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SS-31 (Elamipretide)

SS-31, also known as Elamipretide, is a synthetic tetrapeptide (D-Arginine-Dimethyltyrosine-Lysine-Phenylalanine-NH2) specifically designed to target mitochondrial dysfunction through selective binding to cardiolipin, a unique phospholipid found exclusively in the inner mitochondrial membrane. Originally developed as a mitochondria-penetrating peptide, SS-31 represents a novel therapeutic approach addressing fundamental cellular energetic dysfunction underlying numerous age-related diseases and pathological conditions.

This peptide has gained considerable attention in mitochondrial medicine due to its demonstrated ability to stabilize cardiolipin, optimize electron transport chain organization, and enhance cellular energy production in preclinical and clinical studies. SS-31 exhibits selective mitochondrial accumulation and maintains bioactivity through its unique cationic structure, making it distinctive among therapeutic peptides targeting cellular energetics.

Chemical structure of Elamipretide, showing a sequence of carbon, nitrogen, oxygen, and hydrogen atoms with bonds connecting them.

Overview

SS-31 demonstrates excellent water solubility and selective mitochondrial uptake due to its cationic properties. The peptide's unique structure enables penetration of mitochondrial membranes and selective accumulation within mitochondria based on concentration gradients and tissue mitochondrial density. It is eliminated primarily through renal excretion with minimal hepatic metabolism.

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Chemical structure & Properties

  • Molecular Formula: C32H49N9O5
  • Molecular Weight: ~639.8 Da
  • Sequence: D-Arg-Dmt-Lys-Phe-NH2
  • Half-life: 1-2 hours (plasma elimination)
  • Stability: Stable peptide structure with enhanced membrane penetration properties

Mechanism of Action

SS-31 exerts its therapeutic effects through highly specific mitochondrial targeting and cardiolipin stabilization:

Selective Mitochondrial Targeting and Accumulation

SS-31's unique structure enables selective mitochondrial localization through:

  • Cationic properties facilitating mitochondrial membrane penetration and accumulation
  • Selective binding to the inner mitochondrial membrane based on electrical gradient
  • Tissue-specific uptake proportional to mitochondrial density and metabolic demand
  • Concentration gradients favoring mitochondrial accumulation over cytoplasmic distribution

Cardiolipin Stabilization and Protection

The peptide's primary mechanism involves direct cardiolipin interaction:

  • High-affinity binding to cardiolipin molecules preventing peroxidation and degradation
  • Stabilization of cardiolipin structure maintaining optimal mitochondrial membrane integrity
  • Prevention of cardiolipin loss during oxidative stress and pathological conditions
  • Maintenance of cardiolipin-protein interactions essential for respiratory complex function

Electron Transport Chain Optimization

Through cardiolipin stabilization, SS-31 enhances mitochondrial respiratory efficiency:

  • Improved organization and stability of respiratory complexes I, III, and IV
  • Enhanced electron transport chain supercomplex formation and electron transfer efficiency
  • Reduced electron leakage and subsequent reactive oxygen species production
  • Optimized ATP synthesis through improved respiratory complex organization

Cytochrome C Oxidase Enhancement and Complex IV Function

SS-31 specifically targets and optimizes cytochrome c oxidase activity:

  • Direct interaction with Complex IV enhancing enzymatic activity and stability
  • Improved oxygen utilization efficiency reducing cellular oxygen requirements
  • Enhanced cytochrome c oxidase assembly and maintenance of proper function
  • Reduced oxidative stress generation through improved respiratory complex efficiency

Areas Investigated in

the Research Literature

Cardiovascular Protection and Cardiac Function

Cardiac Mitochondrial Dysfunction: Clinical studies demonstrate SS-31's efficacy in:

  • Significant enhancement in cardiac function in Barth syndrome and heart failure models
  • Improved mitochondrial morphology and enhanced ATP production in cardiomyocytes
  • Decreased apoptotic markers and enhanced cardiomyocyte survival under stress conditions
  • Preservation of cardiac tissue integrity during ischemic and oxidative stress conditions

Mechanism: Direct cardiolipin stabilization in cardiac mitochondria, improved respiratory complex organization, and enhanced cellular energy production supporting cardiac contractile function.

Renal Protection and Function Enhancement

Kidney Disease Treatment: Research indicates significant benefits in:

  • Effective protection against oxidative stress-induced renal mitochondrial damage
  • Significant reductions in serum creatinine and blood urea nitrogen levels
  • Reduced kidney tissue inflammation, fibrosis, and histopathological damage
  • Enhanced renal ATP production and improved cellular energy status

Mechanism: Mitochondrial protection in renal tubular cells, reduced oxidative stress generation, and improved cellular energy production supporting renal function and recovery.

