RESEARCH PROFILE
SS-31
Elamipretide • Mitochondrial-Targeting Tetrapeptide
SS-31, also known as elamipretide, is a synthetic four-amino-acid peptide designed to target the inner mitochondrial membrane. Research has focused on cardiolipin interactions, mitochondrial membrane structure, cellular energy production, oxidative stress, and mitochondrial dysfunction.
An elamipretide drug product is FDA approved under accelerated approval for a specific rare-disease indication, while research into other mitochondrial, cardiac, muscular, and age-related applications remains investigational.
FDA APPROVED FOR BARTH SYNDROME IN A SPECIFIC DRUG PRODUCT • OTHER USES INVESTIGATIONAL
SS-31 AT A GLANCE
Generic / Research Name
Elamipretide / SS-31
Other Research Names
MTP-131 • Bendavia
Compound Type
Synthetic mitochondria-targeting tetrapeptide
Primary Target
Inner mitochondrial membrane / cardiolipin
Primary Research Focus
Mitochondrial structure • ATP-related bioenergetics • Oxidative stress • Cellular energetics
Human Evidence
Multiple clinical trials across several disease states
FDA Status
Elamipretide is FDA approved under accelerated approval as FORZINITY for Barth syndrome in qualifying patients
IMPORTANT DISTINCTION
SS-31 is not simply an experimental “longevity peptide.”
The compound has been investigated in more than 150 peer-reviewed publications, according to the Project profile, and has undergone human clinical research in several disease states.
Most importantly, an elamipretide drug product now has a narrow FDA-approved indication.
FORZINITY is approved for Barth syndrome in adult and pediatric patients weighing at least 30 kg.
That approval does not establish SS-31 as an approved treatment for:
Healthy aging
Athletic performance
Fatigue
Weight loss
General mitochondrial enhancement
Heart failure
Primary mitochondrial myopathy
Dry age-related macular degeneration
Those uses remain investigational or unsupported.
WHAT IS SS-31?
SS-31 is a synthetic four-amino-acid peptide developed to selectively interact with mitochondrial membranes.
It is commonly known in research literature as:
SS-31
Elamipretide
MTP-131
Bendavia
Its best-characterized target is cardiolipin, a phospholipid found predominantly within the inner mitochondrial membrane.
Cardiolipin helps organize mitochondrial membrane architecture and supports proteins involved in cellular energy production.
SS-31 research centers on whether binding to cardiolipin can help preserve mitochondrial structure and function under cellular stress.
WHY MITOCHONDRIA MATTER
Mitochondria are responsible for much of the ATP production used to power cellular processes.
Mitochondrial dysfunction can affect tissues with high energy requirements, including:
Skeletal muscle
Cardiac muscle
Nervous tissue
Retinal tissue
This has led researchers to investigate elamipretide across several diseases characterized by mitochondrial dysfunction.
FROM RESEARCH COMPOUND TO APPROVED DRUG
Unlike many peptides in the Croix research library, elamipretide progressed through extensive clinical development and eventually received FDA accelerated approval for a specific indication.
That makes SS-31 scientifically and regulatorily different from compounds supported almost entirely by preclinical research.
MECHANISM OF ACTION
SS-31 is designed to concentrate within the inner mitochondrial membrane and interact with cardiolipin.
CARDIOLIPIN INTERACTION
Cardiolipin is a specialized phospholipid that helps maintain mitochondrial membrane structure.
It also interacts with proteins involved in the mitochondrial electron transport system.
SS-31 binds to cardiolipin through electrostatic and hydrophobic interactions.
INNER MITOCHONDRIAL MEMBRANE
By interacting with cardiolipin, SS-31 is proposed to help stabilize the structural environment surrounding proteins involved in mitochondrial energy production.
This differs from compounds that attempt to increase mitochondrial number or broadly stimulate metabolism.
SS-31 is primarily a structural and functional mitochondrial-targeting peptide.
ATP-RELATED BIOENERGETICS
The mitochondrial electron transport system generates the electrochemical gradient used to produce ATP.
Research into SS-31 has examined whether stabilization of mitochondrial membrane architecture can improve energetic efficiency in dysfunctional mitochondria.
OXIDATIVE STRESS
Preclinical studies have also examined effects involving:
Reactive oxygen species
Oxidative stress
Mitochondrial membrane integrity
Cellular injury
MITOCHONDRIAL CRISTAE
The folds of the inner mitochondrial membrane are known as cristae.
Cristae architecture is important for efficient energy production.
The Project source describes research suggesting SS-31 may help preserve or restore cristae organization under certain disease conditions.
IMPORTANT MECHANISM LIMITATION
SS-31 does not simply “create more mitochondria.”
Its primary research rationale involves mitochondrial membrane structure and cardiolipin interactions.
