reviewed april 2026|next review october 2026|88 physicians psi has verified|481 published studies
SS-31 (Elamipretide)
SS-31 (elamipretide) is a synthetic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) that concentrates 1,000 to 5,000 fold in the inner mitochondrial membrane by binding cardiolipin, with FDA Breakthrough Therapy designation for Barth syndrome and Phase III trial data in heart failure.
Evidence landscape: 481 published studies
481 published items. 23 human studies and 138 animal studies.
- 23 Human
- 138 Animal
- 39 Reviews
- 281 Other research
Not FDA-approved. SS-31 (elamipretide) has received FDA Breakthrough Therapy designation for Barth syndrome. It is an investigational drug available only through clinical trial enrollment. Not available through standard pharmacies or specialty pharmacies where a licensed pharmacist prepares a medicine from ingredients for an individual patient.
481 published studies including 23 human studies and 138 animal studies. Multiple Phase II/III clinical trials completed (Barth syndrome, heart failure, renal function, skeletal muscle aging). The Phase III EMBRACE-STEMI (Elamipretide in Myocardial Reperfusion After ST-Elevation Myocardial Infarction) heart failure trial missed its primary endpoint.
Concentrates 1,000 to 5,000 fold in the inner mitochondrial membrane by binding cardiolipin, stabilizing cristae structure and optimizing electron transport chain efficiency. Mechanistically distinct from antioxidant approaches.
PSI Assessment
The clinical trial data for SS-31 tells two stories simultaneously: FDA Breakthrough Therapy designation for Barth syndrome (a rare genetic disease caused by defective cardiolipin remodeling) and a missed primary endpoint in the Phase III EMBRACE-STEMI heart failure trial. Both outcomes are real and both matter. The mechanism is validated - SS-31 concentrates 1,000 to 5,000 fold in the inner mitochondrial membrane by binding cardiolipin, stabilizing the structures where cellular energy production occurs. The MOTION trial demonstrated improved skeletal muscle mitochondrial function in elderly subjects. The animal aging data is among the most consistent in mitochondrial research. But clinical translation has produced mixed results that honest assessment cannot selectively report.
FDA Breakthrough Therapy designation for Barth syndrome. Concentrates 1,000-5,000x in the inner mitochondrial membrane. Phase III EMBRACE heart failure trial missed its primary endpoint.
The mechanism centers on cardiolipin binding in the inner mitochondrial membrane (IMM). Cardiolipin is a phospholipid that anchors the respiratory chain supercomplexes responsible for cellular energy production. When cardiolipin is damaged or depleted (as in aging, Barth syndrome, and heart failure), electron transport becomes inefficient, producing excess reactive oxygen species. SS-31 stabilizes cardiolipin-protein interactions, maintaining cristae structure and supercomplex assembly. The D-amino acid in the sequence (D-Arg) confers protease resistance, contributing to the peptide's stability and mitochondrial accumulation. This upstream approach is mechanistically distinct from antioxidant supplements that scavenge free radicals after they form.
What the evidence supports
SS-31 binds cardiolipin in the inner mitochondrial membrane with 1,000-5,000 fold concentration, stabilizing cristae structure and optimizing electron transport chain efficiency. FDA Breakthrough Therapy designation for Barth syndrome provides regulatory validation. The MOTION trial demonstrated improved skeletal muscle mitochondrial function in elderly subjects. Animal aging data is consistently positive across independent laboratories.
What is not yet established
Whether the heart failure application will advance despite the EMBRACE-STEMI trial missing its primary endpoint. Whether the Barth syndrome indication will achieve FDA approval. Long-term effects of chronic cardiolipin targeting. Whether the renal protective signal will translate to registrational trials.
Research Evidence
The findings below cover what the clinical trial program has established and where the evidence produced mixed signals.
