Peptide profile · Mitochondrial

SS-31 (Elamipretide)

Name: SS-31 (Elamipretide) — Peptide Information
Creator: Michael Carroll

A mitochondria-targeting tetrapeptide that binds cardiolipin in the inner mitochondrial membrane. The FDA approved it in September 2025 as FORZINITY, to improve muscle strength in Barth syndrome [8][9]; phase 3 trials in primary mitochondrial myopathy and in dry age-related macular degeneration missed their primary endpoints [13][14].

Written by Michael Carroll — Owner, Director of Research · Reviewed by the Peptide Initiative Research Team

MitochondrialStrong human trialsFDA approved as FORZINITY for Barth syndrome (accelerated approval, 19 September 2025); every other use is investigational

Suggested dose

40 mg

Once dailyCycle: Continuous daily use — not cycledOnset: Not established outside Barth syndrome

Half-life

Not stated on the FDA label; peak plasma concentration 0.5-1 hour after subcutaneous injection, ~100% of dose recovered in urine by 48 hours

Bioavailability

~92% (subcutaneous)

Molecular weight

639.8 g/mol

Evidence level

Strong human trials

01 · Compound profile

Scientific & efficacy data

Molecular formula

C₃₂H₄₉N₉O₅

Primary benefits

Mitochondrial Protection

Binds cardiolipin in the inner mitochondrial membrane, stabilising cristae structure and respiratory chain supercomplexes [1][15]. Cross-linking mass spectrometry found its binding partners are all known cardiolipin-interacting proteins, including ATP synthase and complexes III and IV [2].

Cellular Energy

By stabilising cardiolipin and altering membrane electrostatics it improves electron transfer efficiency and ATP synthesis [1][15]. In patients this has not translated into a measured functional gain against placebo: the phase 3 trial in 218 adults with mitochondrial myopathy missed both primary endpoints [13].

Anti-Oxidant (Targeted)

Acts inside the mitochondrion rather than scavenging afterwards, reducing the electron leak that generates reactive oxygen species and preventing cardiolipin peroxidation [1][5]. The evidence for this is biochemical and preclinical, not a clinical endpoint.

Mol. weight639.8 g/mol

CAS number736992-21-5

PubChem11764719

Developed · 2004Dr. Hazel Szeto and Dr. Peter Schiller
Weill Cornell Medical College / University of Montreal

Amino acid sequence

D-Arg-dimethylTyr-Lys-Phe-NH2

02 · Dosing

How much do I take?

40 mg · once daily

Continuous — 24 weeks in the phase 3 myopathy trial, up to 168 weeks in the Barth syndrome extension40 mgOnce daily

Full SS-31 (Elamipretide) dosing protocol

Covers timing · dose-adjustment guidance.

SS-31 (Elamipretide)Once daily

How much peptide is in your bottle?

Look at the label on the vial. It’s the number next to mg — like "5 mg".

03 · Suitability

Is this right for me?

Best for mitochondrial health optimization & cellular energy enhancement

Best for

Mitochondrial Health Enthusiasts

If you're focused on optimizing cellular energy at the most fundamental level, SS-31 targets the actual machinery inside your mitochondria. It binds to cardiolipin—the special fat molecule that holds your electron transport chain together—keeping your cellular powerhouses running smoothly [1][2].

Aging Adults Concerned About Cellular Decline

Mitochondrial dysfunction is now recognized as a hallmark of aging [18]. Your cells' energy factories get less efficient over time, producing more harmful byproducts. SS-31 helps protect and restore mitochondrial function, addressing one of the root causes of age-related decline [1].

Heart Health Supporters

Your heart is one of the most energy-demanding organs, packed with mitochondria. Clinical trials have studied SS-31 in heart failure patients because cardiac cells are especially vulnerable to mitochondrial dysfunction [1]. Supporting heart mitochondria supports overall cardiovascular function.

