SS-31
Evidence: B/C — Meaningful Human EvidenceMitochondrial / Cellular Aging
Evidence Snapshot
Regulatory Context
FDA granted accelerated approval to Forzinity (elamipretide) in September 2025 for Barth syndrome patients weighing at least 30 kg only; this narrow, intermediate-endpoint-based approval does not extend to broader mitochondrial, anti-aging, exercise, cardiac, renal, neurologic, or ophthalmic uses.
Research Takeaway
Peer-reviewed literature explicitly identifies the mitochondria-targeted tetrapeptide SS-31 as elamipretide.
See all 13 evidence claims →Quick Summary
Elamipretide, also known by the development codes SS-31 and MTP-131, is a mitochondria-targeting tetrapeptide that binds cardiolipin in the inner mitochondrial membrane. In September 2025, FDA granted accelerated approval to the finished product Forzinity (elamipretide) for a narrow indication: improving muscle strength in adult and pediatric patients with genetically confirmed Barth syndrome weighing at least 30 kg, based on an intermediate endpoint. This approval does not extend to broader mitochondrial, anti-aging, exercise, cardiac, renal, neurologic, or ophthalmic uses.
Mechanism & Research Overview
Elamipretide, also known by the development codes SS-31 and MTP-131, is a mitochondria-targeting tetrapeptide that binds cardiolipin in the inner mitochondrial membrane. In September 2025, FDA granted accelerated approval to the finished product Forzinity (elamipretide) for a narrow indication: improving muscle strength in adult and pediatric patients with genetically confirmed Barth syndrome weighing at least 30 kg, based on an intermediate endpoint. This approval does not extend to broader mitochondrial, anti-aging, exercise, cardiac, renal, neurologic, or ophthalmic uses.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
Peer-reviewed literature explicitly identifies the mitochondria-targeted tetrapeptide SS-31 as elamipretide.
Supported
FDA granted accelerated approval to FORZINITY (elamipretide) in September 2025 to improve muscle strength in adult and pediatric patients with Barth syndrome weighing at least 30 kg.
Sources: FDA Accelerated Approval Announcement — First Treatment for Barth Syndrome; Forzinity Prescribing Information
Supported
FDA approval of FORZINITY for Barth syndrome does not establish efficacy of SS-31/elamipretide for general mitochondrial wellness, anti-aging, exercise enhancement, heart failure, kidney disease, neurodegeneration, or other unapproved uses.
Sources: Forzinity Prescribing Information; FDA Accelerated Approval Announcement — First Treatment for Barth Syndrome
Supported
In the randomized crossover portion of TAZPOWER, elamipretide did not demonstrate superiority over placebo on the trial's two primary endpoints of 6-minute walk distance and Barth Syndrome Symptom Assessment fatigue.
Sources: Barth Syndrome Phase 2/3 and Extension; 168-week Barth Extension; FDA Accelerated Approval Announcement — First Treatment for Barth Syndrome
Supported
MMPOWER-3 provided Class I evidence that elamipretide did not improve six-minute walk distance or fatigue at 24 weeks versus placebo in the broad primary mitochondrial myopathy population. A post hoc genetic-subgroup analysis suggested a possible signal in selected mtDNA maintenance/replisome disorders, but this finding is hypothesis-generating and requires prospective confirmation.
Supported
No evidence in the cited trials or labeling supports an anti-aging, longevity, or exercise-performance benefit for elamipretide/SS-31.
Sources: Forzinity Prescribing Information; The MMPOWER-3 Randomized Clinical Trial
Supported
Current Forzinity labeling identifies injection-site reactions as the most common adverse reaction, serious hypersensitivity as a contraindication, benzyl-alcohol toxicity risk (not approved for neonates), eosinophil elevations during longer exposure, and limited pregnancy, lactation, geriatric, dialysis, and lower-weight pediatric data. In the small Barth crossover study, local administration reactions occurred in 100% of elamipretide-treated patients versus 67% on placebo.
Sources: Forzinity Prescribing Information; Barth Syndrome Phase 2/3 and Extension
Supported
TAZPOWER studied a source-specific clinical regimen of elamipretide in genetically confirmed Barth syndrome; any dosing information from that protocol must remain labeled as study context.
Supported
The TAZPOWER protocol explicitly identifies the investigational product as elamipretide (MTP-131), establishing MTP-131 as a development name for elamipretide.
Supported
FORZINITY contains elamipretide as a hydrochloride salt; the labeled peptide sequence is D-Arg-2,6-dimethyl-Tyr-Lys-Phe-NH2.
Sources: Forzinity Prescribing Information
Supported
FDA labeling describes elamipretide as a mitochondrial cardiolipin binder that localizes to the inner mitochondrial membrane.
Sources: Forzinity Prescribing Information
Supported
The 168-week open-label TAZPOWER extension reported sustained tolerability and improvements in several functional and cardiac measures in a very small cohort.
Sources: 168-week Barth Extension
Supported
FORZINITY was approved through the accelerated approval pathway and continued approval depends on verification and description of clinical benefit in required confirmatory study work.