Evidence by condition
Evidence dimensions across SS-31's clinical indications. Barth syndrome and heart failure have the deepest human evidence (though with mixed signals). Renal function, age-related decline, and skeletal muscle have human data from smaller studies.
| Condition | Mechanism | Animal evidence | Human evidence | Replication |
|---|---|---|---|---|
| Barth Syndrome | ||||
| Heart Failure | ||||
| Renal Disease | ||||
| Age-Related Mito Decline | ||||
| Skeletal Muscle |
SS-31 received FDA Breakthrough Therapy designation for Barth syndrome based on the TAZPOWER (Tafazzin Pathway With Elamipretide) clinical trial showing functional improvement in patients with this rare genetic disease caused by defective cardiolipin remodeling. The mechanism of binding and stabilizing cardiolipin is directly relevant to this pathology.
Breakthrough Therapy designation reflects FDA recognition that preliminary clinical evidence suggests substantial improvement over existing therapies. Barth syndrome has no approved treatment. Full FDA approval has not yet been granted.
The Phase III EMBRACE-STEMI trial, designed to demonstrate reduced infarct size in ST-elevation myocardial infarction, did not meet its primary endpoint. Phase II trials had previously shown improved cardiac function markers in heart failure with reduced ejection fraction.
The missed Phase III primary endpoint is the single most important negative finding in the SS-31 evidence base. It does not invalidate the Phase II findings but means the efficacy question in heart failure remains open.
The MOTION trial (Campbell et al., 2019) demonstrated improved skeletal muscle mitochondrial function in elderly subjects, providing initial translational evidence that the animal aging findings have human relevance.
This was a small Phase II study. Whether SS-31 can meaningfully slow or reverse age-related functional decline in larger human populations is not established.
23 Human|138 Animal|39 Reviews
View all 481 indexed studiesHow SS-31 (Elamipretide) Works
SS-31 (elamipretide) is a synthetic four-amino-acid peptide, which means it is one of the smallest peptides that can function as a targeted drug. It is designed to go directly into the energy-producing structures of cells (mitochondria) and stabilize the inner membrane where energy production occurs.
SS-31 works by going directly to your mitochondria, the parts of your cells that produce energy, and stabilizing the inner membrane where energy production happens. Think of mitochondria like power plants: as they age or malfunction, they become less efficient and produce more waste (free radicals). SS-31 helps the machinery run more cleanly by stabilizing a critical component called cardiolipin, rather than cleaning up damage after it happens.
For a more detailed view of the biology, here is what researchers have observed at the molecular level.
SS-31 is a cell-permeable, mitochondria-targeted tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) that concentrates 1,000 to 5,000 fold in the inner mitochondrial membrane by binding cardiolipin, an anionic phospholipid essential for electron transport chain function. By stabilizing cardiolipin-protein interactions, SS-31 maintains cristae structure, optimizes supercomplex assembly, reduces electron leak at complexes I and III, and decreases reactive oxygen species production. In Barth syndrome, a genetic deficiency in tafazzin impairs cardiolipin remodeling, making the cardiolipin interaction particularly relevant. The D-amino acid in the sequence confers protease resistance.
What is SS-31 (Elamipretide) being studied for?
Researchers are studying SS-31 (Elamipretide) across several health conditions. Each condition below is labeled with the strength of evidence that exists for that specific use, not for SS-31 (Elamipretide) overall. This means a compound can have human studies for one condition but only animal data for another.
Barth Syndrome
·Human TrialsSS-31 received FDA Breakthrough Therapy designation for Barth syndrome, a rare genetic disease caused by defective cardiolipin remodeling. Clinical data shows functional improvement in patients.
Limitations: Barth syndrome is extremely rare. Full FDA approval has not yet been granted. Long-term efficacy and safety data is still being collected.
Heart Failure
·Human TrialsPhase II data showed improved cardiac function markers, but the Phase III EMBRACE-STEMI trial missed its primary endpoint.
Limitations: The missed Phase III primary endpoint is a meaningful negative signal. The Phase II improvements were in surrogate markers, not hard clinical outcomes.
Renal Disease
·Animal StudiesEarly clinical studies suggest potential renal protective effects, but the evidence is limited.
Limitations: Small sample size. Preliminary findings. No Phase III renal trials completed.