Those Recovering from Oxidative Stress

Whether from intense exercise, illness, or environmental factors, oxidative stress damages your mitochondria from the inside out. SS-31 works as an antioxidant exactly where reactive oxygen species are produced—right at the inner mitochondrial membrane—neutralizing them before they cause harm [1].

Consider alternatives if

Mitochondrial support through supplementsCoQ10 (Ubiquinol), PQQ (Pyrroloquinoline quinone), NAD+ precursors (NMN, NR), Alpha-lipoic acid

Cellular energy and anti-agingEpithalon, MOTS-c, Humanin, NAD+ IV therapy

Heart and vascular supportBPC-157, Thymosin Beta-4, CoQ10, Omega-3 fatty acids

Do not use if

You have had a serious hypersensitivity reaction to elamipretide or any excipient — the label's only contraindication [8]The patient is a neonate — the formulation contains benzyl alcohol [8]You are pregnant or breastfeeding — there is no human data; the label's animal studies showed no developmental effects at 4 to 10 times the clinical exposure [8]Body weight is under 30 kg — outside the approved indication and untested [8]

Use with caution if

Your eGFR is below 30 mL/min and you are not on dialysis — the label halves the dose to 20 mg once daily [8]You are on dialysis — elamipretide has not been studied in renal failure on dialysis [8]You are 65 or over — no elamipretide trial enrolled that age group [8]You are taking anything else — the label reports interaction studies only for aspirin, clopidogrel and heparin, all negative, and carries no drug-interactions section [8]

Not sure?

Compare SS-31 (Elamipretide) with similar peptides to find the best fit for your goals.

SS-31 (Elamipretide) vs NAD+

04 · Administration

How do I use it?

Subcutaneous injection

Route

Subcutaneous injection (just under the skin)—the standard method used in clinical trials with approximately 92% bioavailability

Best sites

Abdominal area (about 2 inches away from the belly button)Front or outer thigh (middle section)Back of the upper arm

SS-31 (Elamipretide) dosing protocol SS-31 (Elamipretide) injection guide

Covers reconstitution · step-by-step technique · storage · a sample daily schedule.

05 · Safety

Is it safe?

1 common side effect · 1 serious

In the 24-week phase 3 trial in primary mitochondrial myopathy, adverse events were reported by 98.2% (107 of 109) of participants on elamipretide against 76.1% (83 of 109) on placebo, and injection-site reactions were the only adverse event above 10% in the treated group. Serious adverse events were 4.6% (5 of 109) against 2.8% (3 of 109) and none were judged treatment-related; discontinuation for an adverse event was 7.3% (8 of 109) against 1.8% (2 of 109). There were no deaths and no hospitalisations [13]. In the 12-patient Barth syndrome crossover trial behind the approval, every patient had an injection-site reaction on elamipretide — 12 of 12 (100%) against 8 of 12 (67%) on placebo — with erythema 100% against 25% and induration 67% against 17% [8]. The label carries two warnings: serious hypersensitivity reactions, and benzyl alcohol toxicity, for which the product is not approved in neonates. It also reports blood eosinophil counts rising during treatment, peaking around day 90 and returning to normal over 6 to 12 months [8].

Every safety figure above comes from company-run trials in diagnosed patients: 218 adults with primary mitochondrial myopathy over 24 weeks [13], 176 adults with dry age-related macular degeneration over 48 weeks [14], and 12 patients with Barth syndrome followed into a 168-week open-label extension [6][10]. No elamipretide trial enrolled anyone aged 65 or over, none enrolled healthy people, and there is no human pregnancy data — the label's reassurance there is from animal studies at 4 to 10 times the clinical exposure [8]. Nothing has been published on elamipretide for ageing, athletic performance or general mitochondrial support, so the safety record above does not extend to those uses.