Mechanistic evidence involving mitochondrial stabilization should not be interpreted as proof that SS-31 improves energy, athletic performance, cognition, or longevity in healthy people.
WHAT THE RESEARCH SHOWS
SS-31 has a substantially larger human clinical research base than many compounds in the Croix research library.
However, results vary considerably by indication.
BARTH SYNDROME
Barth syndrome is a rare genetic disorder involving abnormal cardiolipin remodeling and mitochondrial dysfunction.
The Project source identifies the TAZPOWER trial as the pivotal Phase 2/3 study supporting development of elamipretide in Barth syndrome.
The randomized crossover portion did not show statistically significant differences versus placebo on either co-primary endpoint.
However, longer-term open-label extension data showed improvements from baseline in measures including:
Six-minute walk distance
Muscle strength
These data contributed to FDA accelerated approval.
FDA ACCELERATED APPROVAL
In September 2025, FDA approved FORZINITY (elamipretide) under accelerated approval for Barth syndrome in adult and pediatric patients weighing at least 30 kg.
The Project profile notes that continued approval may depend on confirmation of clinical benefit through additional study.
HEART FAILURE
Multiple Phase 1 and Phase 2 studies have investigated elamipretide in heart failure, including patients with preserved ejection fraction.
The Project profile characterizes results as mixed or largely negative.
As of the Project source date, there is no FDA-approved heart-failure indication for elamipretide.
PRIMARY MITOCHONDRIAL MYOPATHY
Elamipretide has also been investigated in primary mitochondrial myopathy.
The Project source identifies the MMPOWER and MMPOWER-2 Phase 2 studies.
Research continued into this indication, but it was not FDA approved as of the Project profile date.
DRY AGE-RELATED MACULAR DEGENERATION
Elamipretide has been studied in dry age-related macular degeneration.
The Project source identifies the ReCLAIM and ReCLAIM-2 programs.
These studies provide additional human clinical evidence but do not establish an FDA-approved indication.
PRECLINICAL EVIDENCE
The Project profile also describes extensive laboratory and animal research involving:
Cardiolipin binding
Cristae stabilization
ATP-related bioenergetics
Reactive oxygen species
Ischemia-reperfusion injury
Cardiac dysfunction
Age-related muscle dysfunction
Acute kidney injury
HEALTHY-ADULT & ANTI-AGING EVIDENCE
This distinction is particularly important for the Croix website:
The Project source identifies no published human randomized controlled trial establishing SS-31 as an anti-aging or athletic-performance intervention in healthy adults.
Disease-specific clinical evidence should not be generalized to healthy individuals.
IMPORTANT EVIDENCE LIMITATION
SS-31 has meaningful human clinical evidence.
But that evidence is indication specific.
Barth syndrome data do not establish that SS-31:
Extends lifespan
Slows normal aging
Improves athletic performance
Increases energy in healthy adults
Improves cognition
Causes fat loss
Acts as a general mitochondrial “upgrade”
SAFETY & RESEARCH CONSIDERATIONS
SS-31 has more human safety information than many investigational peptides because elamipretide has undergone multiple clinical trials and now has an FDA-approved formulation.
Safety information nevertheless depends heavily on the specific product, population, dose, and indication.
INJECTION-SITE REACTIONS
The Project source identifies injection-site reactions among the most commonly reported effects in clinical research.
These include:
Redness
Swelling
Itching
Pain
Local skin reactions
HYPERSENSITIVITY
The FDA-approved FORZINITY label includes hypersensitivity-related precautions.
The Project source notes that hypersensitivity has been observed and can require discontinuation and appropriate medical evaluation.
BENZYL ALCOHOL
The Project profile identifies benzyl alcohol as an excipient-related consideration for FORZINITY.
This is product-specific and should not automatically be generalized to unrelated SS-31 formulations.
RENAL FUNCTION
The FDA-approved product includes dose considerations for severe renal impairment.
The Project profile specifically distinguishes FDA-labeled renal adjustments from research-community dosing discussions.
DRUG INTERACTIONS
Your Project source states that no significant pharmacokinetic drug interactions have been identified in the FDA label.
However, this does not establish the absence of interactions for unapproved research formulations or populations that have not been adequately studied.
LONG-TERM SAFETY
Long-term safety outside studied and approved contexts remains less certain.
RESEARCH-GRADE PRODUCT QUALITY
A research-grade SS-31 vial is not equivalent to FORZINITY.
Potential differences can include:
Manufacturing standards
Concentration
Excipients
Sterility assurance
Stability
Packaging
Quality control
FDA approval of FORZINITY should therefore never be used to imply that an unrelated research-grade SS-31 product is FDA approved or clinically equivalent.
REGULATORY CONTEXT
ELAMIPRETIDE HAS AN FDA-APPROVED DRUG PRODUCT
This is the most important regulatory distinction for SS-31.