Age-Related Mito Decline
·Animal StudiesAnimal aging studies show SS-31 reverses age-related mitochondrial dysfunction, and the MOTION trial showed skeletal muscle improvement in elderly humans.
Limitations: The MOTION trial was a small Phase II study. Anti-aging applications in healthy individuals have not been tested.
Skeletal Muscle
·Animal StudiesThe MOTION trial showed improved mitochondrial function in skeletal muscle of elderly subjects.
Limitations: Small Phase II study. Functional outcomes (strength, endurance, physical performance) were not the primary endpoints.
Safety and Regulatory Status
FDA Status: Not FDA-approved. FDA Breakthrough Therapy designation for Barth syndrome. Multiple clinical trials completed and ongoing under IND (Investigational New Drug application).
Availability: Investigational drug only. Not available through standard pharmacies or specialty pharmacies where a licensed pharmacist prepares a medicine from ingredients for an individual patient. Access is limited to clinical trial enrollment.
Class context: Generally well-tolerated in multiple Phase II/III clinical trials. Injection site reactions are the most common adverse event. Headache, nausea, and dizziness occurred at low rates. The safety database from clinical trials is substantially larger than for most research peptides.
SS-31 has been evaluated in multiple Phase II and Phase III clinical trials, providing a safety database substantially larger than most research peptides. It is generally well-tolerated, with injection site reactions as the most common adverse event. Headache, nausea, and dizziness have been reported at low rates. No serious drug-related adverse events were reported in published Phase II data.
Peptide Structure
Technical molecular data for researchers and clinicians.
Questions and Comparisons
Questions the evidence raises for a SS-31 (Elamipretide) discussion.
Comparison and Related Research
SS-31 is most often compared with other mitochondrial-targeting compounds. The comparisons below outline how each differs.
Head-to-head comparisons
Full research comparisons covering SS-31 (Elamipretide) and another peptide side by side.
SS-31 (Elamipretide) vs MOTS-c
Both target cellular energy production. MOTS-c is a metabolic regulator. SS-31 protects mitochondrial membranes. Evidence-graded comparison.
View full comparisonRelated compounds
Frequently Asked Questions
References
Each citation links to the original study on PubMed, the U.S. National Library of Medicine database.
- 1.A comprehensive review by the peptide's discoverer describing how SS-31 (elamipretide) was identified and its mechanism of action. SS-31 selectively targets cardiolipin on the inner mitochondrial membrane, stabilizing the electron transport chain and reducing electron leak. This review traces the compound from initial discovery through early clinical development.Szeto HH., 2014 in Clin Pharmacol Ther. View on PubMed
- 2.Demonstrated that a single hour of SS-31 treatment reversed age-related mitochondrial dysfunction in elderly mice. The peptide restored mitochondrial energetics, reduced oxidative stress, and improved skeletal muscle performance. These results were achieved without exercise training, suggesting direct pharmacological reversal of age-related mitochondrial decline.Siegel MP et al., 2013 in Aging Cell. View on PubMed
- 3.A randomized, double-blind, placebo-controlled Phase 2 trial evaluating elamipretide (SS-31) in patients with heart failure with reduced ejection fraction. The trial assessed changes in left ventricular function over 4 weeks of treatment. While the primary endpoint did not achieve statistical significance, the study provided important safety and dose-response data for further development.Butler J et al., 2020 in J Card Fail. View on PubMed
- 4.The TAZPOWER trial evaluated elamipretide in patients with Barth syndrome, a rare genetic disorder of cardiolipin metabolism. The randomized portion showed trends toward improvement in the 6-minute walk test and muscle strength, with statistically significant improvement in a patient-reported symptom measure. The open-label extension demonstrated sustained benefit.Reid Thompson W et al., 2021 in Genet Med. View on PubMed
Medical Disclaimer
This content is for educational and informational purposes only and does not constitute medical advice. The information presented reflects published research as indexed by PSI and should not be used to make treatment decisions. Always consult a qualified healthcare provider before starting, stopping, or modifying any treatment.