Elamipretide and SS-31 are the same molecule — a four-amino-acid peptide that concentrates in the inner mitochondrial membrane and binds cardiolipin. Its uses are best understood as one mechanism tested against a decade of different diseases, with one approval to show for it.
Elamipretide's approved use is Barth syndrome, an ultra-rare genetic cardiolipin disorder — the 2025 FDA approval made it a first-in-class cardiolipin-targeting drug. Its larger trials in primary mitochondrial myopathy produced genotype-dependent results, and aging-biology work remains preclinical.
One mechanism: cardiolipin and the inner membrane
Elamipretide is a Szeto-Schiller tetrapeptide that accumulates in the inner mitochondrial membrane and associates with cardiolipin, the signature phospholipid of that membrane. Stabilizing cardiolipin's environment supports cristae architecture and electron-transport efficiency and reduces excess reactive-oxygen generation — a structural intervention rather than a receptor drug, which is why it was trialed across so many organ systems.
The approved use: Barth syndrome
Barth syndrome is an X-linked disease of cardiolipin remodeling — the one human condition where elamipretide's target is itself the broken part. The development program's long-term extension data in Barth patients underpinned the 2025 approval, making elamipretide a first-in-class approved therapy and, notably, one of the few peptide drugs approved for a mitochondrial membrane target at all.
The near-misses: mitochondrial myopathy
The largest elamipretide program was primary mitochondrial myopathy. A randomized crossover trial reported improved six-minute-walk distance; the larger follow-up program missed its primary endpoints — and then the genotype analyses complicated the story, with signals concentrating in specific genetic subgroups. That arc — early functional signal, missed phase 3, genotype-dependent re-reading — is the honest summary of elamipretide's decade in myopathy.
SS-31
The mitochondria-targeting tetrapeptide discussed here, supplied as research-use-only material with a batch-matched certificate of analysis.
The research frontier: aging biology
Preclinical aging work is where the SS-31 name still dominates: studies in aged animals report partial restoration of mitochondrial function and molecular aging markers. It is rigorous mechanism-of-aging research — and it is animal data. No human aging indication exists, and none is in late-stage development.
Reading an SS-31 vial against this record
Research-market SS-31 is the same tetrapeptide studied in the trials above, sold as research-use-only material. The record worth keeping in view: one ultra-rare-disease approval where the mechanism matched the mutation; carefully qualified myopathy results; animal aging data. That is a genuinely interesting molecule — described accurately, without borrowing the approval's glow for uses it never covered.
SS-31
Research-use-only material, sold by the vial with batch documentation. Check the certificate of analysis against the batch you receive.
What to know now
- Elamipretide = SS-31 — one cardiolipin-binding tetrapeptide behind both names.
- Its approved use is Barth syndrome (2025): the disease where the drug's target is the broken part.
- Mitochondrial myopathy trials: an early six-minute-walk signal, missed phase-3 endpoints, then genotype-dependent re-analysis.
- Aging-biology results are preclinical — aged-animal studies, no human aging indication.
- Describe the research vial against this record, not against the approval's halo.
What we're watching
Genotype-stratified follow-up in mitochondrial myopathy — if a defined subgroup reproduces the early functional signal under randomization, elamipretide's second indication becomes a live question again.
Frequently asked questions
Is elamipretide FDA approved?
Yes — elamipretide received FDA approval in 2025 for Barth syndrome, an ultra-rare genetic disorder of cardiolipin remodeling. That approval does not extend to mitochondrial myopathy, heart failure, or aging uses studied elsewhere in its program.
Are elamipretide and SS-31 the same thing?
Yes. SS-31 is the research designation from the Szeto-Schiller peptide series; elamipretide is the drug name the molecule carried through clinical development.
What does elamipretide do to mitochondria?
It concentrates in the inner mitochondrial membrane and binds cardiolipin, supporting cristae structure and electron-transport efficiency while reducing excess reactive-oxygen generation — a membrane-stabilizing mechanism rather than receptor signaling.
Did elamipretide work for mitochondrial myopathy?
The record is mixed by design standards: a crossover trial showed improved walking distance, the larger program missed primary endpoints, and later genotype analyses found the signal concentrated in specific genetic subgroups. It is not an approved myopathy therapy.
References
- Shirley, M. (2025). Elamipretide: First Approval. Drugs, 86(3), 377–383. https://doi.org/10.1007/s40265-025-02269-8
- Karaa, A., Haas, R., Goldstein, A., et al. (2020). A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy. Journal of Cachexia, Sarcopenia and Muscle, 11(4), 909–918. https://doi.org/10.1002/jcsm.12559
- Karaa, A., Haas, R., Goldstein, A., Vockley, J., & Cohen, B. (2023). Efficacy and safety of elamipretide in individuals with primary mitochondrial myopathy: The MMPOWER-3 randomized clinical trial. Neurology. https://doi.org/10.1212/WNL.0000000000207402
- Karaa, A., Bertini, E., Carelli, V., et al. (2024). Genotype-specific effects of elamipretide in patients with primary mitochondrial myopathy: A post hoc analysis of the MMPOWER-3 trial. Orphanet Journal of Rare Diseases, 19(1), 431. https://doi.org/10.1186/s13023-024-03421-5
- Stealth BioTherapeutics. (2024). Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genetics in Medicine. https://doi.org/10.1016/j.gim.2024.101138
- Mitchell, W., Pharaoh, G., Tyshkovskiy, A., et al. (2025). The Mitochondria-Targeted Peptide Therapeutic Elamipretide Improves Cardiac and Skeletal Muscle Function During Aging Without Detectable Changes in Tissue Epigenetic or Transcriptomic Age. Aging Cell, 24(6), e70026. https://doi.org/10.1111/acel.70026