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PrecisePepResearch Library

Research information only. PrecisePep is an educational library. It is not medical advice and is not intended to assist, encourage or enable self-administration. The compounds documented here are research chemicals — most are not approved for human use. Read the full disclaimer.

PrecisePep/Peptide Library/SS-31

Mitochondrial & Bioenergetic

SS-31

Elamipretide · MTP-131 · Bendavia · D-Arg-Dmt-Lys-Phe-NH₂

A cardiolipin-binding tetrapeptide that concentrates thousands-fold inside mitochondria and restores cristae architecture — the most clinically advanced mitochondrial-targeted drug candidate that exists.

CardiolipinCristaeATPElamipretidePhase 3

00 Overview

SS-31 is a genuine pharmacological curiosity. It was discovered by accident — Szeto and Schiller were working on opioid analogues when they found a peptide that concentrated in mitochondria to a remarkable degree. The structural motif responsible is an alternating aromatic-cationic sequence that allows the peptide to partition into the inner mitochondrial membrane independent of membrane potential, reaching intramitochondrial concentrations one to three orders of magnitude above plasma.

What it does there is bind cardiolipin — the signature phospholipid of the inner membrane, essential for cristae curvature and for the assembly of respiratory-chain supercomplexes. Cardiolipin is peroxidation-prone, and its damage is a common final pathway in mitochondrial dysfunction. SS-31 binds it, stabilises cristae architecture, improves electron-transport efficiency and reduces electron leak — meaning less reactive oxygen species produced at source rather than scavenged afterwards.[1][2]

Under the name elamipretide it has been through an extensive clinical programme: primary mitochondrial myopathy, Barth syndrome, heart failure, dry age-related macular degeneration and ischaemia-reperfusion. Results have been mixed — some trials missing primary endpoints, others positive, and the Barth syndrome programme progressing furthest toward regulatory consideration.[3] That mixed record is more informative than any grey-market claim on this page.

Why the mixed trial record matters

Elamipretide has failed primary endpoints in some indications and succeeded in others. That is what a real drug development programme looks like, and it is a far better guide to what this molecule does than the uniformly positive framing it receives in community protocols. A compound that works in inherited cardiolipin-remodelling disease may do nothing measurable in a healthy 45-year-old.

// Mechanism of action

Cardiolipin binding. The core mechanism. Cardiolipin is the inner-membrane phospholipid that shapes cristae and organises respiratory supercomplexes. SS-31 binds it selectively through electrostatic and hydrophobic interaction, modulating membrane surface electrostatics.[2]

Cristae stabilisation. By stabilising cardiolipin-dependent curvature, SS-31 restores cristae architecture in damaged or aged mitochondria. Cristae shape is not cosmetic — respiratory efficiency depends directly on it.

Improved electron transport and ATP output. Better-organised supercomplexes leak fewer electrons and produce more ATP per unit substrate. This is why the antioxidant effect is described as upstream: fewer ROS are generated rather than more being mopped up.

Adenine nucleotide translocator function. Work in aged mitochondria reports improved ADP sensitivity through increased uptake via the ANT — a specific mechanistic finding relevant to age-related bioenergetic decline.[4]

Membrane-potential independence. Unlike triphenylphosphonium-based mitochondrial targeting, SS-31 does not require an intact membrane potential to accumulate — so it reaches the damaged mitochondria that need it most.

01 Reported benefits

Effects that have been reported. A study-tier entry means a result was published — not that the effect is established, reproducible, or transferable from a rodent to a person.

Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.

Restored cristae architecture and respiratory function [1][2]

Demonstrated across cell and animal models of mitochondrial dysfunction, ischaemia-reperfusion and ageing, with improved supercomplex assembly and ATP production.

In vitro + animal

Reduced mitochondrial ROS production at source [1]

Reduced electron leak rather than downstream radical scavenging — mechanistically distinct from conventional antioxidants and a more defensible intervention point.

In vitro + animal

Improved cardiac and skeletal muscle function in ageing models [5]

The mitochondria-targeted peptide improved cardiac and skeletal muscle function during ageing in animal models — notably without detectable change in epigenetic or transcriptomic age measures.

Animal · in vivo

Renal protection in kidney disease models [6]

SS-31 ameliorates injury across multiple kidney disease models, one of the better-developed pre-clinical areas for the compound.

