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SS-31

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SS-31 (Elamipretide) is a mitochondria-targeted tetrapeptide (D-Arg-dimethylTyr-Lys-Phe-NH2) studied for its ability to stabilize cardiolipin and support mitochondrial function. It is of significant interest in research involving oxidative stress, mitochondrial bioenergetics, and cellular apoptosis regulation. SS-31 selectively localizes to the inner mitochondrial membrane, where it has been shown in vitro to modulate reactive oxygen species (ROS), improve ATP production, and preserve mitochondrial integrity.

Weight .06 kg
Size

10 mg
Shelf Life

36 months
Storage

Lyophilized: freeze at ?20 °C (?4 °F).
Reconstituted: efrigerate at 2–8 °C (35.6–46.4 °F); use within 4 weeks.
Molecular Formula

C??H??N?O?
PubChem CID

11764719
http://www.pubchem.ncbi.nlm.nih.gov/compound/11764719
Disclaimer

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. For research purposes only. Not for human consumption.

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Research & Clinical Profile

FDA Approved — FORZINITY (September 2025)

SS-31

Also known as: Elamipretide · Bendavia · MTP-131 · FORZINITY Category: Mitochondria-Targeting · Anti-Aging Clinical Status: FDA Approved (Barth syndrome) · Phase 3 (other indications) FDA Status: Approved · FORZINITY (Sept 2025)

A mitochondria-targeting tetrapeptide that selectively concentrates in the inner mitochondrial membrane. FDA-approved for Barth syndrome as FORZINITY, with ongoing Phase 3 trials for heart failure, macular degeneration, and primary mitochondrial myopathy.

🧬

Peptide Type

Synthetic Tetrapeptide

📊

Amino Acid Length

4 residues (D-Arg-Dmt-Lys-Phe-NH₂)

🔬

Primary Research Focus

Mitochondrial dysfunction & cardiolipin stabilization

🧪

Current Development Stage

FDA Approved (Barth syndrome) · Phase 3 ongoing

What Is SS-31?

🧠 Simple Explanation

SS-31 is a tiny chain of just 4 building blocks (amino acids) designed to go straight to the power plants inside your cells — called mitochondria. Once there, it latches onto a special fat molecule called cardiolipin, which helps the mitochondria produce energy more efficiently and with less harmful waste.

It was approved by the FDA in September 2025 under the brand name FORZINITY for treating Barth syndrome, a rare genetic condition affecting the heart. Researchers are also studying it for age-related heart failure, eye disease, and muscle weakness.

🔬 Advanced Context

SS-31 (sequence: D-Arg-2′,6′-dimethyltyrosine-Lys-Phe-NH₂) is a cell-permeable, mitochondria-targeted tetrapeptide developed by Stealth BioTherapeutics. Its alternating aromatic-cationic motif enables it to concentrate over 1,000-fold within mitochondria, independent of membrane potential — a key differentiator from other mitochondrial-targeting molecules.

The compound binds selectively to cardiolipin, a phospholipid unique to the inner mitochondrial membrane that is essential for organizing the electron transport chain complexes. By stabilizing cardiolipin and preventing its peroxidation during oxidative stress, SS-31 optimizes electron transfer efficiency, reduces reactive oxygen species (ROS) generation at the source, and enhances ATP production.

SS-31 received FDA accelerated approval in September 2025 as FORZINITY for Barth syndrome. Multiple Phase 2 and Phase 3 trials have been completed or are ongoing for indications including heart failure with preserved ejection fraction (HFpEF), dry age-related macular degeneration (AMD), and primary mitochondrial myopathy (PMM). The compound has received FDA Fast Track designation for both Barth syndrome and PMM.

Molecular Profile

Physicochemical characteristics and key identifiers

Molecular Weight

639.8 g/mol

Structure Type

Synthetic Tetrapeptide

Sequence

D-Arg-Dmt-Lys-Phe-NH₂

Target

Inner Mitochondrial Membrane (Cardiolipin)

Mitochondrial Uptake

1,000-fold concentration

Brand Name

FORZINITY (Barth syndrome)

Developer

Stealth BioTherapeutics

Storage

Per manufacturer labeling

How It Works

Mechanism of action based on preclinical and clinical evidence

STEP 01 →

Mitochondrial Uptake

SS-31's alternating aromatic-cationic structure enables rapid, energy-independent cellular uptake. The peptide concentrates over 1,000-fold within mitochondria within minutes of exposure.

