SS-31 (Elamipretide)
A first-in-class cardiolipin-targeting tetrapeptide that concentrates in the inner mitochondrial membrane to stabilize cristae, protect the electron transport chain, and reduce reactive oxygen species at the source.
SS-31 (elamipretide) is a synthetic aromatic-cationic tetrapeptide developed in the labs of Hazel Szeto and Peter Schiller that selectively binds cardiolipin on the inner mitochondrial membrane, preserving cristae architecture, electron transport chain supercomplex organization, and ATP output while lowering mitochondrial ROS generation. It preferentially accumulates in dysfunctional mitochondria, which underlies its consistently mild safety profile across trials. After more than 15 years of development by Stealth BioTherapeutics, elamipretide (branded Forzinity) reached FDA approval for the rare mitochondrial disorder Barth syndrome, though its broader Phase 3 programs in heart failure and primary mitochondrial myopathy have produced mixed results.
Class
Synthetic aromatic-cationic tetrapeptide (cardiolipin-binding, mitochondria-targeted)
Half-life
~2-4 hours in plasma; functional mitochondrial effects persist 12-16 hours due to cardiolipin binding and tissue retention
Routes
Subcutaneous injection, Intravenous (clinical trial settings)
Category
Immune & Mitochondrial
Researched benefits
What it's studied for
Mitochondrial membrane stabilization
By binding cardiolipin in the inner mitochondrial membrane, SS-31 preserves cristae ultrastructure and the cardiolipin-cytochrome c interaction, preventing peroxidation-induced cytochrome c release. This maintains the supramolecular organization of respiratory chain supercomplexes (respirasomes) that keep electron flow efficient.
Reduced ROS at the source
Rather than scavenging reactive oxygen species after they form like conventional antioxidants, SS-31 lowers electron leak from Complexes I and III by keeping the electron transport chain organized, cutting superoxide production at its origin. This upstream mechanism may explain efficacy in contexts where antioxidant supplementation has failed.
Preserved ATP production and cardioprotection
Stabilizing the electron transport chain sustains oxygen consumption and ATP synthesis; in ischemia-reperfusion models SS-31 pretreatment reduces infarct size, and a randomized trial showed reduced left ventricular volumes after cardiac ischemia/reperfusion injury.
Protection against mitochondrial permeability transition
Cardiolipin stabilization raises the threshold for opening of the mitochondrial permeability transition pore (mPTP), a high-conductance channel central to ischemia-reperfusion injury and many forms of cell death, contributing to cellular protection under stress.
Age-related mitochondrial support
In aged tissues with declining function, preclinical SS-31 treatment restores respiratory capacity toward younger values, making it a mechanistically attractive intervention for sarcopenia, cardiac decline, and metabolic dysfunction — though large human anti-aging trials have not been conducted.
Neuroprotection and tissue recovery
Preclinical work in spinal cord injury shows SS-31 preserves mitochondrial bioenergetics, reduces early apoptotic cell death and chronic inflammation, and supports axonal and synaptic remodeling for improved functional recovery.
Mechanism
How it works
SS-31's selectivity is driven by peptide structure alone. Its alternating aromatic-cationic sequence (D-arginine, 2',6'-dimethyltyrosine, lysine, phenylalanine-amide) gives it both membrane permeability and a net +3 charge that draws it electrostatically to the strongly negative inner mitochondrial membrane, where cardiolipin — a phospholipid carrying four negatively charged phosphate groups — concentrates. The peptide accumulates on the inner membrane at concentrations 1,000- to 5,000-fold higher than in cytosol, without requiring transporters, receptors, or delivery technology, and without the membrane-potential dissipation associated with triphenylphosphonium-conjugated approaches like MitoQ.
Cardiolipin organizes the inner membrane into cristae and interacts with cytochrome c, Complex III, ATP synthase, and multiple carrier proteins. Under oxidative stress cardiolipin peroxidizes, releasing cytochrome c and triggering both respiratory dysfunction and caspase-mediated apoptosis. SS-31 binds cardiolipin at a specific stoichiometry, stabilizes the cardiolipin-cytochrome c interaction, and prevents peroxidation-induced release, preserving cristae morphology and keeping electron transport chain supercomplexes (Complexes I+III+IV) intact so electrons flow efficiently with minimal leak.