Sources: NDA 215244 FORZINITY (elamipretide) Approval Letter
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Safety Consideration
Not broadly approved as a general anti-aging or mitochondrial wellness product.Safety Consideration
Clinical results can be disease-specific and may not generalize to healthy users.Safety Consideration
Injection-site reactions and tolerability issues may occur depending on route/formulation context.Safety Consideration
Long-term use outside trial settings is not well established.Safety Consideration
Unapproved product sourcing creates identity, sterility, and purity risks.Safety Consideration
Labeled adverse reactions include injection-site reactions (most common), serious hypersensitivity (contraindication), benzyl-alcohol toxicity risk (not approved for neonates), and eosinophil elevations during longer exposure; pregnancy, lactation, geriatric, dialysis, and lower-weight pediatric data are limited.Safety Consideration
In the pivotal Barth syndrome crossover study, local administration reactions occurred in 100% of elamipretide-treated patients vs 67% on placebo, including injection-site erythema (100% vs 25%) and injection-site pain (75% vs 42%); long-term safety outside the approved population is not established.
Research Areas Being Studied
Research areas discussed on this page reflect the Mitochondrial / Cellular Aging category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- The MMPOWER-3 Randomized Clinical Trial (2023):
- 168-week Barth Extension ():
- Barth Syndrome Phase 2/3 and Extension ():
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| The MMPOWER-3 Randomized Clinical Trial | 2023 | Broad primary mitochondrial myopathy population (randomized, placebo-controlled) | Class I evidence that elamipretide did not improve six-minute walk distance or fatigue at 24 weeks versus placebo in the broad primary mitochondrial myopathy population. A post hoc genetic-subgroup analysis suggested a possible signal in selected mtDNA maintenance/replisome disorders, but this is hypothesis-generating and requires prospective confirmation.
| ||
| 168-week Barth Extension | 168-week open-label extension in Barth syndrome. Accelerated approval relied on descriptive improvement in knee-extensor muscle strength observed during this extension, not a positive randomized primary endpoint.
| ||||
| Barth Syndrome Phase 2/3 and Extension | 12 male patients aged 12 to 35 years, genetically confirmed Barth syndrome | Pivotal randomized crossover phase in Barth syndrome did not show superiority over placebo for six-minute walk distance or Barth Syndrome Symptom Assessment fatigue score. Local administration reactions: any reaction 100% (elamipretide) vs 67% (placebo); injection-site erythema 100% vs 25%; injection-site pain 75% vs 42%.
|
Animal / Cell / Preclinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| SS-31 ADP sensitivity in aged mitochondria | 2023 | Preclinical/physiology | Aged mitochondria — Improved ADP sensitivity through mitochondrial mechanisms. | Preclinical only; animal/cell findings do not establish human safety or efficacy. | |
| SS-31 mitochondrial interaction landscape | 2020 | Mechanistic study | Mitochondrial proteins/cardiolipin — Maps mitochondrial interactions and clinical trial context. | Preclinical only; animal/cell findings do not establish human safety or efficacy. | |
| The mitochondria-targeted peptide SS-31 binds lipid bilayers and modulates surface electrostatics as a key component of its mechanism of action | 2020 | The peer-reviewed study explicitly identifies SS-31 as elamipretide and examines its interaction with mitochondrial-membrane lipid bilayers, supporting the SS-31 ↔ elamipretide identity bridge. | |||
| SS-31 and aged muscle mitochondrial function | 2019 | Preclinical/physiology | Aging muscle — Improved mitochondrial quality and exercise tolerance in model. | Preclinical only; animal/cell findings do not establish human safety or efficacy. |
Regulatory Documents & Official Trial Registries
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| FDA Accelerated Approval Announcement — First Treatment for Barth Syndrome | 2025 | FDA press announcement, September 2025: accelerated approval of Forzinity (elamipretide) as the first treatment for Barth syndrome, based on an intermediate endpoint (knee-extensor muscle strength improvement). | |||
| Forzinity Prescribing Information | 2025 | FDA-approved prescribing information for Forzinity (elamipretide), revised 09/2025. Labeled indication: improve muscle strength in adult and pediatric patients with genetically confirmed Barth syndrome weighing at least 30 kg. Approval based on improvement in knee-extensor muscle strength (an intermediate endpoint); continued approval may depend on verification of clinical benefit in a confirmatory trial.
| Labeled adverse reactions: injection-site reactions (most common); serious hypersensitivity (contraindication); benzyl-alcohol toxicity risk (not approved for neonates); eosinophil elevations during longer exposure. Limited pregnancy, lactation, geriatric, dialysis, and lower-weight pediatric data. | ||
| NDA 215244 FORZINITY (elamipretide) Approval Letter | 2025 | FDA approved FORZINITY under accelerated approval and required confirmatory evidence to verify and describe the predicted clinical benefit. | |||
| SPIBA-201 Protocol: A Phase 2 Randomized, Double-Blind, Placebo-Controlled Crossover Trial of Elamipretide (MTP-131) in Barth Syndrome | 2021 | The protocol explicitly identifies the investigational product as 'Elamipretide (MTP-131)', establishing the development-name identity bridge and the study-specific regimen. |
Review Articles / Secondary Sources
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Elamipretide review | 2025 | Review | Structure/mechanism/action — Summarizes cardiolipin stabilization and mitochondrial effects. | Secondary source; useful for context but not a substitute for primary study review. | |
| Novel mitochondrial-targeted peptide review | 2024 | Review | Clinical/preclinical therapeutic potential — Reviews broad SS-31/elamipretide research. | Secondary source; useful for context but not a substitute for primary study review. |
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
This page keeps SS-31 content tied to its specific disease and evidence context and does not generalize early clinical-development data into broad wellness claims.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Website/CMS content draft; source verification and legal/privacy review required before public launch. Last updated 2026-07-08.
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