SS-31 (Elamipretide)
SS-31, also known as elamipretide, is a small peptide engineered to travel directly into mitochondria, the structures inside cells responsible for producing energy. In 2025 it became the first mitochondria-targeted peptide to receive FDA approval, for a rare genetic disease called Barth syndrome, giving it a level of clinical validation that's unusual among the compounds covered on this site.
- Sequence
- 4 amino acids
- Format
- Lyophilized powder
- Half-Life
- Short; reported in the range of minutes to a few hours
What Is SS-31?
SS-31 is a small, synthetic tetrapeptide, meaning it's built from just four amino acids, designed with a very specific destination in mind: the inner mitochondrial membrane. Unlike most peptides, which work by binding to receptors on the outside of cells, SS-31 is built to pass through cell membranes and concentrate specifically inside mitochondria, where it interacts directly with the membrane structure itself.
Its target is cardiolipin, a phospholipid that makes up part of the inner mitochondrial membrane and plays a structural role in how efficiently mitochondria produce energy. By stabilizing this membrane component, SS-31 is thought to support healthier mitochondrial function, which is the basis for its research across a wide range of conditions tied to mitochondrial dysfunction.
What SS-31 Is Being Researched For
Barth Syndrome
The most clinically developed area of SS-31 research addresses Barth syndrome, a rare genetic disorder that disrupts normal cardiolipin structure. A Phase 2/3 trial and its long-term extension found meaningful improvements in physical function and cardiac measures in patients treated with elamipretide, ultimately supporting its FDA approval.[1][3]
Mitochondrial Membrane Structure
Foundational biophysical research has examined exactly how SS-31 interacts with mitochondrial membranes at a molecular level, providing the mechanistic basis for its effects across different disease models.[2]
Broader Mitochondrial Dysfunction Research
Beyond Barth syndrome specifically, SS-31 has been studied in models of heart failure, kidney injury, and other conditions where mitochondrial dysfunction is thought to play a role, reflecting how central mitochondrial health is across many different tissues.
How SS-31 Works
Concentrating Inside Mitochondria
Research points to SS-31's structure allowing it to reach concentrations inside mitochondria far higher than in the surrounding cell, a targeting property built directly into its design rather than achieved through a receptor.[2]
Stabilizing the Inner Mitochondrial Membrane
Research points to SS-31 binding to cardiolipin, a phospholipid central to how mitochondria organize the machinery that produces cellular energy. By interacting with this membrane structure, SS-31 is thought to help preserve efficient energy production and reduce the buildup of damaging byproducts.[1][2]
Supporting Function in a Genetic Cardiolipin Disorder
Research points to SS-31's clinical benefit in Barth syndrome being tied directly to its mechanism, since the condition itself is caused by abnormal cardiolipin structure. Long-term trial data found sustained reductions in a biomarker reflecting that abnormal cardiolipin composition, alongside functional improvements.[3]
Reconstitution and Handling
SS-31 is typically supplied as a lyophilized powder in a sealed vial and reconstituted with bacteriostatic water before use in a research setting. Water should be added slowly rather than injected directly into the powder, and the vial should be swirled, not shaken. This is separate from the FDA-approved pharmaceutical form of elamipretide, which is manufactured and administered under clinical supervision.
Since the amount of water used affects the concentration of the final solution, researchers often use a dosage calculator to work this out before mixing. Once reconstituted, the solution is kept refrigerated to help preserve its stability.
Key Takeaways
SS-31 stands out for its precise mechanism, engineered to concentrate inside mitochondria and stabilize a specific membrane component, and for becoming the first mitochondria-targeted peptide to earn FDA approval in 2025. Its research base spans from detailed biophysical studies of how it interacts with membranes to long-term human clinical trial data in Barth syndrome. That approval, tied to a well-understood mechanism, sets it apart from most compounds on this site.
Frequently Asked Questions
What Is SS-31 Derived From?
It's a fully synthetic tetrapeptide, engineered specifically to target and concentrate inside mitochondria rather than derived from a naturally occurring hormone.
What Is SS-31 Approved For?
Its pharmaceutical form, elamipretide, received FDA approval in 2025 for Barth syndrome, a rare genetic mitochondrial disease. Other uses remain investigational.
How Does SS-31 Work?
Research points to it concentrating inside mitochondria and binding cardiolipin, a membrane component central to how mitochondria produce energy, helping stabilize mitochondrial structure and function.
Why Is SS-31 Studied in So Many Different Conditions?
Because mitochondrial dysfunction is implicated in a wide range of diseases, from heart failure to kidney injury to rare genetic disorders, researchers have studied SS-31 across many of these contexts given its direct mechanism.
Has SS-31 Been Tested in Humans?
Yes, extensively for its approved indication. Barth syndrome trials included both an initial randomized, placebo-controlled study and a long-term open-label extension tracking outcomes over more than three years.
Sources and Research
- Thompson WR, Hornby B, Manuel R, et al. A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome, a genetic disorder of mitochondrial cardiolipin metabolism. Genet Med. 2021;23(3):471-478.
- Mitchell W, Ng EA, Tamucci JD, et al. The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action. J Biol Chem. 2020;295(21):7452-7469.
- Thompson WR, Manuel R, Abbruscato A, et al. Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER. Genet Med. 2024;26(7):101138.
Related Reading
For educational and research purposes only. Not medical advice. Always consult a licensed healthcare professional before starting any protocol.