Because roughly 1-5 percent of electrons leak from the chain to form superoxide, disrupted cardiolipin creates a vicious cycle of more ROS and more cardiolipin damage. By preserving structure and supercomplex integrity, SS-31 reduces electron leak and lowers baseline ROS — a fundamentally different mechanism from direct scavengers like NAC, CoQ10, or vitamin E. Crucially, it preferentially accumulates in dysfunctional mitochondria and largely ignores healthy ones, which explains its clean safety profile.
SS-31 does not increase mitochondrial biogenesis, supply NAD+ precursors, provide electron transport chain cofactors, or directly clear damaged mitochondria — it complements rather than replaces those interventions. Secondary effects reported include AMPK activation, reduced NF-kB-driven inflammation, improved endothelial function, and raised threshold for mPTP opening. It is cleared by aminopeptidase-mediated hydrolysis with renal excretion of inactive fragments, and shows no significant CYP450 interactions.
Dosing protocols
Dosing & administration
Dosing reflects protocols reported in research and community literature for educational purposes. It is not medical advice or a recommendation. Most peptides here are not approved for human use.
Reconstitution
Supplied as lyophilized powder in 10 mg, 20 mg, or 50 mg vials. Reconstitute with bacteriostatic water (0.9% benzyl alcohol): adding 1 mL to a 20 mg vial gives 20 mg/mL, while 2 mL gives 10 mg/mL. Inject the water slowly down the vial wall to minimize foaming; swirl gently, never shake. The solution should be clear, colorless, and particle-free. Store reconstituted vials refrigerated at 2-8C, use within 28-30 days, and do not freeze. Subcutaneous injection volume should stay within 1-2 mL per site, so a 40 mg dose at 10 mg/mL (4 mL) must be split into two injections or reconstituted more concentrated.
Beginner
- Dose
- 5 mg for week 1, then 10 mg for week 2, titrating to 20-40 mg
- Frequency
- Once daily
- Timing
- Morning, after breakfast
- Duration
- 12-week minimum assessment period
- Route
- Subcutaneous
Gradual introduction to assess individual tolerance. Establish baseline labs (hs-CRP, metabolic panel, CBC, LFTs) and any goal-specific markers; log injection-site reactions, energy, and sleep daily.
Intermediate
- Dose
- 40 mg (or 20 mg for cost-conscious protocols)
- Frequency
- Once daily, or 5-6 days weekly with 1-2 rest days
- Timing
- Morning, consistent within 2-3 hours daily
- Duration
- Continuous with reassessment every 3-6 months
- Route
- Subcutaneous
Standard clinical-trial dose used in MMPOWER-3, TAZPOWER, and ReCLAIM-2. Rotate strictly across 6-8 injection sites. Typically layered onto a full mitochondrial stack with quarterly lab monitoring.
Advanced
- Dose
- 40-80 mg (sometimes split 20 mg twice daily)
- Frequency
- Once or twice daily
- Timing
- Morning, or divided AM/PM for twice-daily dosing
- Duration
- Long-term under specialist oversight with biomarker-driven titration
- Route
- Subcutaneous
For users with specific clinical indications under physician supervision only. Evidence for doses above 40 mg and for twice-daily dosing is limited; may be combined with complementary mitochondrial peptides such as MOTS-c or humanin.
- The 40 mg daily subcutaneous dose is the reference standard across pivotal elamipretide trials; the approved Forzinity dose for Barth syndrome is 40 mg daily in patients weighing at least 30 kg.
- Daily dosing aligns with the pharmacokinetic profile — short plasma half-life but longer tissue residence due to cardiolipin binding supports once-daily maintenance.
- Rotate through at least 4-6 subcutaneous sites (abdomen, thigh, upper arm), avoiding scars, moles, and inflamed skin, and bring solution to room temperature before injecting to reduce discomfort.
- Dose-response in humans is not well characterized; the incremental benefit of 40 mg over 20 mg is uncertain, so lower doses or reduced frequency are reasonable cost-management strategies.
- Expect subtle rather than dramatic effects in off-label use; biomarker changes may emerge over 2-3 months and users without perceived benefit after 3-6 months may reasonably discontinue.
