.

Step two, animals, in the organ where cardiolipin content is highest. Kidney and heart carry the densest mitochondrial populations, and SS-31 ameliorates kidney disease in animal models Zhu 2022.

Step three, humans, and this is the best single result on the page. Roshanravan 2021 randomized 39 healthy older adults aged 60 to 85 to a single dose of elamipretide or placebo and measured in vivo mitochondrial ATP production in skeletal muscle by phosphorus magnetic resonance spectroscopy. A single dose raised mitochondrial energetic capacity relative to placebo (ΔATPmax P = 0.055; percentage ΔATPmax P = 0.045). That is a non-invasive, in vivo, physical measurement of mitochondrial function in living people, and there is nothing else in this Vault with an endpoint that good.

And the same paper reports the part that gets left out. There was no significant effect of treatment on fatigue resistance in the first dorsal interosseous muscle Roshanravan 2021. The biochemistry moved and the function did not. One dose, 39 people, one muscle — but printing the ATPmax result without that sentence is how a modest finding becomes a marketing claim.

Step four, the disease where the mechanism should be decisive. Barth syndrome is a genetic disorder of mitochondrial cardiolipin metabolism — the exact lipid SS-31 binds. A phase 2/3 randomized, placebo-controlled crossover trial followed by an open-label extension enrolled 12 subjects, of whom 10 continued and 8 reached 36 weeks. In part 1, neither primary endpoint was met. At 36 weeks in the open-label part 2 there were improvements in the six-minute walk test (+95.9 m, p = 0.024) and in a symptom assessment (−2.1 points, p = 0.031) Reid Thompson 2021.

Read that result carefully, because it is the most instructive thing on this page. The randomized, blinded portion failed. The improvement appeared in the unblinded extension, in eight people, against their own earlier selves. An open-label six-minute walk test in a rare disease cohort is the exact design in which expectation and familiarity produce improvement, and the honest reading is that the trial with a control arm did not show what the trial without one did.

Where the chain breaks. (1) The human muscle result is a single dose with a biochemical endpoint and a null functional endpoint Roshanravan 2021. (2) The Barth result is 8 people in an open-label extension after a failed randomized phase Reid Thompson 2021. (3) Elamipretide is given by subcutaneous injection in trials because a cationic tetrapeptide is not orally available. (4) The card's note is the right one to keep: plasma half-life of a few hours, tissue retention far longer — because the drug is bound to a lipid in a membrane, not floating in plasma.

What would have to be true, and how you would know it was not

Three predictions. The first is measurable and almost nobody can get it; the second and third are what an ordinary person can actually do.

1. The definitive read-out exists and it is not a blood test. Phosphorus magnetic resonance spectroscopy of skeletal muscle measures ATPmax in vivo, and it is the endpoint that moved in the randomized human study Roshanravan 2021. Nobody outside a research setting will get one, and saying so is more useful than pretending a blood marker substitutes for it. If a reader ever has access to a research protocol, this is the measurement to ask for.

2. The practical proxy is functional, and the trial says which one failed. Fatigue resistance did not improve in the randomized study Roshanravan 2021, so the honest prediction is a null one. Grip strength and a submaximal VO2 or six-minute walk distance at baseline and at 12 weeks are the measurements. The prediction that cuts against the compound is that these will not move — and a person who finds they do not has reproduced the published result rather than failed.

3. The safety and plausibility check. A CMP for creatinine and liver enzymes and a CBC at baseline and 12 weeks. In anyone using it for a kidney indication by extrapolation from the animal work Zhu 2022, cystatin C is the better filtration estimate than creatinine, and the direction of change over six months is the only thing that would distinguish a real effect from noise.

What will fool you. Feeling more energetic is not a mitochondrial measurement. The one study that measured both found the biochemistry moved and the function did not Roshanravan 2021, which is precisely the gap a subjective impression cannot see across.

What nobody has tested yet

Four experiments nobody has run.

Nobody has run a repeated-dose ATPmax study. The human result is a single dose Roshanravan 2021. Whether eight or twelve weeks of dosing produces a larger effect, the same effect, or a smaller one is the obvious next experiment and it has not been published. Everything anybody claims about chronic SS-31 use rests on a single-dose study.

