Compound profile
SS-31 (Elamipretide)
Stronger clinical signalAlso known as: Elamipretide · Bendavia · MTP-131
A mitochondria-targeted peptide that stabilizes cardiolipin in the inner mitochondrial membrane, supporting energy production and reducing oxidative stress. FDA-approved as elamipretide for Barth syndrome, a rare genetic mitochondrial disease, and one of the few peptides in this category with an actual regulatory approval.
Overview
SS-31 was developed by researchers studying mitochondrial dysfunction as a driver of disease and aging, and it works differently from most peptides on this site: rather than binding a cell-surface receptor, it concentrates inside mitochondria and binds directly to cardiolipin, a phospholipid unique to the inner mitochondrial membrane that is essential for organizing the electron transport chain properly.
Under the name elamipretide, it became the first mitochondria-targeted peptide to receive FDA approval, cleared for Barth syndrome, a rare X-linked genetic disorder that causes a specific cardiolipin abnormality leading to cardiomyopathy, muscle weakness, and growth delay. That approval followed the TAZPOWER trial program, a randomized, placebo-controlled study followed by a long open-label extension, which reported functional and cardiac improvements with extended use even though the initial short randomized phase missed its primary endpoints.
Beyond Barth syndrome, elamipretide and its research designation SS-31 show up across a much broader mitochondrial biology literature, including aging research, heart failure, kidney disease, and eye disease, reflecting genuine scientific interest in cardiolipin stabilization as a general strategy for mitochondrial dysfunction, though most of that broader research remains preclinical or early-stage.
Mechanism (plain language)
Concentrates in the inner mitochondrial membrane and binds cardiolipin, stabilizing its structure and the organization of the electron transport chain, which is thought to reduce excess reactive oxygen species production and improve ATP synthesis efficiency.
How it works
SS-31's alternating pattern of positively charged and aromatic amino acids gives it a strong, selective affinity for cardiolipin, a phospholipid found almost exclusively in the inner mitochondrial membrane where it helps organize the protein complexes of the electron transport chain into efficient configurations. In damaged or dysfunctional mitochondria, cardiolipin can become oxidized or mislocalized, disrupting that organization and increasing electron leakage, which produces excess reactive oxygen species and impairs ATP production.
By binding and stabilizing cardiolipin, SS-31 is proposed to help restore more efficient electron transport chain function and reduce that oxidative byproduct. Research using isolated aged mitochondria has found the peptide improves sensitivity to ADP, the signal that ramps up ATP production when energy demand rises, by increasing its uptake through the adenine nucleotide translocator, a transport protein that shuttles ADP and ATP across the mitochondrial membrane. This mechanism is proposed to apply broadly across tissues with high energy demands, which is why research has extended from the primary cardiac indication into skeletal muscle, kidney, and eye tissue.
What research suggests
The TAZPOWER trial program, including a randomized controlled phase and a 168-week open-label extension, supports meaningful long-term functional and cardiac benefit in Barth syndrome specifically, which is the basis of its FDA approval. Evidence for other conditions, including general aging or exercise-related outcomes, is earlier-stage and largely preclinical.
Reported benefits
What studies, case reports, and the research literature describe, not guaranteed outcomes. The trials behind these findings are in the studies below.
Long-term functional improvement in Barth syndrome
The 168-week open-label extension of the TAZPOWER trial reported sustained improvements in functional assessments and cardiac measures with continued elamipretide use, the basis for its FDA approval.
Improved aged mitochondrial function in preclinical models
Research on isolated aged mitochondria found elamipretide improved ADP sensitivity and electron transport efficiency, supporting its proposed mechanism in age-related mitochondrial decline.
Broader mitochondrial disease research interest
Beyond Barth syndrome, elamipretide has been studied in early-phase trials for heart failure with preserved ejection fraction, primary mitochondrial myopathy, and geographic atrophy, reflecting the breadth of interest in the cardiolipin-stabilization mechanism, though most of these programs remain investigational.
Uncertainties & risks
The FDA approval is specific to Barth syndrome, a rare genetic condition with a defined cardiolipin abnormality, not a general endorsement for aging or fitness-related use. The initial randomized phase of its pivotal trial missed primary endpoints, with benefit emerging mainly in the longer open-label extension, a pattern that invites some caution in interpreting the strength of the effect.
Elamipretide's regulatory approval is a meaningful marker of evidence quality relative to most peptides discussed in fitness and longevity spaces, but it is worth being precise about what was actually approved: a specific rare disease population with molecularly confirmed Barth syndrome, using daily subcutaneous injection under medical supervision. The pivotal trial's primary randomized phase did not meet its prespecified endpoints, and the case for benefit rests substantially on the open-label extension data, which lacks a placebo comparison over that longer period. Other investigational uses in broader aging, heart failure, and eye disease populations remain in earlier trial phases and should not be assumed to carry the same evidence weight as the Barth syndrome approval.
Side effects
Commonly reported
- Injection-site reactions: The most commonly reported adverse event in Barth syndrome trials, given as a daily subcutaneous injection
- Nausea: Reported in a subset of trial participants
Reported in the cited literature, not a complete list, and not medical advice. Individual responses vary; consult a qualified professional.
STACKD study summaries
Start with our in-house roundups, plain-language synthesis of the research, with primary sources cited at the bottom of each.
Primary sources
Secondary citations for verification. Prefer the STACKD summary above for context before opening these.