Neurological Protection and Cognitive Enhancement

Neuroprotective Applications: Preclinical evidence supports potential benefits in:

  • Enhanced neuronal mitochondrial function and energy production
  • Protection against neurodegenerative processes and oxidative neuronal damage
  • Improved cognitive function through optimized brain cellular energetics
  • Enhanced neuroprotection during stroke and ischemic brain injury

Mechanism: Neuronal mitochondrial optimization, reduced oxidative stress in brain tissue, and enhanced cellular energy production supporting neuronal survival and function.

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Current Clinical Evidence

Published Human Studies

Renal Protection Study (Zhu et al., 2022):

  • Study Population: Animal models of kidney disease with clinical translation potential
  • Objective: Evaluate SS-31's renal protective effects and mitochondrial targeting
  • Results: Significant reductions in renal injury markers and improved mitochondrial function
  • Duration: Comprehensive evaluation with mechanistic validation of therapeutic effects

Mitochondrial Dysfunction Study (Du et al., 2024):

  • Study Design: Comprehensive analysis of SS-31's mitochondrial effects
  • Population: Various cellular and animal models of mitochondrial dysfunction
  • Results: Significant improvements in ATP production and reduced oxidative stress markers
  • Follow-up: Detailed characterization of mitochondrial dynamics and bioenergetic enhancement

Cardiac Function Trial (Russo et al., 2022):

  • Study Population: Tafazzin knockdown mice (Barth syndrome model)
  • Intervention: SS-31 treatment for cardiac mitochondrial dysfunction
  • Results: Improved cardiac function, enhanced ATP production, reduced apoptosis
  • Limitations: Preclinical study requiring human clinical validation

MMPOWER-3 Phase 3 Trial (Karaa et al., 2023):

  • Study Design: Randomized, double-blind, placebo-controlled Phase 3 trial
  • Population: 218 participants with genetically confirmed primary mitochondrial myopathy
  • Intervention: Elamipretide (SS-31) 40 mg/day subcutaneously for 24 weeks
  • Results: Did not meet either primary endpoint: 6-minute walk distance or PMMSA total fatigue score
  • Limitations: Results apply to the studied primary mitochondrial myopathy population and should not be generalized to the approved Barth syndrome indication.

Preclinical Research Foundation

Current clinical evidence shows promise but has some considerations:

  • Predominantly preclinical evidence base with limited human clinical trial data
  • Need for large-scale randomized controlled trials in human populations
  • Variable dosing protocols and administration routes across different studies
  • Limited long-term safety data in human clinical applications

Safety Profile and Considerations

Preclinical Safety Data

Non clinical studies evaluated elamipretide across multiple species and models:

  • No major systemic safety liabilities were identified in nonclinical studies.
  • Safety pharmacology studies did not identify significant neurological, respiratory, or cardiovascular liabilities.
  • Repeat-dose studies in rats and dogs found no significant systemic toxicities at exposures above the clinical exposure range.
  • Injection-site reactions were observed in nonclinical studies, consistent with the known route of administration.

Reported Side Effects

Human clinical and FDA label data report:

  • Injection-site reactions are the most common adverse reactions.
  • Reported reactions include redness, pain, itching, induration, bruising, and other local skin reactions.
  • Serious hypersensitivity reactions have also been reported.
  • Full safety information is in the FDA-approved prescribing information for Forzinity.

Potential Concerns

Theoretical Considerations:

  • Limited human clinical experience requiring careful monitoring during initial use
  • Potential interactions with medications affecting mitochondrial function
  • Individual variability in mitochondrial targeting and therapeutic response
  • Unknown effects in patients with severe mitochondrial genetic disorders

Mitochondrial Enhancement Considerations:

  • Theoretical concerns about enhanced cellular energy in malignant conditions
  • Need for careful evaluation in patients with active cancer
  • Monitoring requirements for patients with complex mitochondrial diseases

Contraindications

FORZINITY should not be used in patients with:

  • Serious hypersensitivity to elamipretide or any of the excipients.

Regulatory Status and Legal Considerations

Regulatory information current as of 28 August 2026. This is a summary, not legal or medical advice, and status can change.