Common side effects · experienced by some users

Injection site reactionsThe only adverse event reported by more than 10% of treated participants in the phase 3 myopathy trial [13], and universal in the Barth syndrome trial — 12 of 12 (100%) on elamipretide against 8 of 12 (67%) on placebo, with erythema 100% against 25%, pain 75% against 42%, induration and itching 67% against 17%, and bruising and hives 25% against none [8]. Swelling, bleeding and injection-site nodules were also recorded [13].Management: Rotate daily between the four quadrants of the abdomen and the outer thighs, as the label directs and as trial participants were instructed to do [8][13]. Injection-site reactions were the main reason for discontinuation in the phase 3 trial, at 7.3% against 1.8% on placebo [13].

Less common

Raised blood eosinophil count

These typically resolve with continued use or dose adjustment.

Stop and seek help if

×Any sign of a hypersensitivity reaction — skin or respiratory. The label directs discontinuation for a severe reaction and serious hypersensitivity is its only contraindication [8]
×An injection-site reaction that spreads, worsens, or shows signs of infection. These drove discontinuation in 7.3% of treated participants in phase 3 against 1.8% on placebo [13]
×Your eGFR falling below 30 mL/min — the label halves the dose rather than stopping, but it needs a prescriber's decision [8]
×Your prescriber advises discontinuation

Elamipretide is FDA-approved only to improve muscle strength in Barth syndrome, in patients weighing at least 30 kg, and that approval is an accelerated one pending a confirmatory trial [8][9]. Every other use is investigational. It is a prescription injectable — decisions about starting, stopping or adjusting belong with a prescriber.

With other peptides

!Any other peptide — No human trial has tested elamipretide in combination with another peptide, so no pairing here is supported or ruled out. The SS-31 and NMN combination was studied in aged mice only [19].

With medications

✓Aspirin, clopidogrel, heparin — The only drug-interaction studies on the FDA label. None showed a significant interaction with elamipretide [8].
!Everything else — The label carries no drug-interactions section beyond those three. Elamipretide and its two inactive metabolites are cleared renally — about 100% of a dose is recovered in urine by 48 hours — and the label halves the dose below an eGFR of 30 mL/min, so anything that loads the kidneys is worth raising with a prescriber [8].

With supplements

✓Any supplement — No interaction study has been published. Nothing here is established either way [8].

06 · Effectiveness

How do I know it's working?

Strong human trials · first signs weeks 1-4

Evidence level

Strong human trials

(Phase 3 or FDA approved)

100/100

How it works

Think of your cells like tiny cities, and mitochondria are the power plants that keep everything running. Inside each power plant is a special membrane with folds called cristae—this is where your cells actually make energy (ATP). A fatty molecule called cardiolipin holds this whole structure together like molecular glue. As we age or face stress, cardiolipin gets damaged and the power plant structure falls apart, making less energy and more pollution (oxidative stress) [13]. SS-31 is like a repair crew that goes directly to the cardiolipin and stabilizes it [1]. When the structure stays intact, your power plants work better—more energy, less cellular pollution, healthier cells [1].

Elamipretide (SS-31) is a synthetic tetrapeptide (D-Arg-dimethylTyr-Lys-Phe-NH2) with unique cell-penetrating and mitochondria-targeting properties [1][3]. Its alternating cationic (Arg, Lys) and aromatic (dimethylTyr, Phe) residues enable rapid cellular uptake independent of mitochondrial membrane potential and selective accumulation (several thousand-fold) in the inner mitochondrial membrane (IMM) [3][15]. SS-31 selectively binds to cardiolipin (CL), an anionic phospholipid unique to the IMM that constitutes approximately 20% of IMM lipid content [1][16]. CL is essential for: (1) organizing respiratory chain supercomplexes, (2) maintaining cristae ultrastructure, and (3) proper function of cytochrome c oxidase and other electron transport chain components [2]. By stabilizing CL and modifying membrane electrostatics, SS-31 optimizes electron transfer efficiency, increases ATP synthesis, and reduces electron leak that generates reactive oxygen species (ROS) [1][3]. Additionally, SS-31 prevents CL peroxidation and translocation to the outer membrane—processes that would otherwise trigger cytochrome c release and apoptosis [5]. Cross-linking mass spectrometry has identified SS-31 binding partners including ATP synthase, complex III, complex IV, and enzymes in 2-oxoglutarate metabolism, all of which are established CL-interacting proteins [2]. This multi-target mechanism explains SS-31's broad therapeutic potential across conditions involving mitochondrial dysfunction [1].