💡 Simple Translation

The peptide quickly enters cells and heads straight to the mitochondria — the tiny power plants inside every cell — accumulating there in very high concentrations.

STEP 02 →

Cardiolipin Binding

SS-31 selectively binds to cardiolipin, a phospholipid unique to the inner mitochondrial membrane. This interaction stabilizes the organization of electron transport chain (ETC) supercomplexes and prevents cardiolipin peroxidation.

💡 Simple Translation

Once inside the mitochondria, it attaches to a special fat molecule called cardiolipin that acts like scaffolding for the energy-production machinery, keeping everything in proper working order.

STEP 03 →

Electron Transport Optimization

By stabilizing cardiolipin-ETC interactions, SS-31 improves electron transfer efficiency between Complex III and Complex IV, reducing electron leak and subsequent superoxide generation at the source.

💡 Simple Translation

With the scaffolding stabilized, electrons flow more smoothly through the energy chain — like fixing a kink in a garden hose — so less harmful waste (free radicals) is produced.

STEP 04

Cellular Outcome

The net result is increased ATP synthesis, reduced mitochondrial ROS production, restored mitochondrial membrane potential, and improved cellular bioenergetics — effects observed across cardiac, skeletal muscle, retinal, and renal tissue models.

💡 Simple Translation

The cell produces more energy with less damage. In studies, this translated to stronger heart function, better muscle performance, and protection of delicate tissues like the eyes and kidneys.

Clinical Development Status

Current position in the regulatory pipeline

✓
Preclinical
✓
Phase 1
✓
Phase 2
✓
Phase 3
4
Phase 4
✓
FDA Approved

FDA accelerated approval granted September 2025 for Barth syndrome (FORZINITY). Phase 3 trials ongoing for HFpEF, dry AMD, and primary mitochondrial myopathy. Fast Track designation for Barth syndrome and PMM.

Research Timeline

Key milestones in SS-31 development

2004

Initial Discovery

SS-31 (Szeto-Schiller peptide 31) developed as part of a series of cell-permeable, mitochondria-targeted peptides

2006

Cardiolipin Binding Identified

Key mechanism discovered: selective binding to cardiolipin on the inner mitochondrial membrane

2011

Renal Protection Studies

Demonstrated protection against ischemia-reperfusion kidney injury by preserving mitochondrial structure

2014

ETC Supercomplex Stabilization

Published findings on how cardiolipin binding optimizes electron transport chain organization

2018

Age-Related Muscle Studies

Reversed age-related mitochondrial dysfunction and improved exercise capacity in aged mouse models

2020

EMBRACE-HF & ReCLAIM Trials

Phase 2 results published for heart failure and dry age-related macular degeneration

2021

MMPOWER Phase 3 Results

Phase 3 trial data published for primary mitochondrial myopathy

2025 ✓ FDA APPROVED

FDA Approval — FORZINITY

Accelerated approval granted for Barth syndrome, the first FDA-approved mitochondria-targeted peptide therapy

What Does the Research Show?

Summary of clinical and preclinical findings

📊Key Findings
  • FDA approved for Barth syndrome (September 2025) as FORZINITY
  • Concentrates 1,000-fold in mitochondria within minutes of administration
  • Improved 6-minute walk distance in heart failure trials
  • Reduced mitochondrial ROS production and restored membrane potential across tissue models
📈Research Milestones
  • Developed by Stealth BioTherapeutics (Szeto-Schiller peptide series)
  • FDA Fast Track designation for Barth syndrome and primary mitochondrial myopathy
  • Multiple Phase 2 and Phase 3 clinical trials completed
  • Accelerated approval for Barth syndrome based on cardiolipin remodeling biomarker
🔬Observed Biological Effects
  • Stabilizes cardiolipin on the inner mitochondrial membrane
  • Optimizes electron transport chain efficiency (Complex III–IV coupling)
  • Enhances ATP production while reducing superoxide generation
  • Protects against ischemia-reperfusion injury in cardiac and renal models
🧪Safety Profile in Studies
  • Injection site reactions reported in ~80% of clinical trial participants
  • Headache, dizziness, and nausea reported as common side effects
  • May trigger histamine release — caution advised with MCAS or histamine sensitivity
  • No serious adverse events reported in completed clinical trials

