SS-31 (Elamipretide): A Literature Course in Six Modules

This page is for educational purposes only and is not medical advice; consult a licensed physician about any health decision. Nothing here is a protocol, a recommendation or a suggestion to use any compound. The course below summarises what researchers published about SS-31 (elamipretide), in the words and limits of the studies themselves.

How this course is organised

Six modules move from definition to mechanism, then to reported outcomes, adverse events, pharmacokinetics and regulatory status. Each module ends with a short limits of the evidence note, because most of what is known about SS-31 comes from preclinical models and a small number of rare-disease trials rather than from large, long-duration human studies in general populations.

Module 1 — What SS-31 is and how it has been studied

SS-31 is a synthetic peptide that appears in the literature under more than one name: preclinical papers generally use SS-31, while clinical and regulatory papers use the international nonproprietary name elamipretide. A 2025 review in International Journal of Molecular Sciences described elamipretide as a small, water-soluble aromatic-cationic tetrapeptide whose structure allows it to cross cell membranes and concentrate in mitochondria (PMID 39940712). A 2025 review in Biomedicine & Pharmacotherapy similarly characterised elamipretide as a mitochondria-targeted peptide investigated across a range of disease models (PMID 40294492).

Class and origin

The compound belongs to the class of cell-permeable, mitochondria-targeting peptides; reviews describe its alternating aromatic and cationic residue design as the structural feature responsible for that targeting (PMID 39940712). Reviews in Heart Failure Reviews placed the peptide within the broader research effort to address mitochondrial dysfunction in cardiac and skeletal muscle disease (PMID 35037146).

Forms used in published work

• Human trials: a randomised trial in primary mitochondrial myopathy and a long-term open-label extension in Barth syndrome both administered elamipretide by daily subcutaneous injection (PMID 37268435, PMID 38602181).
• Animal work: a 2019 mouse study of lipopolysaccharide-induced impairment used systemic administration of elamipretide (PMID 31747905), and a 2026 study used SS-31 in a post-cardiac-arrest brain injury model (PMID 41136322).
• Cell work: studies applied SS-31 directly to cultured cells, including aged bone marrow stromal cells (PMID 40570323) and cell lines used for target identification (PMID 38530359).

Limits of the evidence: the verified literature describes what SS-31 is chemically and where it has been tested, but it does not characterise material sold outside of regulated manufacturing, nor the purity, stability or identity of research-labelled powders. Findings from a defined clinical formulation cannot be assumed to transfer to other material.

Module 2 — Mechanism as described in the literature

The mechanistic account that recurs most often centres on the inner mitochondrial membrane. Reviews described elamipretide as associating with cardiolipin, a phospholipid of the inner membrane, and as influencing cristae structure and the efficiency of the electron transport chain (PMID 39940712, PMID 40294492).

Interaction mapping

A 2020 PNAS study set out to define the mitochondrial protein interaction landscape of SS-31 and reported that the peptide interacts with multiple inner-membrane proteins rather than a single binding partner (PMID 32554501). Researchers in that work used chemical interaction-mapping methods in isolated mitochondria, which is a biochemical readout rather than a physiological one (PMID 32554501).

A genetically identified target

A 2024 study in JASN used a genome-wide CRISPR screen and identified phospholipid scramblase 3 (PLSCR3) as a biological target through which the mitoprotective activity of SS-31 was mediated in the models tested (PMID 38530359). That finding is notable because unbiased genetic screens generate hypotheses that do not depend on a pre-chosen candidate protein (PMID 38530359).

Downstream pathways reported in specific models

Beyond membrane biophysics, individual papers reported model-specific pathways: a 2026 study attributed improvement of post-cardiac-arrest brain injury to inhibition of microglial ferroptosis and altered microglial polarisation (PMID 41136322), while a 2025 cell study reported that SS-31 targeted NOS2 while restoring mitochondrial function in aged bone marrow stromal cells (PMID 40570323).

Limits of the evidence: mechanism papers describe what the peptide does to mitochondria in controlled systems. They do not establish that the same mechanism operates at the same magnitude in an intact human, and the existence of several proposed interaction partners means the literature has not converged on a single settled mechanism.

Module 3 — Reported outcomes, study by study

The table summarises models, endpoints and the direction of results as the papers described them. No entry should be read as a promise of benefit; several of the human results were negative on their primary endpoints.

Cardiac literature

Two reviews in Heart Failure Reviews surveyed the cardiac research programme: one examined the rationale for targeting mitochondrial dysfunction with elamipretide in heart failure (PMID 35037146), and the other discussed elamipretide in Barth syndrome cardiomyopathy as a gradual process of restoring mitochondrial energetics (PMID 34623544).

Limits of the evidence: the strongest positive signals come from small, rare-disease cohorts and open-label designs without concurrent control groups, while the largest randomised trial in the verified set reported a negative primary result (PMID 37268435). Animal and cell findings describe biology, not clinical outcomes, and none of the verified studies enrolled healthy volunteers seeking performance, cognitive or anti-ageing endpoints.

Module 4 — SS-31 Side Effects: What Studies Report

Adverse events in the verified literature come mainly from two human studies and from review summaries. The randomised MMPOWER-3 trial in primary mitochondrial myopathy reported on both efficacy and safety of elamipretide given by daily subcutaneous injection over its treatment period (PMID 37268435). The 168-week open-label extension of TAZPOWER likewise reported long-term safety data in patients with Barth syndrome receiving daily subcutaneous dosing (PMID 38602181).

Injection-site reactions

Across the subcutaneous clinical programme, injection-site reactions were the adverse events described most consistently, and the long-term Barth syndrome extension reported them during extended daily dosing (PMID 38602181). The MMPOWER-3 report also documented tolerability findings for subcutaneous administration alongside its efficacy analysis (PMID 37268435).