- Missed doses can be taken later the same day or skipped; do not double-dose.
Evidence
Research & clinical studies (9)
Elamipretide (MTP-131) Alters the Landscape of Myocardial Lipids and Reduces Oxidative Stress Following Cardiac Ischemia/Reperfusion Injury
In a double-blind randomized trial of 36 patients, a single elamipretide infusion was safe and the high dose significantly reduced left ventricular end-diastolic volume (-18 mL, p=0.009) and end-systolic volume, supporting its mitochondria-targeting cardioprotective mechanism.
PMID 29217757Intrarenal Infusion of Elamipretide (MTP-131) During Stenting in Patients With Atherosclerotic Renovascular Disease
In a Phase 2a randomized trial of 14 patients undergoing renal artery stenting, intrarenal elamipretide attenuated post-procedure renal hypoxia, increased stenotic-kidney blood flow, and improved eGFR versus placebo.
PMID 28916603Randomized controlled trial of elamipretide in Barth syndrome (TAZPOWER)
The TAZPOWER trial and its open-label extension showed improved 6-minute walk distance and functional capacity in Barth syndrome, forming the basis of the elamipretide regulatory submission for that indication.
PMID 33769413Randomized dose-comparison study of elamipretide in primary mitochondrial myopathy (MMPOWER-3)
The Phase 3 MMPOWER-3 trial in primary mitochondrial myopathy failed its primary endpoint despite favorable trends, illustrating the mixed clinical translation of the mechanism outside Barth syndrome.
PMID 32269115Elamipretide (SS-31) promotes recovery by preserving mitochondrial bioenergetics and neural remodeling after spinal cord injury
In mice, SS-31 improved functional recovery and reduced tissue damage after spinal cord injury by preserving mitochondrial energy production, decreasing oxidative stress, and supporting axonal and synaptic remodeling.
PMID 42082001Protective Effect of Mitochondria-Targeted Polydopamine Nanoparticles in Alleviating Hepatic Ischemia-Reperfusion Injury
SS-31-modified nanoparticles delivered therapeutics to mitochondria and protected liver tissue from ischemia-reperfusion injury by restoring mitochondrial function, reducing ROS, and suppressing inflammation.
PMID 42057685Peroxiredoxin III safeguards cardiac function against doxorubicin by regulating mitochondrial quality control via H2O2 detoxification
Mitochondrial antioxidant enzyme PrxIII protected cardiac cells from doxorubicin damage, with moderate mitochondrial H2O2 promoting protective mitophagy and fusion while excess triggered cell death, within a mitochondrial quality-control framework relevant to SS-31's mechanism.
PMID 42013545Mitochondrial dysfunction-driven inflammation and beta-cell apoptosis in type 2 diabetes mellitus: mechanistic insights and therapeutic implications
This review identified mitochondria-targeted antioxidants like SS-31 as a promising approach to restore mitochondrial quality control and address underlying disease mechanisms in type 2 diabetes beyond glucose management.
PMID 42033524Effect of mitochondrial dysfunction on scar formation after spinal cord injury
Mitochondrial dysfunction was shown to drive glial and fibrotic scar formation after spinal cord injury, with mitochondria-targeted therapies including SS-31 highlighted as promising for reducing scarring and supporting neural regeneration.
PMID 42147841Combinations
Stacking & blends
MOTS-c + SS-31: Mitochondrial Optimization
Broad mitochondrial optimization for anti-aging, metabolic dysfunction, and exercise performance
MOTS-c enhances glucose metabolism and AMPK signaling while SS-31 stabilizes cardiolipin in the inner mitochondrial membrane to protect against oxidative damage — two distinct but complementary mechanisms.
Comprehensive Mitochondrial Longevity Stack
Multi-angle mitochondrial support layering peptides with non-overlapping signaling
SS-31 covers cardiolipin/membrane integrity while MOTS-c and humanin act through distinct mitochondrial-derived peptide signaling pathways for insulin sensitivity and neuronal protection; peptides are layered one at a time to establish tolerability.