What to expect

Weeks 1-4

What you might notice

•Injection-site reactions — the one effect trials consistently record, and near-universal in the Barth syndrome trial [8]
•Nothing measurable otherwise: the 4-week crossover in mitochondrial myopathy found no significant change in walking distance [11]

What's normal

•Redness, itching, pain or firmness at the injection site [8]
•No felt change — elamipretide has never been tested for subjective effect in healthy people

What's next

→Rotate the site daily between abdominal quadrants and outer thighs [8]
→The dose does not change: 40 mg once daily throughout [8]

Weeks 12-24

What you might notice

•This is where the controlled trials ended, and where they found nothing: both primary endpoints missed at 12 weeks in Barth syndrome [6] and at 24 weeks in the 218-patient phase 3 trial [13]
•Patient-reported fatigue improved against placebo in the smaller phase 2 crossover, though the walking endpoint did not [11]

What's normal

•Continuing injection-site reactions — they were the only adverse event above 10% in phase 3 [13]
•No change on a six-minute walk test compared with placebo [13]

What's next

→Blood eosinophils peak around day 90 on the label's account and normalise over 6 to 12 months [8]

Week 36 onward

What you might notice

•The reported gains in Barth syndrome all come from this window and all come without a control arm: +95.9 m on the six-minute walk test at week 36 [6], cumulatively +96.1 m by week 168 [10]
•Knee extensor strength rose by a median 34 to 68 newtons during the extension — the measure the FDA granted accelerated approval on [8]

What's normal

•Injection-site reactions continuing as the main adverse event out to 168 weeks [10]

What's next

→A confirmatory trial is a condition of the accelerated approval; the benefit is not yet verified [8][9]

Signs it's working · What the trials measured

✓Six-minute walk distance — the primary endpoint in MMPOWER-1, MMPOWER-2, MMPOWER-3 and TAZPOWER [6][11][12][13]
✓Knee extensor strength by hand-held dynamometry — the basis of the FDA approval [8]
✓Fatigue scores on the disease-specific symptom assessments [6][13]
✓Monolysocardiolipin to cardiolipin ratio, in Barth syndrome [10]

Signs it's working · What has never been measured

✓Day-to-day energy, alertness or sleep quality — no elamipretide trial recorded them
✓Exercise recovery or training response in healthy people — no trial has enrolled healthy people
✓Any outcome in anyone aged 65 or over [8]

Not seeing results? Common reasons

•The controlled trials did not find an effect. Both primary endpoints were missed in the 12-week Barth syndrome crossover [6] and in the 24-week phase 3 trial in 218 adults [13] — a compound working as advertised is not the baseline assumption here
•Elamipretide has only been shown to do anything in diagnosed mitochondrial disease. There is no published trial in healthy people, in ageing, or in athletic performance
•Inconsistent daily dosing — the label and every trial dose once a day, every day [8]
•The dose does not go up. 40 mg once daily is the ceiling in every human trial and on the label; there is no next step to try [8]
•Research-grade material with no certificate of analysis. The approved product is a prescription 80 mg/mL solution; anything else is unverified [8]

Key research

[1]“Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential”Tung C, Varzideh F, Farroni E, 2025Finding: This comprehensive review confirmed SS-31's unique ability to selectively bind cardiolipin in mitochondria, stabilizing cristae structure, reducing oxidative stress, and enhancing ATP production. Clinical trials like PROGRESS-HF, TAZPOWER, and MMPOWER-3 demonstrate significant therapeutic potential across multiple conditions involving mitochondrial dysfunction.View study