Animal · in vivo

Improved ADP sensitivity in aged mitochondria [4]

Demonstrated improvement in adenine nucleotide translocator-mediated ADP uptake in aged mitochondria — a specific, measurable bioenergetic effect.

Ex vivo · aged tissue

Human clinical programme across multiple indications [3]

Elamipretide has been evaluated in primary mitochondrial myopathy, Barth syndrome, heart failure with preserved ejection fraction, and dry AMD. Results are mixed: some primary endpoints missed, some positive signals, with the Barth syndrome programme advancing furthest.

Human trials · mixed resultsMixed outcomes

02 Adverse effects & risks

Adverse effects, contraindications and unknowns. The grey-market tier is where under-reporting is worst: uncontrolled use produces no systematic safety surveillance at all, so absence of a reported harm is not evidence of safety.

Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.

Injection-site reactions dominate the human safety profile [3]

Across the elamipretide clinical programme, injection-site erythema, induration and pruritus were the most common adverse events with daily subcutaneous administration.

Human trials

Generally well tolerated systemically in trials [3]

No major systemic safety signal emerged across the clinical programme at studied doses and durations.

Human trials

Efficacy failures are the more informative finding [3]

Missed primary endpoints in several indications are not a safety issue but they are the most important trial result to carry into any interpretation of community claims.

Human trials

03 Dosing ranges

Figures below are documented, not recommended. Study ranges come from published protocols in the stated model; grey-market ranges are what the research community reports using and carry no safety validation of any kind.

Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.

Clinical trial dosing: 40 mg daily subcutaneous [3]

The elamipretide clinical programme has predominantly used 40 mg once-daily subcutaneous administration in primary mitochondrial myopathy and Barth syndrome, with intravenous dosing in acute cardiac settings.

Human trials

The trial dose is roughly eight times the community dose [3]

This is the single most important number on this page. Clinical efficacy — where it was found at all — was found at 40 mg daily. Community protocols use 5 mg. No dose-response data supports the lower figure.

ComparisonCritical discrepancy
SettingDoseRouteOutcome
Primary mitochondrial myopathy40 mg dailySubcutaneousMixed; primary endpoints not consistently met
Barth syndrome40 mg dailySubcutaneousProgramme advanced furthest toward regulatory review
Heart failure / IR injuryTrial-definedIV / SCMixed

04 Synergy & interactions

Combination effects. Almost no peptide combination has been studied as a combination in humans; stack logic is overwhelmingly mechanistic inference and community practice. Each linked compound has its own page.

Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.

No combination studies exist

No trial has combined elamipretide with any other mitochondrial peptide.

Evidence gap

05 Protocols

Whole schedules — dosing, titration, cycle length, and off-time — as documented in trials, as proposed from mechanism, and as circulated in the research community. Reproduced for study and comparison only.

Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.

Elamipretide clinical programme [3]

Registered protocols across primary mitochondrial myopathy, Barth syndrome, heart failure and dry AMD, with 40 mg daily subcutaneous as the predominant regimen and defined functional endpoints.

Registered trialsClinicalTrials.gov

05b Condition-specific interest

SS-31 has a clinical record that almost nothing else in this library can match, and it reads as a warning rather than an endorsement. One accelerated approval in an ultra-rare disease, and three missed primary endpoints in the larger indications people actually cite it for. A compound can have a real, demonstrated mechanism and still fail repeatedly, and this is the clearest example of that on the site.

No approval, no trial

Elamipretide received FDA accelerated approval in September 2025, as Forzinity, to improve muscle strength in patients with Barth syndrome weighing at least 30 kg — the first approved therapy for that disease. Accelerated approval is granted on a surrogate or intermediate endpoint with confirmatory evidence still required, in a specific ultra-rare population. It is not an approval for mitochondrial dysfunction generally, and it is emphatically not an approval for use as a longevity compound.

Study — approved, randomised

Barth syndrome — the approved indication

Pathophysiology
Barth syndrome is an X-linked disorder caused by mutations in TAZ, the gene encoding tafazzin, which remodels cardiolipin. Abnormal cardiolipin destabilises the inner mitochondrial membrane, producing cardiomyopathy, skeletal myopathy, neutropenia and growth delay.

Mechanistic rationale
This is the one disease where the mechanism and the lesion are the same thing. SS-31 binds cardiolipin in the inner mitochondrial membrane and stabilises cristae structure and respiratory chain organisation. In a disease defined by defective cardiolipin remodelling, a cardiolipin-binding peptide is not an extrapolation. The TAZPOWER randomised crossover study and its open-label extension reported improved skeletal muscle strength and cardiac stroke volume, which supported the accelerated approval.

