Overview
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In plain language
SS-31, also called elamipretide, is a lab-made peptide of 4 amino acids that travels into mitochondria, the energy factories inside cells.
In 2025 it received FDA accelerated approval, under the brand name Forzinity, for Barth syndrome, a rare inherited mitochondrial disease. The approval covers only that disease and requires a confirmatory trial. It has been tested for other conditions without clear success.
For students
Elamipretide (D-Arg-Dmt-Lys-Phe-NH2, about 640 Da) is a Szeto–Schiller peptide, named after Hazel Szeto and Peter Schiller, who designed it. Dmt is 2′,6′-dimethyltyrosine. Its alternating aromatic and positively charged residues let it cross cell membranes and concentrate in the inner mitochondrial membrane.
There it binds cardiolipin, a phospholipid needed for the structure of the cristae and for the electron transport chain. The proposed effect is stabilizing mitochondrial membranes and improving energy production.
For researchers and instructors
Clinical evidence. Trials in primary mitochondrial myopathy and heart failure did not meet their primary endpoints. In Barth syndrome, a small trial with open-label extension showed improvements in functional measures, supporting accelerated approval.
Safety. Injection-site reactions are the most common adverse effect.
Regulatory. Accelerated approval for Barth syndrome only (2025). Status is time-sensitive and must be checked for the specific formulation and indication.
Molecular identity
- Amino acids
- 4
- Molecular weight
- ~639.8 Da
- Formula
- Form-dependent
- Sequence
- D-Arg–Dmt–Lys–Phe–NH₂
Origin and history
SS-31 comes from the collaboration of Hazel Szeto at Weill Cornell Medicine in New York and Peter Schiller at the Clinical Research Institute of Montreal. In the early 2000s they designed small, alternating aromatic-and-basic peptides (the “Szeto–Schiller” peptides) and found that SS-31 slips into the inner membrane of mitochondria, where it binds cardiolipin and helps the energy-making machinery work.
Stealth BioTherapeutics developed it as elamipretide. After trials in several conditions, the FDA granted it accelerated approval in September 2025 as Forzinity, the first treatment for Barth syndrome, a rare inherited mitochondrial disease. Approval is for that disease only and requires a confirmatory trial.
Key people
- Hazel H. SzetoPharmacologist, Weill Cornell Medicine
- Peter W. SchillerPeptide chemist, Clinical Research Institute of Montreal
Timeline
- 2000s
Szeto–Schiller peptides designed and tested
- 2010s
Stealth BioTherapeutics runs clinical trials
- 2025
FDA accelerated approval as Forzinity for Barth syndrome
See every peptide on one history timeline.
Human evidence
Clinical trials have investigated mitochondrial diseases; findings vary by condition and endpoint.
Use compound-specific clinical publications and current FDA labeling or regulatory records for claims.
Explore original publications and distinguish preclinical findings from controlled human evidence.
Safety and regulatory status
See every compound on the regulatory tracker.
Regulatory status is time-sensitive and must be checked for the specific formulation and indication.
Product identity, purity, sterility, and endotoxin testing address different risks. This profile is educational and does not provide treatment guidance.
Sources
- Primary scientific source
- FDA: First treatment for Barth syndrome (2025)
- ClinicalTrials.gov search: SS-31 (Elamipretide)
Hernandez Gener, E. (2026, November 7). SS-31 (Elamipretide): molecular data, research history and evidence. VALREXA Biosciences. https://valrexa.com/peptides/ss-31-elamipretide.html
APA style · Last reviewed November 7, 2026 · Our editorial standardsLast reviewed November 7, 2026. Trial and regulatory status can change; confirm in the linked registries. This profile is educational and is not medical advice, a treatment recommendation, or dosing or sourcing guidance. Report an error · Corrections policy