Published Findings

Clinical trials and preclinical studies with linked sources

StudyModelKey FindingYearSource
HFpEF cardiac function trial (EMBRACE-HF)Human (Phase 2)Reduced left ventricular end-diastolic volume and improved cardiac function in heart failure patients2021JACC Heart Failure ↗
Primary mitochondrial myopathy (MMPOWER)Human (Phase 3)Evaluated 6-minute walk test distance improvements in patients with genetically confirmed PMM2021Neurology ↗
Barth syndrome cardiolipin remodelingHuman (Pivotal)Demonstrated improvement in cardiolipin remodeling biomarker, leading to accelerated FDA approval as FORZINITY2025FDA Approval Basis ↗
Mitochondrial ROS and cardiolipin interactionIn Vitro / AnimalSS-31 binds cardiolipin, prevents peroxidation, optimizes ETC supercomplex organization and reduces superoxide production2014Biochim Biophys Acta ↗
Age-related skeletal muscle dysfunctionAnimal (Mouse)Reversed age-related mitochondrial dysfunction, improved exercise capacity and muscle energetics in aged mice2018Aging Cell ↗
Renal ischemia-reperfusion protectionAnimal (Rat)Protected against acute kidney injury by preserving mitochondrial structure and reducing oxidative damage2011J Am Soc Nephrol ↗
Dry age-related macular degeneration (ReCLAIM)Human (Phase 2)Evaluated effects on retinal function and drusen volume in patients with non-exudative AMD2020Ophthalmology ↗
Human (Pivotal)2025

Barth syndrome — FDA approval basis

Improvement in cardiolipin remodeling biomarker leading to FORZINITY accelerated approval

View Source ↗
Human (Phase 2)2021

HFpEF cardiac function (EMBRACE-HF)

Reduced left ventricular end-diastolic volume and improved cardiac function

View Source ↗
Human (Phase 3)2021

Primary mitochondrial myopathy (MMPOWER)

Evaluated 6-minute walk test improvements in PMM patients

View Source ↗
Animal (Mouse)2018

Age-related skeletal muscle dysfunction

Reversed mitochondrial dysfunction, improved exercise capacity in aged mice

View Source ↗
In Vitro / Animal2014

Mitochondrial ROS and cardiolipin interaction

Cardiolipin binding prevents peroxidation, optimizes ETC organization

View Source ↗

⚠️ SS-31 has more extensive human clinical data than most investigational peptides. FDA-approved for Barth syndrome; other indications remain under clinical investigation.

Research Applications

Approved and investigational applications in clinical and preclinical research

  • FDA-approved for Barth syndrome — restoring cardiolipin remodeling in cardiomyocytes
  • Investigated in heart failure with preserved ejection fraction (HFpEF) — Phase 2/3 trials
  • Studied in dry age-related macular degeneration (AMD) — retinal mitochondrial protection
  • Evaluated in primary mitochondrial myopathy (PMM) — improving exercise capacity
  • Explored in age-related skeletal muscle dysfunction — reversing mitochondrial decline
  • Assessed in renal ischemia-reperfusion injury — protecting kidney mitochondria
  • Investigated in cardiac ischemia-reperfusion — reducing infarct size in preclinical models
  • Studied in neurodegenerative disease models — mitochondrial neuroprotection

Delivery Methods Studied in Research

Administration routes evaluated in clinical trials and preclinical studies

Subcutaneous Injection

FDA-approved route for FORZINITY; 40 mg daily for patients weighing ≥30 kg

Intravenous Infusion

Used in clinical trials (EMBRACE-HF, ReCLAIM); hospital-administered dosing

Topical Ophthalmic

Investigated in dry AMD studies for direct retinal delivery

Dosing Information

The FDA-approved dose for Barth syndrome (FORZINITY) is 40 mg subcutaneously once daily for patients weighing at least 30 kg. Clinical trials for other indications have evaluated IV infusion doses of 40 mg, with protocols varying by condition and study design.