[2]“Mitochondrial protein interaction landscape of SS-31”Chavez JD, Tang X, Campbell MD, 2020Finding: Using advanced chemical cross-linking and mass spectrometry, researchers mapped exactly which proteins SS-31 interacts with inside mitochondria. All the interacting proteins are known cardiolipin binders involved in either ATP production or metabolic processes—confirming SS-31's highly targeted mechanism of action.View study

[3]“Structure-activity relationships of mitochondria-targeted tetrapeptide pharmacological compounds”Mitchell W, Tamucci JD, Ng EL, 2022Finding: This study analyzed how SS-31's specific amino acid sequence affects its activity. The research showed SS-31 modulates membrane electrostatics and can permeate cells to target mitochondria. All tested peptide variants were pharmacologically active in restoring mitochondrial membrane potential and promoting cell survival under stress.View study

[4]“SS-31: A promising therapeutic agent against bleomycin-induced pulmonary fibrosis in Mice”Gu Q, Wang Y, Zhang H, 2025Finding: At 5 mg/kg daily, SS-31 significantly reduced lung fibrosis in mice by protecting mitochondrial structure and function. The peptide reduced oxidative stress markers, inflammatory factors (TNF-alpha, IL-1beta, IL-6), and improved overall lung tissue health—demonstrating its potential beyond cardiac applications.View study

[5]“Mitochondrial Cardiolipin-Targeted Tetrapeptide, SS-31, Exerts Neuroprotective Effects Within In Vitro and In Vivo Models of Spinal Cord Injury”Ravenscraft B, Lee DH, Dai H, 2025Finding: SS-31 protected neurons from mitochondrial dysfunction and cell death in both laboratory and animal models of spinal cord injury. The peptide reduced cardiolipin loss, prevented neurite degeneration, and improved behavioral recovery—highlighting its neuroprotective potential.View study

[6]“A phase 2/3 randomized clinical trial followed by an open-label extension to evaluate the effectiveness of elamipretide in Barth syndrome”Reid Thompson W, Hornby B, Manuel R, et al., 2021Finding: Twelve patients with Barth syndrome took 40 mg/day elamipretide and placebo for 12 weeks each in random order, separated by a 4-week washout. Neither primary endpoint was met in that blinded phase. Ten patients continued on 40 mg/day in an open-label extension, and at week 36 there were improvements in 6-minute walk distance (+95.9 m, p=0.024) and on the Barth Syndrome Symptom Assessment (-2.1 points, p=0.031), along with knee extensor strength, patient global impression and some cardiac parameters. The open-label result has no control arm.View study

[7]“Novel Mitochondria-Targeting Peptide in Heart Failure Treatment: A Randomized, Placebo-Controlled Trial of Elamipretide”Daubert MA, Yow E, Dunn G, et al., 2017Finding: Thirty-two patients with heart failure and an ejection fraction of 35% or less received a single 4-hour intravenous infusion of elamipretide at 0.005, 0.05 or 0.25 mg/kg/hour (8 per cohort) or placebo (12). This is an infusion RATE used inside a hospital, not a dose anyone measures out. There were no serious adverse events, and blood pressure and heart rate stayed stable in every cohort. Compared with placebo, the highest-rate cohort showed a 18 mL fall in left ventricular end-diastolic volume (p=0.009) and a 14 mL fall in end-systolic volume (p=0.005) at the end of the infusion. Elamipretide was undetectable in plasma 24 hours after the infusion started.View study

[8]“FORZINITY (elamipretide) injection, for subcutaneous use - FDA prescribing information”U.S. Food and Drug Administration, 2025Finding: FDA prescribing information for FORZINITY (elamipretide), granted accelerated approval in September 2025 to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg. The label lists injection site reactions as the most common adverse reactions and reports absolute bioavailability after subcutaneous injection of approximately 92%. Continued approval may depend on verification of clinical benefit in a confirmatory trial.View study