Community reports
A prescription therapy for an ultra-rare inherited disease, managed by specialist centres. Not a self-directed use.

Components carrying the argument: Cardiolipin binding, cristae stabilisation

Study — randomised, and negative

Primary mitochondrial myopathy — the trial that failed

Pathophysiology
Primary mitochondrial myopathies are inherited disorders of the respiratory chain producing exercise intolerance, weakness and fatigue, with no approved disease-modifying therapy.

Mechanistic rationale
This was the largest and most-watched programme for the compound, and the phase 3 MMPOWER-3 trial missed its primary endpoints on six-minute walk distance in 2023. That result matters more than any mechanistic argument: it is the properly powered test of the idea that stabilising cardiolipin improves function in general mitochondrial disease, and it did not deliver. Anyone citing SS-31 for mitochondrial dysfunction should be citing this trial.

Community reports
Community use for fatigue and mitochondrial complaints is common and generally unaware that the definitive trial in the closest matching population was negative.

Components carrying the argument: Same mechanism, broader population, no benefit shown

Study — randomised, and negative

Heart failure

Pathophysiology
Cardiac muscle is the most mitochondria-dense tissue in the body, and impaired myocardial energetics is a well-described feature of heart failure.

Mechanistic rationale
The rationale was strong enough to run a trial, and the PROGRESS-HF programme missed its primary endpoint. Mitochondrial dysfunction in heart failure is real; correcting it with this compound did not translate into the outcome measured. This is the second of three.

Community reports
Cited in cardiovascular longevity contexts, usually on the mechanism rather than the result.

Components carrying the argument: Myocardial mitochondrial function

Study — randomised, and negative

Dry age-related macular degeneration

Pathophysiology
The retinal pigment epithelium has extremely high metabolic demand, and mitochondrial dysfunction in those cells is implicated in geographic atrophy.

Mechanistic rationale
The ReCLAIM programme did not meet its primary endpoints. Third trial, third miss, third tissue where the mechanistic case looked compelling. Taken together with MMPOWER-3 and PROGRESS-HF, the pattern is informative: the compound does something demonstrable at the mitochondrion, and translating that into a clinical outcome has worked in exactly one setting — the disease where the genetic lesion is in the pathway itself.

Community reports
Occasionally cited for eye health. The trial result is rarely mentioned alongside.

Components carrying the argument: Retinal pigment epithelium energetics

Theorized — and the trial record argues against it

Fatigue, ageing and general mitochondrial complaints

Pathophysiology
Mitochondrial function declines with age, and fatigue is a common symptom with a very long differential — anaemia, hypothyroidism, sleep apnoea, depression, medication effects and deconditioning among them.

Mechanistic rationale
This is the dominant reason people buy SS-31, and it is the use with the least support. Three randomised trials in populations with genuine, measurable mitochondrial pathology failed to show benefit on their primary endpoints. Expecting a larger effect in people whose mitochondria are merely ageing is the opposite of what that record predicts.

Community reports
Improved energy is commonly reported. It is among the most placebo-responsive endpoints in existence, and the common treatable causes of fatigue are diagnosable with a blood test and a sleep study.

Components carrying the argument: Cardiolipin stabilisation — unproven in this population

Theorized — broad preclinical, no clinical translation

Ischaemia-reperfusion and organ protection

Pathophysiology
Ischaemia-reperfusion injury shares a common pathway across organs, with mitochondrial permeability transition as a central event.

Mechanistic rationale
Animal work spans kidney, heart, brain and skeletal muscle, and it is genuinely extensive. The clinical record above is the reason to hold that lightly — broad preclinical efficacy followed by repeated trial failure is a well-worn path, and this compound has now walked most of it.

Community reports
Cited in longevity contexts on the strength of the animal literature.

