SS-31 has a rarer distinction on this site: it's an FDA-approved drug, under a different name, for a specific rare disease — while the vast majority of research and consumer interest in it has nothing to do with that approved use. Both facts matter, and this guide treats them separately.
What Is SS-31?
SS-31 is a synthetic tetrapeptide with an alternating cationic/aromatic amino acid motif that allows it to cross the plasma membrane without a transporter and accumulate 1,000–5,000-fold at the mitochondrial inner membrane. There, it selectively binds cardiolipin, a phospholipid unique to the inner mitochondrial membrane.
Mechanism of Action
By binding cardiolipin, SS-31 stabilizes the folded cristae structure of the inner mitochondrial membrane — where the electron transport chain complexes are physically organized. Cell-culture studies found the peptide reduces oxidative cell death, lowers intracellular reactive oxygen species, and preserves membrane potential, all in a dose-dependent manner, which supports the model that cristae stabilization directly protects ATP production capacity during oxidative stress.
What the Preclinical Research Shows
Multiple independent research groups have reported efficacy across a wide range of disease models sharing mitochondrial dysfunction as a common root cause:
- Cardiomyopathy and heart failure models
- Skeletal muscle injury and atrophy models
- Ischemia and ischemia-reperfusion injury
- Kidney injury and disease models
- Neurodegenerative disease models
- Friedreich's ataxia (a heritable mitochondrial disease)
Human Evidence and Regulatory Status
Unlike most compounds on this site, SS-31 has gone through real human trials and a real FDA approval — for one specific, ultra-rare indication. The TAZPOWER trial (28-week randomized, placebo-controlled, followed by a 168-week open-label extension) tested elamipretide in Barth syndrome, an X-linked genetic disorder that weakens cardiac and skeletal muscle. The 12-week randomized phase missed its primary endpoints, but the open-label extension found significant improvement on the 6-minute walk test (79.7m difference at week 64, 91.0m at week 76) and cardiac outcomes.
In September 2025, the FDA granted accelerated approval to elamipretide — brand name Forzinity — for muscle strength in Barth syndrome, in adult and pediatric patients, dosed at 40mg subcutaneously once daily. It's the first FDA-approved mitochondrial disease therapy.
This approval is narrow: Barth syndrome muscle strength, at a specific dose, under medical supervision. It is not a general approval for mitochondrial health, aging, or any of the broader uses SS-31 is studied for elsewhere. SS-31 sold by research vendors is not Forzinity — it is unapproved bulk peptide material, not established as equivalent in purity or formulation, and not legal to sell for human use outside that approved product.
Where to Source SS-31 for Research
For legitimate research applications, purity and accurate dosing are critical. We only list vendors who provide third-party HPLC testing and batch-specific Certificates of Analysis.
View the SS-31 product page →Frequently Asked Questions
Is SS-31 FDA-approved?
Yes, but only for one narrow use: as Forzinity, for muscle strength in Barth syndrome, approved via the FDA's accelerated approval pathway in September 2025. It is not approved for general mitochondrial health, longevity, or any use outside that specific rare-disease indication.
Is the SS-31 sold by research vendors the same as Forzinity?
No. Forzinity is a specific FDA-approved manufactured product for a specific indication and dose. SS-31 sold for research use is unapproved bulk peptide material and has not been established as equivalent in purity, formulation, or bioavailability.
Does the Barth syndrome approval mean SS-31 is proven for mitochondrial aging or general energy?
No. The approved indication is narrow — muscle strength in a specific genetic disease. The broader mitochondrial-function research (cardiac, kidney, neurodegenerative models) is real but preclinical, and hasn't been tested in the general population the way it was in Barth syndrome patients.
References
1. "The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action." PMC. ncbi.nlm.nih.gov
2. "SS-31, a Mitochondria-Targeting Peptide, Ameliorates Kidney Disease." PMC. pmc.ncbi.nlm.nih.gov
3. "Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER." PubMed. pubmed.ncbi.nlm.nih.gov
4. "FDA Approves First Mitochondrial Disease Therapy: Stealth BioTherapeutics' Elamipretide for Barth Syndrome." United Mitochondrial Disease Foundation. umdf.org
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