⚠️ Dosing for non-approved indications is investigational. The approved dose applies specifically to Barth syndrome. Other indications are still undergoing clinical evaluation.

Formulation & Delivery

How SS-31 is prepared and administered

💉

Subcutaneous Injection

The FDA-approved formulation (FORZINITY) is delivered as a subcutaneous injection. This route provides consistent absorption and allows for self-administration by patients at home.

🏥

IV Infusion (Clinical Trials)

In hospital-based clinical trials (EMBRACE-HF, ReCLAIM), SS-31 was administered via intravenous infusion, allowing precise dose control and rapid systemic distribution.

🧊

Stability & Formulation

SS-31's small size (4 amino acids) and modified structure (including D-Arg and dimethyltyrosine) confer enhanced stability compared to natural peptides, supporting practical pharmaceutical formulation.

🔬

Cell-Permeable Design

The alternating aromatic-cationic motif allows SS-31 to freely cross cell membranes without requiring active transport, enabling rapid mitochondrial accumulation independent of membrane potential.

✅

Pharmaceutical-Grade Manufacturing

As an FDA-approved drug, FORZINITY is manufactured under cGMP standards with rigorous quality controls, batch testing, and regulatory oversight.

Transparency & Regulatory Status

Quality assurance and regulatory standards for SS-31

🏭

cGMP Manufacturing

As an FDA-approved drug, FORZINITY is manufactured under current Good Manufacturing Practice regulations, ensuring consistent quality, purity, and potency across every batch.

📊

Clinical Trial Data

Multiple Phase 2 and Phase 3 trials have generated extensive safety and efficacy data, publicly available through ClinicalTrials.gov and peer-reviewed publications.

🔬

Biomarker Validation

FDA approval for Barth syndrome was based on a validated biomarker for cardiolipin remodeling, providing objective measurement of the compound's biological activity.

📋

FDA Regulatory Oversight

Accelerated approval status means ongoing post-marketing requirements, including confirmatory trials and continued safety monitoring under FDA oversight.

📁

Published Safety Database

Comprehensive adverse event reporting from clinical trials is publicly available, with injection site reactions, headache, and dizziness as the most commonly reported effects.

🛡️

Fast Track Designation

FDA Fast Track status for Barth syndrome and primary mitochondrial myopathy reflects the agency's recognition of serious conditions with unmet medical need.

