SS-31, also called elamipretide, is a lab-made chain of four amino acids. It attaches to cardiolipin, a fat found in the inner membrane of mitochondria. It has been tested in animals and in several human trials, and many of those trials missed their main goals.
Why scientists study it
- In animal and cell models it binds cardiolipin, which steadies the inner membrane of mitochondria and helps the electron transport chain work well again.
- Stealth BioTherapeutics has run trials in heart failure, age-related macular degeneration, primary mitochondrial myopathy and Barth syndrome, and the FDA gave accelerated approval for Barth syndrome in September 2025.
- It reaches mitochondria without needing a membrane potential to build up, which sets it apart from most compounds aimed at mitochondria.
Three studies to know
2014 · Br J Pharmacol
Birk and colleagues described how SS-31 binds cardiolipin. They showed that it brought back ATP production by mitochondria in kidney tissue starved of blood. Read the paper
2014 · Br J Pharmacol
In this review, Szeto pulls together the SS peptide family, how it protects cardiolipin, and its animal and cell tests across models of failing mitochondria. Read the paper
2021 · Genet Med
Reid Thompson and colleagues ran TAZPOWER, a Phase 2/3 trial in Barth syndrome. This was the key program behind the accelerated approval the FDA gave in September 2025. Read the paper
Safety and legal status
- The clinical trial record is large. It spans programs in heart failure, AMD, Barth syndrome and primary mitochondrial myopathy. People generally tolerated it well, and reactions at the injection site were the most common finding.
- The FDA gave it accelerated approval in September 2025 for Barth syndrome in patients who weigh 30 kg or more. The MHRA in the UK has not approved it. Its World Anti-Doping Agency status needs a fresh check each year.
- For laboratory research use only.
Related compounds
- NAD+: Helper molecule in every cell, studied for energy, DNA repair and its drop with age.
- MOTS-c: Small peptide made from a mitochondrial gene, tested in mice for blood sugar and muscle effects.
- Glutathione: The main antioxidant inside cells, made of three amino acids and tested in small human trials.