[9]“Elamipretide: The first cardiolipin-directed mitochondrial therapeutic for Barth syndrome approved under accelerated approval”Drug Discoveries & Therapeutics, 2025Finding: On 19 September 2025 the FDA granted accelerated approval to elamipretide for Barth syndrome — the first approved therapy directed at the mitochondrial cause of the disease. The paper notes that in the randomised, double-blind, placebo-controlled crossover trial elamipretide produced no significant improvement in the 6-minute walk test or fatigue scores, and that the sustained benefits were seen in the 168-week open-label extension. The most common adverse events were mild injection-site reactions. A confirmatory trial is a condition of the approval.View study

[10]“Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER”Hornby B, Reid Thompson W, Almuqbil M, et al., 2024Finding: Ten patients with Barth syndrome entered the open-label extension of TAZPOWER on 40 mg subcutaneous elamipretide daily and eight reached the week-168 visit. Injection-site reactions were the most common adverse event. Six-minute walk distance improved at every extension timepoint, cumulatively 96.1 m by week 168 (p=0.003), fatigue scores stayed below baseline throughout, and three-dimensional left ventricular stroke, end-diastolic and end-systolic volumes improved from baseline to week 168.View study

[11]“A randomized crossover trial of elamipretide in adults with primary mitochondrial myopathy (MMPOWER-2)”Karaa A, Haas R, Goldstein A, et al., 2020Finding: Thirty adults with genetically confirmed primary mitochondrial myopathy took 40 mg/day subcutaneous elamipretide for 4 weeks and placebo for 4 weeks in random order, separated by a 4-week washout. The primary endpoint was missed: 398.3 m walked on elamipretide against 378.5 m on placebo, a 19.8 m difference (95% CI -2.8 to 42.5, p=0.0833). Patient-reported fatigue and muscle complaints did improve against placebo (p=0.0006 and p=0.0018). Injection-site reactions were the most common adverse event at 80%, mostly mild; there were no serious adverse events and no deaths.View study

[12]“Randomized dose-escalation trial of elamipretide in adults with primary mitochondrial myopathy (MMPOWER-1)”Karaa A, Haas R, Goldstein A, et al., 2018Finding: Thirty-six adults with genetically confirmed primary mitochondrial myopathy received intravenous elamipretide at 0.01, 0.1 or 0.25 mg/kg/hour, or placebo, over 2 hours in a dose-escalating sequence for 5 days. Again these are infusion rates, not self-administered doses. The highest rate produced a mean 64.5 m improvement in 6-minute walk distance at day 5 against 20.4 m on placebo (p=0.053), with a dose-dependent trend across rates (p=0.014). No other efficacy or safety endpoint differed. This study set the exposure that the later 40 mg/day subcutaneous trials were built on.View study

[13]“Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial”Karaa A, Bertini E, Carelli V, 2023Finding: In this 24-week phase 3 trial, 218 adults with primary mitochondrial myopathy received 40 mg/day subcutaneous elamipretide or placebo. Elamipretide did not improve six-minute walk distance or total fatigue score compared with placebo. Most adverse events were mild or moderate, and injection site reactions were the only adverse events reported in more than 10% of treated participants.View study

[14]“ReCLAIM-2: A Randomized Phase II Clinical Trial Evaluating Elamipretide in Age-related Macular Degeneration, Geographic Atrophy Growth, Visual Function, and Ellipsoid Zone Preservation”Allingham MJ, Mettu PS, Cousins SW, et al., 2024Finding: One hundred and seventy-six patients aged 55 or over with dry age-related macular degeneration and non-central geographic atrophy took 40 mg subcutaneous elamipretide daily (117) or placebo (59) for 48 weeks. Neither primary endpoint was met. Adverse events were reported in 86% of the elamipretide group and 71% of the placebo group, the most common being injection-site reactions — itching, pain, bruising and redness. Pre-specified analyses showed less progression of ellipsoid zone loss on elamipretide, which is the endpoint the phase 3 programme adopted.View study