How reviews summarised safety

The 2025 IJMS review, covering structure, mechanism and therapeutic potential, summarised the clinical programme including its safety experience (PMID 39940712), and the 2025 Biomedicine & Pharmacotherapy review similarly discussed therapeutic effects and the tolerability context of the trials (PMID 40294492). A 2026 regulatory review of the first approval described the evidence package on which authorisation rested, which includes safety data (PMID 41335372).

Limits of the evidence: safety datasets for elamipretide are small and concentrated in rare mitochondrial diseases; the verified studies did not evaluate long-term safety in healthy adults, in pregnancy, in children outside the trial populations, or in combination with other compounds. Rare adverse events cannot be detected reliably in cohorts of this size, and animal safety data do not transfer directly to humans.

Module 5 — Pharmacokinetics where data exist

The verified papers contain limited formal pharmacokinetic reporting. What they do establish is the route used in humans: both the randomised myopathy trial and the Barth syndrome extension administered elamipretide subcutaneously once daily rather than orally (PMID 37268435, PMID 38602181). Reviews attribute this to the peptide's nature and describe cell entry and mitochondrial accumulation as properties of its aromatic-cationic structure (PMID 39940712).

Distribution at the subcellular level

At the level of where the molecule ends up inside a cell, reviews described concentration of elamipretide at the inner mitochondrial membrane in association with cardiolipin (PMID 40294492), and interaction studies in isolated mitochondria are consistent with binding at that membrane (PMID 32554501). Subcellular localisation, however, is not the same as plasma pharmacokinetics.

Limits of the evidence: none of the verified papers is a dedicated human pharmacokinetic study, so half-life, bioavailability by non-injected routes, metabolism and elimination are not characterised here. Where a number is not in the verified record, this course omits it rather than estimating it.

Module 6 — Regulatory status, stated factually

A 2026 article in Drugs in the journal's "First Approval" series documented that elamipretide received its first regulatory approval, with Barth syndrome as the authorised indication (PMID 41335372). That approval followed the clinical programme in Barth syndrome that included the TAZPOWER open-label extension (PMID 38602181).

What approval does and does not cover

• An approval applies to a specific product, indication and population defined in its labelling; the verified regulatory review describes elamipretide's authorisation in the context of Barth syndrome (PMID 41335372).
• Other indications remain investigational. The randomised trial in primary mitochondrial myopathy did not meet its primary endpoints, and that population is not an approved use on the basis of that trial (PMID 37268435).
• Material labelled "research use only" is not a medicine. RUO labelling indicates the product was not manufactured, tested or released to pharmaceutical standards and is not intended for human or veterinary use.
• Compounded preparations are governed by separate regulatory pathways; in the United States, compounding is restricted by the categories and bulk-substance lists that federal law defines, and eligibility can change over time.

This is general regulatory information, not legal advice. Rules differ between jurisdictions and are revised; a licensed professional is the appropriate source for any specific situation.

Limits of the evidence: regulatory status describes what a health authority concluded about a specific product dossier. It says nothing about unapproved sources, and approval in one indication is not evidence for any other.

What the studies did not test

Reading the verified record as a whole, several gaps stand out:

1. Healthy adults. The human studies enrolled people with primary mitochondrial myopathy or Barth syndrome (PMID 37268435, PMID 38602181), not healthy volunteers.
2. General ageing, cognition or performance outcomes in humans. Cognitive and cellular-ageing findings in the verified set came from mice and cultured cells (PMID 31747905, PMID 40570323).
3. Routes other than subcutaneous injection in humans. The verified trials used subcutaneous administration (PMID 38602181).
4. Combination use. No verified study tested SS-31 alongside other peptides or supplements.
5. Head-to-head comparisons. The reviews summarised elamipretide's own programme rather than comparing it with other mitochondrial interventions (PMID 35037146, PMID 40294492).

Where the literature is silent, this course stays silent. Readers with clinical questions should raise them with a licensed physician.

References

• Elamipretide (SS-31) improves mitochondrial dysfunction, synaptic and memory impairment induced by lipopolysaccharide in mice (Journal of Neuroinflammation, 2019)
• Mitochondrial protein interaction landscape of SS-31 (PNAS, 2020)
• Elamipretide for Barth syndrome cardiomyopathy: gradual rebuilding of a failed power grid (Heart Failure Reviews, 2022)
• Targeting mitochondrial dysfunction with elamipretide (Heart Failure Reviews, 2022)
• Efficacy and Safety of Elamipretide in Individuals With Primary Mitochondrial Myopathy: The MMPOWER-3 Randomized Clinical Trial (Neurology, 2023)
• Genome-Wide CRISPR Screen Identifies Phospholipid Scramblase 3 as the Biological Target of Mitoprotective Drug SS-31 (JASN, 2024)
• Long-term efficacy and safety of elamipretide in patients with Barth syndrome: 168-week open-label extension results of TAZPOWER (Genetics in Medicine, 2024)
• Elamipretide: A Review of Its Structure, Mechanism of Action, and Therapeutic Potential (International Journal of Molecular Sciences, 2025)
• Contemporary insights into elamipretide's mitochondrial mechanism of action and therapeutic effects (Biomedicine & Pharmacotherapy, 2025)
• SS-31 Targets NOS2 to Enhance Osteogenic Differentiation in Aged BMSCs by Restoring Mitochondrial Function (Organogenesis, 2025)
• SS-31 improves post-cardiac arrest brain injury by inhibiting microglial ferroptosis and polarization (Neurotherapeutics, 2026)
• Elamipretide: First Approval (Drugs, 2026)