Overview
SS-31, marketed clinically as elamipretide, is a 4-amino-acid synthetic tetrapeptide developed by Hazel Szeto and Peter Schiller that selectively partitions to the inner mitochondrial membrane and binds cardiolipin, a phospholipid critical to electron-transport-chain organization. It is the most clinically developed mitochondrial-targeted peptide. Stealth Biotherapeutics took it through trials in Leber's hereditary optic neuropathy, primary mitochondrial myopathy (MMPOWER programs), age-related macular degeneration (ReCLAIM), and Barth syndrome. The ATTR cardiomyopathy and dry-AMD programs missed primary endpoints. Barth syndrome (TAZPOWER) reached approval via FDA's accelerated pathway in 2024 (Forzinity). Community / longevity-clinic use of SS-31 frames it as a general 'mitochondrial rejuvenation' peptide; the actual evidence is sharply indication-specific.
Mechanism
Concentrates ~1000-fold in the inner mitochondrial membrane via electrostatic affinity, then binds cardiolipin and stabilizes the cristae structure. Restoring cardiolipin–cytochrome c interactions improves electron-transport-chain efficiency, reduces ROS leak, and preserves ATP production in stressed/aged mitochondria. Effect is downstream-corrective rather than upstream-stimulatory — it does not increase mitochondrial biogenesis directly, but improves the function of existing mitochondria.
Evidence by indication
We classify each indication separately. The same peptide can be Tier 1 for one use and Tier 4 for another. Tiers reflect the published literature, not the strength of community framing.
Barth syndrome (cardiolipin deficiency)
TAZPOWER and TAZPOWER-LTE trials provided sufficient evidence for FDA accelerated approval in 2024 (Forzinity) for adolescents and adults with Barth syndrome — a rare X-linked cardiolipin synthesis disorder. Tier 1 reflects approval for this orphan indication.
Primary mitochondrial myopathy
MMPOWER-3 Phase 3 trial in primary mitochondrial myopathy missed its co-primary endpoints, but post-hoc and crossover-extension data showed signals of benefit on the 6-minute walk test. Tier 2 because the RCT is well-powered but the readout is mixed.
Age-related macular degeneration (geographic atrophy)
ReCLAIM-2 Phase 2b in dry AMD did not meet its primary endpoint. Some secondary signals exist. Tier 3 reflects underpowered Phase 2 evidence and an unconverted hypothesis.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
General 'mitochondrial rejuvenation' / longevity
Used in community/longevity-clinic settings as a general anti-aging mitochondrial intervention. There are no RCTs in healthy aging — the entire trial program was in defined mitochondrial diseases. Mechanism-as-evidence reasoning.
No primary citations are anchored to this indication — the tier reflects the absence of usable literature, not a missing reference.
Studied dose ranges
The ranges below come from published trial protocols where available, and from documented self-experimenter consensus where the literature does not include human dose-finding work. The notes flag which is which.
Clinical trials (MMPOWER, TAZPOWER) used 40–60 mg SubQ once daily. Note the unit math: 40 mg = 40,000 mcg — much higher than typical microgram-dose peptides. The injection volume is non-trivial.
Contraindications
- Pregnancy and breastfeeding (limited human safety data outside trial populations)
- Pediatric use outside formal trials
- Active malignancy (mitochondrial bioenergetics intersects with cancer metabolism in complex ways)
- Known hypersensitivity to elamipretide
Reported side effects
- Injection-site reactions — common; can be substantial given the daily SubQ administration of a large-volume dose
- Headache
- Diarrhea / GI symptoms
- Upper-respiratory-tract symptoms
- Hypersensitivity reactions (rare)
Reconstitution & storage
Trial / approved formulation is supplied as a sterile solution at fixed concentration (40 mg/mL in approved Barth product Forzinity). Compounded research-grade SS-31 powder is reconstituted with sterile saline; concentrations vary by vendor. Dose volumes are larger than typical peptide injections — multi-mL SubQ doses are common.
Storage. Approved product: refrigerate per label. Compounded sterile solutions: refrigerate 2–8 °C. Lyophilized: refrigerate; reconstituted within 30 days typical.
Open the peptide calculator → to compute exact draw volumes for your specific vial and BAC water choice.
Editorial note
DRAFT — pending Wayne's review. SS-31 / elamipretide is a real drug with a real approval pathway, used in community / longevity contexts that do not match the indications it was developed for. Editorial line: respect the Barth-syndrome approval (Tier 1), credit the PMM/AMD work as Tier 2-3, and do not let the longevity framing get to anything above Tier 4. Compounded vendor pricing is high; some clinics market it aggressively.
Citations
- [1]Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathyKaraa A, Haas R, Goldstein A, Vockley J, Weaver WD, Cohen BH · Neurology · 2018 · PMID 29643127Anchor RCT for primary mitochondrial myopathy. Demonstrates dose-dependent functional improvement. Foundation for Tier 2 PMM indication.View source
- [2]Subcutaneous elamipretide in patients with Barth syndrome: a randomized, placebo-controlled, double-blind crossover trial (TAZPOWER)Reid Thompson W, Hornby B, Manuel R, et al. · Genetics in Medicine · 2021 · PMID 33704569Pivotal RCT in Barth syndrome that supported the 2024 accelerated approval. Tier 1 anchor.View source