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Peptide Encyclopedia / SS-31

Encyclopedia

SS-31

SS-31 is a cell-permeable tetrapeptide that targets mitochondria, binding cardiolipin on the inner membrane to stabilize cristae and support energy production. As elamipretide it won FDA accelerated approval in September 2025 as Forzinity for muscle strength in Barth syndrome, while uses like heart failure and mitochondrial myopathy stay investigational. Below you'll find reported dosing, safety, and legal status. Educational only, not medical advice.

Track SS-31 →Dose tools
CategoryLongevity / Anti-aging
Regulatory statusFDA-approved (accelerated approval, September 2025) as FORZINITY (elamipretide, Stealth BioTherapeutics) to improve muscle strength in adult and pediatric Barth syndrome patients weighing >=30 kg; continued approval contingent on a confirmatory trial.

Mechanism

A cell-permeable mitochondria-targeting tetrapeptide that binds reversibly to cardiolipin on the inner mitochondrial membrane, helping stabilize cristae structure and improve mitochondrial electron transport and energy production.

Half-life

Relatively short; reported on the order of a few hours after subcutaneous dosing. It is a peptide. Exact published human values vary by study.

Regulatory status

FDA-approved (accelerated approval, September 2025) as FORZINITY (elamipretide, Stealth BioTherapeutics) to improve muscle strength in adult and pediatric Barth syndrome patients weighing >=30 kg; continued approval contingent on a confirmatory trial. Other indications (heart failure, primary mitochondrial myopathy, dry AMD) are NOT approved and remain investigational.

Safety

In trials, injection-site reactions were common. Use outside the narrow approved Barth syndrome indication is off-label/investigational. Long-term and anti-aging safety/efficacy are not established.

Evidence

Human clinical trials; FDA-approved for one rare disease, investigational for other indications.

Track SS-31 in PepWise

Log every dose and injection site, get the reconstitution and units math automatically, follow your cycle, and record how you feel, then export a provider report. SS-31 tracker, free to start.

Sources

  1. Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. British Journal of Pharmacology. 2014;171:2029-2050. https://pubmed.ncbi.nlm.nih.gov/24117165/
  2. Thompson WR, et al. A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome. Genetics in Medicine. 2021;23:471-478. https://pubmed.ncbi.nlm.nih.gov/33077895/
  3. Thompson WR, et al. Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genetics in Medicine. 2024;26(7):101133. https://pubmed.ncbi.nlm.nih.gov/38602181/
  4. Sweetwyne MT, et al. The mitochondrial-targeted peptide, SS-31, improves glomerular architecture in mice of advanced age. Kidney International. 2017;91:1126-1145. https://pubmed.ncbi.nlm.nih.gov/28063595/
  5. Mitchell W, Pharaoh G, Tyshkovskiy A, et al. 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. 2025;24(6):e70026. https://pubmed.ncbi.nlm.nih.gov/40080911/
  6. Chavez JD, et al. Mitochondrial protein interaction landscape of SS-31. Proceedings of the National Academy of Sciences. 2020;117(26):15363-15373. https://pubmed.ncbi.nlm.nih.gov/32541025/
  7. Birk AV, et al. The mitochondria-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. Journal of the American Society of Nephrology. 2013;24:1250-1261. https://pubmed.ncbi.nlm.nih.gov/23813215/
  8. Machiraju P, et al. SS-31 treatment ameliorates cardiac mitochondrial morphology and defective mitophagy in a murine model of Barth syndrome. Scientific Reports. 2024;14:13551. https://pubmed.ncbi.nlm.nih.gov/38866837/

PepWise is an informational and educational tracking tool, not medical advice and not a medical device. SS-31 may be experimental, restricted, or prescription-only; many research peptides are not FDA-approved. Consult a licensed healthcare provider before starting, changing, or stopping any protocol. Operated by STC Consulting, Inc.