FORZINITY (elamipretide HCl) received FDA accelerated approval in September 2025.
The Project source identifies the approved indication as:
Treatment of Barth syndrome in adult and pediatric patients weighing at least 30 kg.
ACCELERATED APPROVAL
Accelerated approval allows FDA to approve certain drugs based on an endpoint considered reasonably likely to predict clinical benefit.
Continued approval can be contingent upon confirmatory evidence.
Therefore:
FDA accelerated approval is genuine FDA approval.
But it remains tied to the specific product, indication, patient population, labeling, and regulatory conditions.
OTHER USES REMAIN INVESTIGATIONAL
The Project source identifies continued or previous research involving:
Primary mitochondrial myopathy
Heart failure
Dry age-related macular degeneration
Other mitochondrial disorders
These uses should not be represented as FDA approved unless their regulatory status changes.
RESEARCH-GRADE SS-31
Research-grade SS-31 products sold by research suppliers are not FORZINITY and should not be represented as FDA-approved drug products.
IMPORTANT REGULATORY DISTINCTION
FDA approval of FORZINITY ≠ FDA approval of every SS-31 product
Approval for Barth syndrome ≠ approval for anti-aging
Approval for Barth syndrome ≠ approval for athletic performance
Clinical investigation ≠ approved indication
Research-grade SS-31 ≠ FDA-approved FORZINITY
ANALYTICAL DOCUMENTATION
Croix maintains available third party analytical documentation only for specific samples and lots that can be matched to corresponding laboratory reports.
LOT SPECIFIC ANALYTICAL DOCUMENTATION
Analytical documentation is displayed only when Croix has a corresponding laboratory report that can be matched to the specific product and lot.
No matching SS-31 COA is currently displayed.
IMPORTANT COA LIMITATION
When analytical documentation becomes available, results should apply only to the specific sample identified in the corresponding laboratory report.
A Certificate of Analysis for one sample does not establish the composition, purity, sterility, safety, efficacy, or characteristics of another sample, lot, batch, or product.
Croix requires the product, strength, lot or batch, sample ID, laboratory, and report date to be matched before analytical documentation is represented as supporting a product.
A passing COA does not establish FDA approval, clinical efficacy, medical suitability, or the characteristics of unrelated lots.
SELECTED RESEARCH & REFERENCES
U.S. Food and Drug Administration
FORZINITY (elamipretide) — Highlights of Prescribing Information.
Primary regulatory source for the FDA-approved elamipretide product and Barth syndrome indication.
U.S. Food and Drug Administration
Approval Package for FORZINITY (elamipretide HCl).
FDA regulatory review materials relating to accelerated approval.
Stealth BioTherapeutics
FDA Accelerated Approval of FORZINITY (elamipretide HCl), the First Therapy for Barth Syndrome.
Regulatory and development context.
Thompson WR, et al.
Long-term efficacy and safety of elamipretide in patients with Barth syndrome.
Human clinical research involving the TAZPOWER development program and long-term follow-up.
Thompson WR, et al.
Natural-history comparison research examining elamipretide efficacy in patients with Barth syndrome.
Mitchell W, et al.
The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action.
Journal of Biological Chemistry.
Mechanistic research involving mitochondrial membranes and cardiolipin-related biology.
Chavez JD, et al.
Research examining mitochondrial protein interaction landscapes associated with SS-31.
Szeto HH.
Research and reviews examining SS-31/elamipretide, cardiolipin, mitochondrial energetics, and therapeutic potential.
Barth Syndrome Foundation
Information regarding FDA approval of the first medication for Barth syndrome.
EVIDENCE NOTE
SS-31 differs substantially from many research peptides because elamipretide has undergone extensive human clinical investigation and now exists as an FDA-approved prescription drug product for a narrowly defined indication.
That evidence should not be generalized to unrelated SS-31 products or unapproved uses.
RESEARCH & EDUCATIONAL INFORMATION
This profile is provided for research and educational reference. It does not constitute individualized medical advice or establish that SS-31 is safe or effective for uses outside appropriately studied and approved contexts.
SS-31, also known as elamipretide, is a mitochondria-targeting tetrapeptide studied across several mitochondrial and disease-related research programs.
An elamipretide drug product, FORZINITY, received FDA accelerated approval for the treatment of Barth syndrome in adult and pediatric patients weighing at least 30 kg.
That approval applies to the specific FDA-approved drug product and indication. It should not be interpreted as FDA approval of unrelated research-grade SS-31 products or uses involving healthy aging, athletic performance, general energy enhancement, or other investigational applications.
Evidence and regulatory status can differ by formulation, indication, population, and intended use.
Analytical documentation presented by Croix applies only to the specific samples and lots identified in corresponding laboratory reports.