FDA Status

  • Classification: FDA-approved for Barth syndrome only; investigational for all other uses
  • Approval Status: FDA accelerated approval for Barth syndrome only as Forzinity on September 19, 2025; not approved for other uses.
  • Clinical Trials: Multiple ongoing studies for various indications
  • Regulatory Position: Investigational new drug (IND) status for clinical research

Research Applications

  • Academic Studies: Extensive use in mitochondrial research protocols
  • Clinical Trials: Available through approved research protocols
  • Orphan Drug Status: Designated for certain rare mitochondrial diseases

Legal Availability

  • Commercial Status: Available by prescription as Forzinity for Barth syndrome only; not commercially available for any other indication
  • Research Access: Available through clinical trial participation
  • Quality Control: Manufacturing under clinical trial standards
  • Clinical Use: Limited to approved research and clinical trial settings
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Conclusion

What the evidence supports

SS-31 (elamipretide) is a mitochondria-targeting peptide that stabilizes cardiolipin and has been studied in human trials across several mitochondrial and age-related conditions, with mixed results outside its approved use. It received FDA accelerated approval for Barth syndrome only (as Forzinity, September 2025); for all other uses it remains investigational, without established efficacy or dosing. This page summarizes the published research and nothing further.

SS-31 SCIENTIFIC

DATA SUMMARY

MOLECULAR CHARACTERISTICS
RESEARCH APPLICATIONS SUMMARY
CLINICAL EVIDENCE SUMMARY
SAFETY PROFILE
REGULATORY STATUS
Parameter
Molecular Weight
Amino Acid Length
Half-Life
Bioavailability
Detection Window
Value
approx. 639.8 Da
4 residues (tetrapeptide)
~1-2 hours (plasma)
Selective mitochondrial accumulation
Up to 4 hours (tissue)
Application
Cardiac / Barth Syndrome
Renal Protection
Neuroprotection
Mitochondrial Bioenergetics
Reported outcome (model)
Improved cardiac function, enhanced ATP production
Reduced creatinine/BUN, mitochondrial protection
Enhanced neuronal energy, neuroprotection
Cardiolipin stabilization, optimized ETC
Study Type
Renal Protection Study
Cardiac Function Trial
Mitochondrial Study
Population
Animal kidney disease models
Barth syndrome mouse model
Various dysfunction models
Results
Reduced injury markers, improved function
Enhanced cardiac function, reduced apoptosis
Improved ATP, reduced oxidative stress
Limitations
Preclinical data only
Animal study, human validation needed
Predominantly preclinical evidence
Parameter
Acute Toxicity
Organ Toxicity
Adverse Events
Long-term Safety
Finding
Well tolerated in trials up to 40 mg; injection-site reactions most common
No significant systemic toxicity in nonclinical studies; serious hypersensitivity reactions reported in humans
Minimal: rare injection site reactions, mild fatigue
Well-tolerated in extended protocols
Authority
FDA
WADA Status
Orphan Drug
Classification
Approved (Barth syndrome); investigational for all other uses
Research compound
Designated status
Status
FDA accelerated approval (Forzinity) for Barth syndrome, 19 Sep 2025; investigational for all other uses
Not specifically prohibited
For rare mitochondrial diseases

About this library

This library is published for education. It summarizes published research on compounds studied in this field. Many have no approved medical use, and several cannot lawfully be compounded in the United States. The presence of a page here does not mean Paragon offers that compound. Nothing on these pages is an offer to treat.

This page is general education about a compound studied in this field. Nothing here is medical advice, a recommendation, or an offer to prescribe or supply. A page appearing in this library does not mean Paragon Sports Medicine offers that compound.

Disclaimer: This information is provided for educational purposes only and does not constitute medical advice. Elamipretide is FDA-approved as Forzinity for Barth syndrome only; all other uses described on this page are investigational. Patients interested in SS-31 should consult with qualified healthcare providers about clinical trial opportunities.

Statements on this page have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Many peptides described here are not FDA approved for the uses discussed, and some cannot lawfully be compounded in the United States. Nothing on this page is medical advice or a recommendation for any individual. Whether any therapy is appropriate depends on your history, your laboratory results, and a clinical evaluation. Individual results vary. This page is published for education. Use of this site does not create a physician-patient relationship.

References

01
Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential. Int J Mol Sci. 2025.
02
Elamipretide (SS-31) improves mitochondrial dysfunction, synaptic and memory impairment induced by lipopolysaccharide in mice. J Neuroinflammation. 2019.
03
Elamipretide (SS-31) treatment attenuates age-associated post-translational modifications of heart proteins. Geroscience. 2021.
04
Elamipretide (SS-31) Attenuates Idiopathic Pulmonary Fibrosis by Inhibiting the Nrf2-Dependent NLRP3 Inflammasome in Macrophages. Antioxidants (Basel). 2023.
05
SS-31@Fer-1 Alleviates ferroptosis in hypoxia/reoxygenation cardiomyocytes via mitochondrial targeting. Biomed Pharmacother. 2025.