Nobody has explained the gap between the biochemistry and the function. ATP production rose and fatigue resistance did not Roshanravan 2021. Either ATPmax is not the rate-limiting step for that task, or the effect size is too small to show, or the muscle chosen was wrong. A study designed to distinguish those three is the one that decides whether this compound is useful.

Nobody has repeated the Barth result with a control arm to 36 weeks. The randomized phase failed and the open-label extension improved Reid Thompson 2021. A longer randomized trial is the only thing that separates a real slow-onset effect from an open-label artifact, and in a disease this rare it may never be run — which is a reason to hold the question open rather than to resolve it in the compound's favor.

Nobody has tested cardiolipin composition as a responder marker. The mechanism predicts that people with abnormal cardiolipin species or oxidized cardiolipin respond and people with normal cardiolipin do not. Cardiolipin profiling by mass spectrometry on a muscle or platelet sample, used to stratify a trial, would test the mechanism directly — and would explain why a genetic cardiolipin disease was the first indication tried.

SS-31 — its own safety story, not its class's

Elamipretide is not approved for any indication, and the material sold as SS-31 is research-grade peptide. The class block above does not describe either situation.

Injection site reactions are the dominant reported adverse effect in the trial program. Elamipretide is given subcutaneously, and local reactions are consistently the commonest finding across studies Tung 2025. That is unremarkable for a cationic peptide and it is what a user should expect first.

The systemic safety record is small because the trials are small. Thirty-nine people for one dose Roshanravan 2021; twelve people in a rare-disease trial Reid Thompson 2021. An uncommon harm cannot be detected in populations that size, so the absence of one in the literature is not evidence of its absence.

The mechanistic concern nobody has addressed. Cardiolipin peroxidation and cytochrome c release are not only pathology — they are the physiological route by which a damaged cell is removed Tung 2025. A compound that stabilizes that step everywhere, chronically, is interfering with a quality-control mechanism as well as with a disease mechanism. Nobody has tested what that does over years, and the honest position is that this is an open question rather than a settled non-issue.

Identity is a real problem for this specific peptide. Its activity depends on D-arginine, on 2',6'-dimethyltyrosine — a non-standard residue — and on C-terminal amidation. An L-arginine substitution, an ordinary tyrosine, or a free acid C-terminus each give a peptide of nearly the same mass with different or absent activity, and mass-based purity testing will not tell them apart.

What this page will not do. Recommend a dose or route. The human evidence is one single-dose study with a positive biochemical endpoint and a null functional one, and one rare-disease trial whose randomized phase did not meet its endpoints Roshanravan 2021 Reid Thompson 2021. That is a genuinely interesting mechanism with genuinely thin clinical evidence, and both halves of that sentence belong on the page.

Sources read for this page

• Tung C, et al. Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. International Journal of Molecular Sciences 2025 · PMID 39940712
• Sabbah HN. Contemporary insights into elamipretide's mitochondrial mechanism of action and therapeutic effects. Biomedicine and Pharmacotherapy 2025 · PMID 40294492
• Roshanravan B, et al. In vivo mitochondrial ATP production is improved in older adult skeletal muscle after a single dose of elamipretide in a randomized trial. PLOS ONE 2021 · PMID 34264994
• Reid Thompson W, et al. A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism. Genetics in Medicine 2021 · PMID 33077895
• Zhu Y, et al. SS-31, a Mitochondria-Targeting Peptide, Ameliorates Kidney Disease. Oxidative Medicine and Cellular Longevity 2022 · PMID 35707274

SS-31 — safety, predicted from mechanism

SS-31 — interference & stacking

Bloodwork to run alongside SS-31

Baseline first, then again at 8–12 weeks.

The Longevity Baseline panel covers these in one order — 13 markers, $219.10 with the discount applied.

Check results you already have → · All 103 markers A–Z

SS-31 — frequently asked questions

SS-31 inside a finished plan

One arm of 4 Protocol Blueprints, free to read in full.

What SS-31 is used for

SS-31 appears under 5 goals in the goal router.

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