SS-31 (Elamipretide): Mitochondria-Targeting With a Real Approval
A mitochondria-targeting tetrapeptide, FDA-approved in September 2025 for Barth syndrome — a real approval in one narrow rare disease, not a general muscle or longevity drug.
What is SS-31 (Elamipretide)?
SS-31 (elamipretide) is a small, mitochondria-targeting tetrapeptide that concentrates in the inner mitochondrial membrane and stabilizes cardiolipin, a lipid essential to mitochondrial energy production. It received FDA approval in September 2025 for Barth syndrome, a rare inherited mitochondrial muscle disease, after an extension study showed meaningful improvement in a 6-minute walk test. That approval is genuinely narrow, though: a larger 218-person trial in a different mitochondrial-muscle condition (MMPOWER-3) showed no improvement in walking distance or fatigue, and separate heart-failure and dry-AMD trials both missed their primary endpoints. It's grouped with longevity research because of its mitochondrial mechanism, but that broader case rests mostly on animal data plus this one rare-disease approval.
Quick facts
- Half-Life
- ~7-10 hours
- Class
- Mitochondria-targeting tetrapeptide (cardiolipin-stabilizing)
- Brand Names
- FDA-approved for Barth syndrome (Sept 2025) — general research-vendor form has no trademarked brand
- Legal Status
- FDA-approved for Barth syndrome specifically; general/off-label research use is not FDA-approved for that purpose — sold RUO outside the approved indication
- Category
- Mitochondrial Health
- Storage
- Store the lyophilized vial refrigerated (2-8°C) or at -20°C, away from light. Once reconstituted, keep refrigerated at 2-8°C and use promptly.
Dosing at a glance
Research-vendor convention: 40mg vial reconstituted with 2mL bacteriostatic water. The FDA-approved Barth syndrome product is a pre-filled subcutaneous formulation, not a lyophilized research vial. Run the numbers in the reconstitution calculator.
Doses shown are those reported in published research, not a recommendation.
What the evidence supports
| Claim | Grade | Basis |
|---|---|---|
| Muscle Function (mitochondrial disease) | Bgrade | FDA-approved Sept 2025 for Barth syndrome (TAZPOWER extension); MMPOWER-3 (n=218) in a different mitochondrial-muscle condition showed no gain in walking or fatigue. |
| Longevity / Mitochondrial Health | Cgrade | Heart-failure and dry-AMD trials both missed primary endpoints; general longevity case rests on animal data plus the narrow rare-disease approval. |
SS-31 (Elamipretide) Mechanism of Action
Targeting the Inner Mitochondrial Membrane
SS-31 is a small, positively-charged tetrapeptide that selectively concentrates in the inner mitochondrial membrane, where it binds and stabilizes cardiolipin — a lipid essential to the structure of the electron transport chain and efficient ATP production. Stabilizing cardiolipin is thought to reduce electron leakage and reactive oxygen species production in dysfunctional mitochondria.
A Narrow, Real Approval
SS-31 (as elamipretide) received FDA approval in September 2025 specifically for Barth syndrome, a rare inherited mitochondrial disease causing muscle weakness and cardiomyopathy. This is a genuine regulatory approval, not a research-community claim — but it applies to one narrow, rare population, not muscle function or mitochondrial health broadly.
SS-31 (Elamipretide) Dosage and Protocols
Approved vs. Research Dosing
The FDA-approved Barth syndrome regimen uses a pre-filled subcutaneous formulation dosed daily; research-vendor protocols commonly cite around 40mg subcutaneous daily from a reconstituted vial, mirroring the approved dose. Outside the approved indication, there's no validated dose-finding data to guide use.
SS-31 (Elamipretide) Side Effects and Safety
Injection-Site Reactions Most Common
In the Barth syndrome trial program, injection-site reactions were the most commonly reported effect. Given the mixed results across other trial populations (heart failure, dry AMD, the broader mitochondrial-muscle trial), comprehensive safety data outside the approved rare-disease population remains limited.
SS-31 (Elamipretide) Research Evidence
A Real Win, With a Real Miss Right Next to It
The TAZPOWER extension study tracked 8 Barth syndrome patients out to 168 weeks and saw them walk roughly 96 meters farther on a 6-minute walk test — the data that supported FDA approval. But MMPOWER-3, a larger 218-person, 24-week trial in a different mitochondrial-muscle condition, saw no improvement in walking distance or fatigue. Separately, heart-failure and dry age-related macular degeneration trials both missed their primary endpoints. The win is real but genuinely narrow.
Regulatory and Legal Status
SS-31 is FDA-approved specifically for Barth syndrome as of September 2025. Use outside that approved indication — including general mitochondrial-health or longevity research use — is not FDA-approved for that purpose, and is sold by research-peptide vendors as an unapproved compound (RUO) in that context. Researchers and users should verify the legal status of off-label SS-31 use in their jurisdiction.
SS-31 (Elamipretide) Stacking and Combinations
Standalone Mitochondrial Research
SS-31 is typically studied and used standalone, targeting mitochondrial function specifically. It's sometimes discussed alongside other mitochondrial-derived peptides like MOTS-c or Humanin in longevity research contexts, though no formal combination trial data exists for any pairing.
SS-31 (Elamipretide) Pharmacokinetics
Short Half-Life, Rapid Mitochondrial Uptake
SS-31 has a plasma half-life of roughly 7-10 hours, but its relevant pharmacology is really about mitochondrial concentration rather than plasma persistence — it accumulates selectively in mitochondria-dense tissue (heart, skeletal muscle) far above plasma levels.
Contraindications
- pregnancy
- known hypersensitivity
Trials and reviews
- TAZPOWER extensionBarth syndrome program2025
~96m farther on a 6-minute walk test over 168 weeks, leading to FDA approval
- MMPOWER-3Neurology2020
n=218, no improvement in walking distance or fatigue in a different mitochondrial-muscle condition
Frequently asked questions
What is a typical SS-31 (Elamipretide) dose?
Published research protocols report 40 mg, 1x daily. This is the range described in the literature, not a recommendation.
What is the half-life of SS-31 (Elamipretide)?
~7-10 hours.
Is SS-31 (Elamipretide) backed by strong evidence?
SS-31 (Elamipretide) carries a REGEN research grade of B. REGEN Research Tier B — a real FDA approval, but narrow (one rare disease), with a larger trial in a related condition showing no benefit.
How is SS-31 (Elamipretide) administered?
Routes reported in the literature: subcutaneous.
Who should avoid SS-31 (Elamipretide)?
Contraindications noted in the literature include pregnancy, known hypersensitivity.