SS-31 (Elamipretide)
SS-31 is the research name for elamipretide, a four-amino-acid peptide. FDA granted it accelerated approval in 2025 for Barth syndrome; other uses are still investigational.
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Quick answer
SS-31 is a research name for elamipretide, a small synthetic peptide aimed at mitochondria, the energy-making parts of cells. In September 2025 FDA gave it accelerated approval, under the brand name Forzinity, for one rare condition: Barth syndrome. [1] For other uses, including aging, heart failure and eye disease, it is still investigational. Unlike most peptides discussed online, it has real regulator and trial records, so this page is mostly about what those records say.
Names that point to the same molecule
Elamipretide has also been called SS-31, MTP-131 and Bendavia in research and trial records. [2] The FDA label gives its sequence as D-Arg-2,6-dimethyl-Tyr-Lys-Phe-NH2, with one amino acid in the D form, and describes it as a "mitochondrial cardiolipin binder". [3] Cardiolipin is a fat found in the inner mitochondrial membrane. A molecule, a brand (Forzinity) and an unproven online "SS-31" product are not interchangeable; we cannot verify what any non-prescription product contains.Barth syndrome: what the evidence is
Barth syndrome is a rare genetic condition that can weaken muscle and the heart. FDA's label describes a randomized, double-blind, crossover trial in 12 people aged 12 or older, followed by an open-label extension of up to 192 weeks. Elamipretide was not superior to placebo on the two main goals, a 6-minute walk and a fatigue score. Muscle strength was a secondary measure: no increase in the randomized period, but increases in the open-label part. [3] That strength result, an "intermediate" outcome, is what the accelerated approval rests on. The published 168-week extension reported sustained improvements in walking and fatigue, but with no placebo group, 10 participants entering and 8 reaching week 168. [5] Label: promising but limited.Where it fits
See peptides and mitochondrial disorders, mitochondria and oxidative stress in aging, and approved, investigational and unapproved peptides for how these categories differ.Frequently asked questions
Is SS-31 the same as elamipretide?
Yes, in research records elamipretide is also called SS-31 and MTP-131. The approved product is the brand Forzinity, for Barth syndrome only. [2][3]
Is elamipretide approved in the US?
Yes, for Barth syndrome in people weighing at least 30 kg, under FDA accelerated approval. [3]
Does it help with aging or energy?
Proper evidence not found. A small healthy-aging study is registered, and no results were read. [10]
Why was the approval "accelerated"?
FDA based it on a muscle-strength measure and requires a confirmatory trial. The main randomized-trial goals were not met. [3]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: approved medicine (with regulator and indication), promising but limited, mixed, no good evidence of benefit for a given use, and marketing claim. A biomarker is a lab or imaging value, which is not the same as feeling or functioning better.
Regulatory status
| Place | What we read | Source |
|---|---|---|
| United States | Forzinity (elamipretide) injection, approved medicine under accelerated approval for improving muscle strength in adults and children with Barth syndrome weighing at least 30 kg. FDA says continued approval may depend on a confirmatory trial. | [3][4] |
| Other regulators | EMA, MHRA, Health Canada, TGA: not verified. The EMA page we tried did not load. | n/a |
Accelerated approval means FDA approved the drug on an intermediate result that is expected to predict benefit, not on proof of long-term benefit. The approval letter requires a randomized, placebo-controlled trial in people aged 5 and older with Barth syndrome to confirm benefit. [4] This is not legal advice, and approvals change.
Other uses studied (not approved)
- Primary mitochondrial myopathy. The phase 3 MMPOWER-3 trial randomized 218 adults. It did not meet either main goal (walking distance or fatigue); the difference in walking was -3.2 meters versus placebo. [6] Label: no good evidence of benefit in that trial.
- Dry age-related macular degeneration. The phase 2 ReCLAIM-2 trial (176 patients) missed its two main goals. A secondary imaging measure of photoreceptor-layer loss was lower with elamipretide. [7] A phase 3 trial (ReNEW) is listed as active, with estimated primary completion in August 2027. [8] Label: promising but limited, unconfirmed.
- Heart failure with reduced ejection fraction. In the 71-patient PROGRESS-HF phase 2 trial, the heart-volume measure did not differ from placebo. [9] Label: no good evidence of benefit so far.
- Healthy aging. One phase 2 study of physical function in healthy older people (estimated 30 participants) is registered as recruiting. [10] Label: insufficient evidence; claims of anti-aging benefit are marketing claims.
Safety
The label's most common adverse reactions were injection-site reactions; in the Barth crossover trial every participant had one on elamipretide. [3] The label also warns of hypersensitivity reactions, including serious allergic reactions, and rises in eosinophils (a white blood cell) that returned to baseline. It warns against use in newborns because the product contains benzyl alcohol. [3] These warnings come from a very small trial population (12 males), so rarer problems are unknown. Anyone considering it should talk with the prescribing specialist; we give no use or dosing guidance.
References
- U.S. Food and Drug Administration. openFDA Drugs@FDA record for Forzinity (NDA 215244), approval status date 2025-09-19. Read 2026-10-22.
- U.S. National Library of Medicine. ClinicalTrials.gov record NCT02245620, a phase 2 study of elamipretide (MTP-131, Bendavia) in older adults. Read 2026-10-22.
- U.S. Food and Drug Administration. Forzinity (elamipretide) injection, prescribing information (Drugs@FDA, NDA 215244). Read 2026-10-22.
- U.S. Food and Drug Administration. Approval letter, NDA 215244 (Forzinity, elamipretide), accelerated approval. Read 2026-10-22.
- Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genet Med 2024. Read 2026-10-22.
- Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial. Neurology 2023. Read 2026-10-22.
- ReCLAIM-2: A Randomized Phase II Clinical Trial Evaluating Elamipretide in Age-related Macular Degeneration. Ophthalmol Sci 2025. Read 2026-10-22.
- U.S. National Library of Medicine. ClinicalTrials.gov record NCT06373731, ReNEW phase 3 trial of elamipretide in dry AMD. Read 2026-10-22.
- Effects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The PROGRESS-HF Phase 2 Trial. J Card Fail 2020. Read 2026-10-22.
- U.S. National Library of Medicine. ClinicalTrials.gov record NCT07275424, healthy aging and physical function with elamipretide. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.