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Frequently Asked Questions

Common questions about SS-31 / Elamipretide

SS-31 (also known as Elamipretide, Bendavia, or MTP-131) is a synthetic tetrapeptide consisting of 4 amino acids (D-Arg-Dmt-Lys-Phe-NH₂). It was developed as part of the Szeto-Schiller peptide series by Stealth BioTherapeutics. Unlike naturally-derived peptides, SS-31 was rationally designed with an alternating aromatic-cationic motif that enables it to penetrate cells and concentrate specifically in mitochondria.
Yes. SS-31 received FDA accelerated approval in September 2025 under the brand name FORZINITY for the treatment of Barth syndrome, a rare genetic condition affecting mitochondrial function in the heart. This makes it the first FDA-approved mitochondria-targeted peptide therapy. It is also in Phase 3 clinical trials for other indications including heart failure, dry age-related macular degeneration, and primary mitochondrial myopathy.
SS-31's alternating aromatic-cationic amino acid structure allows it to freely cross cell membranes and concentrate over 1,000-fold within mitochondria — independently of mitochondrial membrane potential. Once inside, it selectively binds to cardiolipin, a phospholipid unique to the inner mitochondrial membrane that is essential for organizing the electron transport chain. This stabilizes energy production and reduces harmful reactive oxygen species at the source.
Beyond its approved indication for Barth syndrome, SS-31 is under active clinical investigation for heart failure with preserved ejection fraction (HFpEF), dry age-related macular degeneration (AMD), and primary mitochondrial myopathy (PMM). Preclinical studies have also explored its potential in renal ischemia-reperfusion injury, neurodegenerative diseases, and age-related skeletal muscle decline.
In clinical trials, the most common side effect is injection site reactions, reported in approximately 80% of participants. Other reported effects include headache, dizziness, and nausea. SS-31 may trigger histamine release, so caution is advised for individuals with mast cell activation syndrome (MCAS) or histamine sensitivity. No serious adverse events have been reported in completed clinical trials.
The FDA-approved formulation (FORZINITY) is administered as a subcutaneous injection of 40 mg once daily for patients weighing at least 30 kg. In clinical trials for other indications, it has also been administered via intravenous infusion in hospital settings. Morning administration is generally recommended to align with daytime energy production.
SS-31 was developed by Stealth BioTherapeutics, a clinical-stage biopharmaceutical company focused on mitochondrial medicine. The company has conducted multiple Phase 2 and Phase 3 clinical trials across several indications and received FDA Fast Track designation for both Barth syndrome and primary mitochondrial myopathy.
SS-31 is unique in its mechanism — it directly targets cardiolipin on the inner mitochondrial membrane, optimizing electron transport chain efficiency at the source. This differs from antioxidant approaches (like CoQ10 or MitoQ) that primarily scavenge free radicals after they're produced, and from NAD+ precursors (like NMN/NR) that boost a metabolic cofactor. SS-31 is the only mitochondria-targeted peptide with FDA approval.
Barth syndrome is a rare, X-linked genetic disorder caused by mutations in the TAFAZZIN gene, which is responsible for cardiolipin remodeling. This leads to abnormal mitochondrial function, primarily affecting the heart (cardiomyopathy), skeletal muscles (weakness and fatigue), immune system (neutropenia), and growth. SS-31's ability to stabilize cardiolipin directly addresses the underlying molecular defect.

Sources & References

Effects of Elamipretide on Left Ventricular Function in Patients With Heart Failure With Reduced Ejection Fraction: The EMBRACE-HF Randomized Clinical Trial ↗

Butler J et al. · JACC Heart Failure (2021) · DOI: 10.1016/j.jchf.2020.07.006

Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy (MMPOWER) ↗

Karaa A et al. · Neurology (2021) · DOI: 10.1212/WNL.0000000000012391

Elamipretide in patients with Barth syndrome: a randomized, double-blind, placebo-controlled clinical trial ↗

Thompson R et al. · Clinical and Translational Science (2023) · DOI: 10.1111/cts.13601

Targeting mitochondrial cardiolipin and the cytochrome c/cardiolipin complex to promote electron transport and optimize mitochondrial ATP synthesis ↗

Birk AV et al. · Biochimica et Biophysica Acta — Bioenergetics (2014) · DOI: 10.1016/j.bbabio.2013.10.013

Mitochondrial-targeted peptide rapidly improves mitochondrial energetics and skeletal muscle performance in aged mice ↗

Siegel MP et al. · Aging Cell (2018) · DOI: 10.1111/acel.12776

Mitochondria-targeted peptide accelerates ATP recovery and reduces ischemic kidney injury ↗

Szeto HH et al. · Journal of the American Society of Nephrology (2011) · DOI: 10.1681/ASN.2010080808

ReCLAIM-2: A Phase 2 Study of Elamipretide in Dry Age-Related Macular Degeneration ↗

Stealth BioTherapeutics · Ophthalmology (2020)

⚠️ Important Notice

This page is for educational and informational purposes only. It is not intended to diagnose, treat, cure, or prevent any disease.

SS-31 (Elamipretide / FORZINITY) is FDA-approved only for Barth syndrome. All other indications discussed are investigational. Information is derived from peer-reviewed literature and clinical trial data. Nothing on this page constitutes medical advice or personal recommendations. Consult a healthcare provider for medical decisions.

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SS-31
10 mg
Original price was: $79.99.Current price is: $54.99.
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