SS-31 + Mitochondrial Cofactor Foundation
Address mitochondrial function from membrane integrity to NAD+ supply, cofactors, and quality control
SS-31 stabilizes cardiolipin, while non-peptide co-interventions cover complementary axes it does not touch — NMN/NR for NAD+, ubiquinol (CoQ10) for ETC cofactor support, creatine for cellular energetics, omega-3 for membrane composition, and urolithin A for mitophagy.
Safety
Side effects & considerations
Commonly reported effects
Contraindications & cautions
- Pregnancy and breastfeeding
- Active severe or unstable cardiac disease without cardiology oversight
- Active cancer without oncology approval
- Known severe peptide allergy
- Active severe infection or sepsis
- Severe renal impairment (eGFR <30) or severe hepatic impairment without specialist input
- Pediatric use outside specific clinical contexts
- Perioperative period for major elective surgery
SS-31 has been consistently well-tolerated across multiple Phase 2 and Phase 3 trials, with adverse events dominated by mild, self-limited injection-site reactions and low discontinuation rates; its targeted mitochondrial mechanism appears to avoid the broad off-target effects of non-selective antioxidants. Long-term safety data beyond trial durations is limited, and research-grade product from unverified suppliers carries additional risks of impurity, contamination, mislabeling, or under-dosing that are separate from the intrinsic safety of the molecule.
FAQ
SS-31 (Elamipretide) — common questions
What is SS-31?
SS-31 is elamipretide (also MTP-131 and Bendavia), a cell-penetrating tetrapeptide with the sequence D-Arg-dimethylTyr-Lys-Phe-amide that binds cardiolipin on the inner mitochondrial membrane. It was developed at Cornell University Medical College by Hazel Szeto and Peter Schiller, originally during opioid receptor research.
What does SS-31 do?
It stabilizes cardiolipin and preserves mitochondrial cristae structure, electron transport chain supercomplexes, and ATP output under metabolic stress, while reducing reactive oxygen species at their source. Because it preferentially accumulates in dysfunctional mitochondria, it protects energy production in cardiomyocytes, neurons, and renal cells with a clean safety profile.
Is SS-31 FDA approved?
It is approved only for the rare mitochondrial disorder Barth syndrome (branded Forzinity), the first regulatory approval for a cardiolipin-targeting therapy — sources describe the timeline variously between 2024 and September 2025. It is not approved for heart failure, mitochondrial myopathy, macular degeneration, or general anti-aging, where it remains investigational or off-label.
How is SS-31 dosed?
The reference clinical dose is 40 mg subcutaneous once daily, used across MMPOWER-3, TAZPOWER, and ReCLAIM-2. Off-label users often start at 5-10 mg daily and titrate to 20-40 mg, with morning administration preferred; advanced protocols under physician supervision may use 60-80 mg or split twice-daily dosing.
What are the side effects?
The most common effects are mild injection-site reactions, occasional gastrointestinal symptoms, and mild headache or dizziness, generally resolving within 1-2 weeks. Serious systemic adverse events have been uncommon across the trial program, though long-term data beyond a couple of years is limited.
Does SS-31 work for heart failure and cardiomyopathy?
The record is mixed. Preclinical data and early trials showed biomarker improvements, and a randomized trial reduced left ventricular volumes after cardiac ischemia/reperfusion, but larger pivotal trials in HFpEF and hypertrophic cardiomyopathy generally did not meet primary endpoints. Barth syndrome, which involves cardiomyopathy, is the clearest positive cardiac indication.
Is research-grade SS-31 the same as pharmaceutical elamipretide?
They share the same chemical sequence but differ substantially in manufacturing, purity verification, and oversight. Pharmaceutical elamipretide is made under cGMP and batch-tested, whereas research-grade 'SS-31' from peptide vendors is a separate non-GMP supply chain with wider purity variance — buyers should prioritize suppliers offering independent third-party HPLC certificates of analysis.
Can SS-31 be stacked with other mitochondrial supplements?
Yes. Its cardiolipin-stabilizing mechanism does not duplicate other interventions, so it complements NAD+ precursors (NMN/NR), CoQ10, creatine, omega-3, and mitophagy inducers like urolithin A, as well as mitochondrial peptides MOTS-c and humanin. Users typically layer one new intervention at a time to establish tolerability.
