Longevity · Cardiolipin-binding mitochondrial peptide · Compounded 503A
SS-31 (Elamipretide): the mitochondria-targeted peptide.
SS-31 (also called elamipretide, MTP-131, or Bendavia) is a small synthetic peptide engineered to cross the mitochondrial inner membrane and bind cardiolipin — the unique phospholipid that anchors the electron transport chain. It is the most clinically studied mitochondrial-targeted peptide of the last decade, with trials in heart failure, mitochondrial myopathy, and age-related macular degeneration.
What SS-31 (Elamipretide) is
SS-31 is a synthetic tetrapeptide (D-Arg-Dmt-Lys-Phe-NH2) engineered with alternating aromatic and basic residues. The alternating charge gives it the unusual ability to selectively concentrate in the inner mitochondrial membrane — at concentrations roughly 1,000-fold higher than in cytoplasm.
It binds cardiolipin, the phospholipid unique to the inner mitochondrial membrane that anchors and organizes the electron transport chain supercomplexes. With age and disease, cardiolipin becomes peroxidized and disorganized — and ATP production falls.
Stealth BioTherapeutics developed SS-31 under the name elamipretide. It has been studied in heart failure (PROGRESS-HF), Barth syndrome, mitochondrial myopathy, and dry age-related macular degeneration. The FDA has not yet approved it for any indication.
How it works
SS-31 selectively binds cardiolipin in the inner mitochondrial membrane. By stabilizing cardiolipin's structure, it preserves the assembly of electron transport chain supercomplexes — the protein machines that generate ATP.
This stabilization improves ATP production efficiency, reduces electron leak, and lowers the generation of reactive oxygen species — addressing mitochondrial dysfunction from multiple angles simultaneously.
Unlike free-radical scavengers that work downstream of damage, SS-31 acts upstream — preventing the peroxidation cycle from starting. This 'inner membrane stabilization' is the mechanistic distinction from most antioxidant therapies.
What patients use it for
Mitochondrial energy
By stabilizing cardiolipin and supercomplex assembly, SS-31 supports ATP production capacity — particularly relevant in tissues with high energy demand: heart, skeletal muscle, brain, retina.
Reduced oxidative stress
Upstream prevention of cardiolipin peroxidation lowers the generation of reactive oxygen species at the source — a different angle than downstream antioxidants.
Cardiac support
The PROGRESS-HF and EMBRACE-HFpEF trials evaluated elamipretide in heart failure with reduced and preserved ejection fraction — mixed results but signal in subpopulations.
Vision and retinal aging
Phase 2 ReCLAIM trial evaluated elamipretide in dry AMD with geographic atrophy. The retina has the highest mitochondrial density per gram of any tissue.
Evidence summary
Birk AV et al. (JASN, 2013) showed that SS-31 selectively binds cardiolipin and prevents its peroxidation — the foundational mechanism paper.
Reid Thompson W et al. (Genetics in Medicine, 2020) — the TAZPOWER trial — evaluated elamipretide in Barth syndrome and demonstrated improvement in functional capacity.
Butler J et al. (PROGRESS-HF, JACC: HF, 2020) evaluated elamipretide in heart failure with reduced ejection fraction. Primary endpoints were not met; subgroup signals were noted.
Honest framing: SS-31 is the most studied mitochondrial peptide with multiple Phase 2/3 trials — but no FDA approval and a mix of positive mechanism and mixed outcome data. Be cautious of providers overstating clinical certainty.
Dosing and clinical context
General clinical context only. Kindr Health physicians determine the appropriate dose and protocol for each patient based on history and labs. This is not a prescription or dosing recommendation.
Most commonly subcutaneous injection. Clinical trial dosing has typically been 40 mg daily for systemic indications.
Compounded dosing varies by indication and protocol. Course-based use is common.
Compounded SS-31 from licensed 503A pharmacies is the typical U.S. dispensing pathway. Not FDA-approved.
Safety and contraindications
Generally well-tolerated in the clinical trial literature. The most common adverse events have been local injection-site reactions.
Long-term human safety data is more robust here than for most peptides in this category because of the Phase 2/3 trial program.
Contraindications: pregnancy, lactation, known hypersensitivity. Use under physician supervision.
Who it's typically considered for
- Adults with documented mitochondrial dysfunction or related symptoms (fatigue, exercise intolerance)
- Patients prioritizing healthspan and longevity-axis interventions
- Patients on or considering NAD+ protocols (SS-31 and NAD+ act on different parts of mitochondrial function — complementary)
- Adults with retinal aging concerns under specialist supervision
Frequently asked questions
Is SS-31 FDA-approved?
No. SS-31 (elamipretide) has been studied in multiple Phase 2/3 trials but has not received FDA approval for any indication. Compounded SS-31 is prepared by licensed 503A pharmacies under physician prescription for off-label use.
SS-31 vs NAD+ — which is better?
They address different mitochondrial problems. NAD+ supports the substrates for energy production. SS-31 stabilizes the membrane machinery that uses those substrates. They are commonly used together, not as alternatives.
How quickly does SS-31 work?
Subjective energy effects vary — some patients report changes in 2–4 weeks, others longer. The clinical trial endpoints have typically been measured at 12+ weeks.
Is SS-31 safe long-term?
Long-term safety is better characterized here than for most compounded peptides because of the trial program. Periodic reassessment with your physician is still appropriate.
Will SS-31 help with chronic fatigue?
Mitochondrial dysfunction is implicated in some chronic fatigue presentations. The mechanism is aligned, but direct RCT evidence in chronic fatigue syndrome is limited. Discuss with your physician.
Can SS-31 be used in menopause?
Yes. Estrogen withdrawal affects mitochondrial function directly — and many midlife fatigue and exercise-intolerance complaints have a mitochondrial component. SS-31's mechanism is well-aligned.
SS-31 vs MOTS-c?
Both are mitochondrial peptides but mechanistically different. SS-31 stabilizes the inner membrane. MOTS-c signals from mitochondria to nucleus to regulate metabolism. They're often considered complementary, not alternatives.
Sources
- Birk AV et al. The mitochondrial-targeted compound SS-31 re-energizes ischemic mitochondria by interacting with cardiolipin. JASN (2013). — pubmed.ncbi.nlm.nih.gov/23687355
- Reid Thompson W et al. A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate elamipretide in Barth syndrome. Genetics in Medicine (2020). — pubmed.ncbi.nlm.nih.gov/32661345
- Butler J et al. Effects of elamipretide on left ventricular function in patients with heart failure with reduced ejection fraction: the PROGRESS-HF phase 2 trial. JACC: Heart Failure (2020). — pubmed.ncbi.nlm.nih.gov/32466834
- Szeto HH. First-in-class cardiolipin-protective compound as a therapeutic agent to restore mitochondrial bioenergetics. British Journal of Pharmacology (2014). — pubmed.ncbi.nlm.nih.gov/24438608
Considering SS-31 (Elamipretide)?
A Kindr Health physician reviews every longevity intake — peptides are prescribed only when medically indicated based on your history and labs. There is no charge for the initial review.
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Medically reviewed by Dr. Ana Lisa Carr, MD, MBA
Board-Certified Family Medicine Physician · Lead Provider / Medical Reviewer
NPI 1689841744 · Last reviewed: May 10, 2026
Last reviewed May 10, 2026. Compounded medications are prepared by FDA-registered 503A pharmacies and are not FDA-approved drug products. Prescriptions require a clinical evaluation; a Kindr Health physician determines eligibility. Not for use in pregnancy. This page provides educational information and is not medical advice.