In clinical trials
Hormones & metabolism
Elamipretide
Also called SS-31, bendavia, MTP-131
Elamipretide is a mitochondria-targeting peptide with FDA accelerated approval for Barth syndrome. Learn how it works and what that approval does not show.
- Reviewed by
- William Maish, MD MBA MPH, Clinical Product Lead
- Published
- October 5, 2026
- Last updated
- October 5, 2026
Key takeaway
Elamipretide is a mitochondria-targeting peptide that binds cardiolipin, a key molecule in the energy-producing inner membrane of mitochondria, developed by Stealth BioTherapeutics. It received FDA accelerated approval in 2025 as Forzinity for Barth syndrome, a rare genetic disorder of cardiolipin, making it the first approved treatment for that condition. Its approval rests on a muscle-strength surrogate measure with a confirmatory trial still required, and its other studied uses remain investigational.
At a glance
| What it is | A mitochondria-targeting tetrapeptide, sold as Forzinity |
| Approved for | Improving muscle strength in adults and children with Barth syndrome who weigh at least 30 kg (accelerated approval, 2025) |
| Key fact | It is the first approved treatment for Barth syndrome, and a confirmatory trial is required |
| Route | Subcutaneous injection, once daily |
| Evidence strength | FDA approved (for Barth syndrome) |
What is elamipretide?
Elamipretide is a small peptide designed to concentrate inside mitochondria, the energy-producing structures of cells, where it binds a membrane lipid called cardiolipin. It is developed by Stealth BioTherapeutics and is given by subcutaneous injection. Its approved use is Barth syndrome, a rare genetic disorder of cardiolipin that affects the heart, muscles, and immune system; it has also been studied in other mitochondrial and eye diseases, where it remains investigational.
How does elamipretide work?
Elamipretide binds cardiolipin1 in the inner mitochondrial membrane and helps stabilize the folded structure (cristae) where energy production takes place. By supporting that architecture, it is intended to improve the efficiency of the electron transport chain that generates ATP and to reduce harmful reactive oxygen species. In Barth syndrome, which is caused by mutations in the TAFAZZIN gene that disrupt cardiolipin remodeling, this mechanism is the rationale for treatment. Mechanism describes how the drug is thought to act, separate from the clinical outcomes that trials measure.
Is it FDA-approved?
Yes, for one use, through the accelerated pathway. The FDA granted elamipretide accelerated approval2 on September 19, 2025, as Forzinity, to improve muscle strength in adults and children with Barth syndrome who weigh at least 30 kg. It is the first approved treatment for the condition. The regulatory path was contentious:
- An earlier submission was turned down after the drug missed a walking-distance endpoint.
- The approval was ultimately based on a knee-extensor muscle-strength measure.
- A confirmatory randomized trial was required after approval.
Its other studied uses are not approved.
What is elamipretide prescribed for?
Elamipretide is prescribed to improve muscle strength in adults and children with Barth syndrome who weigh at least 30 kg, under specialist care. It is not approved for the other conditions in which it has been studied, such as dry age-related macular degeneration or primary mitochondrial myopathy, where trials did not lead to approval.
What are the side effects?
According to the prescribing information, the most common side effects are:
- Injection-site reactions such as redness, pain, hardening, itching, bruising, and hives
More serious considerations include:
- Serious allergic reactions
- A benzyl alcohol preservative, so it is not approved for newborns
More for hormones & metabolism
Sources: the 168-week open-label extension of the TAZPOWER trial (Thompson et al., Genetics in Medicine, 2024, DOI: 10.1016/j.gim.2024.1011381) and a related outcomes analysis (Gwaltney et al., Orphanet Journal of Rare Diseases, 2025, DOI: 10.1186/s13023-025-03693-53), both indexed on PubMed; and FDA prescribing information for Forzinity. This document is educational and does not constitute medical advice.