[15]“The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action”Mitchell W, Ng EA, Tamucci JD, 2020Finding: This biophysical study reports that SS-31 accumulates 1,000- to 5,000-fold at the inner mitochondrial membrane. Its binding to anionic lipids such as cardiolipin changes membrane surface electrostatics, which the authors identify as a key component of how the peptide works.View study

[16]“Cardiolipin, the Mitochondrial Signature Lipid: Implication in Cancer”Ahmadpour ST, Maheo K, Servais S, 2020Finding: This review states that cardiolipin is a mitochondria-specific phospholipid comprising about 20% of the inner mitochondrial membrane, and describes its role in organizing respiratory chain complexes and mitochondrial membrane structure.View study

[17]“Role of cardiolipin in skeletal muscle function and its therapeutic implications”Yoo Y, Yeon M, Yoon MS, 2025Finding: This review reports that cardiolipin accounts for roughly 18% of inner mitochondrial membrane mass, that cardiolipin levels are reduced in aged skeletal muscle alongside impaired respiratory capacity and structural degradation, and that cardiolipin depletion disrupts cristae organization, lowers electron transport chain efficiency and increases reactive oxygen species production.View study

[18]“Interactions between mitochondrial dysfunction and other hallmarks of aging: Paving a path toward interventions that promote healthy old age”Li Y, Berliocchi L, Li Z, 2023Finding: This review treats mitochondrial dysfunction as one of the established hallmarks of aging and examines how it interacts with the other hallmarks, describing it as one of the most important drivers of cellular aging.View study

[19]“SS-31 and NMN: Two paths to improve metabolism and function in aged hearts”Whitson JA, Bitto A, Zhang H, 2020Finding: In aged mice, SS-31 improved diastolic heart function while nicotinamide mononucleotide (NMN) improved systolic function at high workload. The combination produced both effects and raised steady-state NAD(H) levels more than either drug alone, leading the authors to conclude that combined treatment may be more effective for age-related cardiac dysfunction than either agent given alone.View study

[20]“Pharmacological targeting of mitochondrial function and reactive oxygen species production prevents colon 26 cancer-induced cardiorespiratory muscle weakness”Smuder AJ, Roberts BM, Wiggs MP, 2020Finding: In mice bearing colon-26 tumors, daily SS-31 preserved body weight and muscle weights, prevented atrophy of type I and type IIa muscle fibers, and prevented the loss of diaphragm and limb muscle function seen in untreated tumor-bearing mice, alongside reduced mitochondrial reactive oxygen species production.View study

07 · Clinical trials

Tested in people

33 registered studies, 2 still enrolling.

registered studies

recruiting now

phase 3 or 4

with published results

By phase

Phase 210

Phase 19

Phase 1/25

Phase 33

Phase 41

Phase 2/31

No phase4

A trial spanning two phases is counted in both, so these can sum above the total. Observational studies carry no phase.

What kind of research

Gave the drug32

Records only0

About 2,231 people took part in the studies that actually administered SS-31 (Elamipretide). Observational studies analyse the records of people already taking it — nobody was given anything for the study, so they are counted separately and cannot show cause and effect.

Most recent

NCT07531251Phase 4Recruiting48 enrolled
Clinical Trial in Patients With Barth Syndrome- 4TAZPower
Stealth BioTherapeutics Inc.
ISRCTN8470557548 enrolled
A Phase IIIb/IV, randomized, double-blind, parallel-group, placebo-controlled, trial to evaluate the efficacy and safety of daily subcutaneous injections of elamipretide in patients with genetically confirmed Barth syndrome
Stealth BioTherapeutics (United States)
NCT07275424Phase 2Recruiting30 enrolled
Study of Healthy Aging and Physical Function With Elamipretide
David Marcinek

See all 33 trials for SS-31 (Elamipretide)

Sources: ClinicalTrials.gov, the EU Clinical Trials Information System and ISRCTN, deduplicated so a study registered twice is counted once. A study is counted when SS-31 (Elamipretide) is named as an intervention; studies that only mention it in passing are not.