Components carrying the argument: Mitochondrial permeability transition, cristae integrity

IndicationTrialResultThe thing to know
Barth syndromeTAZPOWERPositive — approved Sept 2025The lesion is in the pathway itself
Primary mitochondrial myopathyMMPOWER-3Missed primary endpointsThe definitive test of the general idea
Heart failurePROGRESS-HFMissed primary endpointMost mitochondria-dense tissue there is
Dry AMDReCLAIMMissed primary endpointsThird compelling rationale, third miss
Fatigue / ageingNoneThe dominant use; least supported
Approval typeAcceleratedConfirmatory evidence still required
What actually has evidence for these conditions

For Barth syndrome and primary mitochondrial disease: specialist metabolic care, cardiac surveillance, management of neutropenia, physiotherapy and nutritional support. Elamipretide is now an option in Barth syndrome specifically, prescribed and monitored.

For fatigue: the diagnosable causes are worth excluding before anything else, because they are common and treatable — anaemia, iron deficiency, hypothyroidism, diabetes, sleep apnoea, depression, medication effects, and simple deconditioning. A blood panel and a sleep assessment answer most of it. Graded exercise, sleep regularity and treating depression have effect sizes no mitochondrial compound has demonstrated.

For heart failure: the four pillars — ACE inhibitor or ARNI, beta-blocker, mineralocorticoid receptor antagonist, SGLT2 inhibitor — each with independent mortality data. Cardiac rehabilitation is under-referred and improves survival.

For dry AMD: AREDS2 supplementation in the appropriate group, smoking cessation, and the complement inhibitors now approved for geographic atrophy with their modest effect and real injection burden.

06 Handling, reconstitution & storage

Physical-chemistry reference for laboratory handling of the lyophilised material. Reproduced so that stability and concentration mathematics can be studied — see the calculator for the arithmetic and the reconstitution guide for sterile technique.

Reconstitution

Supplied lyophilised, commonly 50 mg per vial in the research market. At 5 mg daily a 50 mg vial is ten days — which is exactly why circulating protocols describe the first phase as "one vial".

Storage

Lyophilised: −20 °C long-term. Reconstituted: 2–8 °C, protected from light.

Common vial sizes

Commonly 50 mg lyophilised vials.

Stability notes

The D-amino acid content of the sequence confers resistance to enzymatic degradation, contributing to stability relative to all-L peptides.

07 Legal & regulatory status

Regulatory status changes and differs by country. This is a summary for orientation, not legal advice — check your own jurisdiction.

Investigational. Elamipretide is a clinical-stage drug candidate (Stealth BioTherapeutics) with no marketing approval to date. Regulatory review has been pursued for Barth syndrome; approval status should be verified against current regulator listings.

Material sold as "SS-31" in the research market is not the clinical product and carries none of its manufacturing controls.

Regulatory and trial claims re-checked against primary sources on 16 August 2026. Checked: elamipretide FDA approval Sept 2025; MMPOWER-3, ReCLAIM, PROGRESS-HF. Approvals, trial readouts and compounding decisions move faster than anything else on this page — a date here means someone looked, not that nothing has changed since.

Anti-doping

Athletes subject to WADA, USADA, UKAD, NCAA or military testing should assume any peptide is prohibited unless they have verified otherwise against the current WADA Prohibited List. Several classes here (growth-hormone secretagogues, TB-4 analogues, metabolic modulators) are explicitly named. Check the current list — it is republished annually.

§ Sources & further reading

Links resolve to PubMed records, trial registries, publisher pages or primary documents. Where a body of work rather than a single paper is cited, the link opens a PubMed query so the full result set — including newer papers than this page — can be reviewed. Verify every claim against the primary source before relying on it.

  1. Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. 2025.Review or meta-analysis
  2. Mitchell W, et al. The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action. J Biol Chem. 2020.In vitro / cell study
  3. ClinicalTrials.gov: registered elamipretide trials (mitochondrial myopathy, Barth syndrome, HFpEF, dry AMD)Registered clinical trial
  4. The mitochondrially targeted peptide elamipretide (SS-31) improves ADP sensitivity in aged mitochondria by increasing uptake through the adenine nucleotide translocator (ANT). GeroScience. 2023.Pre-clinical / animal study
  5. The Mitochondria-Targeted Peptide Therapeutic Elamipretide Improves Cardiac and Skeletal Muscle Function During Aging Without Detectable Changes in Tissue Epigenetic or Transcriptomic Age.Pre-clinical / animal study
  6. SS-31, a Mitochondria-Targeting Peptide, Ameliorates Kidney Disease.Review or meta-analysis
Reminder

For educational and research reference only. Nothing on this site is medical advice, a recommendation, or an instruction to administer any substance to a human being. Every figure on this page is a record of what has been reported, not a recommendation. Full disclaimer.