08 · Questions

Frequently asked

What makes SS-31 different from other mitochondrial supplements like CoQ10?+

CoQ10 is an electron carrier that participates in the electron transport chain, while SS-31 targets the structural foundation—cardiolipin—that holds the entire energy-producing machinery together [1][2]. Think of CoQ10 as providing fuel, while SS-31 repairs and maintains the engine itself. They work through completely different mechanisms and can actually complement each other.

Is SS-31 FDA approved?+

Yes, elamipretide (the pharmaceutical name for SS-31) received FDA approval in September 2025 for treating Barth syndrome, a rare genetic mitochondrial disorder [8]. This makes it the first FDA-approved medication specifically targeting mitochondria [9]. For other uses like general anti-aging or performance, it remains a research compound.

How long does it take to feel effects from SS-31?+

No trial has measured how quickly a healthy person feels anything, because no trial has enrolled healthy people. In patients, the blinded phases came back empty: the 4-week crossover in mitochondrial myopathy missed its walking endpoint [11], the 12-week Barth syndrome crossover missed both of its primary endpoints [6], and the 24-week phase 3 trial missed both of its own [13]. The gains that were reported came later and without a control arm — 6-minute walk distance improved cumulatively by 96.1 m over 168 weeks of open-label treatment in Barth syndrome [10]. Anyone promising an effect in two to four weeks is not quoting a trial.

Can I take SS-31 if I don't have a mitochondrial disease?+

SS-31's FDA approval is specifically for Barth syndrome, but research interest extends to general mitochondrial dysfunction associated with aging, heart failure, and other conditions [1][8]. For healthy individuals interested in mitochondrial optimization, it remains a research compound and should only be used under medical supervision.

Why is SS-31 injected rather than taken orally?+

As a peptide, SS-31 would be broken down by digestive enzymes if taken orally. Subcutaneous injection allows the full molecule to enter your bloodstream intact, achieving approximately 92% bioavailability [8]. The peptide then crosses cell membranes and concentrates specifically in mitochondria [3].

Does SS-31 have any effects on weight or body composition?+

SS-31 isn't a weight loss compound, but by improving mitochondrial function it could theoretically support better metabolism. Some research in cancer cachexia (muscle wasting) showed SS-31 helped preserve muscle mass by maintaining mitochondrial energy production [20]. However, it's not marketed or studied primarily for weight management.

Can SS-31 help with brain health and cognitive function?+

Research shows SS-31 has neuroprotective effects in models of spinal cord injury and neurodegeneration [5]. Your brain cells are packed with mitochondria and highly sensitive to energy deficits. By protecting brain mitochondria, SS-31 could theoretically support cognitive health, though more human studies are needed.

Is it safe to use SS-31 long-term?+

The longest published follow-up is 168 weeks: ten Barth syndrome patients entered an open-label extension on 40 mg daily and eight reached week 168, with injection-site reactions the most common adverse event throughout [10]. The 24-week phase 3 trial in 218 adults found serious adverse events in 4.6% on elamipretide against 2.8% on placebo, none treatment-related, and no deaths or hospitalisations [13]. That record is from diagnosed patients under trial supervision. There is no long-term data in healthy people, and none in anyone over 65 — no elamipretide trial enrolled that age group [8].

09 · Further reading

History & related research

History · since 2004

The Accidental Discovery That Rescued Dying Mitochondria

Born from a failed painkiller experiment, SS-31 became the world's first FDA-approved drug to target mitochondria — but only after surviving stock crashes, trial failures, and a company on the brink of collapse.

Read the full history of SS-31 (Elamipretide)

Studied for

Lyme Disease Fatigue

Peptide Database

Scientific & efficacy data

How much do I take?

Is this right for me?

How do I use it?

Is it safe?

How do I know it's working?

Tested in people

Frequently asked

History & related research